Sunday, August 3, 2014

When Good Meteor Showers Go Bad: Prospects for the 2014 Perseids

When Good Meteor Showers Go Bad: Prospects for the 2014 Perseids:



A 2013 Perseid. Credit:

A brilliant capture of a 2013 Perseid fireball. Credit: Fred Locklear.
It’s that time of year again, when the most famous of all meteor showers puts on its best display.

Why are the Perseids such an all ‘round favorite of sky watchers?  Well, while it’s true that other annual meteor showers such as the Quadrantids and Geminids can exceed the Perseids in maximum output, the Perseids do have a few key things going for them. First, the shower happens in mid-August, which finds many northern hemisphere residents camping out under warm, dark skies prior to the start of the new school year. And second, unlike showers such as the elusive Quads which peak over just a few hours, the Perseids enjoy a broad span of enhanced activity, often covering a week or more.

Credit: JPL

The orientation of the orbital path of Comet 109P/Swift-Tuttle and the position of the Earth on August 12th. Credit: JPL-Horizons.
These are all good reasons to start watching for Perseids now. Here’s the low down on the Perseid meteors for 2014:

The History: The Perseids are sometimes referred to as “The Tears of Saint Lawrence,” who was martyred right around the same date on August 10th, 258 A.D. The source of the shower is comet 109P Swift-Tuttle, which  was first identified as such by Schiaparelli in 1866. The comet itself visited the inner solar system again recently in 1992 on its 120 year orbit about the Sun, and rates were enhanced throughout the 1990s.

A 2013 Perseid pierces the plane of the Milky Way.

A 2013 Perseid pierces the plane of the Milky Way. Credit: Stephen Rahn.
Unlike most showers, the Perseids have a very broad peak, and observers and automated networks such as UKMON and NASA’s All Sky Camera sites have already begun to catch activity starting in late July.

Credit: The UK-MON network.

A pair of early 2014 Perseids recently captured by UKMON’s Wilcot station. Credit: The UK-MON network.
In recent years, the rates for the Perseids have been lowering a bit but are still enhanced, with ZHRs at 91(2010), 58(2011), 122(2012), and 109(2013). It’s also worth noting that the Perseids typically exhibit a twin peak maximum within a 24 hour span. The International Meteor Organization maintains an excellent page for quick look data to check out what observers worldwide are currently seeing. The IMO also encourages observers worldwide to submit meteor counts by location. Note that the phase of the Moon was near Full in 2011, with observing circumstances very similar to 2014.

The Prospects for 2014: Unfortunately, the 2014 Perseid meteors have a major strike going against them this year: the Moon will be at waning gibbous during its peak and just two days past Full illumination. This will make for short exposure times and light polluted skies. There are, however, some observational strategies that you can use to combat this: one is to place a large building or hill between yourself and the Moon while you observe — another is to start your morning vigil a few days early, before the Moon reaches Full. The expected Zenithal Hourly Rate for 2014 is predicted to hover around 90 and arrive around 00:15 to 2:00 UT on August 13th favoring Europe, Africa and the Middle East.

Created by Author

The orientation of Earth’s shadow during the projected peak of the Perseids on August 13th at 00:15 Universal Time.  The positions where the Sun, Moon, and radiant of the Perseids are directly overhead are also noted. Created by Author.
The Radiant: It’s strange but true: meteor shower radiants wander slightly across the sky during weeks surrounding peak activity, due mostly to the motion of the Earth around the Sun. Because of this, the radiant of the Perseids is not actually in the constellation Perseus on the date that it peaks! At its maximum, the radiant actually sits juuusst north of the constellation that it’s named for on the border of Camelopardalis and Cassiopeia. This is a great pedantic point to bring up with your friends on your August meteor vigil… they’ll sure be glad that you pointed this out to ‘em and hopefully, invite you back for next year’s Perseid watch.

The actual position of the radiant sits at 3 Hours 04’ Right Ascension and +58 degrees north declination.

Credit: Starry Night Education software.

The movement of the radiant of the Perseids. The sky is simulated for latitude 30 degrees north at 2:00 AM local on August 13th. Credit: Starry Night Education software.
Meteor-speak: Don’t know your antihelion from a zenithal hourly rate? We wrote a whole glossary that’ll have you talking meteors like a pro for Adrian West’s outstanding Meteorwatch site a few years back. Just remember, the crucial “ZHR” of a shower that is often quoted is an ideal extrapolated rate… light pollution, the true position of the radiant, observer fatigue and limited field of view all conspire to cause you to see less than this predicted maximum. The universe and its meteor showers are indeed a harsh mistress!

Observing: But don’t let this put you off. As Wayne Gretsky said, “You miss 100% of the shots that you don’t take,” and the same is true with meteor observing: you’re sure to see exactly zero if you don’t observe at all. Some of my most memorable fireball sightings over the years have been Perseids. And remember, the best time to watch for meteors is after local midnight, as the Earth is turned forward into the meteor stream. Remember, the car windshield (Earth) gets the bugs (meteors) moving down the summer highway…

Good luck, and let us know of those tales of Perseid hunting and send those meteor pics in to Universe Today!

Tagged as:
2014 perseids,
meteor observing,
perseid meteor shower,
perseid meteors,
perseid prospects,
swift-tuttle
Posted by Nelio Inacio at 7:20 PM 0 comments

Observing Alert – Delta Aquarid Meteor Shower Peaks Tonight

Observing Alert – Delta Aquarid Meteor Shower Peaks Tonight:



Watch for the southern Delta Aquarid meteor shower to peak over the next two mornings July 29-30. Credit: John Chumack

Watch for the southern Delta Aquarid meteor shower to peak over the next two mornings July 29-30. The best time for viewing for northern observers will be the hour before the start of dawn. Credit: John Chumack
With the southern Delta Aquarid meteor shower peaking tomorrow morning, the summer meteor-watching season officially begins. While not a rich shower from mid-northern latitudes, pleasant weather and a chance to see the flaming remains of a comet seem motivation enough to go out for a look. With a rate 10-15 per meteors an hour you’re bound to catch a few.

The farther south you live, the better it gets. Observers in the southern hemisphere can expect double that number because the shower’s radiant will be much higher in the sky. Any meteors flashing south of the radiant won’t get cut off by the southern horizon like they do further north.

The annual shower gets its name from Delta Aquarii, a dim star in the dim zodiac constellation Aquarius. You don’t need to know the constellations to enjoy the show, but if you know the general direction of the radiant you’ll be able to tell shower members from the nightly sprinkle of random meteors called sporadics. If you can trace the path of a meteor backward toward Aquarius, chances are it’s an Aquarid.



A Southern Delta Aquarid meteor captured on July 30, 2013. Credit: John Chumack
There are actually two meteor showers in Aquarius active this time of year – the northern and southern Delta Aquarids. The northern version sprinkles fewer meteors and peaks in mid-August.

The Southern Deltas peak over the next two mornings – July 29 and 30 – but will be out all week. Both serve as a warm-up for the upcoming Perseid meteor shower that climaxes on August 12.

Tonight’s shower will suffer no interference from moonlight, making for ideal meteor watching. Unfortunately, Perseid rates will be reduced by a bright waning gibbous moon.

Don’t be surprised if you see a few Perseids anyway. The shower’s just becoming active. If you can draw a meteor’s trail back to the northeastern sky, it just might be a member. Read more about Perseid prospects from our own David Dickinson.

Meteors from Delta Aquarid meteor shower radiate from near the star Delta Aquarii not far from the bright star Fomalhaut in the Southern Fish low in the south before dawn. Stellarium

Meteors from Delta Aquarid meteor shower radiate from near the star Delta Aquarii not far from the bright star Fomalhaut in the Southern Fish low in the south before dawn. Stellarium
Nearly all meteor showers originate from clouds of sand to seed-sized bits of debris spewed by vaporizing comet ice as they swing near the sun. The Delta Aquarids may trace its origin to dust boiled off Comet 96P/Machholz.

The best time to watch the shower is in the early morning hours before dawn when the radiant rises in the south-southeastern sky above the bright star Fomalhaut. Try to get away from city lights. Point your lawn chair south and spend some time in heavenly contemplation as you wait for Aquarius to toss a few javelins of light your way.

Tagged as:
96P/Machholz,
comet,
Delta Aquarid,
meteor shower,
radiant
Posted by Nelio Inacio at 7:19 PM 0 comments

X-ray Glow: Evidence of a Local Hot Bubble Carved by a Supernova

X-ray Glow: Evidence of a Local Hot Bubble Carved by a Supernova:



An artist's conception of the hot local bubble. Image Credit: NASA

An artist’s conception of the hot local bubble. Image Credit: NASA
I spent this past weekend backpacking in Rocky Mountain National Park, where although the snow-swept peaks and the dangerously close wildlife were staggering, the night sky stood in triumph. Without a fire, the stars, a few planets, and the surprisingly bright Milky Way provided the only light to guide our way.

But the night sky as seen by the human eye is relatively dark. Little visible light stretching across the cosmos from stars, nebulae, and galaxies actually reaches Earth. The entire night sky as seen by an X-ray detector, however, glows faintly.

The origins of the soft X-ray glow permeating the sky have been highly debated for the past 50 years. But new findings show that it comes from both inside and outside the Solar System.

Decades of mapping the sky in X-rays with energies around 250 electron volts — about 100 times the energy of visible light — revealed soft emission across the sky. And astronomers have long searched for its source.

At first, astronomers proposed a “local hot bubble” of gas — likely carved by a nearby supernova explosion during the past 20 million years — to explain the X-ray background. Improved measurements made it increasingly clear that the Sun resides in a region where interstellar gas is unusually sparse.

But the local bubble explanation was challenged when astronomers realized that comets were an unexpected source of soft X-rays. In fact, this process, known as solar wind charge exchange, can occur anywhere atoms interact with solar wind ions.

After this discovery, astronomers turned their eyes to within the Solar System and began to wonder whether the X-ray background might be produced by the ionized particles in the solar wind colliding with diffuse interplanetary gas.

In order to solve the outstanding mystery, a team of astronomers led by Massimilliano Galeazzi from the University of Miami developed an X-ray instrument capable of taking the necessary measurements.

Galeazzi and colleagues rebuilt, tested, calibrated, and adapted X-ray detectors originally designed by the University of Wisconsin and flown on sounding rockets in the 1970s. The mission was named DXL, for Diffuse X-ray emission from the Local Galaxy.

On Dec. 12, 2012, DXL launched from the White Sands Missile Range in New Mexico atop a NASA Black Brant IX sounding rocket. It reached a peak altitude of 160 miles and spent a total of five minutes above Earth’s atmosphere.

The data collected show that the emission is dominated by the local hot bubble, with, at most, 40 percent originating from within the Solar System.

“This is a significant discovery,” said lead author Massimiliano Galeazzi from the University of Miami in a press release. “Specifically, the existence or nonexistence of the local bubble affects our understanding of the galaxy in the proximity to the Sun and can be used as foundation for future models of the Galaxy structure.”

It’s now clear that the Solar System is currently passing through a small cloud of cold interstellar gas as it moves through the Milky Way.

Colors indicate the density of interstellar helium near Earth and its enhancement in a downstream cone as the neutral atoms respond to the sun's gravity (blue is low density, red is high). Also shown are the observing angles for DXL and ROSAT. Image Credit: NASA's Goddard Space Flight Center

Colors indicate the density of interstellar helium near Earth and its enhancement in a downstream cone as the neutral atoms respond to the sun’s gravity (blue is low density, red is high). Also shown are the observing angles for DXL and ROSAT. Image Credit: NASA’s Goddard Space Flight Center
The cloud’s neutral hydrogen and helium atoms stream through the Solar System at about 56,000 mph (90,000 km/h). The hydrogen atoms quickly ionize, but the helium atoms travel at a path largely governed by the Sun’s gravity. This creates a helium focusing cone — a breeze focused downstream from the Sun — with a much greater density of neutral atoms. These easily collide with solar wind ions and emit soft X-rays.

The confirmation of the local hot bubble is a significant development in our understanding of the interstellar medium, which is crucial for understanding star formation and galaxy evolution.

“The DXL team is an extraordinary example of cross-disciplinary science, bringing together astrophysicists, planetary scientists, and heliophysicists,” said coauthor F. Scott Porter from NASA’s Goddard Space Flight Center. “It’s unusual but very rewarding when scientists with such diverse interests come together to produce such groundbreaking results.”

The paper has been published in Nature.

Tagged as:
Local Hot Bubble,
Soft X-ray Emission,
Solar System
Posted by Nelio Inacio at 7:18 PM 0 comments

ALMA Observes Binary Star System with Wacky Disks

ALMA Observes Binary Star System with Wacky Disks:



ALMA data of HK Tau shown in a composite image with Hubble infrared and optical data. Credit: B. Saxton (NRAO/AUI/NSF); K. Stapelfeldt et al. (NASA/ESA Hubble)

ALMA data of HK Tau shown in a composite image with Hubble infrared and optical data. Image Credit: B. Saxton / K. Stapelfeldt et al. / NASA / ESA
When it comes to exoplanets, we’ve discovered an array of extremes — alien worlds that seem more like science fiction than reality. But there are few environments more extreme than a binary star system in which planet formation can occur. Powerful gravitational perturbations from the two stars can easily grind a planet to dust, let alone prevent it from forming in the first place.

A new study has uncovered a striking pair of wildly misaligned planet-forming disks in the young binary star system HK Tau. It’s the clearest picture ever of protoplanetary disks around a double star, shedding light on the birth and eventual orbit of the planets in a multiple star system.

The “Atacama Large Millimeter/submillimeter Array (ALMA) has given us an unprecedented view of a main star and its binary companion sporting mutually misaligned protoplanetary disks,” said Eric Jensen from Swarthmore College in a press release. “In fact, we may be seeing the formation of a solar system that may never settle down.”

The two stars in the system — located roughly 450 light-years away in the constellation Taurus — are less than four million years old and are separated by about 58 billion kilometers, or 13 times the distance of Neptune from the Sun.

ALMA’s high sensitivity and unprecedented resolution allowed Jensen and colleagues to fully resolve the rotation of HK Tau’s two protoplanetary disks.

“It’s easier to observe spread-out gas and dust because it has more surface area – just in the same way that it might be hard to see a small piece of chalk from a distance, but if you ground up the chalk and dispersed the cloud of chalk dust, you could see it from farther away,” Jensen told Universe Today.

The key velocity data taken with ALMA that helped the astronomers determine that the disks in HK Tau were misaligned. The red areas represent material moving away from Earth and the blue indicates material moving toward us. Credit: NASA/JPL-Caltech/R. Hurt (IPAC)

The key velocity data taken with ALMA. The red areas represent material moving away from Earth and the blue indicates material moving toward us. Image Credit: NASA / JPL-Caltech / R. Hurt (IPAC)
The carbon monoxide gas orbits both stars in two broad belts that are clearly rotating — the side spinning away from us is redshifted, while the side spinning toward us is blueshifted.

“What we find in this binary system is that the two orbiting disks are oriented very differently from each other, with about a 60 or 70 degree angle between their orbital planes,” Jensen told Universe Today. Because the disks are so misaligned it’s clear that at least one is also out of sync with the orbit of their host stars.

“This clear misalignment has given us a remarkable look at a young binary star system,” said coauthor Rachel Akeson from the NASA Exoplanet Science Institute at the California Institute of Technology. “Though there have been hints before that this type of misaligned system exists, this is the cleanest and most striking example.”

Stars and planets form out of vast clouds of dust and gas. Small pockets in these clouds collapse under the pull of gravity. But as the pocket shrinks, it spins rapidly, with the outer region flattening into a turbulent disk. Eventually the central pocket becomes so hot and dense that it ignites nuclear fusion — in the birth of a star — while the outer disk — now the protoplanetary disk — begins to form planets.

Despite forming from a flat, regular disk, planets can end up in highly eccentric orbits, and may be misaligned with the star’s equator. One likely explanation is that a binary companion star influences them — but only if its orbit is initially misaligned with the planets.

“Because these disks are misaligned with the binary orbit, then so too will be the orbits of any planets they form,” Jensen told Universe Today. “So in the long run, the binary companion will influence those planet orbits, causing them to oscillate and tend to come more into line with the binary orbit, and at the same time become more eccentric.”

Looking forward, the researchers want to determine if this type of system is typical or not. If it is, then tidal forces from companion stars may easily explain the orbital properties that make the present sample of exoplanets so unlike the planets of our own Solar System.

The results will appear in Nature on July 31, 2014.

Tagged as:
ALMA,
protoplanetary disks
Posted by Nelio Inacio at 7:16 PM 0 comments

Mysterious Molecules in Space Named?

Mysterious Molecules in Space Named?:



The diffuse interstellar bands. Image Credit: P. Jenniskens, F. X. Desert

The diffuse interstellar bands. Image Credit: P. Jenniskens, F. X. Desert
It’s a well-kept secret that the vacuum of space is not — technically speaking — a vacuum. Strong winds generated from supernova explosions push material into the interstellar medium, tainting space with the heavier elements generated by nuclear fusion. These lonely molecules account for a significant amount of all the hydrogen, carbon, silicon, and other atoms in the Universe.

Although these molecules remain mysterious, since we don’t know their exact chemical composition or atomic arrangements, they’re likely the cause of diffuse interstellar bands: unknown fingerprints within the spectra of distant astronomical objects.

New research, however, offers a tantalizing new possibility: these mysterious molecules may be silicon hydrocarbons.

Researchers on Earth should be able to identify the interstellar molecules easily. They simply have to demonstrate which molecules in the laboratory absorb light at the same wavelengths as the diffuse interstellar bands. But despite decades of effort, the identity of the molecules has remained a mystery.

“Not a single one has been definitively assigned to a specific molecule,” said coauthor Neil Reilly from the Harvard-Smithsonian Center for Astrophysics in a press release.

Now, Michael McCarthy from the Harvard-Smithsonian Center for Astrophysics, Reilly, and their colleagues are pointing to an unusual set of molecules — silicon-terminated carbon chain radicals such as SiC3H, SiC4H and SC5H — as potential twins to those found in interstellar space.

The researchers, however, were unable to create every spectral absorption line (over 400) responsible for the diffuse interstellar bands. But they think that longer molecules in this silicon-containing hydrocarbon family might cause the lines.

Absorption wavelength as a function of the number of carbon atoms in the silicon-terminated carbon chains SiC_(2n+1)H, for the extremely strong pi-pi electronic transitions. When the chain contains 13 or more carbon atoms - not significantly longer than carbon chains already known to exist in space - these strong transitions overlap with the spectral region occupied by the elusive diffuse interstellar bands (DIBs). CREDIT: D. Kokkin, ASU

Absorption wavelength as a function of the number of carbon atoms in the silicon-terminated carbon chains SiC_(2n+1)H. When the chain contains 13 or more carbon atoms — not significantly longer than carbon chains already known to exist in space — these strong transitions overlap with the spectral region occupied by the elusive diffuse interstellar bands. Image Credit: D. Kokkin, ASU
So the group remains cautious. History shows that while many possibilities have been proposed as the source of diffuse interstellar bands, none have been proven definitely. And they certainly need to conduct further research before they can say with certainty they’ve identified the mysterious interstellar molecules.

“The interstellar medium is a fascinating environment,” said McCarthy. “Many of the things that are quite abundant there are really unknown on Earth.”

Tagged as:
Diffuse Interstellar Bands,
Interstellar Molecules
Posted by Nelio Inacio at 7:16 PM 0 comments

Early Tidal and Rotational Forces Helped Shape Moon

Early Tidal and Rotational Forces Helped Shape Moon:



Using a precision formation-flying technique, the twin GRAIL spacecraft will map the moon's gravity field, as depicted in this artist's rendering. Radio signals traveling between the two spacecraft provide scientists the exact measurements required as well as flow of information not interrupted when the spacecraft are at the lunar farside, not seen from Earth. The result should be the most accurate gravity map of the moon ever made. The mission also will answer longstanding questions about Earth's moon, including the size of a possible inner core, and it should provide scientists with a better understanding of how Earth and other rocky planets in the solar system formed. GRAIL is a part of NASA's Discovery Program. Image credit: NASA/JPL-Caltech

An artist’s conception of how the twin GRAIL spacecraft map the moon’s gravity field. Image credit: NASA / JPL-Caltech
The shape of the moon deviates from a simple sphere in a way that scientists have struggled to explain. But new research shows that tidal forces during the moon’s early history can explain most of its large-scale topography. As the moon cooled and solidified more than four billion years ago, the sculpting effects of tidal and rotational forces became frozen in place.

Astronomers think the moon formed when a rogue planet, larger than Mars, struck the Earth in a great, glancing blow. A cloud rose 13,700 miles (22,000 kilometers) above the Earth, where it condensed into innumerable solid particles that orbited the Earth. Over time these moonlets combined to form the moon.

So the moon was sculpted by Earth’s gravity from the get-go. Although scientists have long postulated that tidal forces helped shape the molten moon, the new study provides a much more detailed understanding of the additional forces at play.

Ian Garrick-Bethell from UCSC and colleagues studied topographic data gathered by NASA’s Lunar Reconnaissance Orbiter (LRO) and information about the moon’s gravity field collected by the agency’s twin GRAIL (Gravity Recovery and Interior Laboratory) spacecraft.

Not long after the moon’s formation, the crust was decoupled from the mantle below by an intervening ocean of magma. This caused immense tidal forces. At the poles, where the flexing and heating was greatest, the crust became thinner, while the thickest crust formed at the equators. Garrick-Bethel likened this to a lemon shape with the long axis of the lemon pointing at the Earth.

But this process does not explain why the bulge is now only found on the far side of the moon. You would expect to see it on both sides, because tides have a symmetrical effect.

“In 2010, we found one area that fits the tidal heating effect, but that study left open the rest of the moon and didn’t include the tidal-rotational deformation. In this paper we tried to bring all those considerations together,” said Garrick-Bethell in a press release.

Any rotational forces would cause the spinning moon to flatten slightly at the poles and bulge out near the equator. It would have had a similar effect on the moon’s shape as the tidal heating did — both of which left distinct signatures in the moon’s gravity field. Because the crust is lighter than the underlying mantle, gravity signals reveal variations in the moon’s internal structure, many of which may be due to previous forces.

Interestingly, Garrick-Bethell and colleagues discovered that the moon’s overall gravity field is no longer aligned with the topography. The long axis of the moon doesn’t point directly toward Earth as it likely did when the moon first formed; instead, it’s offset by about 30 degrees.

“The moon that faced us a long time ago has shifted, so we’re no longer looking at the primordial face of the moon,” said Garrick-Bethell. “Changes in the mass distribution shifted the orientation of the moon. The craters removed some mass, and there were also internal changes, probably related to when the moon became volcanically active.”

The details and timing of these processes are still uncertain, but the new analysis should help shed light on the tidal and rotational forces abundant throughout the Solar System and the Galaxy. These simple forces, after all, have helped shape our nearest neighbor and the most distant exoplanet.

The results have been published today in Nature.

Tagged as:
Moon's Evolution,
Moon's Formation,
tidal forces
Posted by Nelio Inacio at 7:15 PM 0 comments

Numerous Jets Spied with New Sky Survey

Numerous Jets Spied with New Sky Survey:



Caption: The area shown here was part of the very first image taken for the UWISH2 survey. It shows on the top a region of massive star formation (called G35.2N) with two spectacular jets. On the bottom an intermediate mass young stellar cluster (Mercer14) can be seen. Several jets are visible in its vicinity, as well as a region of photo-ionized material surrounding a young massive star. Credit: University of Kent

The area shown here was part of the very first image taken for the UWISH2 survey. Near the top is a region of massive star formation (called G35.2N) with two spectacular jets. Near the bottom is an intermediate mass young stellar cluster (Mercer14). Several jets are visible in its vicinity, as well as a region of photo-ionized material surrounding a young massive star. Image Credit: University of Kent
Jets — narrow beams of matter spat out at a high speed — typically accompany the most enigmatic astronomical objects. We see them wherever gas accretes onto compact objects, such as newborn stars or black holes. But never before have astronomers detected so many at once.

This remarkable discovery is expected to prompt significant changes in our understanding of the planetary nebulae population in the Galaxy, as well as properties of jets ejected from young forming stars.

The results come from a five-year survey (officially dubbed UWISH2) covering approximately 180 degrees of the northern sky, or 1450 times the size of the full moon. The survey utilizes the 3.8-meter UK Infrared Telescope on Mauna Kea, Hawai’i.

Caption: This image shows a field that contains a newly discovered photogenic planetary nebulae. Internally dubbed by the research team as the "Jelly-Fish PN" it shows an almost circular ring of emission from molecular hydrogen with a variety of structure in the ring itself and inside. The central ionizing source responsible for the radiation is a white dwarf, which is too faint at the near infrared wavelengths to be visible in the image. Image Credit: University of Kent

This image shows a field that contains a newly discovered photogenic planetary nebulae, known as “Jelly-Fish PN.” It shows an almost circular ring of emission from molecular hydrogen with a variety of structure in the ring itself and inside. Image Credit: University of Kent
At these longer wavelengths, any cosmic dust becomes transparent, allowing us to see regions previously hidden from view. This includes jets from protostars and planetary nebulae, as well as supernova remnants, the illuminated edges of vast clouds of gas and dust, and the warm regions that envelope massive stars and their associated clusters of smaller stars.

Based on current estimates using these data, the project expects to identify about 1000 jets from young stars — at least 90 percent of which are new discoveries — as well as 300 planetary nebulae — at least 50 percent of which are also new.

“These discoveries are very exciting,” said lead author Dirk Froebrich from the University of Kent in a press release. “We will ultimately have much better statistics, meaning we will be able to investigate the physical mechanisms that determine the jet lengths, as well as their power. This will bring us much closer to answering some of the fundamental questions of star formation: How are these jets launched and how much energy, mass and momentum do they feed back into the surrounding interstellar medium.”

Tagged as:
jets,
UWISH2
Posted by Nelio Inacio at 7:14 PM 0 comments

Surprise! Classical Novae Produce Gamma Rays

Surprise! Classical Novae Produce Gamma Rays:



These images show Fermi data centered on each of the four gamma-ray novae observed by the LAT. Colors indicate the number of detected gamma rays with energies greater than 100 million electron volts (blue indicates lowest, yellow highest). Image Credit: NASA/DOE/Fermi LAT Collaboration

These images show Fermi data centered on each of the four gamma-ray novae. Colors indicate the number of detected gamma rays with energies greater than 100 million electron volts (blue indicates lowest, yellow highest). Image Credit: NASA / DOE / Fermi LAT Collaboration
In a classical nova, a white dwarf siphons material off a companion star, building up a layer on its surface until the temperature and pressure are so high (a process which can take tens of thousands of years) that its hydrogen beings to undergo nuclear fusion, triggering a runaway reaction that detonates the accumulated gas.

The bright outburst, which releases up to 100,000 times the annual energy output of our Sun, can blaze for months. All the while, the white dwarf remains intact, with the potential of going nova again.

It’s a relatively straightforward picture — as far as complex astrophysics goes. But new observations with NASA’s Fermi Gamma-ray Space Telescope unexpectedly show that three classical novae — V959 Monocerotis 2012, V1324 Scorpii 2012, and V339 Delphini 2013 — and one rare nova, also produce gamma rays, the most energetic form of light.

“There’s a saying that one is a fluke, two is a coincidence, and three is a class, and we’re now at four novae and counting with Fermi,” said lead author Teddy Cheung from the Naval Research Laboratory in a press release.

The first nova detected in gamma rays was V407 Cygni — a rare star system in which a white dwarf interacts with a red giant — reported in March 2010.

One explanation for the gamma-ray emission is that the blast from the nova hits the hefty wind from the red giant, creating a shock wave that accelerates any charged particles to near the speed of light. These rapid particles, in turn, produce gamma rays.

But the gamma-ray peak follows the optical peak by a couple of days. This likely happens because the material the white dwarf ejects initially blocks the high-energy photons from escaping. So the gamma rays cannot escape until the material expands and thins.

But the later three novae are from systems that don’t have red giants and therefore the winds. There’s nothing for the blast wave to crash into.

“We initially thought of V407 Cygni as a special case because the red giant’s atmosphere is essentially leaking into space, producing a gaseous environment that interacts with the explosion’s blast wave,” said coauthor Steven Shore from the University of Pisa. “But this can’t explain more recent Fermi detections because none of those systems possess red giants.”

In a more typical system it’s likely that the blast creates multiple shock waves that expand into space at slightly different speeds. Faster shocks could blast into slower ones, creating the interaction necessary to produce gamma rays. Although, the team remains unsure if this is the case.

Astronomers estimate that between 20 and 50 novae occur each year in the Milky Way galaxy. Most go undetected, their visible light obscured by intervening dust, and their gamma rays dimmed by distance. Hopefully, future observations of nearby novae will shed light on the mysterious process producing gamma rays.

The results will appear in Science on August 1.

Tagged as:
Classical Novae,
Fermi Space Telescope,
Gamma rays
Posted by Nelio Inacio at 7:13 PM 0 comments

Hubble Spots Farthest Lensing Galaxy Yet

Hubble Spots Farthest Lensing Galaxy Yet:



Credit: NASA, ESA, K.-V. Tran (Texas A&M University), and K. Wong (Academia Sinica Institute of Astronomy & Astrophysics)

These Hubble Space Telescope images reveal the most distant cosmic lens yet found, a massive elliptical galaxy whose powerful gravity is magnifying the light from a faraway galaxy behind it. In the enlarged view, the lighter-colored blobs at the upper right and lower left are the distorted and magnified shapes of a more distant spiral galaxy behind the foreground elliptical. Image Credit: NASA, ESA, K.-V. Tran (Texas A&M University), and K. Wong (Academia Sinica Institute of Astronomy & Astrophysics)
Sometimes there’s a chance alignment — faraway in the universe, where objects are separated by unimaginable distances measured in billions of light-years — when a galaxy cluster in the foreground intersects light from an even more distant object. The conjunction plays visual tricks, where the galaxy cluster acts like a lens, appearing to magnify and bend the distant light.

The rare cosmic alignment can bring the distant universe into view. Now, astronomers have stumbled upon a surprise: they’ve detected the most distant cosmic magnifying glass yet.

Seen above as it looked 9.6 billion years ago, this monster elliptical galaxy breaks the previous record holder by 200 million light-years. It’s bending, distorting and magnifying the distant spiral galaxy, whose light has taken 10.7 billion years to reach Earth.

“When you look more than 9 billion years ago in the early universe, you don’t expect to find this type of galaxy-galaxy lensing at all,” said lead researcher Kim-Vy Tran from Texas A&M University in a Hubble press release.

“Imagine holding a magnifying glass close to you and then moving it much farther away. When you look through a magnifying glass held at arm’s length, the chances that you will see an enlarged object are high. But if you move the magnifying glass across the room, your chances of seeing the magnifying glass nearly perfectly aligned with another object beyond it diminishes.”

The team was studying star formation in data collected by the W. M. Keck Observatory in Hawai’i, when they came across a strong detection of hot hydrogen gas that appeared to arise form a massive, bright elliptical galaxy. It struck the team as odd. Hot hydrogen is a clear sign of star birth, but it was detected in a galaxy that looked far too old to be forming new stars.

“I was very surprised and worried,” Tran recalled. “I thought we had made a major mistake with our observations.”

So Tran dug through archived Hubble images, which revealed a smeared, blue object next to the larger elliptical. It was the clear signature of a gravitational lens.

“We discovered that light from the lensing galaxy and from the background galaxy were blended in the ground-based data, which was confusing us,” said coauthor Ivelina Momcheva of Yale University. “The Keck spectroscopic data hinted that something interesting was going on here, but only with Hubble’s high-resolution spectroscopy were we able to separate the lensing galaxy from the more distant background galaxy and determine that the two were at different distances. The Hubble data also revealed the telltale look of the system, with the foreground lens in the middle, flanked by a bright arc on one side and a faint smudge on the other — both distorted images of the background galaxy. We needed the combination of imaging and spectroscopy to solve the puzzle.”

By gauging the intensity of the background galaxy’s light, the team was able to measure the giant galaxy’s total mass. All in all it weighs 180 billion times more than our Sun. Although this may seem big, it actually weighs four times less than the Milky Way galaxy.

“There are hundreds of lens galaxies that we know about, but almost all of them are relatively nearby, in cosmic terms,” said lead author Kenneth Wong from the Academia Sinica Institute of Astronomy & Astrophysics. “To find a lens as far away as this one is a very special discovery because we can learn about the dark-matter content of galaxies in the distant past. By comparing our analysis of this lens galaxy to the more nearby lenses, we can start to understand how that dark-matter content has evolved over time.”

Interestingly, the lensing galaxy is underweight in terms of its dark-matter content. In the past, astronomers have assumed that dark matter and normal matter build up equally in a galaxy over time. But this galaxy, suggests this is not the case.

The team’s results appeared in the July 10 issue of The Astrophysical Journal Letters and is available online.

Tagged as:
Gravitational Lensing,
Hubble Space Telescope,
Keck Observatory
Posted by Nelio Inacio at 7:12 PM 0 comments

Rosetta’s Comet Is Too Hot For Complete Ice Surface, Spacecraft En Route Reveals

Rosetta’s Comet Is Too Hot For Complete Ice Surface, Spacecraft En Route Reveals:



Graphic of the instrument on the Rosetta spacecraft that measured the comet's temperature in mid-July 2014. Credit: European Space Agency

Graphic of the instrument on the Rosetta spacecraft that measured the comet’s temperature in mid-July 2014. Credit: European Space Agency
Anyone eager for a comet countdown? It’s just a few days now until the Rosetta spacecraft arrives near Comet 67P/Churyumov–Gerasimenko on August 6, and with each passing day more detail becomes visible.

The “rubber duckie”-shaped comet has an average surface temperature of –70 degrees Celsius (-94 degrees Fahrenheit), which is far warmer than scientists expect. At 20 to 30 degrees Celsius (68 to 86 degrees Fahrenheit) warmer than predicted, the scientists say that the comet is too hot to be covered in ice. It must instead of a dark crust.

“This result is very interesting, since it gives us the first clues on the composition and physical properties of the comet’s surface,” stated Fabrizio Capaccioni, principal investigator of the visible, infrared and thermal imaging spectrometer (VIRTIS) that took the measurements.

Capaccioni, who is from Italy’s INAF-IAPS, led a team that took measurements of the comet between July 13 and July 21. What they found was also consistent with the findings from other close-up views of comets, such as 1P/Halley. Observations from afar already revealed that Rosetta had low reflectivity, so this is consistent with those far-off looks.

“This doesn’t exclude the presence of patches of relatively clean ice, however, and very soon, VIRTIS will be able to start generating maps showing the temperature of individual features,” stated Capaccioni.

Source: European Space Agency

Tagged as:
Comet 67P/Churyumov–Gerasimenko
Posted by Nelio Inacio at 7:12 PM 0 comments

Companion Planet Could Keep Alien Earths Warm In Old Age: Study

Companion Planet Could Keep Alien Earths Warm In Old Age: Study:

Want to stay on top of all the space news? Follow @universetoday on Twitter

An artist's concept of a rocky world orbiting a red dwarf star. (Credit: NASA/D. Aguilar/Harvard-Smithsonian center for Astrophysics).

An artist’s concept of a rocky world orbiting a red dwarf star. (Credit: NASA/D. Aguilar/Harvard-Smithsonian center for Astrophysics).
People are generally social creatures, and in the case of planets that generally is the case as well. Many of these alien worlds we have discovered are in groups of two or more around their parent star or stars. A new study, however, goes a step further and says that a companion planet could actually save another planet in its old age.

“Planets cool as they age. Over time their molten cores solidify and inner heat-generating activity dwindles, becoming less able to keep the world habitable by regulating carbon dioxide to prevent runaway heating or cooling,” the University of Washington stated.

“But astronomers … have found that for certain planets about the size of our own, the gravitational pull of an outer companion planet could generate enough heat — through a process called tidal heating — to effectively prevent that internal cooling, and extend the inner world’s chance at hosting life.”

The researchers ran computer models finding that tidal heating, which is known to happen on Jupiter’s moons Europa and Io, can also happen in planets the size of Earth that are in non-circular orbits around dwarf stars. An outer planet would keep the orbit from stabilizing in a circle, generating tidal heating and keeping conditions potentially warm enough for life.

The study, led by the University of Arizona’s Christa Van Laerhoven, will be available in the Monthly Notices of the Royal Astronomical Society and is available now in preprint version on Arxiv.

Tagged as:
companion planet
Posted by Nelio Inacio at 7:11 PM 0 comments

Top Five Breakthroughs From Hubble's Workhorse Camera

Top Five Breakthroughs From Hubble's Workhorse Camera:

Hubble Deep Field
Several hundred never before seen galaxies are visible in this "deepest-ever" view of the universe, called the Hubble Deep Field (HDF), made with the Wide Field and Planetary Camera 2 aboard NASA's Hubble Space Telescope. Image credit: NASA/STScI
›  Full image and caption


May 04, 2009

Deepest photograph of the universe. Hubble's famous "Deep Field" picture (above), taken by the Wide Field and Planetary Camera 2, left the world with its mouth agape when it was first revealed in 1996. In just a small patch of sky, more than 1,000 galaxies located billions of light-years away could be seen floating in space like sea creatures at the bottom of an endless ocean. Our world and our galaxy suddenly seemed very small.


Observations of comet collision with Jupiter. The Wide Field and Planetary Camera 2 gave the world a rare, stunning view of Comet Shoemaker-Levy 9 plunging into the gas giant Jupiter in 1994. The images revealed the event in great detail, including ripples expanding outward from the impact.


The birth and death of stars. The Wide Field and Planetary Camera 2 brought the cosmos down to Earth with its exquisite pictures of stars in all stages of development. Its famed picture of the "Pillars of Creation" and other images of colorful dying stars offered the first, glorious views of a star's life. The camera also took the first pictures of the dusty disks around stars where planets are born, demonstrating that planet-forming environments are common in the universe.


The age and rate of expansion of our universe. Our universe formed from a colossal explosion known as the Big Bang, and has been stretching apart ever since. Hubble's Wide Field and Planetary Camera 2, by observing stars that vary periodically in brightness, was able to calculate the pace of this expansion to an unprecedented degree of error of 10 percent. The camera also played a leading role in discovering that the expansion of the universe is accelerating, driven by a mysterious force called "dark energy." Together, these findings led to the calculation that our universe is approximately 13.7 billion years old.


Most galaxies harbor huge black holes. Before Hubble, astronomers suspected, but had no proof, that supermassive black holes lurk deep in the bellies of galaxies. The Wide Field and Planetary Camera 2, together with spectroscopy data from Hubble, showed that most galaxies in the universe do indeed harbor monstrous black holes up to billions of times the mass of our sun.

Media contact: DC Agle/JPL
(818) 393-9011
Posted by Nelio Inacio at 7:09 PM 0 comments

NASA, Japan Release Most Complete Topographic Map of Earth

NASA, Japan Release Most Complete Topographic Map of Earth:

World map
NASA and Japan's Ministry of Economy, Trade and industry (METI) released the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) to the worldwide public on June 29, 2009.

› Full image and caption/related images


June 29, 2009

PASADENA, Calif. – NASA and Japan released a new digital topographic map of Earth Monday that covers more of our planet than ever before. The map was produced with detailed measurements from NASA's Terra spacecraft.


The new global digital elevation model of Earth was created from nearly 1.3 million individual stereo-pair images collected by the Japanese Advanced Spaceborne Thermal Emission and Reflection Radiometer, or Aster, instrument aboard Terra. NASA and Japan's Ministry of Economy, Trade and Industry, known as METI, developed the data set. It is available online to users everywhere at no cost.


"This is the most complete, consistent global digital elevation data yet made available to the world," said Woody Turner, Aster program scientist at NASA Headquarters in Washington. "This unique global set of data will serve users and researchers from a wide array of disciplines that need elevation and terrain information."


According to Mike Abrams, Aster science team leader at NASA's Jet Propulsion Laboratory in Pasadena, Calif., the new topographic information will be of value throughout the Earth sciences and has many practical applications. "Aster's accurate topographic data will be used for engineering, energy exploration, conserving natural resources, environmental management, public works design, firefighting, recreation, geology and city planning, to name just a few areas," Abrams said.


Previously, the most complete topographic set of data publicly available was from NASA's Shuttle Radar Topography Mission. That mission mapped 80 percent of Earth's landmass, between 60 degrees north latitude and 57 degrees south. The new Aster data expand coverage to 99 percent, from 83 degrees north latitude and 83 degrees south. Each elevation measurement point in the new data is 30 meters (98 feet) apart.


"The Aster data fill in many of the voids in the shuttle mission's data, such as in very steep terrains and in some deserts," said Michael Kobrick, Shuttle Radar Topography Mission project scientist at JPL. "NASA is working to combine the Aster data with that of the Shuttle Radar Topography Mission and other sources to produce an even better global topographic map."


NASA and METI are jointly contributing the Aster topographic data to the Group on Earth Observations, an international partnership headquartered at the World Meteorological Organization in Geneva, Switzerland, for use in its Global Earth Observation System of Systems. This "system of systems" is a collaborative, international effort to share and integrate Earth observation data from many different instruments and systems to help monitor and forecast global environmental changes.


NASA, METI and the U.S. Geological Survey validated the data, with support from the U.S. National Geospatial-Intelligence Agency and other collaborators. The data will be distributed by NASA's Land Processes Distributed Active Archive Center at the U.S. Geological Survey's Earth Resources Observation and Science Data Center in Sioux Falls, S.D., and by METI's Earth Remote Sensing Data Analysis Center in Tokyo.


Aster is one of five Earth-observing instruments launched on Terra in December 1999. Aster acquires images from the visible to the thermal infrared wavelength region, with spatial resolutions ranging from about 15 to 90 meters (50 to 300 feet). A joint science team from the U.S. and Japan validates and calibrates the instrument and data products. The U.S. science team is located at JPL.


For visualizations of the new Aster topographic data, visit: http://www.nasa.gov/topics/earth/features/20090629.html .


Data users can download the Aster global digital elevation model at: https://wist.echo.nasa.gov/~wist/api/imswelcome and http://www.gdem.aster.ersdac.or.jp .


For more information about NASA and agency programs, visit: http://www.nasa.gov .


JPL is managed for NASA by the California Institute of Technology in Pasadena.


Media Contacts:


Alan Buis 818-354-0474

Jet Propulsion Laboratory, Pasadena, Calif.

Alan.buis@jpl.nasa.gov


Steve Cole 202-358-0918

NASA Headquarters, Washington

Stephen.e.cole@nasa.gov


2009-103
Posted by Nelio Inacio at 7:08 PM 0 comments

NASA's Spitzer Images Out-of-This-World Galaxy

NASA's Spitzer Images Out-of-This-World Galaxy:

NASA's Spitzer Space Telescope has imaged a coiled galaxy with an eye-like object at its center.
The "eye" at the center of the galaxy is actually a monstrous black hole surrounded by a ring of stars.

› Full image and caption


July 23, 2009

PASADENA, Calif. -- NASA's Spitzer Space Telescope has imaged a wild creature of the dark -- a coiled galaxy with an eye-like object at its center.


The galaxy, called NGC 1097, is located 50 million light-years away. It is spiral-shaped like our Milky Way, with long, spindly arms of stars. The "eye" at the center of the galaxy is actually a monstrous black hole surrounded by a ring of stars. In this color-coded infrared view from Spitzer, the area around the invisible black hole is blue and the ring of stars, white.


The black hole is huge, about 100 million times the mass of our sun, and is feeding off gas and dust along with the occasional unlucky star. Our Milky Way's central black hole is tame by comparison, with a mass of a few million suns.


"The fate of this black hole and others like it is an active area of research," said George Helou, deputy director of NASA's Spitzer Science Center at the California Institute of Technology in Pasadena. "Some theories hold that the black hole might quiet down and eventually enter a more dormant state like our Milky Way black hole."


The ring around the black hole is bursting with new star formation. An inflow of material toward the central bar of the galaxy is causing the ring to light up with new stars.


"The ring itself is a fascinating object worthy of study because it is forming stars at a very high rate," said Kartik Sheth, an astronomer at NASA's Spitzer Science Center. Sheth and Helou are part of a team that made the observations.


In the Spitzer image, infrared light with shorter wavelengths is blue, while longer-wavelength light is red. The galaxy's red spiral arms and the swirling spokes seen between the arms show dust heated by newborn stars. Older populations of stars scattered through the galaxy are blue. The fuzzy blue dot to the left, which appears to fit snuggly between the arms, is a companion galaxy.


"The companion galaxy that looks as if it's playing peek-a-boo through the larger galaxy could have plunged through, poking a hole," said Helou. "But we don't know this for sure. It could also just happen to be aligned with a gap in the arms."


Other dots in the picture are either nearby stars in our galaxy, or distant galaxies.


This image was taken during Spitzer's "cold mission," which lasted more than five-and-a-half years. The telescope ran out of coolant needed to chill its infrared instruments on May 15, 2009. Two of its infrared channels will still work perfectly during the new "warm mission," which is expected to begin in a week or so, once the observatory has been recalibrated and warms to its new temperature of around 30 Kelvin (about minus 406 degrees Fahrenheit).


NASA's Jet Propulsion Laboratory, Pasadena, Calif., manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology, also in Pasadena. Caltech manages JPL for NASA. Spitzer's infrared array camera, which made the observations, was built by NASA's Goddard Space Flight Center, Greenbelt, Md. The instrument's principal investigator is Giovanni Fazio of the Harvard-Smithsonian Center for Astrophysics.


For more information about Spitzer, visit http://www.spitzer.caltech.edu/spitzer and http://www.nasa.gov/spitzer .

Whitney Clavin 818-354-4673

Jet Propulsion Laboratory, Pasadena, Calif.

whitney.clavin@jpl.nasa.gov
2009-114
Posted by Nelio Inacio at 7:08 PM 0 comments

NASA's Moon Mapper Beholds Home

NASA's Moon Mapper Beholds Home:

false-color image of Earth, seen from moon
This false-color image of Earth was taken from 200 kilometers (124 miles) above the lunar surface was taken by the Moon Mineralogy Mapper, one of two NASA instruments onboard the Indian Space Research Organization's Chandrayaan-1 spacecraft.
Full image and caption


August 03, 2009

This image of Earth taken from 200 kilometers (124 miles) above the lunar surface was taken by the Moon Mineralogy Mapper, one of two NASA instruments onboard the Indian Space Research Organization's Chandrayaan-1 spacecraft. Australia is visible in the lower center of the image. The image is presented as a false-color composite with oceans a dark blue, clouds white, and vegetation an enhanced green. The image data were acquired on July 22, 2009.


The Moon Mineralogy Mapper instrument is a state-of-the-art imaging spectrometer designed to provide the first map of the entire lunar surface at high spatial and spectral resolution. Scientists will use this information to answer questions about the moon's origin and development and the evolution of terrestrial planets in the early solar system. Future astronauts will use it to locate resources, possibly including water, that can support exploration of the moon and beyond.


The Moon Mineralogy Mapper was selected as a Mission of Opportunity through the NASA Discovery Program. Carle Pieters of Brown University, Providence, R.I., is the principal investigator and has oversight of the instrument as a whole, as well as the Moon Mineralogy Mapper Science Team. NASA's Jet Propulsion Laboratory, Pasadena, Calif., designed and built the Moon Mineralogy Mapper and is home to its project manager, Mary White. JPL manages the program for NASA's Science Mission Directorate, Washington. The Chandrayaan-1 spacecraft was constructed, launched, and is operated by the Indian Space Research Organisation.


More information about Chandrayaan-1 is at :


http://www.isro.org/Chandrayaan .


More information about NASA's Moon Mineralogy Mapper is at :


http://m3.jpl.nasa.gov .

Media contact: DC Agle/JPL
818-393-9011
Posted by Nelio Inacio at 7:07 PM 0 comments

Glint of Sunlight Confirms Liquid in Northern Lake District of Titan

Glint of Sunlight Confirms Liquid in Northern Lake District of Titan:

This image shows the first flash of sunlight reflected off a lake on Saturn's moon Titan.
This image shows the first flash of sunlight reflected off a lake on Saturn's moon Titan. › Full image and caption


December 17, 2009

PASADENA, Calif. -- NASA's Cassini Spacecraft has captured the first flash of sunlight reflected off a lake on Saturn's moon Titan, confirming the presence of liquid on the part of the moon dotted with many large, lake-shaped basins.

Cassini scientists had been looking for the glint, also known as a specular reflection, since the spacecraft began orbiting Saturn in 2004. But Titan's northern hemisphere, which has more lakes than the southern hemisphere, has been veiled in winter darkness. The sun only began to directly illuminate the northern lakes recently as it approached the equinox of August 2009, the start of spring in the northern hemisphere. Titan's hazy atmosphere also blocked out reflections of sunlight in most wavelengths. This serendipitous image was captured on July 8, 2009, using Cassini's visual and infrared mapping spectrometer.

The new infrared image is available online at: http://www.nasa.gov/cassini, http://saturn.jpl.nasa.gov and http://wwwvims.lpl.arizona.edu.

This image will be presented Friday, Dec. 18, at the fall meeting of the American Geophysical Union in San Francisco.

"This one image communicates so much about Titan -- thick atmosphere, surface lakes and an otherworldliness," said Bob Pappalardo, Cassini project scientist, based at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's an unsettling combination of strangeness yet similarity to Earth. This picture is one of Cassini's iconic images."

Titan, Saturn's largest moon, has captivated scientists because of its many similarities to Earth. Scientists have theorized for 20 years that Titan's cold surface hosts seas or lakes of liquid hydrocarbons, making it the only other planetary body besides Earth believed to harbor liquid on its surface. While data from Cassini have not indicated any vast seas, they have revealed large lakes near Titan's north and south poles.

In 2008, Cassini scientists using infrared data confirmed the presence of liquid in Ontario Lacus, the largest lake in Titan's southern hemisphere. But they were still looking for the smoking gun to confirm liquid in the northern hemisphere, where lakes are also larger.

Katrin Stephan, of the German Aerospace Center (DLR) in Berlin, an associate member of the Cassini visual and infrared mapping spectrometer team, was processing the initial image and was the first to see the glint on July 10th.

"I was instantly excited because the glint reminded me of an image of our own planet taken from orbit around Earth, showing a reflection of sunlight on an ocean," Stephan said. "But we also had to do more work to make sure the glint we were seeing wasn't lightning or an erupting volcano."

Team members at the University of Arizona, Tucson, processed the image further, and scientists were able to compare the new image to radar and near-infrared-light images acquired from 2006 to 2008.




They were able to correlate the reflection to the southern shoreline of a lake called Kraken Mare. The sprawling Kraken Mare covers about 400,000 square kilometers (150,000 square miles), an area larger than the Caspian Sea, the largest lake on Earth. It is located around 71 degrees north latitude and 337 degrees west latitude.

The finding shows that the shoreline of Kraken Mare has been stable over the last three years and that Titan has an ongoing hydrological cycle that brings liquids to the surface, said Ralf Jaumann, a visual and infrared mapping spectrometer team member who leads the scientists at the DLR who work on Cassini. Of course, in this case, the liquid in the hydrological cycle is methane rather than water, as it is on Earth.

"These results remind us how unique Titan is in the solar system," Jaumann said. "But they also show us that liquid has a universal power to shape geological surfaces in the same way, no matter what the liquid is."

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The visual and infrared mapping spectrometer team is based at the University of Arizona, Tucson.

Jia-Rui C. Cook 818-354-0850

Jet Propulsion Laboratory, Pasadena, Calif.

jia-rui.c.cook@jpl.nasa.gov

2009-199
Posted by Nelio Inacio at 7:07 PM 0 comments

Keck Telescopes Gaze into Young Star's 'Life Zone.'

Keck Telescopes Gaze into Young Star's 'Life Zone.':

Planets form around a young star in this artist's concept. Using the Keck Interferometer in Hawaii, astronomers have probed the structure of a dust disk around MWC 419 to within 50 million miles of the star. Credit: David A. Hardy/www.astroart.org
Planets form around a young star in this artist's concept. Using the Keck Interferometer in Hawaii, astronomers have probed the structure of a dust disk around MWC 419 to within 50 million miles of the star. Credit: David A. Hardy/http://www.astroart.org

› Larger image


December 23, 2009

The inner regions of young planet-forming disks offer information about how worlds like Earth form, but not a single telescope in the world can see them. Now, for the first time, astronomers using the W. M. Keck Observatory in Hawaii have measured the properties of a young solar system at distances closer to the star than Venus is from our sun.


To achieve the feat, the team used the Keck Interferometer to combine infrared light gathered by both of the observatory's twin 10-meter (33-foot) telescopes, which are separated by 85 meters (93 yards). The double-barreled approach gives astronomers the effective resolution of a single 85-meter telescope -- several times larger than any now planned.


"Nothing else in the world provides us with the types of measurements the Keck Interferometer does," said Wesley Traub of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "In effect, it's a zoom lens for the Keck telescopes."


The Keck Interferometer was developed by JPL and the W.M. Keck Observatory. It is managed by the W.M. Keck Observatory, which operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the island of Hawaii and is a scientific partnership of the California Institute of Technology in Pasadena, the University of California and NASA. NASA's Exoplanet Science Institute, also in Pasadena, manages time allocation on the telescope for NASA.


For more information, please visit: http://www.nasa.gov/topics/universe/features/keck-life-zone.html
Posted by Nelio Inacio at 7:06 PM 0 comments
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