Across The Universe - Precise New Measurements From Hubble Confirm the Accelerating Expansion of the Universe. Still no Idea Why it’s Happening

Precise New Measurements From Hubble Confirm the Accelerating Expansion of the Universe. Still no Idea Why it’s Happening:

In the 1920s, Edwin Hubble made the groundbreaking revelation that the Universe was in a state of expansion. Originally predicted as a consequence of Einstein’s Theory of General Relativity, this confirmation led to what came to be known as Hubble’s Constant. In the ensuring decades, and thanks to the deployment of next-generation telescopes – like the aptly-named Hubble Space Telescope (HST) – scientists have been forced to revise this law.

In short, in the past few decades, the ability to see farther into space (and deeper into time) has allowed astronomers to make more accurate measurements about how rapidly the early Universe expanded. And thanks to a new survey performed using Hubble, an international team of astronomers has been able to conduct the most precise measurements of the expansion rate of the Universe to date.

This survey was conducted by the Supernova H0 for the Equation of State (SH0ES) team, an international group of astronomers that has been on a quest to refine the accuracy of the Hubble Constant since 2005. The group is led by Adam Reiss of the Space Telescope Science Institute (STScI) and Johns Hopkins University, and includes members from the American Museum of Natural History, the Neils Bohr Institute, the National Optical Astronomy Observatory, and many prestigious universities and research institutions.

Illustration of the depth by which Hubble imaged galaxies in prior Deep Field initiatives, in units of the Age of the Universe. Credit: NASA and A. Feild (STScI)

The study which describes their findings recently appeared in The Astrophysical Journal under the title “Type Ia Supernova Distances at Redshift >1.5 from the Hubble Space Telescope Multi-cycle Treasury Programs: The Early Expansion Rate“. For the sake of their study, and consistent with their long term goals, the team sought to construct a new and more accurate “distance ladder”.

This tool is how astronomers have traditionally measured distances in the Universe, which consists of relying on distance markers like Cepheid variables – pulsating stars whose distances can be inferred by comparing their intrinsic brightness with their apparent brightness. These measurements are then compared to the way light from distance galaxies is redshifted to determine how fast the space between galaxies is expanding.

From this, the Hubble Constant is derived. To build their distant ladder, Riess and his team conducted parallax measurements using Hubble’s Wide Field Camera 3 (WFC3) of eight newly-analyzed Cepheid variable stars in the Milky Way. These stars are about 10 times farther away than any studied previously – between 6,000 and 12,000 light-year from Earth – and pulsate at longer intervals.

To ensure accuracy that would account for the wobbles of these stars, the team also developed a new method where Hubble would measure a star’s position a thousand times a minute every six months for four years. The team then compared the brightness of these eight stars with more distant Cepheids to ensure that they could calculate the distances to other galaxies with more precision.

Illustration showing three steps astronomers used to measure the universe’s expansion rate (Hubble constant) to an unprecedented accuracy, reducing the total uncertainty to 2.3 percent. Credits: NASA/ESA/A. Feild (STScI)/and A. Riess (STScI/JHU)

Using the new technique, Hubble was able to capture the change in position of these stars relative to others, which simplified things immensely. As Riess explained in a NASA press release:

“This method allows for repeated opportunities to measure the extremely tiny displacements due to parallax. You’re measuring the separation between two stars, not just in one place on the camera, but over and over thousands of times, reducing the errors in measurement.”

Compared to previous surveys, the team was able to extend the number of stars analyzed to distances up to 10 times farther. However, their results also contradicted those obtained by the European Space Agency’s (ESA) Planck satellite, which has been measuring the Cosmic Microwave Background (CMB) – the leftover radiation created by the Big Bang – since it was deployed in 2009.

By mapping the CMB, Planck has been able to trace the expansion of the cosmos during the early Universe – circa. 378,000 years after the Big Bang. Planck’s result predicted that the Hubble constant value should now be 67 kilometers per second per megaparsec (3.3 million light-years), and could be no higher than 69 kilometers per second per megaparsec.

The Big Bang timeline of the Universe. Cosmic neutrinos affect the CMB at the time it was emitted, and physics takes care of the rest of their evolution until today. Credit: NASA/JPL-Caltech/A. Kashlinsky (GSFC).

Based on their sruvey, Riess’s team obtained a value of 73 kilometers per second per megaparsec, a discrepancy of 9%. Essentially, their results indicate that galaxies are moving at a faster rate than that implied by observations of the early Universe. Because the Hubble data was so precise, astronomers cannot dismiss the gap between the two results as errors in any single measurement or method. As Reiss explained:

“The community is really grappling with understanding the meaning of this discrepancy… Both results have been tested multiple ways, so barring a series of unrelated mistakes. it is increasingly likely that this is not a bug but a feature of the universe.”

These latest results therefore suggest that some previously unknown force or some new physics might be at work in the Universe. In terms of explanations, Reiss and his team have offered three possibilities, all of which have to do with the 95% of the Universe that we cannot see (i.e. dark matter and dark energy). In 2011, Reiss and two other scientists were awarded the Nobel Prize in Physics for their 1998 discovery that the Universe was in an accelerated rate of expansion.

Consistent with that, they suggest that Dark Energy could be pushing galaxies apart with increasing strength. Another possibility is that there is an undiscovered subatomic particle out there that is similar to a neutrino, but interacts with normal matter by gravity instead of subatomic forces. These “sterile neutrinos” would travel at close to the speed of light and could collectively be known as “dark radiation”.

This illustration shows the evolution of the Universe, from the Big Bang on the left, to modern times on the right. Credit: NASA

Any of these possibilities would mean that the contents of the early Universe were different, thus forcing a rethink of our cosmological models. At present, Riess and colleagues don’t have any answers, but plan to continue fine-tuning their measurements. So far, the SHoES team has decreased the uncertainty of the Hubble Constant to 2.3%.

This is in keeping with one of the central goals of the Hubble Space Telescope, which was to help reduce the uncertainty value in Hubble’s Constant, for which estimates once varied by a factor of 2.

So while this discrepancy opens the door to new and challenging questions, it also reduces our uncertainty substantially when it comes to measuring the Universe. Ultimately, this will improve our understanding of how the Universe evolved after it was created in a fiery cataclysm 13.8 billion years ago.

Further Reading: NASA, The Astrophysical Journal

The post Precise New Measurements From Hubble Confirm the Accelerating Expansion of the Universe. Still no Idea Why it’s Happening appeared first on Universe Today.

Across The Universe - Proxima Centauri Just Released a Deadly Flare, so it’s Probably not a Great Place for Habitable Planets

Proxima Centauri Just Released a Deadly Flare, so it’s Probably not a Great Place for Habitable Planets:

Since it’s discovery was announced in August of 2016, Proxima b has been an endless source of wonder and the target of many scientific studies. As the closest extra-solar planet to our Solar System – and a terrestrial planet that orbits within Proxima Centauri’s circumstellar habitable zone (aka. “Goldilocks Zone”) – scientists have naturally wondered whether or not this planet could be habitable.

Unfortunately, many of these studies have emphasized the challenges that life on Proxima b would likely face, not the least of which is harmful radiation from its star. According to a recent study, a team of astronomers used the ALMA Observatory to detect a large flare emanating from Proxima Centauri. This latest findings, more than anything, raises questions about how habitable its exoplanet could be.

The study, titled “Detection of a Millimeter Flare from Proxima Centauri“, recently appeared in The Astrophysical Journal Letters. Led by Meredith A. MacGregor, an NSF Astronomy and Astrophysics Postdoctoral Fellow at the Carnegie Institution for Science, the team also included members from the Harvard-Smithsonian Center for Astrophysics (CfA) and the University of Colorado Boulder.

Artist’s impression of Proxima b, which was discovered using the Radial Velocity method. Credit: ESO/M. Kornmesser

For the sake of their study, the team used data obtained by the Atacama Large Millimeter/submillimeter Array (ALMA) between January 21st to April 25th, 2017. This data revealed that the star underwent a significant flaring event on March 24th, where it reached a peak that was 1000 times brighter than the star’s quiescent emission for a period of ten seconds.

Astronomers have known for a long time that when compared to stars like our Sun, M-type stars are variable and unstable. While they are the smallest, coolest, and dimmest stars in our Universe, they tend to flare up at a far greater rate. In this case, the flare detected by the team was ten times larger than our Sun’s brightest flares at similar wavelengths.

Along with a smaller preceding flare, the entire event lasted fewer than two minutes of the 10 hours that ALMA was observing the star between January and March of last year. While it was already known that Proxima Centauri, like all M-type stars, experiences regular flare activity, this one appeared to be a rare event. However, stars like Proxima Centauri are also known to experienced regular, although smaller, X-ray flares.

All of this adds up to a bad case for habitability. As MacGregor explained in a recent NRAO press statement:

“It’s likely that Proxima b was blasted by high energy radiation during this flare. Over the billions of years since Proxima b formed, flares like this one could have evaporated any atmosphere or ocean and sterilized the surface, suggesting that habitability may involve more than just being the right distance from the host star to have liquid water.”

Artist’s impression of the surface of the planet Proxima b orbiting the red dwarf star Proxima Centauri. The double star Alpha Centauri AB is visible to the upper right of Proxima itself. Credit: ESO

MacGregor and her colleagues also considered the possibility that Proxima Centauri is circled by several disks of dust. This was suggested by a previous study (also based on ALMA data) that indicated that the light output of both the star and flare together pointed towards the existence of debris belts around the star. However, after examining the ALMA data as a function of observing time, they were able to eliminate this as a possibility.

As Alycia J. Weinberger, also a researcher with the Carnegie Institution for Science and a co-author on the paper, explained:

“There is now no reason to think that there is a substantial amount of dust around Proxima Cen. Nor is there any information yet that indicates the star has a rich planetary system like ours.”

To date, studies that have looked at possible conditions on Proxima b have come to different conclusions as to whether or not it could retain an atmosphere or liquid water on its surface. While some have found room for “transient habitability” or evidence of liquid water, others have expressed doubt based on the long-term effects that radiation and flares from its star would have on a tidally-locked planet.

In the future, the deployment of next-generation instruments like the James Webb Space Telescope are expected to provide more detailed information on this system. With precise measurements of this star and its planet, the question of whether or not life can (and does) exist in this system may finally be answered.

And be sure to enjoy this animation of Proxima Centauri in motion, courtesy of NRAO outreach:

Further Reading: NRAO, The Astrophysical Journal Letters

The post Proxima Centauri Just Released a Deadly Flare, so it’s Probably not a Great Place for Habitable Planets appeared first on Universe Today.

Across The Universe - Did the Milky Way Steal These Stars or Kick Them Out of the Galaxy?

Did the Milky Way Steal These Stars or Kick Them Out of the Galaxy?:

Despite thousands of years of research and observation, there is much that astronomers still don’t know about the Milky Way Galaxy. At present, astronomers estimate that it spans 100,000 to 180,000 light-years in diameter and consisting of 100 to 400 billion stars. In addition, for decades, there have been unresolved questions about how the structure of our galaxy evolved over the course of billions of years.

For example, astronomers have long suspected that galactic halo came from – giant structures of stars that orbit above and below the flat disk of the Milky Way – were formed from debris left behind by smaller galaxies that merged with the Milky Way. But according to a new study by an international team of astronomers, it appears that these stars may have originated within the Milky Way but were then kicked out.

The study recently appeared in the journal Nature under the title “Two chemically similar stellar overdensities on opposite sides of the plane of the Galactic disk“. The study was led by Margia Bergmann, a researcher from the Max Planck Institute for Astronomy, and included members from the Australian National University, the California Institute of Technology, and multiple universities.

Artist’s impression of the Milky Way Galaxy. Credit: NASA/JPL-Caltech/R. Hurt (SSC-Caltech)

For the sake of their study, the team relied on data from the W.M. Keck Observatory to determine the chemical abundance patterns from 14 stars located in the galactic halo. These stars were located in two different halo structures – the Triangulum-Andromeda (Tri-And) and the A13 stellar overdensities – which are bout 14,000 light years above and below the Milky Way disc.

As Bergemann explained in a Keck Observatory press release:

“The analysis of chemical abundances is a very powerful test, which allows, in a way similar to the DNA matching, to identify the parent population of the star. Different parent populations, such as the Milky Way disk or halo, dwarf satellite galaxies or globular clusters, are known to have radically different chemical compositions. So once we know what the stars are made of, we can immediately link them to their parent populations.”

The team also obtained spectra from one additional using the European Southern Observatory’s Very Large Telescope (VLT) in Chile. By comparing the chemical compositions of these stars with the ones found in other cosmic structures, the scientists noticed that the chemical compositions were almost identical. Not only were they similar within and between the groups being studies, they closely matched the abundance patterns of stars found within the Milky Way’s outer disk.

Computer model of the Milky Way and its smaller neighbor, the Sagittarius dwarf galaxy. Credit: Tollerud, Purcell and Bullock/UC Irvine

From this, they concluded that these stellar population in the Galactic Halo were formed in the Milky Way, but then relocated to locations above and below the Galactic Disk. This phenomena is known as “galactic eviction”, where structures are pushed off the plane of the Milky Way when a massive dwarf galaxy passes through the galactic disk. This process causes oscillations that eject stars from the disk, in whichever the dwarf galaxy is moving.

“The oscillations can be compared to sound waves in a musical instrument,” added Bergemann. “We call this ‘ringing’ in the Milky Way galaxy ‘galactoseismology,’ which has been predicted theoretically decades ago. We now have the clearest evidence for these oscillations in our galaxy’s disk obtained so far!”

These observations were made possible thanks to the High-Resolution Echelle Spectrometer (HiRES) on the Keck Telescope. As Judy Cohen, the Kate Van Nuys Page Professor of Astronomy at Caltech and a co-author on the study, explained:

“The high throughput and high spectral resolution of HIRES were crucial to the success of the observations of the stars in the outer part of the Milky Way. Another key factor was the smooth operation of Keck Observatory; good pointing and smooth operation allows one to get spectra of more stars in only a few nights of observation. The spectra in this study were obtained in only one night of Keck time, which shows how valuable even a single night can be.”

360-degree panorama view of the Milky Way (an assembled mosaic of photographs) by ESO. Credit: ESO/S. Brunier

These findings are very exciting for two reasons. On the one hand, it demonstrates that halo stars likely originated in the Galactic think disk – a younger part of the Milky Way. On the other hand, it demonstrates that the Milky Way’s disk and its dynamics are much more complex than previously thought. As Allyson Sheffield of LaGuardia Community College/CUNY, and a co-author on the paper, said:

“We showed that it may be fairly common for groups of stars in the disk to be relocated to more distant realms within the Milky Way – having been ‘kicked out’ by an invading satellite galaxy. Similar chemical patterns may also be found in other galaxies, indicating a potential galactic universality of this dynamic process.”

As a next step, the astronomers plan to analyze the spectra of additional stars in the Tri-And and A13 overdensities, as well as stars in other stellar structures further away from the disk. They also plan to determine masses and ages of these stars so they can constrain the time limits of when this galactic eviction took place.

In the end, it appears that another long-held assumption on galactic evolution has been updated. Combined with ongoing efforts to probe the nuclei of galaxies – to see how their Supermassive Black Holes and star formation are related – we appear to be getting closer to understanding just how our Universe evolved over time.

Further Reading: W.M. Keck Observatory, Nature

The post Did the Milky Way Steal These Stars or Kick Them Out of the Galaxy? appeared first on Universe Today.

Across The Universe - The dinosaur-murdering asteroid maybe also triggered an underwater volcano meltdown

The dinosaur-murdering asteroid maybe also triggered an underwater volcano meltdown:

The cataclysmic asteroid that wiped out the dinosaurs might have also triggered massive volcanic eruptions deep beneath the ocean, new research says. It’s yet another way the extraterrestrial impact could have killed off more than 70 percent of life on Earth — that is, if the timing isn’t just a coincidence.

Roughly 66 million years ago, a 6-mile-wide asteroid crashed into Mexico’s Yucatán Peninsula — causing a massive, worldwide earthquake. That Earth-shaking impact might have made underwater volcanoes spit up magma even more ferociously than usual, according to a study published today in the journal Science Advances. These events might have added to the asteroid’s apocalyptic aftershocks — which include wildfires, global cooling, and...

Continue reading…

Across The Universe - An Elephant's Trunk in Cepheus

An Elephant's Trunk in Cepheus:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 January 16

An Elephant's Trunk in Cepheus

Image Credit &
Copyright:

Processing -
Robert Gendler,
Roberto
Colombari

Data -
Subaru Telescope (NAOJ),
Robert Gendler,
Adam Block



Explanation:

With
image data from telescopes large and small,
this close-up features the dusty Elephant's Trunk Nebula.

It winds through the emission nebula and young star cluster
complex IC 1396, in the
high and far off
constellation of
Cepheus.

Also known as vdB 142, the cosmic elephant's trunk is over
20 light-years long.

The colorful view highlights bright, swept-back
ridges that outline the region's pockets of cool
interstellar dust and gas.

Such embedded, dark,
tendril-shaped clouds contain
the raw material for star formation and hide
protostars within.

Nearly 3,000 light-years distant, the relatively faint IC 1396 complex
covers a large region on the sky, spanning over 5 degrees.

This dramatic scene spans a 1 degree wide field,
about the size of 2 Full Moons.



Tomorrow's picture: orion away

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Across The Universe - Venus and the Triply Ultraviolet Sun

Venus and the Triply Ultraviolet Sun:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 4

Venus and the Triply Ultraviolet Sun

Image Credit:
NASA/SDO
& the AIA, EVE, and HMI teams;
Digital Composition:
Peter L. Dove



Explanation:
An unusual type of solar eclipse occurred in 2012.

Usually it is the
Earth's Moon that
eclipses the Sun.

That year, most unusually, the planet
Venus took a turn.

Like a solar eclipse by the Moon, the phase of Venus became a continually thinner
crescent as Venus became increasingly
better aligned with the Sun.

Eventually the alignment became perfect and the
phase of Venus dropped to zero.

The dark spot of Venus crossed our parent star.

The situation could technically be labeled a Venusian
annular eclipse with an extraordinarily large
ring of fire.

Pictured here during the occultation, the Sun was imaged in three colors of ultraviolet light by the Earth-orbiting
Solar Dynamics Observatory,
with the dark region toward the right corresponding to a
coronal hole.

Hours later, as Venus continued in its orbit, a
slight crescent phase appeared again.

The next Venusian transit across the Sun will occur in
2117.





Tomorrow's picture: bubble versus cloud

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Authors & editors:
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Jerry Bonnell (UMCP)
NASA Official: Phillip Newman
Specific rights apply.
NASA Web
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Across The Universe - Galaxy NGC 474: Shells and Star Streams

Galaxy NGC 474: Shells and Star Streams:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 6

Explanation:
What's happening to galaxy NGC 474?

The multiple layers of emission appear strangely complex and unexpected given the relatively featureless appearance of the
elliptical galaxy in less deep images.

The cause of the shells is currently unknown, but possibly
tidal tails related to debris left over from absorbing numerous small galaxies in the past billion years.

Alternatively the shells
may be like ripples in a pond,
where the ongoing collision with the spiral galaxy just above
NGC 474
is causing density
waves to ripple through the galactic giant.

Regardless of the actual cause, the
featured image
dramatically highlights the increasing consensus that at least some elliptical
galaxies
have formed in the recent past, and that the outer halos of most
large galaxies are not really smooth
but have complexities induced by frequent
interactions with --
and accretions of --
smaller nearby galaxies.

The halo of our own
Milky Way Galaxy
is
one example of such
unexpected complexity.

NGC 474 spans about 250,000
light years and lies about 100 million light years distant toward the constellation of the Fish
(Pisces).

Across The Universe - Total Solar Lunar Eclipse

Total Solar Lunar Eclipse:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 9

Explanation:

This digitally processed and composited picture
creatively compares two famous eclipses in one;
the total lunar eclipse (left)
of January 31,
and the total solar eclipse
of August 21,
2017.

The Moon appears near mid-totality in both the back-to-back total eclipses.

In
the lunar eclipse, its surface remains faintly illuminated in Earth's
dark reddened shadow.

But in the solar eclipse the Moon is in silhouette
against the Sun's bright disk, where
the otherwise dark lunar surface is just visible due to
earthshine.

Also seen in the lunar-aligned image pair
are faint stars in the night sky surrounding the eclipsed Moon.

Stunning details of prominences and coronal streamers surround
the eclipsed Sun.

The total phase of the Great American Eclipse of August 21 lasted
about 2 minutes
or less for locations along the Moon's shadow path.

From planet Earth's night side, totality for the Super Blue Blood Moon
of January 31 lasted
well over an hour.

Across The Universe - Roadster, Starman, Planet Earth

Roadster, Starman, Planet Earth:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 10

Explanation:

Don't panic.

It's just a spacesuited mannequin
named Starman.

As the sunlit crescent of
planet Earth
recedes in the background,
Starman is comfortably seated at the wheel of a Tesla Roadster
in this final image of the payload launched by a
Falcon Heavy
rocket on February 6.

Internationally
designated 2018-017A,
roadster and Starman are headed for space beyond the orbit of Mars.

The successful Falcon Heavy rocket has now become the most
powerful rocket in operation and the roadster
one of four
electric cars launched from planet Earth.

The other three were launched to the Moon by historically
more powerful (but not reusable)
Saturn V rockets.

Still, Starman's roadster is probably the only one that would be
considered street legal.

Across The Universe - Car Orbiting Earth

Car Orbiting Earth:

Discover the cosmos!
Each day a different image or photograph of our fascinating universe is
featured, along with a brief explanation written by a professional astronomer.


2018 February 13

Car Orbiting Earth

Credit:
SpaceX



Explanation:
Last week, a car orbited the Earth.

The car, created by humans and robots on the Earth, was
launched by the
SpaceX Company to demonstrate the ability of its
Falcon Heavy Rocket
to place spacecraft out in the
Solar System.

Purposely fashioned to be
whimsical, the
iconic car
was thought a better demonstration object than concrete blocks.

A mannequin clad in a spacesuit -- dubbed the
Starman --
sits in the driver's seat.

The featured image is a frame from a
video
taken by one of three cameras mounted on
the car.

These cameras, connected to the car's battery, are now out of power.

The car, attached to a second stage booster,
soon left Earth
orbit and will
orbit the Sun between
Earth and the
asteroid belt
indefinitely -- perhaps until billions of years from now when our
Sun expands into a
Red Giant.

If ever recovered,
what's left of the car may become a unique window into technologies developed on Earth in the
20th and early
21st centuries.




Tomorrow's picture: heart of the heart

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Across The Universe - Astronomers use a Galaxy Cluster as an Extremely Powerful “Natural Telescope” to Peer Even Farther into the Universe

Astronomers use a Galaxy Cluster as an Extremely Powerful “Natural Telescope” to Peer Even Farther into the Universe:

When it comes to studying some of the most distant and oldest galaxies in the Universe, a number of challenges present themselves. In addition to being billions of light years away, these galaxies are often too faint to see clearly. Luckily, astronomers have come to rely on a technique known as Gravitational Lensing, where the gravitational force of a large object (like a galactic cluster) is used to enhance the light of these fainter galaxies.

Using this technique, an international team of astronomers recently discovered a distant and quiet galaxy that would have otherwise gone unnoticed. Led by researchers from the University of Hawaii at Manoa, the team used  the Hubble Space Telescope to conduct the most extreme case of gravitational lensing to date, which allowed them to observe the faint galaxy known as eMACSJ1341-QG-1.

The study that describes their findings recently appeared in The Astrophysical Journal Letters under the title “Thirty-fold: Extreme Gravitational Lensing of a Quiescent Galaxy at z = 1.6″. Led by Harald Ebeling, an astronomer from the University of Hawaii at Manoa, the team included members from the Niels Bohr Institute, the Centre Nationale de Recherche Scientifique (CNRS), the Space Telescope Science Institute, and the European Southern Observatory (ESO).

The quiescent galaxy eMACSJ1341-QG-1 as seen by the Hubble Space Telescope. The yellow dotted line traces the boundaries of the galaxy’s gravitationally lensed image. The inset on the upper left shows what eMACSJ1341-QG-1 would look like if we observed it directly, without the cluster lens. Credit: Harald Ebeling/UH IfA

For the sake of their study, the team relied on the massive galaxy cluster known as eMACSJ1341.9-2441 to magnify the light coming from eMACSJ1341-QG-1,  a distant and fainter galaxy. In astronomical terms, this galaxy is an example of a “quiescent galaxy”, which are basically older galaxies that have largely depleted their supplies of dust and gas and therefore do not form new stars.

The team began by taking images of the faint galaxy with the Hubble and then conducting follow-up spectroscopic observations using the ESO/X-Shooter spectrograph – which is part of the Very Large Telescope (VLT) at the Paranal Observatory in Chile. Based on their estimates, the team determined that they were able to amplify the background galaxy by a factor of 30 for the primary image, and a factor of six for the two remaining images.

This makes eMACSJ1341-QG-1 the most strongly amplified quiescent galaxy discovered to date, and by a rather large margin! As Johan Richard – an assistant astronomer at the University of Lyon who performed the lensing calculations, and a co-author on the study – indicated in a University of Hawaii News release:

“The very high magnification of this image provides us with a rare opportunity to investigate the stellar populations of this distant object and, ultimately, to reconstruct its undistorted shape and properties.”

A spiral galaxy ablaze in the blue light of young stars from ongoing star formation (left) and an elliptical galaxy bathed in the red light of old stars (right). Credit: Sloan Digital Sky Survey, CC BY-NC.

Although other extreme magnifications have been conducted before, this discovery has set a new record for the magnification of a rare quiescent background galaxy. These older galaxies are not only very difficult to detect because of their lower luminosity; the study of them can reveal some very interesting things about the formation and evolution of galaxies in our Universe.

As Ebeling, an astronomer with the UH’s Institute of Astronomy and the lead author on the study, explained:

“We specialize in finding extremely massive clusters that act as natural telescopes and have already discovered many exciting cases of gravitational lensing. This discovery stands out, though, as the huge magnification provided by eMACSJ1341 allows us to study in detail a very rare type of galaxy.”

Quiescent galaxies are common in the local Universe, representing the end-point of galactic evolution. As such, this record-breaking find could provide some unique opportunities for studying these older galaxies and determining why star-formation ended in them. As Mikkel Stockmann, a team member from the University of Copenhagen and an expert in galaxy evolution, explained:

“[A]s we look at more distant galaxies, we are also looking back in time, so we are seeing objects that are younger and should not yet have used up their gas supply. Understanding why this galaxy has already stopped forming stars may give us critical clues about the processes that govern how galaxies evolve.”

An artist’s impression of the accretion disc around the supermassive black hole that powers an active galaxy. Credit: NASA/Dana Berry, SkyWorks Digital

In a similar vein, recent studies have been conducted that suggest that the presence of a Supermassive Black Hole (SMBH) could be what is responsible for galaxies becoming quiescent. As the powerful jets these black holes create begin to drain the core of galaxies of their dust and gas, potential stars find themselves starved of the material they would need to undergo gravitational collapse.

In the meantime, follow-up observations of eMACSJ1341-QG1 are being conducted using telescopes at the Paranal Observatory in Chile and the Maunakea Observatories in Hawaii. What these observations reveal is sure to tell us much about what will become of our own Milky Way Galaxy someday, when the last of the dust and gas is depleted and all its stars become red giants and long-lived red dwarfs.

Further Reading: University of Hawa’ii News, The Astrophysical Journal Letters

The post Astronomers use a Galaxy Cluster as an Extremely Powerful “Natural Telescope” to Peer Even Farther into the Universe appeared first on Universe Today.

NASA releases New Horizons flyover video

NASA releases New Horizons flyover video:

This new, detailed global mosaic color map of Pluto is based on a series of three color filter images obtained by the Ralph/Multispectral Visual Imaging Camera aboard New Horizons during the NASA spacecraft’s close flyby of Pluto in July 2015. The mosaic shows how Pluto’s large-scale color patterns extend beyond the hemisphere facing New Horizons at closest approach, which were imaged at the highest resolution. North is up; Pluto’s equator roughly bisects the band of dark red terrains running across the lower third of the map. Pluto’s giant, informally named Sputnik Planitia glacier – the left half of Pluto’s signature “heart” feature – is at the center of this map. Note: Click on the image to view in the highest resolution. Image & Caption Credit: NASA/JHUAPL/SwRI

Using actual New Horizons data and digital elevation models of Pluto and its largest moon, Charon, mission scientists have created flyover movies that offer spectacular new perspectives of the many unusual features that were discovered and which have reshaped our views of the Pluto system – from a vantage point even closer than the spacecraft itself.

This dramatic Pluto flyover begins over the highlands to the southwest of the great expanse of nitrogen ice plain informally named Sputnik Planitia. The viewer first passes over the western margin of Sputnik, where it borders the dark, cratered terrain of Cthulhu Macula, with the blocky mountain ranges located within the plains seen on the right. The tour moves north past the rugged and fractured highlands of Voyager Terra and then turns southward over Pioneer Terra – which exhibits deep and wide pits – before concluding over the bladed terrain of Tartarus Dorsa in the far east of the encounter hemisphere.

Digital mapping and rendering were performed by Paul Schenk and John Blackwell of the Lunar and Planetary Institute in Houston.

Video courtesy of NASA

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NASA prepares its Martian explorers for solar conjunction radio silence

NASA prepares its Martian explorers for solar conjunction radio silence:

With the Sun sitting between Earth and Mars, called a solar conjunction, NASA will suspend communications with its explorers at the Red Planet for nearly two weeks. Image Credit: NASA / JPL

For more than twenty years, NASA has had explorers surveying the Red Planet. Dutifully, the stalwart robotic travelers have followed commands beamed from their Earth-bound handlers and returned gigabytes of information of their Martian observations.

However, for a few days every 26 months, communication from Earth to Mars takes a Sun-induced break. Beginning July 22, 2017, and lasting through August 1, 2017, NASA will avoid sending commands to its Mars-based craft.

Animation of a Mars Solar Conjunction. Animation Credit: NASA / JPL

The Sun giveth, the Sun taketh away

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While the Sun provides life-supporting energy to Earth and supplies power to solar panels on spacecraft, its highly ionized corona holds a significant potential to disrupt data transmission when it sits between the two planets. Although the two planets won’t be directly obscured by the Sun, the far-reaching effects of its outer layer can still induce data loss.

“Out of caution, we won’t talk to our Mars assets during that period because we expect significant degradation in the communication link, and we don’t want to take a chance that one of our spacecraft would act on a corrupted command,” stated Chad Edwards, manager of the Mars Relay Network Office at NASA’s Jet Propulsion Laboratory (JPL), in a release issued by the agency.

Though commands won’t be sent to Mars during the conjunction window, telemetry will still be sent to Earth. Should data loss occur, the robotic craft can be instructed to repeat its transmission once clear of solar interference.

This command black-out period extends for two days both before and after a solar conjunction event.

Able to work independently

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Even though no commands will be sent to Mars during the conjunction, NASA’s rovers and orbiting spacecraft will still have work to do. In fact, engineers have been preparing the explorers far ahead to ensure observations run unabated.

“The vehicles will stay active, carrying out commands sent in advance,” stated JPL’s Mars Program Chief Engineer, Hoppy Price.

While the agency’s two active rovers – Curiosity and Opportunity – will be conducting pre-programmed investigations, they will remain stationary during the blackout.

Although the lack of communications may sound worrisome, all of the orbiters/rovers have already endured at least one Mars Solar Conjunction. Indeed, the Mars Odyssey orbiter will be undergoing its eighth conjunction, while Opportunity holds the surface record at just one less than its orbiting cousin.

“All of these spacecraft are now veterans of conjunction. We know what to expect,” concluded Edwards.

Curiosity will remain stationary during the blackout period, but will still conduct investigations. Image Credit: NASA / JPL / MSSS

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AIDA mission to validate crucial asteroid deflection technology

AIDA mission to validate crucial asteroid deflection technology:

ESA’s Asteroid Impact Mission is joined by two triple-unit CubeSats to observe the impact of the NASA-led Demonstration of Autonomous Rendezvous Technology (DART) probe with the secondary Didymos asteroid, planned for late 2022. Image & Caption Credit: ESA / ScienceOffice.org

While there is currently no imminent asteroid threat and none of the known near-Earth objects (NEOs) is on collision course with our planet, humanity should be prepared for the worst. With that thought in mind, NASA and ESA are developing the Asteroid Impact and Deflection Assessment (AIDA) mission; its main goal is to demonstrate the kinetic impact technique that could change the motion of a potentially hazardous asteroid.

The AIDA mission will consist of two spacecraft sent to the binary asteroid called 65803 Didymos. Built by ESA, the Asteroid Impact Mission (AIM) will be launched in October 2020 and is expected to be injected into the orbit of the larger asteroid. NASA’s contribution to this endeavor, the Double Asteroid Redirection Test (DART), will be launched into space nearly one year later and slated to crash into the smaller asteroid in October 2022. AIM will be just in place to observe the impact and study its aftermath.

“This mission, in partnership with ESA and NASA, will allow us to validate the technology of the kinetic impactor and also to improve our understanding of threatening asteroids,” Patrick Michel, AIM/AIDA investigator at the Côte d’Azur Observatory (OCA), told Astrowatch.net.

LEFT: Artist’s rendering of ESA’s desk-sized Asteroid Impact Mission (AIM). Image Credit: ESA – Science Office. RIGHT: Artist’s rendering of NASA’s Demonstration of Autonomous Rendezvous Technology (DART) spacecraft. Image Credit: NASA

Therefore, the mission would be essential for the most one of the most important asteroid deflection technology – the kinetic impactor. In particular, AIDA will demonstrate the feasibility of this technique based on the data gathered by observing DART’s crash into Didymos’ moon with a velocity of about six km/s. AIM will orbit the asteroid in order to perform detailed before-and-after observations of the structure of the space rock itself, as well as its orbit, to thoroughly characterize the kinetic impact and the consequences.

“To make sure a technique is valid and that we know how to use it, we need a test. Otherwise, we can talk, but it will remain on paper and we cannot guarantee anything. And this is why we still push for the AIDA space mission to happen,” Michel said.

He noted that the success of AIDA will have many implications for planetary defense, science, and asteroid mining because the knowledge needed for these three aims is essentially the same. According to Michel, it will prove that asteroids are the only natural risk that we can predict and prevent by making the necessary steps.

“AIDA, if done, will accomplish the step that will allow us to tell the future generations: we did our duty, we have now a validated tool to prevent the risk! And it will also come with science and technology returns, which contributes to [inspiring] young generations,” Michel noted.

The AIM spacecraft is still in its conceptual phase. When it comes to DART, the probe was recently moved by NASA from concept development to preliminary design phase.



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VASIMR plasma engine: Earth to Mars in 39 days?

VASIMR plasma engine: Earth to Mars in 39 days?:

Artist’s impression of a 200-megawatt VASIMR spacecraft. Images Credit: Ad Astra Rocket Company

In Arthur C. Clarke’s classic science fiction novels and movies 2001: A Space Odyssey and 2010: Odyssey Two, the spaceships Discovery and Alexei Leonov make interplanetary journeys using plasma drives. Nuclear reactors heat hydrogen or ammonia to a plasma state that’s energetic enough to provide thrust.

In 1983, seven-time Space Shuttle Astronaut Franklin Chang Diaz turned Clarke’s speculations into reality with an engine known as the Variable Specific Impulse Magnetoplasma Rocket (VASIMR).

An electric power source ionizes hydrogen, deuterium, or helium fuel into a plasma by stripping away electrons. Magnetic fields then direct the charged gas in the proper direction to provide thrust.

“A rocket engine is a canister holding high-pressure gas,” Chang Diaz explained. “When you open a hole at one end, the gas squirts out and the rocket goes the other way. The hotter the stuff in the canister, the higher the speed it escapes and the faster the rocket goes. But if it’s too hot, it melts the canister.”

The VASIMR engine is different, Chang Diaz explained, because of the fuel’s electrical charge: “When gas gets above 10,000 [kelvins], it changes to plasma – an electrically charged soup of particles. And these particles can be held together by a magnetic field. The magnetic field becomes the canister, and there is no limit to how hot you can make the plasma.”

VASIMR® operation diagram. Credit & Copyright: Ad Astra Rocket Company © all rights reserved

Chang Diaz has pointed out that hydrogen would be an advantageous fuel for the VASIMR engine because the spacecraft would not have to lift off carrying all the fuel it needs for the journey.

VASIMR® System. Image Credit: Ad Astra Rocket Company

“We’re likely to find hydrogen pretty much anywhere we go in the Solar System,” he said.

A spacecraft using conventional chemical rockets would take eight months to get to Mars during opposition. However, the VASIMR engine would make the journey in as little as 39 days.

Chang Diaz explained: “Remember, you are accelerating the first half of the journey – the other half you’re slowing, so you will reach Mars but not pass it. The top speed with respect to the Sun would be about 32 miles per second [or 51.5 km/s]. But that requires a nuclear power source to heat the plasma to the proper temperature.”

The use of nuclear power in space is not without its controversy. In 1997, there was widespread public concern when NASA’s Cassini probe, which carried a plutonium battery, made a flyby of Earth to perform a gravity assist. Although NASA denied that the risk to the public, should an accident occur, was no greater than that posed every day by other sources of radiation, some scientists, including the popular theoretical physicist Michio Kaku, disagreed.

In April 1970, the Atomic Energy Commission was deeply concerned about the return of Apollo 13 to Earth. Where an Apollo mission would usually leave the lunar module’s descent stage on the Moon, the unsuccessful Apollo 13 dropped its lunar module Aquarius, with its plutonium-powered scientific experiments, into the ocean, raising concerns about radioactive contamination.

Elon Musk, CEO of Space Exploration Technologies Corporation (SpaceX), is skeptical about the viability of the VASIMR engine. One reason is the concern about radioactive debris falling to Earth in the event of an accident.

Musk is also skeptical that the VASIMR engine would be a significant improvement over chemical rockets, stating: “So people like Franklin – basically it’s a very interesting ion engine he’s got there, but it requires a big nuclear reactor. The ion engine is going to help a little bit, but not a lot in the absence of a big nuclear reactor.” Musk also points out that the big nuclear reactor would add a lot of weight to a rocket.

Chang Diaz dismisses the concerns about nuclear reactors in space, stating: “People are afraid of nuclear power. Chernobyl, Three Mile Island, Fukushima – it is a little misunderstood. But if humans are truly going to explore space, we eventually will have to come to grips with the concept.”

Another vocal critic of the VASIMR engine is Robert Zubrin, president of The Mars Society, who designed the Mars Direct plan to colonize Mars and wrote the popular book The Case For Mars. He has gone as far as to call the VASIMR engine a “hoax”.

Zubrin wrote in SpaceNews: “To achieve his much-repeated claim that VASIMR could enable a 39-day one-way transit to Mars, Chang Diaz posits a nuclear reactor system with a power of 200,000 kilowatts and a power-to-mass ratio of 1,000 watts per kilogram. In fact, the largest space nuclear reactor ever built, the Soviet[-era] Topaz, had a power of 10 kilowatts and a power-to-mass ratio of 10 watts per kilogram. There is thus no basis whatsoever for believing in the feasibility of Chang Diaz’s fantasy power system.”

Chang Diaz, however, says in his paper: “Assuming advanced technologies [emphasis added] that reduce the total specific mass to less than 2 kg/kW, trip times of less than 60 days will be possible with 200 MW of electrical power. One-way trips to Mars lasting less than 39 days are even conceivable using 200 MW of power if technological advances allow the specific mass to be reduced to near or below 1 kg/kW.”

LEFT: Artist’s rendition of a lunar tug with 200 kW solar powered VASIMR®. RIGHT: Artist’s rendition of a human mission to Mars with 10 MW NEP-VASIMR®. Images Credit: Ad Astra Rocket Company

In other words, Chang Diaz is allowing for further developments that would enable such a reactor.

Zubrin, however, stated: “[T]he fact that the [Obama] administration is not making an effort to develop a space nuclear reactor of any kind, let alone the gigantic super-advanced one needed for the VASIMR hyper drive, demonstrates that the program is being conducted on false premises.”

The 2011 NASA research paper “Multi-MW Closed Cycle MHD Nuclear Space Power Via Nonequilibrium He/Xe Working Plasma” by Ron J. Litchford and Nobuhiro Harada, indicates that such developments are feasible in the near future.

Whether the VASIMR engine is viable or not, in 2015, NASA awarded Chang Diaz’s firm – Ad Astra Rocket Company™ – a three-year, $9 million contract. Up to now, the VASIMR engine has fired at fifty kilowatts for one minute – still a long way from Chang Diaz’s goal of 200 megawatts.

In its current form, the VASIMR engine uses argon for fuel. The first stage of the rocket heats the argon to plasma and injects it into the booster. There, a radio frequency excites the ions in a process called ion cyclotron resonance heating. As they pick up energy, they are spun into a stream of superheated plasma and accelerated out the back of the rocket.

Video courtesy of Ad Astra Rocket Company

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Contract brings Dream Chaser flights closer to reality

Contract brings Dream Chaser flights closer to reality:

Image Credit: SNC

CAPE CANAVERAL, Fla. — In development for more than ten years, the Dream Chaser space plane is one step closer to flight. Sierra Nevada Corporation (SNC) has signed a contract with United Launch Alliance (ULA) to send the spacecraft to orbit.

“ULA is pleased to partner with Sierra Nevada Corporation to launch its Dream Chaser cargo system to the International Space Station in less than three years,” said Gary Wentz, ULA vice president of Human and Commercial Systems via a release issued by ULA. “We recognize the importance of on time and reliable transportation of crew and cargo to Station and are honored the Atlas V was selected to continue to launch cargo resupply missions for NASA.”

The contract calls for two Atlas V 552 flights that will boost the Dream Chaser to the International Space Station (ISS) as part of Sierra Nevada’s Cargo Resupply Services 2 (CRS2) contract with NASA.

The Dream Chaser is currently in testing at NASA Armstrong Flight Research Center near Edwards Air Force Base in California. The craft underwent its first ground tow to verify how the vehicle would behave during taxi operations upon returning from space. Additional tests at Armstrong are planned including glide flights dropped from a helicopter. According to SNC the software on the test vehicle is the operational version that will be used for the orbital vehicles.

The first Atlas V flight of Dream Chaser is currently slated to occur in 2020, launching from Space Launch Complex 41 at Cape Canaveral Air Force Station, in Florida. The flight will use an Atlas 552 with a dual engine Centaur upper stage. The second flight is scheduled for 2021. The Atlas V was chosen as the launch vehicle in part for its Category 3 certification from NASA (the designation identifies that it may be used for NASA’s most complex and critical missions).

“SNC recognizes the proven reliability of the Atlas V rocket and its availability and schedule performance makes it the right choice for the first two flights of the Dream Chaser,” said Mark Sirangelo, corporate vice president of SNC’s Space Systems.  “ULA is an important player in the market and we appreciate their history and continued contributions to space flights and are pleased to support the aerospace community in Colorado and Alabama,” added Sirangelo.

The Dream Chaser was originally part of NASA’s Commercial Crew program but was not selected during the Commercial Crew transportation Capability (CCtCap) phase of the program. Those missions were instead awarded to SpaceX for their Crewed Dragon and Boeing for their CST-100 Starliner capsule.

Dream Chaser is a lifting body design that returns via a runway instead of the more traditional parachute landings of SpaceX and Boeing. The cargo version of the Dream Chaser is designed to carry both pressurized and unpressurized cargo to and from the ISS with return and disposal services.





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