Wednesday, July 16, 2014

Discover and Explore with the Chandra Skymap

Discover and Explore with the Chandra Skymap:

American Archives Month (each October) is an exciting time around here. We spend a lot of time working through the Chandra archive to bring you the best and most interesting objects in the X-ray Universe that have made their way across space and time (via photons) to Chandra's detectors.

Skymap

It has been a personal goal of mine, since taking this job as Chandra science imager about four years ago, to create an interactive tool for the public to engage with the Chandra archive of released imagery in a new and innovative way. For this to work, a few pieces of the puzzle had to fall into place.

I've blogged about metadata before and -- as you might expect -- accurate, detailed and complete metadata for our entire archive of public images is the keystone to creating a tool such as the new Chandra Skymap. Metadata is what drives all of the content behind the application. Since there's no good way to automate the “retro-tagging” (that is, tagging images we’ve already released in the past) of our image archive, it took a few years to get through all of those images by hand. We finally completed that task at the end of last year and then set our sights upon creating the Skymap tool.

There were some false starts along the way, mainly due to limitations as a programmer, learning new languages and libraries. But as I was pulling my hair out trying to figure this out last summer, a colleague recommended utilizing javascript with the D3 (Data-Driven Documents) visualization library. I was vaguely familiar with D3, mainly from playing around with interactive data visualizations published by The New York Times and written by Mike Bostock (the creator of D3). D3 turned out to be the answer to the coding problems, but the new challenge was to learn javascript. Thankfully, the D3 documentation is extensive and Mike Bostock and many other programmers have provided a wealth of resources in the form of small bits of example code that could be utilized as part of a larger project. Through all of this, I developed two new skills: first, the ability to completely tax my computer by testing how many browser tabs I could hold open at once, and, second, honing the ability to construct the perfect Google query regarding a particular javascript or D3 question. Utilizing countless examples and answers to questions on StackExchange, I was able to build the Skymap I had pictured in my head years ago. This has been an extremely rewarding and fulfilling project and I'm very excited to share this new application with you today!

Here are some helpful tips to get you started using the new Chandra Skymap:

1. Everything about this tool is interactive. You can zoom into the map using your mouse scroll wheel, or by pinch-zoom, or using the buttons at the top left. You can also pan around by clicking and dragging while in zoom-mode.

2. You'll notice that as you hover over data points, the points are highlighted and a small information window pops up with a synopsis of the press release for that particular object. Each data point is also a link to the release for that object. Click on the point and you will go to its Photo Album page.

3. The controls at the bottom offer up various ways for you to filter the data to your liking. Also note that most of the text in the controls are actually links to more information -- click on them to find out more. If you're only interested in which distant galaxies Chandra has observed, de-select everything but "Galaxies & Galaxy Clusters" in the "Categories" panel and you'll only see distant galaxies in the Skymap.

4. If you would like to filter the data by the date of the release, click and drag to draw a box in the bottom panel "Release Date Filter" and then resize to your liking or drag it across the timeline to watch press releases pop into and out of the Skymap as you pan across time.

5. You might notice that some areas are clustered with overlapping data points. Some of these are multiple releases for the same object at different times, or closely spaced but separate objects. Careful use of the zoom feature and/or filters should allow you to uncover any data point. For example, if you happen to notice two data points from two different categories overlapping each other, you can toggle the category underneath off and then on to bring it to the front. Using the "Release Data Filter" can also help to uncover buried data points.

6. If you see a term on the map that you are unfamiliar with, click on the underlined link to find out more either from the Chandra site, or from Wikipedia.

Be sure to come back often, as the Chandra Skymap will instantly populate with new releases as they are published. We also envisioned some new features that will hopefully be added in the near future.

Enjoy discovering all that Chandra has to offer!

-Joe DePasquale, CXC



Posted by Nelio Inacio at 4:12 PM 0 comments

Preserving the Legacy of the X-ray Universe

Preserving the Legacy of the X-ray Universe:

Chandra Archive Collection

Every year, October is designated as American Archive Month. While many people may think "archive" means only dusty books and letters, there are, in fact, many other types of important archives. This includes the use of archives for major telescopes and observatories like NASA's Chandra X-ray Observatory.


The Chandra Data Archive (CDA) plays a central role in the mission by enabling the astronomical community - as well as the general public - access to data collected by the observatory. The primary role of the CDA is to store and distribute data, which the CDA does with the help of powerful search engines. The CDA is one of the legacies of the Chandra mission that will serve both the scientific community and the public for decades to come.

To celebrate and support American Archive Month, we have selected images from a group of eight objects in the CDA to be released to the public for the first time. These images represent the observations of thousands of objects that are permanently available to the world thanks to Chandra's archive.

More at http://chandra.harvard.edu/photo/2013/archives/

-Megan Watzke, CXC

Posted by Nelio Inacio at 4:11 PM 0 comments

FITS and Starts

FITS and Starts:

In continued recogintion of American Archives month, we've dusted off some raw data from recent Chandra press releases over the past year for inclusion in our openFITS collection. This brings the total collection up to 20 objects including supernova remnants, active galaxies, star forming regions, black holes, and pulsars and neutron stars. These data are ripe for exploration. The new data sets include the Vela Pulsar Jet, and supernova remnants

W49B and G1.9+0.3 (which also happens to be the Milky Way's most recent supernova remnant).

W49B



W49B is a special case for openFITS. We have somewhat broken with tradition and have provided more data than what was used in creating the press image (though technically, this isn't more data, just a different representation of the same data). W49B has been extensively observed with Chandra with over 2 days worth of observation time devoted to collecting information about this source. As a result, we have a very rich data set to work with, which can be sliced and diced into many different component images emphasizing different elements emitting X-ray light. I wrote a blog post about the quality of this data and provided some behind-the-scenes insight into the image earlier this year. In creating a multi-wavelength composite image, we decided to take a "less-is-more" approach and utilize two low and high energy, broad-band X-ray images colored green and blue in combination with radio and infrared data colored magenta and yellow respectively. This allowed for a dynamic, feature-rich and aesthetically pleasing image in which the component parts were clearly distinguishable, allowing the science behind this supernova remnant to shine through.

Well, now is your chance to dig in to the X-ray data and see what you can do with up to 6 different wavelengths of X-ray light!

-Joe DePasquale, Chandra Science Imager

Posted by Nelio Inacio at 4:11 PM 0 comments

Getting a Sense of Place in our Universe

Getting a Sense of Place in our Universe:

The biggest news this week, by far, has been a new study suggesting that Earth-sized planets in habitable zones may be very common. This is exciting news – who wouldn't want to have more cosmic planetary friends out there that maybe one day we'll be able to explore? By the latest accounts, there could be billions of Earth-like planets out there in our Milky Way galaxy.

Solar System

While this is indeed mind-boggling, it got us thinking about the sheer vastness and the enormous scale of the Universe that we can explore using modern telescopes. We live in one galaxy - the Milky Way - that astronomers estimate contains roughly 400 billion stars. The Earth is not in a particularly special place in this giant collection of stars. We're about two-thirds away from the center in one of the spiral arms, in the galactic suburbs, so to speak.

What's happening in the downtown where the supermassive black hole lies and the density of stars is much higher? Chandra and other telescopes have been looking to see. We've learned an incredible amount about this area over the years with Chandra including:

- How the black hole behaves,

- What it likes to eat,

- And even what it has done hundreds of years before we had the technology to observe it.

It's very humbling to consider our small place in the very big Galaxy. It's even more so when we think about our Galaxy being just one of billions of galaxies (each of which has its own billions of stars and probably planets). Most of these galaxies aren't alone in space. Rather, they belong to groups or clusters of galaxies that are bound together by gravity. Chandra has done some amazing work studying these collections of galaxies since most of them are filled with hot gas that emits X-rays. It's hard to summarize all that the mission has done in this area of astrophysics, but a decent snapshot can be found by perusing the images we've released on the subject.

And just when you think you've wrapped your head around what the cosmos has to offer, we have to throw in the mysteries of dark energy and dark matter that account for 96% of the Universe. That's right, all of the stuff we can see with telescopes - planets, stars, galaxies, clusters - account for a mere tiny fraction of what is out there in the Universe. So take a few minutes to enjoy the incredible work Kepler is doing in discovering planets in our Galaxy, and then maybe take another one to consider how much we still have yet to explore.

-Megan Watzke, CXC







Posted by Nelio Inacio at 4:10 PM 0 comments

Exploring the Third Dimension of Cassiopeia A

Exploring the Third Dimension of Cassiopeia A:

Casa

One of the most famous objects in the sky - the Cassiopeia A supernova remnant – will be on display like never before, thanks to NASA's Chandra X-ray Observatory and a new project from the Smithsonian Institution. A new three-dimensional (3D) viewer, being unveiled today, will allow users to interact with many one-of-a-kind objects from the Smithsonian as part of a large-scale effort to digitize many of the Institutions objects and artifacts.


Scientists have combined data from Chandra, NASA's Spitzer Space Telescope, and ground-based facilities to construct a unique 3D model of the 300-year old remains of a stellar explosion that blew a massive star apart, sending the stellar debris rushing into space at millions of miles per hour. The collaboration with this new Smithsonian 3D project will allow the astronomical data collected on Cassiopeia A, or Cas A for short, to be featured and highlighted in an open-access program -- a major innovation in digital technologies with public, education, and research-based impacts.

To coincide with Cas A being featured in this new 3D effort, a specially-processed version of Chandra's data of this supernova remnant is also being released. This new image shows with better clarity the appearance of Cas A in different energy bands, which will aid astronomers in their efforts to reconstruct details of the supernova process such as the size of the star, its chemical makeup, and the explosion mechanism. The color scheme used in this image is the following: low-energy X-rays are red, medium-energy ones are green, and the highest-energy X-rays detected by Chandra are colored blue.

More at http://chandra.harvard.edu/photo/2013/casa/

-Megan Watzke, CXC







Posted by Nelio Inacio at 4:10 PM 0 comments

Carnival of Space #328

Carnival of Space #328:

Welcome to this week's Carnival of Space. It's been a busy Universe out there so let's jump right into it.

The Urban Astronomer has an excellent recap of Hubble's observations of a very unusual asteroid. This asteroid not only has a comet-like tail, it has six of them. Oh yeah, and they apparently change.

Over at the Smithsonian's Air & Space blog, they discuss a very provocative issue: if we go back to the Moon, where should we go and, maybe more importantly, where shouldn't we?

In advance of the recent Maven launch to Mars, the good folks over at Universe Today feature an excellent video that summarizes where the Curiosity rover has been and also where it will be heading in the future.

Here at the Chandra blog, we discuss how the 3D model of the Cassiopeia A supernova remnant is now being featured in an exciting new 3D viewer created by the Smithsonian that was just rolled out last week.

Casa

The Here, There, and Everywhere (HTE) project traveled to the Phillips Library in Aurora, Illinois, and you can find out the reaction to the exhibit at the HTE blog.

Saturn

The stunning new image of Saturn (and Mars, Venus, and the Earth too) is highlighted in this post of the Meridian Journal. Learn more about this image that made the rounds of many news outlets and websites last week.

The Next Big Thing (NBT) looks at current research and testing being done to determine the best ways to bring back sample returns from destinations such as the Moon and asteroids. The NBT also reports that NBC will follow Virgin Galactic's development of SpaceShipTwo and broadcast Richard Branson and his children going into orbit in August 2014.

Stay tuned for more news from our very own Universe.

-Megan Watzke, CXC
Posted by Nelio Inacio at 4:09 PM 0 comments

Getting the Upper Hand on Understanding Neutron Stars

Getting the Upper Hand on Understanding Neutron Stars:

posted by chandra
on Wed, 2013-12-11 16:30


PSR B1509-58

When we released Chandra’s image of the pulsar known as PSR B1509-58 (or, B1509, for short), it received a lot of attention. It's a fascinating object. The pulsar at the center of the image is a rapidly spinning dense star that is spewing out energetic particles into beautiful structures spanning trillions of miles that glow in X-ray light. And, it looks like a giant hand. This fact helped trigger a whole host of other comments about this object found some 17,000 light years from Earth.

This month, scientists announced that they've been studying B1509 for reasons that have nothing to do with its hand-shaped appearance. Rather, they are trying to figure out how such a tiny object (the 12-mile-wide pulsar) can be so powerful. Researchers at the Los Alamos National Laboratory in New Mexico put out a press release that talks about this fascinating work.

In short, neutron stars like the one found in B1509 give scientists an opportunity to study forces in nature so extreme that they are impossible to recreate here on Earth.

This is an exciting and important example of how science in space can help research here on the ground, and vice versa. That's just the hand we've been dealt in our Universe (ba-da-dum).

-Megan Watzke, CXC
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Posted by Nelio Inacio at 4:08 PM 0 comments

Doubling Down With Rare White Dwarf Systems

Doubling Down With Rare White Dwarf Systems:

amcvn

In the middle of the twentieth century, an unusual star was spotted in the constellation of Canes Venatici (Latin for "hunting dogs"). Years later, astronomers determined that this object, dubbed AM Canum Venaticorum (or, AM CVn, for short), was, in fact, two stars. These stars revolve around each other every 18 minutes, and are predicted to generate gravitational waves - ripples in space-time predicted by Einstein.

The name AM CVn came to represent a new class of objects where one white dwarf star is pulling matter from a very compact companion star, such as a second white dwarf. (White dwarf stars are dense remains of Sun-like stars that have run out of fuel and collapsed to the size of the Earth.) The pairs of stars in AM CVn systems orbit each other extremely rapidly, whipping around one another in an hour, and in one case as quickly as five minutes. By contrast, the fastest orbiting planet in our Solar System, Mercury, orbits the Sun once every 88 days.

Despite being known for almost 50 years, the question has remained: where do AM CVn systems come from? New X-ray and optical observations have begun to answer that with the discovery of the first known systems of double stars that astronomers think will evolve into AM CVn systems.

The two binary systems - known by their shortened names of J0751 and J1741 - were observed in X-rays by NASA's Chandra X-ray Observatory and ESA's XMM-Newton telescope. Observations at optical wavelengths were made using the McDonald Observatory's 2.1-meter telescope in Texas, and the Mt. John Observatory 1.0-meter telescope in New Zealand.

The artist's illustration depicts what these systems are like now and what may happen to them in the future. The top panel shows the current state of the binary that contains one white dwarf (on the right) with about one-fifth the mass of the Sun and another much heavier and more compact white dwarf about five or more times as massive (unlike Sun-like stars, heavier white dwarfs are smaller).

More at http://chandra.harvard.edu/photo/2013/amcvn/

-Megan Watzke, CXC

Posted by Nelio Inacio at 4:08 PM 0 comments

Finding Patterns

Finding Patterns:

Clouds

Image: Frank Kovalchek, Wikimedia Commons

One of our favorite games to play with our kids is trying to find recognizable objects in clouds as they pass by on a sunny day. One cloud might look like an elephant, the next, a pirate ship.

The phenomenon where our brains find seemingly significant patterns in images or sounds has an actual name: pareidolia. For example, we might think we see a human on the face of the Moon, a lizard on Mars (see below) or recognize words when we play a recording in reverse. Even Leonardo da Vinci – a man of many talents - suggested that artists could use pareidolia as a creative exercise for painting.

NASA's Curiosity Image of Mars
pareidolia

Image: NASA/JPL-Caltech

One of our favorite places to experiment with pareidolia is in images from space. Take a look at this image of the object known as B1509-58, which was released from NASA's Chandra X-ray Observatory back in 2009.

B1509-58

Credit: NASA/CXC/SAO/P.Slane, et al.

Not surprisingly, this object was nicknamed the “Hand of God,” which quickly became a much more popular name than its slightly dull astronomical handle.

At the center of B1509 is a tiny dense spinning dead star known as a pulsar. This little dynamo is responsible for spewing energized particles that, in turn, are responsible for the “fingers” and other structures seen in this X-ray image. Even though scientists can explain this object’s shape without any references to extremities or deities, pareidolia is alive and well. http://chandra.harvard.edu/photo/2009/b1509/

There have been many posts about pareidolia in astronomy images and you can read some great examples here and here.

Here we present our version of cosmic cloud watching, but with Chandra, Spitzer or Hubble images. Starting at the top, we’ve placed the strongest visual objects (to us). Towards the end of the list, you might have to get more creative to find some shapes.

Horsehead Nebula

This object is probably the most obviously named. The image of a horse's head and neck is iconic and has been published in many forms over the past 100 years since its discovery. Hubble's latest image of the Horsehead Nebula shows it in infrared light where we get to see pillars of gas and dust formed by stellar winds and radiation.

What we see: a horse's head and neck.

Horsehead Nebula

Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Circinus X-1

A system where a neutron star is in orbit around a star several times the mass of the Sun, about 20,000 light years from Earth, within our Milky Way Galaxy.

Circinus X-1

Image: X-ray: NASA/CXC/Univ. of Wisconsin-Madison/S.Heinz et al; Optical: DSS; Radio: CSIRO/ATNF/ATCA

What we see: A skull!

Colliding Galaxy Pair

What looks like a celestial hummingbird is really the result of a collision between a spiral and an elliptical galaxy at a whopping 326 million light- years away. The flat disk of the spiral NGC 2936 is warped into the profile of a bird by the gravitational tug of the companion NGC 2937. The object was first cataloged as a "peculiar galaxy" by Halton Arp in the 1960s. This interacting galaxy duo is collectively called Arp 142.

Arp 142

Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

What we see. Definitely a penguin’s head coming out of the water.

NGC 602

The Small Magellanic Cloud - also known as the SMC - is one of the closest galaxies to the Milky Way. Because the SMC is so close and bright, it offers a chance to study phenomena that are difficult to examine in more distant galaxies. This image, a composite of X-ray, infrared and optical data, shows a cluster of bright young stars with masses similar to that of our Sun.

NGC 602

Image: X-ray: NASA/CXC/Univ.Potsdam/L.Oskinova et al; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech

What we see: Many people see a face, but we see a Pac man eating its dots.

Eta Carinae

Eta Carinae is a mysterious, extremely bright and unstable star located a mere stone's throw - astronomically speaking - from Earth at a distance of only about 7,500 light years. Eta Carinae is about 100 times bigger than our sun and is burning about one million times brighter than our own star. Radiation and stellar winds from Eta Carinae are sculpting and destroying the surrounding nebula, shown here in this infrared image of its gas and dust.

Eta Carinae

Image: NASA/JPL-Caltech

What we see. A person, in the carved out green areas inside the nebula.

W49b

Supernova remnants—that is, the debris field left behind after the explosion—are like snowflakes: No two are ever exactly the same. W49b has evolved into an unusual shape. Its expanding shell of gas contains important elements such as sulfur and silicon, oxygen and iron. These elements, which are critical to our existence here are Earth, were created both when the star was still living and in the explosion itself.

W49b

Image: X-ray: NASA/CXC/MIT/L.Lopez et al.; Infrared: Palomar; Radio: NSF/NRAO/VLA

What we see: Could be a flying bat.

On Pinterest? Pin horseheads and faces from http://www.pinterest.com/kimberlyarcand/2013-interesting-astronomy-images/

-Kim Arcand & Megan Watzke, CXC

Adapted from an earlier blog post at http://www.huffingtonpost.com/kimberly-k-arcand/i-spy-a-horses-head_b_45...
Posted by Nelio Inacio at 4:06 PM 0 comments

Extreme Power of Black Hole Revealed

Extreme Power of Black Hole Revealed:

RX J1532

Astronomers have used NASA's Chandra X-ray Observatory and a suite of other telescopes to reveal one of the most powerful black holes known. The black hole has created enormous structures in the hot gas surrounding it and prevented trillions of stars from forming.

The black hole is in a galaxy cluster named RX J1532.9+3021 (RX J1532 for short), located about 3.9 billion light years from Earth. The image here is a composite of X-ray data from Chandra revealing hot gas in the cluster in purple and optical data from the Hubble Space Telescope showing galaxies in yellow. The cluster is very bright in X-rays implying that it is extremely massive, with a mass about a quadrillion - a thousand trillion - times that of the sun. At the center of the cluster is a large elliptical galaxy containing the supermassive black hole.

The large amount of hot gas near the center of the cluster presents a puzzle. Hot gas glowing with X-rays should cool, and the dense gas in the center of the cluster should cool the fastest. The pressure in this cool central gas is then expected to drop, causing gas further out to sink in towards the galaxy, forming trillions of stars along the way. However, astronomers have found no such evidence for this burst of stars forming at the center of this cluster.

This problem has been noted in many galaxy clusters but RX J1532 is an extreme case, where the cooling of gas should be especially dramatic because of the high density of gas near the center. Out of the thousands of clusters known to date, less than a dozen are as extreme as RX J1532. The Phoenix Cluster is the most extreme, where, conversely, large numbers of stars have been observed to be forming.

More at http://chandra.harvard.edu/photo/2014/rxj1532/

-Megan Watzke, CXC
Posted by Nelio Inacio at 4:05 PM 0 comments

A New Look at an Old Friend

A New Look at an Old Friend:

Cena A

Astronomers have used NASA's Chandra X-ray Observatory and a suite of other telescopes to reveal one of the most powerful black holes known. The black hole has created enormous structures in the hot gas surrounding it and prevented trillions of stars from forming.

The black hole is in a galaxy cluster named RX J1532.9+3021 (RX J1532 for short), located about 3.9 billion light years from Earth. The image here is a composite of X-ray data from Chandra revealing hot gas in the cluster in purple and optical data from the Hubble Space Telescope showing galaxies in yellow. The cluster is very bright in X-rays implying that it is extremely massive, with a mass about a quadrillion - a thousand trillion - times that of the sun. At the center of the cluster is a large elliptical galaxy containing the supermassive black hole.

The large amount of hot gas near the center of the cluster presents a puzzle. Hot gas glowing with X-rays should cool, and the dense gas in the center of the cluster should cool the fastest. The pressure in this cool central gas is then expected to drop, causing gas further out to sink in towards the galaxy, forming trillions of stars along the way. However, astronomers have found no such evidence for this burst of stars forming at the center of this cluster.

This problem has been noted in many galaxy clusters but RX J1532 is an extreme case, where the cooling of gas should be especially dramatic because of the high density of gas near the center. Out of the thousands of clusters known to date, less than a dozen are as extreme as RX J1532. The Phoenix Cluster is the most extreme, where, conversely, large numbers of stars have been observed to be forming.

More at http://chandra.harvard.edu/photo/2014/cena/

-Megan Watzke, CXC
Posted by Nelio Inacio at 4:04 PM 0 comments

Runaway Pulsar Firing an Extraordinary Jet

Runaway Pulsar Firing an Extraordinary Jet:

IGR J11014

An extraordinary jet trailing behind a runaway pulsar is seen in this composite image that contains data from NASA's Chandra X-ray Observatory (purple), radio data from the Australia Compact Telescope Array (green), and optical data from the 2MASS survey (red, green, and blue). The pulsar - a spinning neutron star - and its tail are found in the lower right of this image (mouse over the image for a labeled version). The tail stretches for 37 light years , making it the longest jet ever seen from an object in the Milky Way galaxy, as described in our press release.

The pulsar, originally discovered by ESA's INTEGRAL satellite, is called IGR J1104-6103 and is moving away from the center of the supernova remnant where it was born at a speed between 2.5 million and 5 million miles per hour. This supersonic pace makes IGR J1104-6103 one of the fastest moving pulsars ever observed.

A massive star ran out of fuel and collapsed to form the pulsar along with the supernova remnant, the debris field seen as the large purple structure in the upper left of the image. The supernova remnant (known as SNR MSH 11-61A) is elongated along the top-right to bottom left direction, roughly in line with the tail's direction. These features and the high speed of the pulsar suggest that jets could have played an important role in the supernova explosion that formed IGR J1104-6103.

In addition to its exceptional length, the tail behind IGR J1104-6103 has other interesting characteristics. For example, there is a distinct corkscrew pattern in the jet. This pattern suggests that the pulsar is wobbling like a top as it spins, while shooting off the jet of particles.

More at http://chandra.harvard.edu/photo/2014/igrj11014/

-Megan Watzke, CXC
Posted by Nelio Inacio at 4:04 PM 0 comments

Life Is Too Fast, Too Furious for This Runaway Galaxy

Life Is Too Fast, Too Furious for This Runaway Galaxy:

posted by chandra
on Tue, 2014-03-04 16:57


ESO 137-001

The spiral galaxy ESO 137-001 looks like a dandelion caught in a breeze in this new composite image from the Hubble Space Telescope and the Chandra X-ray Observatory.

The galaxy is zooming toward the upper right of this image, in between other galaxies in the Norma cluster located over 200 million light-years away. The road is harsh: intergalactic gas in the Norma cluster is sparse, but so hot at 180 million degrees Fahrenheit that it glows in X-rays detected by Chandra (blue).

The spiral plows through the seething intra-cluster gas so rapidly - at nearly 4.5 million miles per hour - much of its own gas is caught and torn away. Astronomers call this "ram pressure stripping." The galaxy's stars remain intact due to the binding force of their gravity.

Tattered threads of gas, the blue jellyfish-tendrils sported by ESO 137-001 in the image, illustrate the process. Ram pressure has strung this gas away from its home in the spiral galaxy and out over intergalactic space. Once there, these strips of gas have erupted with young, massive stars, which are pumping out light in vivid blues and ultraviolet.

More at http://chandra.harvard.edu/photo/2014/eso137/

-Megan Watzke, CXC
Disclaimer: This service is provided as a free forum for registered users. Users' comments do not reflect the views of the Chandra X-ray Center and the Harvard-Smithsonian Center for Astrophysics.

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Posted by Nelio Inacio at 4:03 PM 0 comments

Chandra & XMM-Newton Provide Direct Measurement of Distant Black Hole's Spin

Chandra & XMM-Newton Provide Direct Measurement of Distant Black Hole's Spin:

RX J1131

Multiple images of a distant quasar are visible in this combined view from NASA's Chandra X-ray Observatory and the Hubble Space Telescope. The Chandra data, along with data from ESA's XMM-Newton, were used to directly measure the spin of the supermassive black hole powering this quasar. This is the most distant black hole where such a measurement has been made, as reported in our press release.

Gravitational lensing by an intervening elliptical galaxy has created four different images of the quasar, shown by the Chandra data in pink. Such lensing, first predicted by Einstein, offers a rare opportunity to study regions close to the black hole in distant quasars, by acting as a natural telescope and magnifying the light from these sources. The Hubble data in red, green and blue shows the elliptical galaxy in the middle of the image, along with other galaxies in the field.

The quasar is known as RX J1131-1231 (RX J1131 for short), located about 6 billion light years from Earth. Using the gravitational lens, a high quality X-ray spectrum - that is, the amount of X-rays seen at different energies - of RX J1131 was obtained.

The X-rays are produced when a swirling accretion disk of gas and dust that surrounds the black hole creates a multimillion-degree cloud, or corona near the black hole. X-rays from this corona reflect off the inner edge of the accretion disk. The reflected X-ray spectrum is altered by the strong gravitational forces near the black hole. The larger the change in the spectrum, the closer the inner edge of the disk must be to the black hole.

The authors of the new study found that the X-rays are coming from a region in the disk located only about three times the radius of the event horizon, the point of no return for infalling matter. This implies that the black hole must be spinning extremely rapidly to allow a disk to survive at such a small radius.

More at http://chandra.harvard.edu/photo/2014/rxj1131/

-Megan Watzke, CXC
Posted by Nelio Inacio at 4:03 PM 0 comments

What Makes an Astronomical Image Beautiful?

What Makes an Astronomical Image Beautiful?:

Submitted by chandra on Wed, 03/12/2014 - 14:19.

Astronomy is renowned for the beautiful images it produces. It's not hard to be impressed by an image like the Pillars of Creation or the Bullet Cluster, and the more eye-catching an image is, the bigger an audience it can potentially reach. So, as part of our job in astronomy outreach, we have each spent time thinking about what makes an astronomy image beautiful. As professionals, we’d like to go well beyond the intuition of the person who says, "I don't know anything about art, but I know what I like". One approach(1) is to list the key elements that make an image beautiful.

Two famous images, the Pillars of Creation from the Hubble Space Telescope on the left and the Bullet Cluster from the Chandra X-ray Observatory, Hubble and ground-based observatories on the right. Credit: left: NASA, ESA, STScI, J. Hester and P. Scowen (Arizona State University); right: X-ray: NASA/CXC/CfA/M.Markevitch et al.; Optical: NASA/STScI; Magellan/U.Arizona/D.Clowe et al.; Lensing Map: NASA/STScI; ESO WFI; Magellan/U.Arizona/D.Clowe et al.

Lars Lindberg Christensen and collaborators have done just that, in an excellent paper in the most recent issue of the open journal "Communicating Astronomy with the Public". After years of experience working with images from the Hubble Space Telescope, they have defined a set of 6 criteria that are important in determining the appeal of an astronomical image. These 6 criteria are photogenic resolution (equivalent to the number of stars which can fit side by side across an image), definition (the amount of structure or contrast in an image), color, composition (how the object or objects of interest fill the field of view), signal-to-noise ratio, and how well instrumental artifacts have been removed.

Here, I'll highlight a few of these criteria and how they relate to the images we make with Chandra data. There are some key differences between the optical or infrared data obtained with telescopes like Hubble or the Spitzer Space Telescope, and the X-ray data obtained with Chandra.

For the photogenic resolution they define a quantity rphoto that is the number of effective resolution elements across the field of view (FOV). The equation is rphoto=FOV/θeffective, where θeffective is the effective angular resolution. A higher rphoto results in a better quality image. So one tactic is to push for a very large FOV by making a mosaic of a large number of adjacent images, as some amateur astronomers do, or as Chandra users did to make a large mosaic of the Carina Nebula. The other option is to use data from a telescope with a very small θeffective, where Hubble is unsurpassed at optical wavelengths and Chandra is unsurpassed at X-ray wavelengths.



A mosaic of Chandra images of the Carina Nebula. Credit: NASA/CXC/PSU/L.Townsley et al.

The authors point out that the domain with high values of the photogenic resolution - between 1000 and 10,000 - was dominated for many years by Hubble, but that more recently other observatories such as Chandra, the MPG/ESO 2.2-meter telescope, the Canada France Hawaii Telescope and ESO's VISTA and VST telescopes have joined Hubble. We're happy to have been included in this elite group.

To make a color image using optical or infrared data, observations have to be made using different filters chosen in advance, such as B (blue), V (visual) and R (red). A color is then assigned to the image obtained with each filter – in this case blue, green and red are the obvious choices – and the images are combined to make a color image. With Chandra, the energy (or wavelength) of individual photons is recorded, so different wavelength ranges can be chosen afterwards, giving us extra flexibility in making an image. By picking out different wavelength ranges the same dataset can be used to show different features, so we can experiment to see what makes the most striking image, or the most useful one to explain a particular science result. The greatest flexibility with choosing different wavelength ranges comes when the signal-to-noise ratio is high.

This leads me to describe the main challenge for producing beautiful Chandra images: sometimes the signal-to-noise ratio isn't high. X-ray photons trace energetic events, such as regions close to a black hole, or the exploded guts of a massive star, but they tend to arrive from the cosmos in a trickle, rather than a flood. This limitation was most apparent early in the mission, when lots of different targets were observed and Chandra's observations usually involved short exposures. Later in the mission much deeper observations have been done, giving much higher signal-to-noise ratios and better images. For example, you can see the dramatic difference between these two images of the supernova remnant Cassiopeia A. The early Chandra image shown on the left had an exposure time of only 2 hours and doesn't look nearly as photogenic as a later image shown on the right, with an exposure time of 11 1/2 days.

Images of the supernova remnant Cassiopeia A. A comparison is shown between an early, short exposure (2 hr) Chandra image (left) and a later, deeper exposure (11.5 days; right). Credit: left: NASA/CXC/SAO/Rutgers/J.Hughes; right: NASA/CXC/MIT/UMass Amherst/M.D.Stage et al.

The signal-to-noise ratio is connected to the 2nd criterion, the definition in an image. If the signal-to-noise ratio is low because few counts have been detected, then this can seriously limit the amount of detailed structure that you can see in an image. Think about how much detail you can see in a painting that is well lit, compared to looking at one in the dark. Again, deep exposures help a lot. The deep observation of Cas A has significantly sharper features and more complicated structure than the shallow one.

Only a limited number of very deep observations can be made with Chandra each year. This means there is intense competition between astronomers to convince the members of the Chandra Time Assignment Committee to approve any observing proposals requiring a lot of observing time. Therefore, the science case has to be particularly strong, which becomes an advantage for us, because it means that we can publicize interesting science at the same time as showing off beautiful new images.

When we have only low signal-to-noise X-ray data to work with, we sometimes combine it with optical or infrared images, to capitalize on the high signal-to-noise in these other wavelengths. This can give a striking image, such as in this view of NGC 602.



A composite image of the star-forming region NGC 602, with Chandra X-ray data shown in purple, Hubble optical data shown in red, green and blue, and Spitzer infrared data shown in red. Credit: X-ray: NASA/CXC/Univ.Potsdam/L.Oskinova et al; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech.

The final criterion is instrumental artifact removal, where the relatively low count rates for Chandra are an advantage. When you detect a lot of very bright objects you tend to accumulate a lot of artifacts, so optical observations can require a lot of clean-up work. According to Christensen et al., one to two hundred hours can be spent manually cleaning a large image. Chandra images aren't free of artifacts, but they're not as much of a problem.

In their conclusion, Christensen et al. explain that the ideal case is for all six criteria to be fulfilled, giving a great image. It’s still possible to produce a great image with less, but it becomes more difficult and compromises have to be made, as they note.

Having explained some of the factors that help us produce beautiful Chandra images, we invite you to explore our photo album of images or our 3D image wall.

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(1): In this blog post I've discussed only one approach for thinking about how beautiful an image is. There are other approaches that consider aesthetics in general. My colleague Kimberley Arcand is involved in a project called "Aesthetics and Astronomy" which studies “the perception of multi-wavelength astronomical imagery and the effects of the scientific and artistic choices in processing astronomical data.”

-Peter Edmonds, CXC
Posted by Nelio Inacio at 4:02 PM 0 comments

Hardy Star Survives Supernova Blast

Hardy Star Survives Supernova Blast:

Submitted by chandra on Thu, 03/20/2014 - 14:01.

deml241

When a massive star runs out fuel, it collapses and explodes as a supernova. Although these explosions are extremely powerful, it is possible for a companion star to endure the blast. A team of astronomers using NASA's Chandra X-ray Observatory and other telescopes has found evidence for one of these survivors.

This hardy star is in a stellar explosion's debris field - also called its supernova remnant - located in an HII region called DEM L241. An HII (pronounced "H-two") region is created when the radiation from hot, young stars strips away the electrons from neutral hydrogen atoms (HI) to form clouds of ionized hydrogen (HII). This HII region is located in the Large Magellanic Cloud, a small companion galaxy to the Milky Way.

A new composite image of DEM L241 contains Chandra data (purple) that outlines the supernova remnant. The remnant remains hot and therefore X-ray bright for thousands of years after the original explosion occurred. Also included in this image are optical data from the Magellanic Cloud Emission Line Survey (MCELS) taken from ground-based telescopes in Chile (yellow and cyan), which trace the HII emission produced by DEM L241. Additional optical data from the Digitized Sky Survey (white) are also included, showing stars in the field.

More at http://chandra.harvard.edu/photo/2014/deml241/

-Megan Watzke, CXC
Posted by Nelio Inacio at 4:01 PM 0 comments

Monster "El Gordo" Galaxy Cluster is Bigger than Thought

Monster "El Gordo" Galaxy Cluster is Bigger than Thought:

posted by chandra
on Thu, 2014-04-03 11:22


El Gordo

This is a composite image of X-rays from Chandra and optical data from Hubble of the galaxy cluster ACT-CL J0102-4915, located about 7 billion light years from Earth. This cluster has been nicknamed "El Gordo" (or, "the fat one" in Spanish) because of its gigantic mass.

Scientists first announced the discovery of El Gordo with Chandra and ground-based optical telescopes in 2012. They determined that El Gordo is the most massive, the hottest, and gives off the most X-rays of any known galaxy cluster at its distance or beyond.

New data from the Hubble Space Telescope suggests El Gordo weighs as much as 3 million billion times the mass of our Sun. This is about 43 percent higher than the original estimate based on the X-ray data and dynamical studies.

More at http://chandra.harvard.edu/photo/2014/elgordo/

-Megan Watzke, CXC
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Posted by Nelio Inacio at 4:01 PM 0 comments

Supernova Cleans Up its Surroundings

Supernova Cleans Up its Surroundings:

G352.7-0.1

Supernovas are the spectacular ends to the lives of many massive stars. These explosions, which occur on average twice a century in the Milky Way, can produce enormous amounts of energy and be as bright as an entire galaxy. These events are also important because the remains of the shattered star are hurled into space. As this debris field - called a supernova remnant - expands, it carries the material it encounters along with it.

Astronomers have identified a supernova remnant that has several unusual properties. First, they found that this supernova remnant - known as G352.7-0.1 (or, G352 for short) - has swept up a remarkable amount of material, equivalent to about 45 times the mass of the Sun.

Another atypical trait of G352 is that it has a very different shape in radio data compared to that in X-rays. Most of the radio emission is shaped like an ellipse, contrasting with the X-ray emission that fills in the center of the radio ellipse. This is seen in a new composite image of G352 that contains X-rays from NASA's Chandra X-ray Observatory in blue and radio data from the National Science Foundation's Karl G. Jansky Very Large Array in pink. These data have also been combined with infrared data from the Spitzer Space Telescope in orange, and optical data from the Digitized Sky Survey in white. (The infrared emission to the upper left and lower right are not directly related to the supernova remnant.)

A recent study suggests that, surprisingly, the X-ray emission in G352 is dominated by the hotter (about 30 million degrees Celsius) debris from the explosion, rather than cooler (about 2 million degrees) emission from surrounding material that has been swept up by the expanding shock wave. This is curious because astronomers estimate that G352 exploded about 2,200 years ago, and supernova remnants of this age usually produce X-rays that are dominated by swept-up material. Scientists are still trying to come up with an explanation for this behavior.

More at http://chandra.harvard.edu/photo/2014/g352/

-Megan Watzke, CXC
Posted by Nelio Inacio at 4:00 PM 0 comments

Professional and Amateur Astronomers Join Forces

Professional and Amateur Astronomers Join Forces:

Pro-Am

We are perhaps living in the midst of a new "Golden Age" of astronomy. In the four hundred years since Galileo first trained his refracting optical telescope on the Moon, and Jupiter and its moons, we've seen staggering advances in the technology of telescopes. We've also benefited from the discoveries of light beyond the visible portions of the electromagnetic spectrum and the development of instruments sensitive to those wavelengths.

NASA developed and implemented its Great Observatories program to extend our view of the Universe far beyond that which our human eyes can see, giving us glimpses of the cosmos beyond our ancestors' wildest dreams. Over the past two decades, advancements in professional-grade detectors, optics and computing power have been welcomed by amateur astronomers as well. With a modest investment and a great deal of patience, a dedicated amateur astronomer can produce images that rival those of professional ground-based observatories from just ten years ago. In the spirit of Global Astronomy Month 2014, we present four views of our cosmos brought to you by NASA and two very dedicated amateur astronomers, Detlef Hartmann and Rolf Olsen, in an Astro Pro-Am collaboration.

After I spoke at the NorthEast Astro Imaging Conference in 2013, I decided to further investigate the depth and quality of both professional and amateur data that is available to anyone willing to do a little digging. I chose this as an opportunity to help forge a relationship between amateur astrophotographers and NASA by identifying several high-quality images that would be ideal candidates for a multi-wavelength, professional-amateur (or “pro-am”) collaboration. This was also a great venue to raise interest and awareness among the amateur astronomer/astrophotographer community as to the wealth of data available in NASA's various mission archives. People are often surprised when they learn that data from NASA's Great Observatories program is free to use.

I sought out the work of talented astrophotographers on astrobin, which eventually led me to the work of Detlef Hartmann. I reached out to Detlef regarding a possible collaboration combining his excellent work with data from Chandra and possibly other NASA observatories. He was enthusiastic about the idea and so we got to work identifying potential image candidates, most of which had very good X-ray data from Chandra and infrared data from NASA's Spitzer Space Telescope available. Detlef utilizes his own remote observatory in the Austrian Alps, which affords him the ability to take very long exposures in very good seeing conditions thus producing stunning images. This is a common theme among amateur astrophotographers that sets them apart from the professional observatories that are often oversubscribed and for which it is difficult to devote large amounts of time to one research project; amateur astronomers have the luxury of time.

Pro-Am
Centaurus A - Optical

It was by chance that I came across this blog post by "Bad Astronomer" Phil Plait detailing an amazing optical image of Cen A by Rolf Olsen. This extremely deep image of Cen A teases out the faintest details in the extended structure of this galaxy - all from a 10" telescope that Rolf built himself! In an effort to extend this Pro-Am collaboration to other astrophotographers, I contacted Rolf to see if he would be interested in working together on a multi-wavelength image of Cen-A and was met with the same enthusiastic response as Detlef's. We iterated a few times on an image combining Rolf's amazing work with our newly updated, deeper X-ray image, and again infrared data from Spitzer. Cen A is famous for its bright X-ray jet, but if you look very closely at Rolf's image, he also managed to capture faint evidence of that same jet in optical wavelengths as well.

This image release is hopefully the beginning of a fruitful collaboration with amateur astronomers around the world. We hope to release more images in the future. In the meantime, enjoy these four images and keep looking up!

-Joe DePasquale, Chandra Science Imager
Posted by Nelio Inacio at 4:00 PM 0 comments

Core-Halo Age Gradients in Young Stellar Clusters

Core-Halo Age Gradients in Young Stellar Clusters:

We are delighted to welcome a trio of guest bloggers to discuss their work related to the newest Chandra press release on star clusters and star formation. Konstantin Getman, Eric Feigelson, and Michael Kuhn are colleagues at Penn State University and are all involved in the Massive Young Star-Forming Complex Study in Infrared and X-ray (MYStIX) project led from that institution.

Mike Eric Kosta
Figure 1: From left to right, Michael Kuhn, Eric Feigelson, and Konstantin Getman.

For decades there has been much debate about how clusters of stars form from molecular clouds. In the simplest case of a small gravitationally collapsing cloud, a single star cluster ’rapidly’ forms during a few hundred thousand years. But in the case of star formation distributed in a filamentary and turbulent cloud, which may be more realistic for giant molecular clouds, multiple small clusters may form over a period of million(s) of years, later interacting and merging to form a single massive star cluster.

Wide age spreads for young stars in clusters are found using traditional age methods, and would seem to support the slow mode of star formation. For instance, recent optical studies of the nearest rich young stellar cluster, the Orion Nebula Cluster (ONC), often considered to be a benchmark of star formation, based on the optical ground-based and Hubble Space Telescope data find that the cluster has a mean age of around 2 million years and an age spread of 2-3 million years around the mean. However, several problems affect the age estimate analysis in ONC. Firstly, the optical data are blinded by the bright gas near the cluster core, thus missing many stellar members in the center. Secondly, the age estimates for individual stars could be highly uncertain. It thus can be difficult to disentangle real astrophysical ages from the observed age spread in the cluster.

In this context, we present a new estimator of pre-main sequence stellar ages derived from X-ray and near-infrared (NIR) properties of young stars that can be applied to more distant and obscured clusters than the nearby ONC. The method is also less sensitive to Galactic field stars and bright background light from the nebula. When applied to the ONC, our Chandra-based sample has nearly uniform sensitivity to young stars across the entire cluster. And instead of evaluating the age spread for individual stars, we estimate median ages of stars in rings at different distances from the center of the cluster (Figure 2). By doing so we discover that the core of the ONC cluster is younger (1.2 million years old) than the halo of the cluster (about 2 million years old). We obtain even more dramatic results – with a core only 0.2 Myr old – for the second-richest cluster in the Orion Molecular Clouds, NGC 2024 associated with Flame Nebula.

The first implication of our results is that age spreads in young stellar clusters are real: they do not arise from a single nearly-instantaneous burst of star formation. If clusters truly formed exceedingly rapidly, our age estimates for different cluster subregions would be similar. Our results, however, do not specify a precise mechanism of asynchronous formation. Perhaps star formation continues longer in the core region, accelerating until the gas is depleted. Perhaps gaseous filaments feed material for continued star formation into the core. Perhaps older stars are ejected into the cluster halo during subcluster mergers. Or perhaps all of these mechanisms are involved.

We hope that computer simulations of the movement of cloud material and newborn stars can now focus on reproducing our results for the Orion and Flame Nebula clusters to give realistic understanding of cluster formation processes. And we will extend our empirical studies to other rich young stellar clusters in the solar neighborhood.

ONC

Figure 2: Chandra images of the ONC (left) and NGC 2024 (right) young stellar clusters. Rings at different distances from the centre of the cluster used in our age analysis are marked by the ellipses of different colors. The numbers state our derived median ages for the stars (in million years) within the different rings of the clusters.
Posted by Nelio Inacio at 3:59 PM 0 comments

NASA's Chandra Delivers New Insight into Formation of Star Clusters

NASA's Chandra Delivers New Insight into Formation of Star Clusters:

Flame Nebula

Stars are often born in clusters, in giant clouds of gas and dust. Astronomers have studied two star clusters using NASA's Chandra X-ray Observatory and infrared telescopes and the results show that the simplest ideas for the birth of these clusters cannot work, as described in our latest press release.

This composite image shows one of the clusters, NGC 2024, which is found in the center of the so-called Flame Nebula about 1,400 light years from Earth. In this image, X-rays from Chandra are seen as purple, while infrared data from NASA's Spitzer Space Telescope are colored red, green, and blue.

A study of NGC 2024 and the Orion Nebula Cluster, another region where many stars are forming, suggest that the stars on the outskirts of these clusters are older than those in the central regions. This is different from what the simplest idea of star formation predicts, where stars are born first in the center of a collapsing cloud of gas and dust when the density is large enough.

The research team developed a two-step process to make this discovery. First, they used Chandra data on the brightness of the stars in X-rays to determine their masses. Next, they found out how bright these stars were in infrared light using data from Spitzer, the 2MASS telescope, and the United Kingdom Infrared Telescope. By combining this information with theoretical models, the ages of the stars throughout the two clusters could be estimated.

According to the new results, the stars at the center of NGC 2024 were about 200,000 years old while those on the outskirts were about 1.5 million years in age. In Orion, the age spread went from 1.2 million years in the middle of the cluster to nearly 2 million years for the stars toward the edges.

More at http://chandra.harvard.edu/photo/2014/flame/

-Megan Watzke, CXC
Posted by Nelio Inacio at 3:59 PM 0 comments
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