RELEASE : 13-181 NASA'S Chandra Turns up Black Hole Bonanza in Galaxy Next Door WASHINGTON -- Using data from NASA's Chandra X-ray Observatory, astronomers have discovered an unprecedented bonanza of black holes in the Andromeda Galaxy, one of the nearest galaxies to the Milky Way.

Using more than 150 Chandra observations, spread over 13 years, researchers identified 26 black hole candidates, the largest number to date, in a galaxy outside our own. Many consider Andromeda to be a sister galaxy to the Milky Way. The two ultimately will collide, several billion years from now.

"While we are excited to find so many black holes in Andromeda, we think it's just the tip of the iceberg," said Robin Barnard of Harvard-Smithsonian Center for Astrophysics (CfA) in Cambridge, Mass., and lead author of a new paper describing these results. "Most black holes won't have close companions and will be invisible to us."

The black hole candidates belong to the stellar mass category, meaning they formed in the death throes of very massive stars and typically have masses five to 10 times that of our sun. Astronomers can detect these otherwise invisible objects as material is pulled from a companion star and heated up to produce radiation before it disappears into the black hole.

The first step in identifying these black holes was to make sure they were stellar mass systems in the Andromeda Galaxy itself, rather than supermassive black holes at the hearts of more distant galaxies. To do this, the researchers used a new technique that draws on information about the brightness and variability of the X-ray sources in the Chandra data. In short, the stellar mass systems change much more quickly than the supermassive black holes.

To classify those Andromeda systems as black holes, astronomers observed that these X-ray sources had special characteristics: that is, they were brighter than a certain high level of X-rays and also had a particular X-ray color. Sources containing neutron stars, the dense cores of dead stars that would be the alternate explanation for these observations, do not show both of these features simultaneously. But sources containing black holes do.

The European Space Agency's XMM-Newton X-ray observatory added crucial support for this work by providing X-ray spectra, the distribution of X-rays with energy, for some of the black hole candidates. The spectra are important information that helps determine the nature of these objects.

"By observing in snapshots covering more than a dozen years, we are able to build up a uniquely useful view of M31," said co-author Michael Garcia, also of CfA. "The resulting very long exposure allows us to test if individual sources are black holes or neutron stars."

The research group previously identified nine black hole candidates within the region covered by the Chandra data, and the present results increase the total to 35. Eight of these are associated with globular clusters, the ancient concentrations of stars distributed in a spherical pattern about the center of the galaxy. This also differentiates Andromeda from the Milky Way as astronomers have yet to find a similar black hole in one of the Milky Way's globular clusters.

Seven of these black hole candidates are within 1,000 light-years of the Andromeda Galaxy's center. That is more than the number of black hole candidates with similar properties located near the center of our own galaxy. This is not a surprise to astronomers because the bulge of stars in the middle of Andromeda is bigger, allowing more black holes to form.

"When it comes to finding black holes in the central region of a galaxy, it is indeed the case where bigger is better," said co-author Stephen Murray of Johns Hopkins University and CfA. "In the case of Andromeda we have a bigger bulge and a bigger supermassive black hole than in the Milky Way, so we expect more smaller black holes are made there as well."

This new work confirms predictions made earlier in the Chandra mission about the properties of X-ray sources near the center of M31. Earlier research by Rasmus Voss and Marat Gilfanov of the Max Planck Institute for Astrophysics in Garching, Germany, used Chandra to show there was an unusually large number of X-ray sources near the center of M31. They predicted most of these extra X-ray sources would contain black holes that had encountered and captured low mass stars. This new detection of seven black hole candidates close to the center of M31 gives strong support to these claims.

"We are particularly excited to see so many black hole candidates this close to the center, because we expected to see them and have been searching for years," said Barnard.

These results will be published in the June 20 issue of The Astrophysical Journal. Many of the Andromeda observations were made within Chandra's Guaranteed Time Observer program.

NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra Program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass.

For Chandra images, multimedia and related materials, visit:


http://www.nasa.gov/chandra

For an additional interactive image, podcast, and video on the finding, visit:

http://chandra.si.edu

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RELEASE : 13-180 Marks on Martian Dunes May Reveal Tracks of Dry Ice Sleds PASADENA, Calif. -- NASA research indicates hunks of frozen carbon dioxide -- dry ice -- may glide down some Martian sand dunes on cushions of gas similar to miniature hovercraft, plowing furrows as they go.

Researchers deduced this process could explain one enigmatic class of gullies seen on Martian sand dunes by examining images from NASA's Mars Reconnaissance Orbiter (MRO) and performing experiments on sand dunes in Utah and California.

"I have always dreamed of going to Mars," said Serina Diniega, a planetary scientist at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., and lead author of a report published online by the journal Icarus. "Now I dream of snowboarding down a Martian sand dune on a block of dry ice."

The hillside grooves on Mars, called linear gullies, show relatively constant width -- up to a few yards or meters across -- with raised banks or levees along the sides. Unlike gullies caused by waterflows on Earth and possibly on Mars, they do not have aprons of debris at the downhill end of the gully. Instead, many have pits at the downhill end.

"In debris flows, you have water carrying sediment downhill, and the material eroded from the top is carried to the bottom and deposited as a fan-shaped apron," said Diniega. "In the linear gullies, you're not transporting material. You're carving out a groove, pushing material to the sides."

Images from MRO's High Resolution Imaging Science Experiment (HiRISE) camera show sand dunes with linear gullies covered by carbon dioxide frost during the Martian winter. The location of the linear gullies is on dunes that spend the Martian winter covered by carbon dioxide frost. The grooves are formed during early spring, researchers determined by comparing before-and-after images from different seasons. Some images have even caught bright objects in the gullies.

Scientists theorize the bright objects are pieces of dry ice that have broken away from points higher on the slope. According to the new hypothesis, the pits could result from the blocks of dry ice completely sublimating away into carbon-dioxide gas after they have stopped traveling.

"Linear gullies don't look like gullies on Earth or other gullies on Mars, and this process wouldn't happen on Earth," said Diniega. "You don't get blocks of dry ice on Earth unless you go buy them."

That is exactly what report co-author Candice Hansen, of the Planetary Science Institute in Tucson, Ariz., did. Hansen has studied other effects of seasonal carbon-dioxide ice on Mars, such as spider-shaped features that result from explosive release of carbon-dioxide gas trapped beneath a sheet of dry ice as the underside of the sheet thaws in spring. She suspected a role for dry ice in forming linear gullies, so she bought some slabs of dry ice at a supermarket and slid them down sand dunes.

That day and in several later experiments, gaseous carbon dioxide from the thawing ice maintained a lubricating layer under the slab and also pushed sand aside into small levees as the slabs glided down even low-angle slopes.

The outdoor tests did not simulate Martian temperature and pressure, but calculations indicate the dry ice would act similarly in early Martian spring where the linear gullies form. Although water ice, too, can sublimate directly to gas under some Martian conditions, it would stay frozen at the temperatures at which these gullies form, the researchers calculate.

"MRO is showing that Mars is a very active planet," Hansen said. "Some of the processes we see on Mars are like processes on Earth, but this one is in the category of uniquely Martian."

Hansen also noted the process could be unique to the linear gullies described on Martian sand dunes.

"There are a variety of different types of features on Mars that sometimes get lumped together as 'gullies,' but they are formed by different processes," she said. "Just because this dry-ice hypothesis looks like a good explanation for one type doesn't mean it applies to others."
The University of Arizona Lunar and Planetary Laboratory operates the HiRISE camera, which was built by Ball Aerospace & Technologies Corp. of Boulder, Colo. JPL manages MRO for NASA's Science Mission Directorate in Washington. Lockheed Martin Space Systems of Denver built the orbiter.

To see images of the linear gullies and obtain more information about MRO, visit:

 

http://www.nasa.gov/mro

For more about HiRISE, visit:

http://hirise.lpl.arizona.edu

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MEDIA ADVISORY : M13-095 NASA Schedules Media Events and Coverage for New Solar Mission Launch WASHINGTON -- NASA's Interface Region Imaging Spectrograph (IRIS) mission is scheduled to launch at 7:27 p.m. PDT (10:27 p.m. EDT) Wednesday, June 26, from Vandenberg Air Force Base in California.

Launch on an Orbital Sciences Corporation Pegasus XL rocket is targeted for the middle of a five-minute launch window. Live NASA Television coverage of the launch begins at 6 p.m. PDT (9 p.m. EDT). NASA TV also will air an IRIS prelaunch news conference and science briefing beginning at noon PDT (3 p.m. EDT) on Tuesday, June 25.

IRIS is a NASA Small Explorer Mission to observe how solar material moves, gathers energy and heats up as it travels through a little-understood region in the sun's lower atmosphere. This interface region between the sun's photosphere and corona powers its dynamic million-degree atmosphere and drives the solar wind.

The drop of the air-launched Pegasus from Orbital's L-1011 carrier aircraft will occur over the Pacific Ocean at an altitude of 39,000 feet, about 100 miles northwest of Vandenberg off the central coast of California, south of Big Sur.

The IRIS News Center at Kennedy's Vandenberg Resident Office will be staffed starting Monday, June 24 and may be reached between 8 a.m. and 4:30 p.m. at 805-605-3051.

For complete details on media registration, media events, and live launch coverage on NASA Television, visit:

http://go.nasa.gov/13L6djG

NASA also will host a Google+ Hangout at 1:30 p.m. EDT June 25, on the IRIS mission. Social media followers may submit questions on Twitter and Google+ in advance and during the event using the hashtag #askNASA.

Before the hangout begins, NASA will open a thread on its Facebook page where questions may be posted. The hangout can be viewed live on NASA's Google+ page, the NASA Television YouTube channel or NASA TV. For more information and to join the hangout, visit:

http://go.nasa.gov/17039WY

Extensive prelaunch and launch day coverage of the IRIS spacecraft will be available on NASA's home page at:

http://www.nasa.gov

To view the IRIS webcast and launch blog, and learn more about the mission, visit:

http://www.nasa.gov/iris

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A team of scientists lead by Francois Fressin of the Harvard-Smithsonian Center for Astrophysics, used the latest data from NASA's Kepler mission to find that one in six stars have "a planet 0.8 - 1.25 times the size of Earth in an orbit of 85 days or less." Extrapolated out to the Universe as a whole, the potential number becomes mind-boggling.

With the advent of powerful space infrared telescopes like the Spitzer Space Telescope and the (recently deceased) Herschel Space Telescope, astronomers have been able to study the properties of dust in galaxies so remote that their light has been traveling towards us for over ninety percent of the age of the universe. That these distant objects are detected at all is because they are very bright in the infrared, and they are bright because they are making huge numbers of stars whose light warms the dust that in turn radiates at infrared wavelengths.

In the image below A field of distant galaxies as seen at long infrared wavelengths over a region about one-third the size of the moon. The poor spatial resolution of infrared telescopes coupled with the great distances of the galaxies preclude seeing their spiral (or other) structures, but their different colors are apparent. A new study of 2500 distant infrared galaxies concludes they are more varied than local galaxies, probably due to different kinds of dust and dusty conditions in these early objects. 

 

                                

Local galaxies - those only hundreds of millions of light-years away in our cosmic neighborhood - provide a template for understanding how galaxies behave, and are the basis for models of their distant cousins. It has been known for decades that the early universe was actively making stars in galaxies. A key question for astronomers is whether distant galaxies are different enough from local ones that different physical processes need to be included in the models, or whether comparisons with local objects are valid.

CfA astronomer Ho Seong Hwang and a large team of his collaborators have analyzed a large sample of distant galaxies to address this question. The Herschel Space Telescope during its lifetime observed many distant infrared galaxies. The astronomers selected 2500 of them from a set of over fifty thousand, based on their having clear detections at several infrared wavelengths with ancillary data from other missions. The sample was selected in a way that was independent of observer preferences, like extreme brightness, that might compromise the conclusions, the first time this has been done for such a large sample.

The results were surprising. The scientists found that the dust in remote luminous galaxies tended to be warmer than it is in local galaxies of the same luminosity. Together with other indicators, the data suggest that the character of the dust and its environments have evolved with time in ways that are still not well known. Probably as a result of the dust variations there also appears to be a greater diversity of types of galaxies in the early universe.

Finally, the new paper notes, in accord with other recent papers, that there are indications that these galaxies may have started forming sooner after the big bang than had been anticipated in some old models.

In 2012, the Brightest of Reionizing Galaxies (BoRG) survey, which uses Hubble's WFC3 to search for the brightest galaxies around 13 billion years ago, when light from the first stars burned off a fog of cold hydrogen in a process called reionisation located five clustered galaxies so distant that their light has taken 13.1 billion years to reach us. We are seeing them just 600 million years after the Universe's birth in the Big Bang.

Galaxy clusters are the largest structures in the Universe, comprising hundreds to thousands of galaxies bound together by gravity. This developing cluster, or protocluster, seen as it looked 13 billion years ago, presumably has grown into one of today's massive cities of galaxies, comparable to the nearby Virgo cluster of more than 2000 galaxies.

"These galaxies formed during the earliest stages of galaxy assembly, when galaxies had just started to cluster together," says the study's leader, Michele Trenti (University of Cambridge, UK and University of Colorado). "The result confirms our theoretical understanding of the buildup of galaxy clusters. And, Hubble is just powerful enough to find the first examples of them at this distance."

Most galaxies in the Universe reside in groups and clusters, and astronomers have probed many of these in detail at a range of distances. But finding clusters in the early phases of construction has been challenging because they are rare and dim.

"We need to look in many different areas because the odds of finding something this rare are very small," says Trenti who used Hubble's sharp-eyed Wide Field Camera 3 (WFC3) to pinpoint the galaxy clusters. "It's like playing a game of Battleship: the search is hit and miss. Typically, a region has nothing, but if we hit the right spot, we can find multiple galaxies."

Because these distant, fledgling clusters are so dim, the team hunted for the systems' brightest galaxies. These brilliant galaxies act as billboards, advertising cluster construction zones. From simulations, the astronomers expect galaxies at early epochs to be clustered together. Because brightness correlates with mass, the most luminous galaxies pinpoint the location of developing clusters.

These powerful light beacons are found in deep wells of dark matter, an invisible form of matter that makes up the underlying gravitational scaffolding for galaxy formation. The team expects many fainter galaxies that were not seen in these observations to inhabit the same neighborhood.

The five bright galaxies spotted by Hubble are about one-half to one-tenth the size of our Milky Way, yet are comparable in brightness. The galaxies are bright and massive because they are being fed large amounts of gas through mergers with other galaxies. The team's simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical radio similar to the Virgo Cluster's Messier 87 (image at top of page).

These observations demonstrate the progressive buildup of galaxies and provide further support for the hierarchical model of galaxy assembly, in which small objects accrete mass, or merge, to form bigger objects over a smooth and steady, but dramatic, process of collision and collection.

The team estimated the distance to the newly found galaxies based on their colors. Astronomers now plan to follow up with spectroscopic observations, which will help them precisely calculate the cluster's distance. These observations will also yield the velocities of the galaxies and show whether they are gravitationally bound to each other.

The image below at left, taken in visible and near-infrared light, reveals the location of five galaxies clustered together just 600 million years after the Universe’s birth in the Big Bang. The circles pinpoint the galaxies. The sharp-eyed Wide Field Camera 3 aboard the NASA/ESA Hubble Space Telescope spied the galaxies in a random sky survey.

 

          

 

The developing cluster is the most distant ever observed. The average distance between them is comparable to that of the galaxies in the Local Group, consisting of two large spiral galaxies, the Milky Way and the Andromeda Galaxy, and a few dozen small dwarf galaxies. The close-up images at right, taken in near-infrared light, show the galaxies.

Simulations show that the galaxies will eventually merge and form the brightest central galaxy in the cluster, a giant elliptical similar to the Virgo cluster’s Messier 87. Galaxy clusters are the largest structures in the Universe, comprising hundreds to thousands of galaxies bound together by gravity. The developing cluster presumably will grow into a massive galactic city, similar in size to the nearby Virgo Cluster, a collection of more than 2000 galaxies.

 The Daily Galaxy via Cfa and ESA/Hubble Information Center

Image Credit: NASA, ESA, M. Trenti (University of Cambridge, UK and University of Colorado, Boulder, USA), L. Bradley (STScI), and the BoRG team; ESA GOOD-S

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About Elizabeth Howell

Elizabeth Howell (M.Sc. Space Studies '12) is an award-winning freelance space journalist living in Ottawa, Canada. She reported on three shuttle launches, including the first launch "tweetup" during STS-129. Besides Universe Today, she regularly writes for SPACE.com, the Space Exploration Network and All About Space, among other publications. You can follow her on Twitter @howellspace or contact her at her website.

M31 and M33 are the nearest spiral-galaxy analogues to our own Milky Way, and distances for those galaxies are important since they help constrain the expansion rate and age of the Universe (image credit: R. B. Andreo, cropped/assembly by DM).

Optical and near-infrared images highlight how dust obscures light emitted from targets along the sight-line, and that the level of obscuration is wavelength dependent. New distances established for M31 and M33 are based on near-infrared observations, which are less sensitive to that obscuration (image credit: Alves et al. 2001).

A relation exists between a Cepheid’s periodic brightness variations and its mean luminosity. Astronomers use that trend, which was discovered in the early 1900s by Henrietta Leavitt, to establish distances to galaxies hosting Cepheids. In the above figure the horizontal axis features the pulsation period, and the vertical axis defines a proxy for luminosity (image credit: Fig 2 from Riess et al., arXiv/ApJ).

A subset of the distances deduced for M33, as compiled from estimates featured in the NASA/IPAC Extragalactic Database (Steer & Madore). On the vertical axis is the distance to the galaxy in units of lightyears, and the year is cited on the horizontal axis.  The red arrow and black datum indicate the new near-infrared based distance from Gieren et al. (image credit: DM).

Gieren et al. used the 8.2-m Very Large Telescope (Yepun) to image stars in M33, and deduce the distance to that galaxy (image credit: G. Hüdepohl/ESO).

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by Jason Major on June 10, 2013

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Like gravitational parking spaces, Lagrange points provide locations where spacecraft can be positioned to conduct valuable scientific observations of the Universe and perhaps someday even offer foundations for more permanent human outposts. Named after Italian-French mathematician Joseph-Louis Lagrange, who first proposed their existence in a 1772 paper, there are 5 such points within the Earth-Sun (as well as the Earth-Moon) orbital relationship, named numerically L1 through L5. Although there’s no actual physical mass at each of these locations, objects can be placed into orbit around them… in fact, the solar system has been doing just that for billions of years!

For a better idea of how Lagrange points work, Sixty Symbols has released a video featuring Professor Mike Merrifield, professor of astronomy at the University of Nottingham. Check it out above.

Credit: Sixty Symbols videos by Brady Haran

Tagged as: L1, L2, Lagrange, Lagrangian, orbit, Sixty Symbols, space, video