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  • richardmitnick 12:16 pm on March 23, 2017 Permalink | Reply
    Tags: Andromeda galaxy, Andromeda's Bright X-Ray Mystery Solved by NuSTAR, , , , , , Swift J0042.6+4112   

    From JPL-Caltech: “Andromeda’s Bright X-Ray Mystery Solved by NuSTAR” 

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    JPL-Caltech

    March 23, 2017
    Elizabeth Landau
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-354-6425
    elizabeth.landau@jpl.nasa.gov

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    NASA’s Nuclear Spectroscope Telescope Array, or NuSTAR, has identified a candidate pulsar in Andromeda — the nearest large galaxy to the Milky Way. This likely pulsar is brighter at high energies than the Andromeda galaxy’s entire black hole population. Image credit: NASA/JPL-Caltech/GSFC/JHU


    NASA/NuSTAR

    The Milky Way’s closest neighbor, Andromeda, features a dominant source of high-energy X-ray emission, but its identity was mysterious until now. As reported in a new study, NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) mission has pinpointed an object responsible for this high-energy radiation.

    The object, called Swift J0042.6+4112, is a possible pulsar, the dense remnant of a dead star that is highly magnetized and spinning, researchers say. This interpretation is based on its emission in high-energy X-rays, which NuSTAR is uniquely capable of measuring. The object’s spectrum is very similar to known pulsars in the Milky Way.

    It is likely in a binary system, in which material from a stellar companion gets pulled onto the pulsar, spewing high-energy radiation as the material heats up.

    “We didn’t know what it was until we looked at it with NuSTAR,” said Mihoko Yukita, lead author of a study about the object, based at Johns Hopkins University in Baltimore. The study is published in The Astrophysical Journal.

    This candidate pulsar is shown as a blue dot in a NuSTAR X-ray image of Andromeda (also called M31), where the color blue is chosen to represent the highest-energy X-rays. It appears brighter in high-energy X-rays than anything else in the galaxy.

    The study brings together many different observations of the object from various spacecraft. In 2013, NASA’s Swift satellite reported it as a high-energy source, but its classification was unknown, as there are many objects emitting low energy X-rays in the region. The lower-energy X-ray emission from the object turns out to be a source first identified in the 1970s by NASA’s Einstein Observatory. Other spacecraft, such as NASA’s Chandra X-ray Observatory and ESA’s XMM-Newton had also detected it. However, it wasn’t until the new study by NuSTAR, aided by supporting Swift satellite data, that researchers realized it was the same object as this likely pulsar that dominates the high energy X-ray light of Andromeda.

    Traditionally, astronomers have thought that actively feeding black holes, which are more massive than pulsars, usually dominate the high-energy X-ray light in galaxies. As gas spirals closer and closer to the black hole in a structure called an accretion disk, this material gets heated to extremely high temperatures and gives off high-energy radiation. This pulsar, which has a lower mass than any of Andromeda’s black holes, is brighter at high energies than the galaxy’s entire black hole population.

    Even the supermassive black hole in the center of Andromeda does not have significant high-energy X-ray emission associated with it. It is unexpected that a single pulsar would instead be dominating the galaxy in high-energy X-ray light.

    “NuSTAR has made us realize the general importance of pulsar systems as X-ray-emitting components of galaxies, and the possibility that the high energy X-ray light of Andromeda is dominated by a single pulsar system only adds to this emerging picture,” said Ann Hornschemeier, co-author of the study and based at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.

    Andromeda is a spiral galaxy slightly larger than the Milky Way. It resides 2.5 million light-years from our own galaxy, which is considered very close, given the broader scale of the universe. Stargazers can see Andromeda without a telescope on dark, clear nights.

    “Since we can’t get outside our galaxy and study it in an unbiased way, Andromeda is the closest thing we have to looking in a mirror,” Hornschemeier said.

    NuSTAR is a Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI). The spacecraft was built by Orbital Sciences Corp., Dulles, Virginia. NuSTAR’s mission operations center is at UC Berkeley, and the official data archive is at NASA’s High Energy Astrophysics Science Archive Research Center. ASI provides the mission’s ground station and a mirror archive. JPL is managed by Caltech for NASA.

    For more information on NuSTAR, visit:

    http://www.nasa.gov/nustar

    http://www.nustar.caltech.edu

    See the full article here .

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    NASA JPL Campus

    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 3:10 pm on March 3, 2017 Permalink | Reply
    Tags: Andromeda galaxy, , , , , Halos touching?, , Who cares? Pay your taxes.   

    From Science Vibe: “ASTRONOMERS FEAR Milky Way on COLLISION PATH with ANDROMEDA” 

    [OF COURSE IT IS, WE ALL KNOW THAT ALREADY. BUT, NOT NOW, SO PAY YOUR TAXES.]

    Science Vibe bloc

    SCIENCE VIBE

    March 2, 2017
    No writer credit

    1
    No image caption. No image credit.

    Though the merger of the Milky Way and Andromeda galaxy isn’t expected to happen for another 4 billion years, the recent discovery of a massive halo of hot, ionized gas around Andromeda may mean our galaxies are already touching. Using the Hubble Space Telescope, astrophysicist Nicholas Lehner and a team of scientists were able to identify halo at least 2 million light-years in diameter surrounding the galaxy.

    The Andromeda Galaxy is the largest in a collection of about 54 galaxies in the Local Group, which includes the Milky Way.

    Local Group. Andrew Z. Colvin 3 March 2011
    Local Group. Andrew Z. Colvin 3 March 2011

    With twice as many stars as the Milky Way, it shines 25% brighter and can be seen with the naked eye from rural skies. If the halo extends a million light years in our direction, our two galaxies are much closer to touching than previously thought. We may even be mingling molecules.

    Lehner describes the halos as the “gaseous atmospheres of galaxies.” To find and study the nearly-invisible halo, the team sought out quasars. The brightest quasar, 3C273 in Virgo, can be seen in a 6-inch telescope. Their pinpoint nature makes them the perfect probes for the job.

    “As the light from the quasars travels toward Hubble, the halo’s gas will absorb some of that light and make the quasar appear a little darker in just a very small wavelength range,” J. Christopher Howk, an associate professor of physics at Notre Dame, told reporters. “By measuring the dip in brightness, we can tell how much halo gas from M31 there is between us and that quasar.”

    Astronomers have observed halos around 44 other galaxies, but never one as massive as Andromeda, where so many quasars are available to clearly define its extent. The previous 44 were all extremely distant galaxies, with only a single quasar to determine halo size and structure.

    The halo is estimated to contain half the mass of the stars in the Andromeda galaxy itself, in the form of hot diffuse gas. Although it is mostly composed of ionized hydrogen, Andromeda’s aura is rich in heavier elements that likely come from supernovae. They erupt within the galaxy and blow iron, silicon, oxygen and other elements into space. Nearly half of all the heavy elements made by Andromeda’s stars have been expelled beyond the galaxy’s 200,000-light-year-diameter stellar disk.

    See the full article here .

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  • richardmitnick 2:37 pm on February 22, 2017 Permalink | Reply
    Tags: Andromeda galaxy, , , ,   

    From Fermi: “NASA’s Fermi Finds Possible Dark Matter Ties in Andromeda Galaxy” 

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    Fermi

    Feb. 21, 2017
    Claire Saravia
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    NASA’s Fermi Gamma-ray Space Telescope has found a signal at the center of the neighboring Andromeda galaxy that could indicate the presence of the mysterious stuff known as dark matter. The gamma-ray signal is similar to one seen by Fermi at the center of our own Milky Way galaxy.

    1

    Gamma rays are the highest-energy form of light, produced by the universe’s most energetic phenomena. They’re common in galaxies like the Milky Way because cosmic rays, particles moving near the speed of light, produce gamma rays when they interact with interstellar gas clouds and starlight.

    Surprisingly, the latest Fermi data shows the gamma rays in Andromeda — also known as M31 — are confined to the galaxy’s center instead of spread throughout. To explain this unusual distribution, scientists are proposing that the emission may come from several undetermined sources. One of them could be dark matter, an unknown substance that makes up most of the universe.


    NASA’s Fermi telescope has detected a gamma-ray excess at the center of the Andromeda galaxy that’s similar to a signature Fermi previously detected at the center of our own Milky Way. Watch to learn more.
    Credits: NASA’s Goddard Space Flight Center/Scott Wiessinger, producer

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    The gamma-ray excess (shown in yellow-white) at the heart of M31 hints at unexpected goings-on in the galaxy’s central region. Scientists think the signal could be produced by a variety of processes, including a population of pulsars or even dark matter.
    Credits: NASA/DOE/Fermi LAT Collaboration and Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF

    “We expect dark matter to accumulate in the innermost regions of the Milky Way and other galaxies, which is why finding such a compact signal is very exciting,” said lead scientist Pierrick Martin, an astrophysicist at the National Center for Scientific Research and the Research Institute in Astrophysics and Planetology in Toulouse, France. “M31 will be a key to understanding what this means for both Andromeda and the Milky Way.”

    A paper describing the results will appear in an upcoming issue of The Astrophysical Journal.

    Another possible source for this emission could be a rich concentration of pulsars in M31’s center. These spinning neutron stars weigh as much as twice the mass of the sun and are among the densest objects in the universe. One teaspoon of neutron star matter would weigh a billion tons on Earth. Some pulsars emit most of their energy in gamma rays. Because M31 is 2.5 million light-years away, it’s difficult to find individual pulsars. To test whether the gamma rays are coming from these objects, scientists can apply what they know about pulsars from observations in the Milky Way to new X-ray and radio observations of Andromeda.

    Now that Fermi has detected a similar gamma-ray signature in both M31 and the Milky Way, scientists can use this information to solve mysteries within both galaxies. For example, M31 emits few gamma rays from its large disk, where most stars form, indicating fewer cosmic rays roaming there. Because cosmic rays are usually thought to be related to star formation, the absence of gamma rays in the outer parts of M31 suggests either that the galaxy produces cosmic rays differently, or that they can escape the galaxy more rapidly. Studying Andromeda may help scientists understand the life cycle of cosmic rays and how it is connected to star formation.

    “We don’t fully understand the roles cosmic rays play in galaxies, or how they travel through them,” said Xian Hou, an astrophysicist at Yunnan Observatories, Chinese Academy of Sciences in Kunming, China, also a lead scientist in this work. “M31 lets us see how cosmic rays behave under conditions different from those in our own galaxy.”

    The similar discovery in both the Milky Way and M31 means scientists can use the galaxies as models for each other when making difficult observations. While Fermi can make more sensitive and detailed observations of the Milky Way’s center, its view is partially obscured by emission from the galaxy’s disk. But telescopes view Andromeda from an outside vantage point impossible to attain in the Milky Way.

    “Our galaxy is so similar to Andromeda, it really helps us to be able to study it, because we can learn more about our galaxy and its formation,” said co-author Regina Caputo, a research scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “It’s like living in a world where there’s no mirrors but you have a twin, and you can see everything physical about the twin.”

    While more observations are necessary to determine the source of the gamma-ray excess, the discovery provides an exciting starting point to learn more about both galaxies, and perhaps about the still elusive nature of dark matter.

    “We still have a lot to learn about the gamma-ray sky,” Caputo said. “The more information we have, the more information we can put into models of our own galaxy.”

    NASA’s Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

    For more information on Fermi, visit:

    http://www.nasa.gov/fermi

    See the full article here .

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    NASA’s Fermi Gamma-ray Space Telescope is an astrophysics and particle physics partnership, developed in collaboration with the U.S. Department of Energy and with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden and the United States.

     
  • richardmitnick 11:59 am on February 11, 2017 Permalink | Reply
    Tags: Andromeda constellation, Andromeda galaxy, , ,   

    From ESA: “A spiral in Andromeda” 

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    European Space Agency

    2
    Andromeda Galaxy NGC 7640 NASA/ESA

    Not to be confused with our neighbouring Andromeda Galaxy, the Andromeda constellation is one of the 88 modern constellations. More importantly for this image, it is home to the pictured NGC 7640.

    Andromeda Galaxy Adam Evans
    Andromeda Galaxy Adam Evans

    Many different classifications are used to identify galaxies by shape and structure — NGC 7640 is a barred spiral type. These are recognisable by their spiral arms, which fan out not from a circular core, but from an elongated bar cutting through the galaxy’s centre. Our home galaxy, the Milky Way, is also a barred spiral galaxy. NGC 7640 might not look much like a spiral in this image, but this is due to the orientation of the galaxy with respect to Earth — or to Hubble, which acted as photographer in this case! We often do not see galaxies face on, which can make features such as spiral arms less obvious.

    There is evidence that NGC 7640 has experienced some kind of interaction in its past. Galaxies contain vast amounts of mass, and therefore affect one another via gravity. Sometimes these interactions can be mild, and sometimes hugely dramatic, with two or more colliding and merging into a new, bigger galaxy. Understanding the history of a galaxy, and what interactions it has experienced, helps astronomers to improve their understanding of how galaxies — and the stars within them — form.

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 2:17 pm on October 18, 2016 Permalink | Reply
    Tags: Andromeda galaxy, , , Doppler effect, M98 (or NGC 4192), , Virgo supercluster   

    From Slate: “A Spiral Galaxy Defying the Cosmic Flow” 

    SLATE

    slate.com

    Oct. 18 2016
    Phil Plait

    1
    M98, a galaxy that, for a short time, is swimming upstream against the expansion of the Universe. ESO/Acknowledgements: Flickr user jbarring

    I’d like to introduce you to an interesting galaxy today. The reason it’s interesting is because it’s surprising, and in a way that caught me off guard.

    It’s called M98 (or NGC 4192; every object in the sky is in multiple catalogs and has multiple handles), and it’s a spiral galaxy much like the Milky Way. It’s located about 50 million light-years away, which isn’t exactly close on a cosmic scale but isn’t all that far away either. If I had to make an analogy, it’s like it’s in the next town over.

    We see M98 at a pretty low angle, so it appears nearly edge-on to us; spiral galaxies are pretty flat, and can have wildly different appearances depending on our viewing angle. Still, the spiral pattern is obvious enough, and you can see bright blue regions where stars are being born; those trace the arms. There is also lots of patchy dust along the arms; molecules of silica and aluminum as well as complex carbon-based molecules that are more like soot than anything else.

    I like the central region of the galaxy; it’s bright but from this angle is cut in half by a dust lane, distorting the apparent shape of the usually elliptical hub.

    All in all, it’s quite lovely, and that shot by the New Technology Telescope [NTT] really shows it off.

    ESO/NTT at Cerro La Silla, Chile
    ESO/NTT ESO NTT Interior
    ESO/NTT at Cerro La Silla, Chile

    But in that way it’s like a zillion other spirals. So what makes this one special?

    Unlike nearly every single other galaxy in the Universe, this one isn’t moving away from us. It’s moving toward us.

    There’s no danger of a collision! At its speed of 150 km/sec, it would take a hundred billion years to get here, so don’t wait up. Also, it’s probably not heading directly at us, because it’s part of the Virgo Cluster, a grouping of about thousand galaxies bound by their own gravity.

    Virgo Supercluster
    Virgo Supercluster

    It’s the closest true cluster to us, and our own small Local Group of a couple dozen galaxies is like a small town near a bigger one. M98 is part of the Virgo Cluster, so it’s in orbit around the cluster center. We’re way outside the cluster, so it can’t hit us.

    Here’s the fun bit. The Universe, as you may know, is expanding. One way to think of it is that space itself is getting bigger, and as it does galaxies are swept along with it. Galaxies aren’t really moving away from each other, they’re just floating along with the local flow.


    Access mp4 video here .

    But in many ways it’s like they really are moving away. One way is that their light is redshifted; the wavelength of the light they emit is stretched (it’s very similar to the Doppler effect that makes a motorcycle go EEEEEEeoowwwwwww as it passes you, changing the pitch of the noise). Practically every galaxy in the Universe shows this redshift, and in fact that’s how all this was discovered in the first place. The farther away a galaxy is, the more it’s light is shifted.

    But not every galaxy shows it. Close by galaxies have much lower redshifts, and if the galaxy itself is moving rapidly through space (and not just with it), that local velocity will get added to or subtracted from the recession velocity.

    One example of this is the monstrous Andromeda galaxy, which is headed toward us at high speed.

    Andromeda Galaxy Adam Evans
    Andromeda Galaxy Adam Evans

    We actually will collide with it, though not for quite some time (like, 4 billion years). But it shows a distinct blueshift in its light; it’s moving around faster than space is expanding.

    M98 is doing the same thing. That surprised me when I saw it in a catalog; it’s far enough away that the Universal expansion should make it recede from us at about 1,000 km/sec.

    But then I saw it was in the Virgo Cluster, and I understood. The massive gravity of all those galaxies means they orbit the center at a decent clip, so some galaxies are redshifted more than average as they head away from us, in the part of their orbit taking them to the other side of the cluster. Some have lower velocities because they’re headed toward us in their orbits.

    But M98 is still unusual because it can completely overcome the recession of the cluster, and actually be physically headed toward us. That’s almost certainly because it’s recently interacted with another galaxy in the cluster; when galaxies pass each other one can be flung away at high speed, something like a slingshot effect. M98 may very well have done this, and that’s why it’s blueshifted, not redshifted.

    As you look to more distant clusters this gets rare or nonexistent, because at that distance the cosmic expansion dominates, and it doesn’t matter how fast the galaxy is moving: It can’t overcome that recession. All galaxies past a certain distance are redshifted, which is yet another reason (among many, many others) that we know the Universe actually is expanding.

    That’s pretty cool. I like surprises when I’m reading up on lovely astronomical objects; that means I’ve learned something. M98 is headed toward us, a rare blueshifted galaxy. Huh. That just adds to its beauty and intrigue to me.

    It’s a really beautiful Universe, and it’s also a really interesting one. I’d say that’s its best quality.

    See the full article here .

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    Slate is a daily magazine on the Web. Founded in 1996, we are a general-interest publication offering analysis and commentary about politics, news, business, technology, and culture. Slate’s strong editorial voice and witty take on current events have been recognized with numerous awards, including the National Magazine Award for General Excellence Online. The site, which is owned by Graham Holdings Company, does not charge for access and is supported by advertising revenues.

     
  • richardmitnick 11:00 am on October 5, 2016 Permalink | Reply
    Tags: Andromeda galaxy, , ,   

    From Sky & Telescope: “Resolving Andromeda — How to See Stars 2.5 Million Light-Years Away” 

    SKY&Telescope bloc

    Sky & Telescope

    October 5, 2016
    Bob King

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    The Hubble Space Telescope easily resolves millions of individual stars in an outer region of the Andromeda Galaxy, also known as M31.
    NASA / ESA / Hubble Heritage Team

    I always figured I’d have to wait until the next supernova to see an individual star among the trillion that comprise the Andromeda Galaxy.

    At the galaxy’s distance of 2.5 million light-years, the stars blend into a luminous stellar fog. Whenever I show Andromeda to the public, I make sure to remind each viewer that the haze they see is actually the light of billions of individual stars too far and faint to resolve into individual pinpoints.

    In binoculars and small telescopes, it’s easy to distinguish the core, where stars are more strongly concentrated, from the less populated arms. Those with 10-inch and larger telescopes can survey the galaxy’s brighter globular star clusters and stellar associations with the aid of detailed maps. But individual stars?

    Several years back, I briefly observed a bright nova just outside the galaxy’s nucleus in my 15-inch reflector when it peaked around magnitude +14.9. That was a lucky break as most novae in M31 max out around magnitude +17-19 and require telescopes upwards of 20-inches to track down.

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    In this wide-field photo of the Andromeda Galaxy, the bright OB association NGC 206 resembles its visual appearance. The massive star cloud is located at the southwestern end of the galaxy’s disk at the junction of two spiral arms.
    Patrick Winkler / Online Photo Gallery

    Then one fall night, while hunting down globulars and other minute delights in the galaxy, I shifted the scope to NGC 206, M31’s largest and brightest star cloud. The object, which resembles a weakly condensed 10th-magnitude comet superimposed on Andromeda’s southwestern arm, measures 4.2′ across. Its true size is about 4,000 light-years across or nearly three times the distance from Earth to the star Deneb in the Northern Cross, making it one of the largest star clouds in the Local Group of galaxies.

    Local Group. Andrew Z. Colvin 3 March 2011
    Local Group. Andrew Z. Colvin 3 March 2011

    If you haven’t observed it yet, you’ve probably noticed this distinctive hazy patch in photos of Andromeda. NGC 206 also goes by the name OB 78 and resembles the vast Perseus OB 1 association which includes Mirfak, the brightest star in Perseus, and the popular Double Cluster.

    OB associations, named after the brilliant class O and B stars they contain, are loosely organized gaggles of young stars and star clusters born in the collapse of a giant molecular cloud. True star clusters, more compact by nature, keep hold of their stars through gravitational attraction. Thinly spread OB associations make easy prey for galactic tides, which pull associations apart and disperse their members far and wide.

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    This closeup of NGC 206 reveals a rich gathering of hot blue supergiant stars. The cloud is similar in size to the spectacular Tarantula Nebula in the Large Magellanic Cloud and NGC 604 in M33, the Pinwheel Galaxy. I’ve included a “triangle guide” here and in the sketch below to help you get oriented. North is up. Michael A. Siniscalchi

    NGC 206 is home to some 300 brilliant blue stars, the youngest of which are just 10 million years old, incredibly young by stellar standards. Stars 20 times more massive than the Sun are common with a few topping out at more than 40x solar! Inspired by these superlatives and photos that showed good resolution of the cloud, I cranked up the magnification to 242x and then 357x, allowed my eyes to fully adapt to the darkened field of view and got the surprise of my life. Stars!

    NGC 206 appeared in three sections: a tiny ~30″ wide knot dotted by a 16th magnitude star, a brighter, clumpy northern “cloud” and a fainter, more distended southern section separated by a relatively haze-free gap (in other words, no unresolved stars). Direct vision revealed several faint stellar points around and within the cluster, some of which were members of the association and not Milky Way foreground suns.

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    NGC 206 lies at the intersection of two of Andromeda’s spiral arms and was likely spawned in a collision of massive dust clouds at their intersection.
    Jim Misti

    But the thing that positively electrified the view was seeing OB 78 materialize into a rich spray of barely visible stars with averted vision. They came and went with the vagaries of my eye’s position and seeing conditions, but there was no question I was seeing cluster stars based on location and star density compared to the ambient Milky Way foreground. The scene reminded me of the grainy interiors of the remote globular clusters NGC 7006 in Delphinus and the “Intergalactic Wanderer,” NGC 2419, in Lynx.

    In all three cases, it was next to impossible to hold so many faint stars in view long enough to see them individually or connect them into patterns. Instead, they appeared as a granulated haze or mist of dim points that flashed in and out of view.

    Stephen Odewahn of the McDonald Observatory surveyed NGC 206 in the 1980s and published a photometric survey of its brightest stars. While most are hopelessly faint for visual observers even with moderately large telescopes, 14 members range between magnitude +14.8 and +17.5, making them somewhat less hopelessly faint.

    A 15-inch scope covers the brighter end of that range with ease, but the number of stars I glimpsed with averted vision implies that in some situations, based on seeing, magnification and experience, we can momentarily best a telescope’s limiting magnitude by a surprising margin.

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    This sketch of the NGC 206 star cloud was made primarily using a 15-inch telescope, but it’s also informed by a view through a 24-inch. A skinny triangle of stars just north of the cloud will help you get oriented. Brighter stars are labeled with B (blue) magnitudes with decimal points omitted. All the stars, with the exception of the 13.1, are listed as association members in Odewahn’s paper. The tiny stellar sprinkles are for illustration purposes and included to convey my impression when viewing the cloud. Bob King

    No one should be content with a single observation of faint nothings, so I re-observed the star cloud on several occasions and confirmed my observation using friends’ 18-inch and 24-inch telescopes. We invited several members of our clubs to view NGC 206 and every one of them was able to at least partially resolve the stellar association in each scope.

    Using a photo labeled with some of the brighter stars from Odewahn’s paper, I was able to clearly see and identify seven stars between magnitudes +14.8 and +15.8 in the 15-inch. I’ve included these in a drawing made using Photoshop that I hope will provide a useful tracking guide for your own explorations.

    While a 24-inch scope reveals even more stars, a 15-inch scope is easily up to the task of breaking out some of Andromeda’s brightest blue supergiant stars from this magnificent clutch of stellar celebrities. Daring amateurs may even want to put a 10 or 12-inch scope to the task. I’d love to know what you’ll see.

    See the full article here .

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    Sky & Telescope magazine, founded in 1941 by Charles A. Federer Jr. and Helen Spence Federer, has the largest, most experienced staff of any astronomy magazine in the world. Its editors are virtually all amateur or professional astronomers, and every one has built a telescope, written a book, done original research, developed a new product, or otherwise distinguished him or herself.

    Sky & Telescope magazine, now in its eighth decade, came about because of some happy accidents. Its earliest known ancestor was a four-page bulletin called The Amateur Astronomer, which was begun in 1929 by the Amateur Astronomers Association in New York City. Then, in 1935, the American Museum of Natural History opened its Hayden Planetarium and began to issue a monthly bulletin that became a full-size magazine called The Sky within a year. Under the editorship of Hans Christian Adamson, The Sky featured large illustrations and articles from astronomers all over the globe. It immediately absorbed The Amateur Astronomer.

    Despite initial success, by 1939 the planetarium found itself unable to continue financial support of The Sky. Charles A. Federer, who would become the dominant force behind Sky & Telescope, was then working as a lecturer at the planetarium. He was asked to take over publishing The Sky. Federer agreed and started an independent publishing corporation in New York.

    “Our first issue came out in January 1940,” he noted. “We dropped from 32 to 24 pages, used cheaper quality paper…but editorially we further defined the departments and tried to squeeze as much information as possible between the covers.” Federer was The Sky’s editor, and his wife, Helen, served as managing editor. In that January 1940 issue, they stated their goal: “We shall try to make the magazine meet the needs of amateur astronomy, so that amateur astronomers will come to regard it as essential to their pursuit, and professionals to consider it a worthwhile medium in which to bring their work before the public.”

     
  • richardmitnick 2:55 pm on July 25, 2016 Permalink | Reply
    Tags: Andromeda galaxy, , ,   

    From Ethan Siegel: “The Stars Of Andromeda, Inside And Out, As Revealed By Hubble” 

    From Ethan Siegel

    Andromeda Galaxy Adam Evans
    Andromeda Galaxy Adam Evans

    The Milky Way’s plane obscures our view of most stars in our own galaxy, but an even grander spiral — Andromeda — lies 2.5 million light years away.

    2
    A Mosaic of the 117 million resolved stars — plus many more unresolved ones — in the disk of the Andromeda galaxy. Image credit: NASA, ESA, J. Dalcanton, B.F. Williams, L.C. Johnson (University of Washington), the PHAT team, and R. Gendler.

    Even at this modest distance, incredible telescope and camera technology is needed to resolve individual stars in a galaxy beyond our own.

    The Hubble Space Telescope recently completed the Panchromatic Hubble Andromeda Treasury, mapping a third of Andromeda’s disk and resolving over 117 million individual stars.

    3
    Closeup of a large region of the Andromeda galaxy’s disk, containing hundreds of open star clusters (identifiable as bright blue sparkles). Image credit: NASA, ESA, J. Dalcanton, B.F. Williams, L.C. Johnson (University of Washington), the PHAT team, and R. Gendler.

    4
    Six of the most spectacular star clusters in Andromeda. The brilliant red star in the fifth image is actually a foreground star in the Milky Way. Over a thousand new clusters were found in this survey. Image Credit: NASA, ESA, and Z. Levay (STScI); Science Credit: NASA, ESA, J. Dalcanton, B.F. Williams, L.C. Johnson (University of Washington), and the PHAT team.

    Far outside of the center, in the outer disk and the faint galactic halo, a different set of populations thrive.

    5
    Image credit: NASA, ESA and T.M. Brown (STScI), of the stars in Andromeda’s outer disc.

    The outer disc of Andromeda (above) shows a wide variety of stars, including many Sun-like ones and older variables.

    6
    Image credit: NASA, ESA and T.M. Brown (STScI), of the stars in Andromeda’s giant stellar stream. The Milky Way’s foreground stars are clearly identified by their diffraction spikes.

    The stars from the giant stellar stream are also densely packed, obscuring the Universe beyond.

    While the diffuse halo’s low-density regions contain many of the oldest, least evolved stars.

    They’re lower in heavy elements than any stars found in the disk, with galaxies up to billions of light years away visible through the gaps in the halo stars.

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

     
  • richardmitnick 10:02 am on March 31, 2016 Permalink | Reply
    Tags: Andromeda galaxy, , , ,   

    From ESA- “Found: Andromeda’s first spinning neutron star” 

    ESA Space For Europe Banner

    European Space Agency

    31 March 2016
    Paolo Esposito
    INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan, Italy
    Email: paoloesp@iasf-milano.inaf.it

    Gian Luca Israel
    INAF-Osservatorio Astronomica di Roma, Italy
    Email: gianluca@oa-roma.inaf.it

    Andrea De Luca
    INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan, Italy
    Email: deluca@iasf-milano.inaf.it

    Norbert Schartel
    XMM-Newton project scientist
    Email: Norbert.Schartel@esa.int

    1
    Andromeda’s spinning neutron star
    Released 31/03/2016
    ESA/Herschel/PACS/SPIRE/J. Fritz, U. Gent/XMM-Newton/EPIC/W. Pietsch, MPE; data: P. Esposito et al (2016)

    ESA/Herschel
    ESA/Herschel

    Decades of searching in the Milky Way’s nearby ‘twin’ galaxy Andromeda have finally paid off, with the discovery of an elusive breed of stellar corpse, a neutron star, by ESA’s XMM-Newton space telescope.

    Andromeda Galaxy NASA Hubble
    Andromeda Galaxy NASA/ESA Hubble

    ESA/XMM Newton
    ESA/XMM Newton

    Andromeda, or [Messier] 31, is a popular target among astronomers. Under clear, dark skies it is even visible to the naked eye. Its proximity and similarity in structure to our own spiral galaxy, the Milky Way, make it an important natural laboratory for astronomers. It has been extensively studied for decades by telescopes covering the whole electromagnetic spectrum.

    Despite being extremely well studied, one particular class of object had never been detected: spinning neutron stars.

    Neutron stars are the small and extraordinarily dense remains of a once-massive star that exploded as a powerful supernova at the end of its natural life. They often spin very rapidly and can sweep regular pulses of radiation towards Earth, like a lighthouse beacon appearing to flash on and off as it rotates.

    These pulsars can be found in stellar couples, with the neutron star cannibalising its neighbour. This can lead to the neutron star spinning faster, and to pulses of high-energy X-rays from hot gas being funnelled down magnetic fields on to the neutron star.

    Binary systems hosting a neutron star like this are quite common in our own Galaxy, but regular signals from such a pairing had never before been seen in Andromeda.

    Now, astronomers systematically searching through the archives of data from XMM-Newton X-ray telescope have uncovered the signal of an unusual source fitting the bill of a fast-spinning neutron star.

    It spins every 1.2 seconds, and appears to be feeding on a neighbouring star that orbits it every 1.3 days.

    “We were expecting to detect periodic signals among the brightest X-ray objects in Andromeda, in line with what we already found during the 1960s and 1970s in our own Galaxy,” says Gian Luca Israel, from INAF-Osservatorio Astronomica di Roma, Italy, one of the authors of the paper describing the results, “But persistent, bright X-ray pulsars like this are still somewhat peculiar, so it was not completely a sure thing we would find one in Andromeda.

    “We looked through archival data of Andromeda spanning 2000–13, but it wasn’t until 2015 that we were finally able to identify this object in the galaxy’s outer spiral in just two of the 35 measurements.”

    While the precise nature of the system remains unclear, the data imply that it is unusual and exotic.

    “It could be what we call a ‘peculiar low-mass X-ray binary pulsar’ – in which the companion star is less massive than our Sun – or alternatively an intermediate-mass binary system, with a companion of about two solar masses,” says Paolo Esposito of INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica, Milan, Italy.

    “We need to acquire more observations of the pulsar and its companion to help determine which scenario is more likely.”

    “The well-known Andromeda galaxy has long been a source of exciting discoveries, and now an intriguing periodic signal has been detected by our flagship X-ray mission,” adds Norbert Schartel, ESA’s XMM-Newton project scientist.

    “We’re in a better position now to uncover more objects like this in Andromeda, both with XMM-Newton and with future missions such as ESA’s next-generation high-energy observatory, Athena.”

    The science team:
    P. Esposito,1? G. L. Israel,2 A. Belfiore,1 G. Novara,3 L. Sidoli,1 G. A. Rodr´ıguez Castillo,2
    A. De Luca,1 A. Tiengo,1;3;4 F. Haberl,5 R. Salvaterra,1 A. M. Read,6 D. Salvetti,1 S. Sandrelli,7
    M. Marelli,1 J. Wilms8 and D. D’Agostino9

    1INAF–Istituto di Astrofisica Spaziale e Fisica Cosmica – Milano, via E. Bassini 15, I-20133 Milano, Italy
    2INAF–Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone, Italy
    3IUSS–Istituto Universitario di Studi Superiori, piazza della Vittoria 15, I-27100 Pavia, Italy
    4INFN–Istituto Nazionale di Fisica Nucleare, Sezione di Pavia, via A. Bassi 6, I-27100 Pavia, Italy
    5Max-Planck-Institut f¨ur extraterrestrische Physik, Giessenbachstraße, D-85748 Garching, Germany
    6Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, U.K.
    7INAF–Osservatorio Astronomico di Brera, via Brera 28, I-20121 Milano, Italy
    8ECAP–Erlangen Centre for Astroparticle Physics, Sternwartstrasse 7, D-96049 Bamberg, Germany
    9CNR–Istituto di Matematica Applicata e Tecnologie Informatiche, via de Marini 6, I-16149 Genova, Italy

    See the full article here .

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    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.

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  • richardmitnick 1:53 pm on January 5, 2016 Permalink | Reply
    Tags: Andromeda galaxy, , ,   

    From NASA NuSTAR: “Andromeda Galaxy Scanned with High-Energy X-ray Vision” 

    NASA NuSTAR
    NuSTAR

    1

    January 5, 2016
    No writer credit found

    NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has captured the best high-energy X-ray view yet of a portion of our nearest large, neighboring galaxy, Andromeda. The space mission has observed 40 X-ray binaries — intense sources of X-rays comprised of a black hole or neutron star that feeds off a stellar companion.

    The results will ultimately help researchers better understand the role of X-ray binaries in the evolution of our universe. According to astronomers, these energetic objects may play a critical role in heating the intergalactic bath of gas in which the very first galaxies formed.

    “Andromeda is the only large spiral galaxy where we can see individual X-ray binaries and study them in detail in an environment like our own,” said Daniel Wik of NASA Goddard Space Flight Center in Greenbelt, Maryland, who presented the results at the 227th meeting of American Astronomical Society in Kissimmee, Florida. “We can then use this information to deduce what’s going on in more distant galaxies, which are harder to see.”

    Andromeda, also known as M31, can be thought of as the big sister to our own Milky Way galaxy. Both galaxies are spiral in shape, but Andromeda is slightly larger than the Milky Way in size. Lying 2.5 million light-years away, Andromeda is relatively nearby in cosmic terms. It can even be seen by the naked eye in dark, clear skies. [It is not mentioned here, but Andromeda and the Milky Way are apparently destined to merge in the distant future.]

    Other space missions, such as NASA’s Chandra X-ray Observatory, have obtained crisper images of Andromeda at lower X-ray energies than the high-energy X-rays detected by NuSTAR.

    NASA Chandra Telescope
    NASA/Chandra

    The combination of Chandra and NuSTAR provides astronomers with a powerful tool for narrowing in on the nature of the X-ray binaries in spiral galaxies.

    In X-ray binaries, one member is always a dead star or remnant formed from the explosion of what was once a star much more massive than the sun. Depending on the mass and other properties of the original giant star, the explosion may produce either a black hole or neutron star. Under the right circumstances, material from the companion star can “spill over” its outermost edges and then be caught by the gravity of the black hole or neutron star. As the material falls in, it is heated to blazingly high temperatures, releasing a huge amount of X-rays.

    With NuSTAR’s new view of a swath of Andromeda, Wik and colleagues are working on identifying the fraction of X-ray binaries harboring black holes versus neutron stars. That research will help them understand the population as a whole.

    “We have come to realize in the past few years that it is likely the lower-mass remnants of normal stellar evolution, the black holes and neutron stars, may play a crucial role in heating of the intergalactic gas at very early times in the universe, around the cosmic dawn,” said Ann Hornschemeier of NASA Goddard, the principal investigator of the NuSTAR Andromeda studies.

    “Observations of local populations of stellar-mass-sized black holes and neutron stars with NuSTAR allow us to figure out just how much power is coming out from these systems.”

    The new research also reveals how Andromeda may differ from our Milky Way. Fiona Harrison, the principal investigator of the NuSTAR mission, added, “Studying the extreme stellar populations in Andromeda tells us about how its history of forming stars may be different than in our neighborhood.”

    Harrison will be presenting the 2015 Rossi Prize lecture at the AAS meeting. The prize, awarded by the AAS’s High-Energy Astrophysics Division, honors physicist Bruno Rossi, an authority on cosmic-ray physics and a pioneer in the field of X-ray astronomy.

    See the full article here .

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    NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA’s Jet Propulsion Laboratory, also in Pasadena, for NASA’s Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Va. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley ; Columbia University, New York; NASA’s Goddard Space Flight Center, Greenbelt, Md.; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, Calif.; ATK Aerospace Systems, Goleta, Calif., and with support from the Italian Space Agency (ASI) Science Data Center.

    NuSTAR’s mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, Calif. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

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  • richardmitnick 10:06 am on December 14, 2015 Permalink | Reply
    Tags: , Andromeda galaxy, , , ,   

    From AAS NOVA: “Featured Image: Reddened Stars Reveal Andromeda’s Dust” 

    AASNOVA

    Amercan Astronomical Society

    14 December 2015
    Susanna Kohler

    1

    As distant light travels on a path toward us, it can be absorbed by intervening, interstellar dust. Much work has been done to understand this “dust extinction” in the Milky Way, providing us with detailed information about the properties of the dust in our galaxy. Far less, however, is known about the dust extinction of other galaxies. The image above, taken with the ultraviolet space telescope GALEX, identifies the locations of four stars in the nearby Andromeda galaxy that are reddened due to extinction of their light by dust within Andromeda.

    NASA Galex telescope
    NASA/GALEX

    In a recent study led by Geoffrey Clayton (Louisiana State University), new, high-signal-to-noise spectra were obtained for these four stars using Hubble’s Space Telescope [HST] Imaging Spectrograph. These observations have allowed the authors to construct dust extinction curves to carefully study the nature of Andromeda’s interstellar dust. To learn about the results, see the paper below.

    NASA Hubble Telescope
    HST

    NASA Hubble Space Telescope Imaging Spectrograph
    NASA Hubble Space Telescope Imaging Spectrograph

    Citation

    Geoffrey C. Clayton et al 2015 ApJ 815 14. doi:10.1088/0004-637X/815/1/14

    See the full article here .

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