A hidden population of exotic neutron stars

A hidden population …

Magnetars — the dense remains of dead stars that erupt sporadically with bursts of high-energy radiation — are some of the most extreme objects known in the universe. A major campaign using NASA’s Chandra X-ray Observatory and several other satellites…

A hidden population …
Griffith Observatory: Astronomy for the Public

Griffith Observatory…

Griffith Observatory is a Los Angeles-based facility that bills itself as the most-visited observatory in the world.

While many professional facilities are solely used by astronomers, Griffith has free public telescopes that are open each evening that the observatory and skies…

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Archive for Galaxy Evolution Explorer

Largest-Known Spiral Galaxy: NGC 6872 – Sci

By alkaon on January 16, 2013 No Comments

Astronomers using NASA’s Galaxy Evolution Explorer have spotted what they say is the biggest spiral galaxy ever seen.

This image shows the giant barred spiral galaxy NGC 6872 (NASA’s Goddard Space Flight Center / ESO / JPL-Caltech / DSS)

The object – giant barred spiral galaxy NGC 6872 – is located in the southern constellation Pavo about 212 million light-years away. It spans more than 522,000 light-years – five times the size of Milky Way Galaxy.

“Without GALEX’s ability to detect the ultraviolet light of the youngest, hottest stars, we would never have recognized the full extent of this intriguing system,” said Dr Rafael Eufrasio, a research assistant at NASA’s Goddard Space Flight Center in Greenbelt, who presented the discovery at the American Astronomical Society meeting in Long Beach, California.

NGC 6872′s size stems from its interaction with a much smaller disk galaxy named IC 4970, which has only about one-fifth the mass of NGC 6872.

Astronomers think large galaxies grew through mergers and acquisitions – assembling over billions of years by absorbing numerous smaller systems. Intriguingly, the gravitational interaction of NGC 6872 and IC 4970 may have done the opposite, spawning what may develop into a new small galaxy.

“The northeastern arm of NGC 6872 is the most disturbed and is rippling with star formation, but at its far end, visible only in the ultraviolet, is an object that appears to be a tidal dwarf galaxy similar to those seen in other interacting systems,” said co-author Prof Duilia de Mello of Catholic University of America in Washington.

The tidal dwarf candidate is brighter in ultraviolet than other regions of the galaxy, a sign it bears a rich supply of hot young stars less than 200 million years old.

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Bibliographic information: Eufrasio RT et al. When the UV Unveils the Largest Spiral. 221st AAS Meeting. Long Beach, CA. January 7, 2013

Article source: http://www.sci-news.com/astronomy/article00822.html

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M81 Galaxy is Pretty in Pink

By alkaon on December 30, 2012 No Comments

The perfectly picturesque spiral galaxy known as Messier 81, or M81, looks sharp in this new composite from NASA’s Spitzer and Hubble space telescopes and NASA’s Galaxy Evolution Explorer.

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NASA Lends Galaxy Evolution Explorer to Caltech

By alkaon on May 18, 2012 No Comments

NASA is lending the Galaxy Evolution Explorer (GALEX) to the California Institute of Technology (Caltech) in Pasadena, where the spacecraft will continue its exploration of the cosmos. In a first-of-a-kind move for NASA, a Space Act Agreement was signed May 14 so the university soon can resume spacecraft operations and data management for the mission using private funds.

“NASA sees this as an opportunity to allow the public to continue reaping the benefits from this space asset that NASA developed using federal funding,” said Paul Hertz, NASA’s Astrophysics Division director at the agency’s headquarters in Washington. “This is an excellent example of a public/private partnership that will help further astronomy in the United States.”

The Galaxy Evolution Explorer spent about nine years as a NASA mission, probing the sky with its sharp ultraviolet eyes and cataloguing hundreds of millions of galaxies spanning 10 billion years of cosmic time.

“This mission was full of surprises, and now more surprises are sure to come,” said Chris Martin, who will remain the mission’s principal investigator at Caltech. “It already has scanned a large fraction of the sky, improving our understanding of how galaxies grow and evolve. The astronomy community will continue those studies, in addition to spending more time on stars closer to home in our own galaxy.”

The spacecraft was placed in standby mode on Feb. 7 of this year. Soon, Caltech will begin to manage and operate the satellite, working with several international research groups to continue ultraviolet studies of the universe. Projects include cataloguing more galaxies across the entire sky; watching how stars and galaxies change over time; and making deep observations of the stars being surveyed for orbiting planets by NASA’s Kepler mission. Data will continue to be made available to the public.

“We’re thrilled that the mission will continue on its path of discovery,” said Kerry Erickson, the mission’s project manager at NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “The Galaxy Evolution Explorer is like the ‘little engine that could,’ forging ahead into unexplored territory.”

During its time at NASA, the Galaxy Evolution Explorer made many discoveries involving various types of objects that light up our sky with ultraviolet light. Perhaps the most surprising of these was the discovery of a gargantuan comet-like tail behind a speeding star called Mira. Other finds included catching black holes “red-handed” as they munch away on stars, spying giant rings of new stars around old, presumed dead galaxies, and independently confirming the nature of dark energy.

For astronomers, the most profound shift in their understanding of galaxy evolution came from the mission’s findings about a “missing link” population of galaxies. These missing members helped explain how the two major types of galaxies in our universe – the “red and dead” ellipticals and the blue spirals – transition from one type to another.

“We were able to trace the life of a galaxy,” Martin said. “With the Galaxy Evolution Explorer’s ultraviolet detectors, we were able to isolate the small amounts of star formation that are the signatures of galaxies undergoing an evolutionary change. We found that galaxies don’t have a single personality, but may change types many times over their lifetime.”

The mission also captured a dazzling collection of snapshots, showing everything from ghostly nebulas to a spiral galaxy with huge, spidery arms. A slideshow showing some of the top images can be seen here: http://www.nasa.gov/mission_pages/galex/gallery-index.html .

Under the new agreement, NASA maintains ownership and liability for the Galaxy Evolution Explorer spacecraft. When Caltech completes science activities, it will decommission the spacecraft for NASA. The mission’s batteries and solar panels have an expected lifetime of 12 years or more, and the spacecraft will remain in orbit for at least 66 years, after which it will burn-up upon re-entry into Earth’s atmosphere. The agreement can be renegotiated when it expires in three years.

Orbital Sciences Corporation in Dulles, Va., which built the spacecraft, will continue performing flight control functions for Caltech associated with monitoring and commanding GALEX and participating in mission planning. Universal Space Network will continue providing the ground stations for communicating with the spacecraft.

Article source: http://www.spacedaily.com/reports/NASA_Lends_Galaxy_Evolution_Explorer_to_Caltech_999.html

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NASA Lends Galaxy Evolution Explorer To Caltech

By alkaon on May 17, 2012 No Comments

WASHINGTON, May 16, 2012 — /PRNewswire-USNewswire/ – NASA is lending the Galaxy Evolution Explorer (GALEX) to the California Institute of Technology (Caltech) in Pasadena, where the spacecraft will continue its exploration of the cosmos. In a first-of-a-kind move for NASA, a Space Act Agreement was signed May 14 so the university soon can resume spacecraft operations and data management for the mission using private funds.

(Logo: http://photos.prnewswire.com/prnh/20081007/38461LOGO)

“NASA sees this as an opportunity to allow the public to continue reaping the benefits from this space asset that NASA developed using Federal funding,” said Paul Hertz, NASA’s Astrophysics Division director at the agency’s headquarters in Washington. “This is an excellent example of a public/private partnership that will help further astronomy in the United States.”

The Galaxy Evolution Explorer spent about nine years as a NASA mission, probing the sky with its sharp ultraviolet eyes and cataloguing hundreds of millions of galaxies spanning 10 billion years of cosmic time.

“This mission was full of surprises, and now more surprises are sure to come,” said Chris Martin, who will remain the mission’s principal investigator at Caltech. “It already has scanned a large fraction of the sky, improving our understanding of how galaxies grow and evolve. The astronomy community will continue those studies, in addition to spending more time on stars closer to home in our own galaxy.”

The spacecraft was placed in standby mode on Feb. 7 of this year. Soon, Caltech will begin to manage and operate the satellite, working with several international research groups to continue ultraviolet studies of the universe. Projects include cataloguing more galaxies across the entire sky; watching how stars and galaxies change over time; and making deep observations of the stars being surveyed for orbiting planets by NASA’s Kepler mission. Data will continue to be made available to the public.

“We’re thrilled that the mission will continue on its path of discovery,” said Kerry Erickson, the mission’s project manager at NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, Calif. “The Galaxy Evolution Explorer is like the ‘little engine that could,’ forging ahead into unexplored territory.”

During its time at NASA, the Galaxy Evolution Explorer made many discoveries involving various types of objects that light up our sky with ultraviolet light. Perhaps the most surprising of these was the discovery of a gargantuan comet-like tail behind a speeding star called Mira. Other finds included catching black holes “red-handed” as they munch away on stars, spying giant rings of new stars around old, presumed dead galaxies, and independently confirming the nature of dark energy.

For astronomers, the most profound shift in their understanding of galaxy evolution came from the mission’s findings about a “missing link” population of galaxies. These missing members helped explain how the two major types of galaxies in our universe — the “red and dead” ellipticals and the blue spirals — transition from one type to another.

“We were able to trace the life of a galaxy,” Martin said. “With the Galaxy Evolution Explorer’s ultraviolet detectors, we were able to isolate the small amounts of star formation that are the signatures of galaxies undergoing an evolutionary change. We found that galaxies don’t have a single personality, but may change types many times over their lifetime.”

The mission also captured a dazzling collection of snapshots, showing everything from ghostly nebulas to a spiral galaxy with huge, spidery arms. A slideshow showing some of the top images can be seen here:

http://www.nasa.gov/mission_pages/galex/gallery-index.html

Under the new agreement, NASA maintains ownership and liability for the Galaxy Evolution Explorer spacecraft. When Caltech completes science activities, it will decommission the spacecraft for NASA. The mission’s batteries and solar panels have an expected lifetime of 12 years or more, and the spacecraft will remain in orbit for at least 66 years, after which it will burn-up upon re-entry into Earth’s atmosphere. The agreement can be renegotiated when it expires in three years.

Orbital Sciences Corporation in Dulles, Va., which built the spacecraft, will continue performing flight control functions for Caltech associated with monitoring and commanding GALEX and participating in mission planning. Universal Space Network will continue providing the ground stations for communicating with the spacecraft.

For graphics and additional information about the Galaxy Evolution Explorer, visit:

http://www.nasa.gov/galex

SOURCE NASA

Article source: http://www.sacbee.com/2012/05/16/4494800/nasa-lends-galaxy-evolution-explorer.html

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Astronomers Identify the Remains in a Murder

By alkaon on May 10, 2012 No Comments

Astronomers Identify the Remains in a Murder

May 10, 2012; 7:02 AM ET

Astronomers have gathered the most direct evidence yet of a huge black hole shredding a star that wandered too close. NASA’s Galaxy Evolution Explorer, a space-based observatory, and the Pan-STARRS1 telescope on the summit of Haleakala in Hawaii were among the first to help identify the stellar remains.

Supermassive black holes, weighing millions to billions times more than the Sun, lurk in the centers of most galaxies. These huge monsters lie quietly until an unsuspecting victim, such as a star, wanders close enough to get ripped apart by their powerful gravitational clutches.

Astronomers had spotted these stellar murders before, but this is the first time they have identified the victim. Using several ground- and space-based telescopes, a team of astronomers led by Suvi Gezari of the Johns Hopkins University in Baltimore, Md., identified the victim as a star rich in helium gas. The star resides in a galaxy 2.7 billion light-years away.

This observation gives answers to the questions what is the harsh environment around black holes like and what types of stars swirl around them. It is not the first time the unlucky star had a brush with the behemoth black hole, just the first time we have direct evidence of this encounter.

The team believes the star’s hydrogen-filled envelope surrounding the core was burned off a long time ago by the same black hole. The star was likely near the end of its life. After most of its hydrogen fuel was consumed, it had become a red giant as it swelled up. Astronomers think the bloated star was looping around the black hole in a highly elliptical orbit, similar to a comet’s elongated orbit around the Sun. On one of its close approaches, the star was stripped of its puffed-up atmosphere by the black hole’s powerful gravity. The stellar remains continued its journey around the center, until it ventured even closer to the black hole to face its ultimate demise.

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Article source: http://www.accuweather.com/en/outdoor-articles/astronomy/astronomers-identify-the-remains-in-a-murder/65002

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Black Hole Caught Red-Handed in a Stellar Homicide

By alkaon on May 3, 2012 No Comments

Computer-simulated image shows gas from a tidally shredded star
This computer-simulated image shows gas from a tidally shredded star
falling into a black hole. Image credit: NASA/JPL-Caltech/JHU/UCSC

› Full image and caption

May 02, 2012

<!–JPLIMAGEMARKER __JPL_ALTTEXT_1__JPL_CAPTION_1
Browse version of image
–>

PASADENA, Calif. – Astronomers have gathered the most direct evidence yet of a supermassive black hole shredding a star that wandered too close. NASA’s Galaxy Evolution Explorer, a space-based observatory, and the Pan-STARRS1 telescope on the summit of Haleakala in Hawaii were among the first to help identify the stellar remains.

Supermassive black holes, weighing millions to billions times more than the sun, lurk in the centers of most galaxies. These hefty monsters lie quietly until an unsuspecting victim, such as a star, wanders close enough to get ripped apart by their powerful gravitational clutches.

Astronomers had spotted these stellar homicides before, but this is the first time they have identified the victim. Using several ground- and space-based telescopes, a team of astronomers led by Suvi Gezari of the Johns Hopkins University, Baltimore, Md., identified the victim as a star rich in helium gas. The star resides in a galaxy 2.7 billion light-years away. The team’s results appear in today’s online edition of the journal Nature.

“When the star is ripped apart by the gravitational forces of the black hole, some part of the star’s remains falls into the black hole, while the rest is ejected at high speeds,” Gezari said. “We are seeing the glow from the stellar gas falling into the black hole over time. We’re also witnessing the spectral signature of the ejected gas, which we find to be mostly helium. It is like we are gathering evidence from a crime scene. Because there is very little hydrogen and mostly helium in the gas, we detect from the carnage that the slaughtered star had to have been the helium-rich core of a stripped star.”

This observation yields insights about the harsh environment around black holes and the types of stars swirling around them. It is not the first time the unlucky star had a brush with the behemoth black hole.

The team believes the star’s hydrogen-filled envelope surrounding the core was lifted off a long time ago by the same black hole. The star may have been near the end of its life. After consuming most of its hydrogen fuel, it had probably ballooned in size, becoming a red giant. Astronomers think the bloated star was looping around the black hole in a highly elliptical orbit, similar to a comet’s elongated orbit around the sun. On one of its close approaches, the star was stripped of its puffed-up atmosphere by the black hole’s powerful gravity. The stellar remains continued its journey around the center, until it ventured even closer to the black hole to face its ultimate demise.

Astronomers predict stripped stars circle the central black hole of our Milky Way galaxy. These close encounters are rare, occurring roughly every 100,000 years. To find this event, Gezari’s team monitored hundreds of thousands of galaxies in ultraviolet light with the Galaxy Evolution Explorer, and in visible light with Pan-STARRS1. Pan-STARRS, short for Panoramic Survey Telescope and Rapid Response System, scans the entire night sky for all kinds of transient phenomena, including supernovae.

The team was looking for a bright flare in ultraviolet light from the nucleus of a galaxy with a previously dormant black hole. Both telescopes spotted one in June 2010. Astronomers continued to monitor the flare as it reached peak brightness a month later and slowly faded during the next 12 months. The brightening event was similar to the explosive energy unleashed by a supernova, but the rise to the peak was much slower, taking nearly one-and-a-half months.

“The longer the event lasted, the more excited we got, because we realized this is either a very unusual supernova or an entirely different type of event, such as a star being ripped apart by a black hole,” said team member Armin Rest of the Space Telescope Science Institute in Baltimore.

By measuring the increase in brightness, the astronomers calculated the black hole’s mass to be several million suns, which is comparable to the size of our Milky Way’s black hole.

Spectroscopic observations with the Multiple Meter Telescope Observatory on Mount Hopkins in Arizona showed the black hole was swallowing lots of helium. Spectroscopy divides light into its rainbow colors, which yields an object’s characteristics, such as its temperature and gaseous makeup.

To completely rule out the possibility of an active nucleus flaring up in the galaxy, the team used NASA’s Chandra X-ray Observatory to study the hot gas. Chandra showed that the characteristics of the gas didn’t match those from an active galactic nucleus.

For images, video and more information about this study, visit: http://hubblesite.org/news/2012/18 .

For graphics and information about the Galaxy Evolution Explorer, visit: http://www.nasa.gov/galex and http://www.galex.caltech.edu .

Whitney Clavin 818-354-4673
Jet Propulsion Laboratory, Pasadena, Calif.
Whitney.clavin@jpl.nasa.gov

J.D. Harrington 202-358-0321
Headquarters, Washington

j.d.harrington@nasa.gov

2012-122

Article source: http://www.jpl.nasa.gov/news/news.cfm?release=2012-122

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Cosmic "leaf blower" robs galaxy of star-making fuel

By alkaon on April 5, 2012 No Comments

Supernova explosions and the jets of a monstrous black hole are scattering a galaxy’s star-making gas like a cosmic leaf blower, a new study finds. The findings, which relied on ultraviolet observations from NASA’s Galaxy Evolution Explorer and a host of other instruments, fill an important gap in the current understanding of galactic evolution.

It has long been known that gas-rich spiral galaxies like our Milky Way smash together to create elliptical galaxies such as the one observed in the study. These big, round galaxies have very little star formation. The reddish glow of aging stars comes to dominate the complexion of elliptical galaxies, so astronomers refer to them as “red and dead.”

The process that drives the dramatic transformation from spiral galactic youth to elderly elliptical is the rapid loss of cool gas, the fuel from which new stars form. Supernova explosions can start the decline in star formation, and then shock waves from the supermassive black hole finish the job. Now astronomers think they have identified a recently merged galaxy where this gas loss has just gotten underway.

“We have caught a galaxy in the act of destroying its gaseous fuel for new stars and marching toward being a red-and-dead type of galaxy,” said Ananda Hota, an astronomer in Pune, India.

“We have found a crucial missing piece to connect and solve the puzzle of this phase of galaxy evolution,” Hota added.

The supermassive black holes that reside in the centers of galaxies can flare up when engorged by gas during galactic mergers. As a giant black hole feeds, colossal jets of matter shoot out from it, giving rise to what is known as an active galactic nucleus. According to theory, shock waves from these jets heat up and disperse the reservoirs of cold gas in elliptical galaxies, thus preventing new stars from taking shape.

The galaxy Hota and his team looked at, called NGC 3801, shows signs of such a process. NGC 3801 is unique in that evidence of a past merger is clearly seen, and the shock waves from the central black hole’s jets have started to spread out recently. The researchers used the galaxy Evolution Explorer to determine the age of the galaxy’s stars and decipher its evolutionary history. The ultraviolet observations show that NGC 3801’s star formation has petered out over the last 100 to 500 million years, demonstrating that the galaxy has indeed begun to leave behind its youthful years. The lack of many big, new, blue stars makes NGC 3801 look yellowish and reddish in visible light, and thus middle-aged.

What’s causing the galaxy to age and make fewer stars? The short-lived blue stars that formed right after it merged with another galaxy have already blown up as supernovae. Data from NASA’s Hubble Space Telescope revealed that those stellar explosions triggered a fast outflow of heated gas from NGC 3801’s central regions. That outflow has begun to banish the reserves of cold gas, and thus cut into NGC 3801’s overall star making.

Some star formation is still happening in NGC 3801, as shown in ultraviolet wavelengths observed by the galaxy Evolution Explorer, and in infrared wavelengths detected by NASA’s Spitzer Space Telescope. But that last flicker of youth will soon be extinguished by colossal shock waves from the black hole’s jets, seen in X-ray light by NASA’s Chandra X-ray Observatory. These blast waves are rushing outward from the galactic center at a velocity of nearly two million mph (3.2 million km/h). The waves will reach the outer portions of NGC 3801 in about 10 million years, scattering any remaining cool hydrogen gas and rendering the galaxy truly red and dead.

Astronomers think the transition captured early-on in the case of NGC 3801 — from the merger of gas-rich galaxies to the rise of an old-looking elliptical — happens quickly on cosmic time scales.

“The quenching of star formation by feedback from the active galactic nucleus probably occurs in just a billion years. That’s not very long compared to the 10-billion-year age of a typical big galaxy,” said Hota. “The explosive shock-wave event caused by the central black hole is so powerful that it can dramatically change the future course of the evolution of an entire galaxy.”

Additional observations for the study in optical light come from the Sloan Digital Sky Survey and in radio using the Very Large Array in New Mexico.

Article source: http://www.astronomy.com/~/link.aspx?_id=364a7787-d51a-48e0-9ea3-1f140e8281a7

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Cygnus Loop Nebula Resembles Human Head In Space, NASA Satellite Reveals (PHOTO)

By alkaon on March 30, 2012 No Comments

By: Tariq Malik Published: 03/29/2012 03:15 PM EDT on SPACE.com

A spectacular photo from a NASA telescope has revealed a wispy blue nebula with an odd twist: It looks like a giant human head in deep space.

The head-in-space nebula photo was snapped by NASA’s Galaxy Evolution Explorer satellite and shows an ultraviolet view of the so-called Cygnus Loop nebula, which is located 1,500 light-years from Earth in the constellation Cygnus, the Swan. It was released March 22 and featured this week on NASA’s website.

What makes the new Cygnus Loop image striking is its odd shape. The nebula looks like a giant human head and neck, which appear in profile facing the left of the image. A bright star serves as an eye while wispy nebula gas traces the outline of jaw, and close-cropped hair.

To be clear, the Cygnus Loop nebula head is an optical illusion, one of many caused when observers see familiar patterns in images. Recent examples of space illusions include images of the so-called Fried Egg nebula and Running Chicken nebula.

The Cygnus Loop nebula is all that remains from a colossal star explosion that occurred between 5,000 and 8,000 years ago.

“The filaments of gas and dust visible here in ultraviolet light were heated by the shockwave from the supernova, which is still spreading outward from the original explosion,” NASA explained in a photo description. “The original supernova would have been bright enough to be seen clearly from Earth with the naked eye.”

The nebula covers an area of the night sky that is more than three times the size of the full moon and is tucked beneath one of the wings of the imaginary swan that makes up the Cygnus constellation.

NASA’s Galaxy Evolution Explorer, which took the Cygnus Loop nebula photo, was launched in April 2003 on a mission to map vast areas of the sky in the ultraviolet range of the light spectrum. The spacecraft completed its primary mission in 2007 and was placed in standby mode as engineers prepare to shut it down for good later this year.

You can follow SPACE.com Managing Editor Tariq Malik on Twitter @tariqjmalik. Follow SPACE.com for the latest in space science and exploration news on Twitter @Spacedotcom and on Facebook.

Copyright 2012 SPACE.com, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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Article source: http://www.huffingtonpost.com/2012/03/29/head-shaped-nebula-photo_n_1389823.html

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NASA Image of the day

The Engine Burns Blue

 
This image shows a cutting-edge solar-electric propulsion thruster in development at NASA's Jet Propulsion Laboratory, Pasadena, Calif., that uses xenon ions for propulsion. An earlier version of this solar-electric propulsion engine has been flying on NASA's Dawn mission to the asteroid belt. This engine is being considered as part of the Asteroid Initiative, a proposal to robotically capture a small near-Earth asteroid and redirect it safely to a stable orbit in the Earth-moon system where astronauts can visit and explore it. This image was taken through a porthole in a vacuum chamber at JPL where the ion engine is being tested. Image credit: NASA/JPL-Caltech
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