NuSTAR = Pegasus-XL - 13.06.12 20:00:42 ЛМВ - Kwajalein

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Black Hole Naps Amidst Stellar Chaos
06.11.13



The Sculptor galaxy is seen in a new light, in this composite image fr om NASA's Nuclear Spectroscopic Telescope Array (NuSTAR) and the European Southern Observatory in Chile. Image credit: NASA/JPL-Caltech/JHU
 › Full image and caption › NuSTAR view only › See latest images
 
 Nearly a decade ago, NASA's Chandra X-ray Observatory caught signs of what appeared to be a black hole snacking on gas at the middle of the nearby Sculptor galaxy. Now, NASA's Nuclear Spectroscopic Telescope Array (NuSTAR), which sees higher-energy X-ray light, has taken a peek and found the black hole asleep.
 "Our results imply that the black hole went dormant in the past 10 years," said Bret Lehmer of the Johns Hopkins University, Baltimore, and NASA's Goddard Space Flight Center, Greenbelt, Md. "Periodic observations with both Chandra and NuSTAR should tell us unambiguously if the black hole wakes up again. If this happens in the next few years, we hope to be watching." Lehmer is lead author of a new study detailing the findings in the Astrophysical Journal.

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The slumbering black hole is about 5 million times the mass of our sun. It lies at the center of the Sculptor galaxy, also known as NGC 253, a so-called starburst galaxy actively giving birth to new stars. At 13 million light-years away, this is one of the closest starbursts to our own galaxy, the Milky Way.
 The Milky Way is all around more quiet than the Sculptor galaxy. It makes far fewer new stars, and its behemoth black hole, about 4 million times the mass of our sun, is also snoozing.
 "Black holes feed off surrounding accretion disks of material. When they run out of this fuel, they go dormant," said co-author Ann Hornschemeier of Goddard. "NGC 253 is somewhat unusual because the giant black hole is asleep in the midst of tremendous star-forming activity all around it."
 The findings are teaching astronomers how galaxies grow over time. Nearly all galaxies are suspected to harbor supermassive black holes at their hearts. In the most massive of these, the black holes are thought to grow at the same rate that new stars form, until blasting radiation from the black holes ultimately shuts down star formation. In the case of the Sculptor galaxy, astronomers do not know if star formation is winding down or ramping up.
 "Black hole growth and star formation often go hand-in-hand in distant galaxies," said Daniel Stern, a co-author and NuSTAR project scientist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "It's a bit surprising as to what's going on here, but we've got two powerful complementary X-ray telescopes on the case."
 Chandra first observed signs of what appeared to be a feeding supermassive black hole at the heart of the Sculptor galaxy in 2003. As material spirals into a black hole, it heats up to tens of millions of degrees and glows in X-ray light that telescopes like Chandra and NuSTAR can see.
 Then, in September and November of 2012, Chandra and NuSTAR observed the same region simultaneously. The NuSTAR observations -- the first-ever to detect focused, high-energy X-ray light from the region -- allowed the researchers to say conclusively that the black hole is not accreting material. NuSTAR launched into space in June of 2012.
 In other words, the black hole seems to have fallen asleep. Another possibility is that the black hole was not actually awake 10 years ago, and Chandra observed a different source of X-rays. Future observations with both telescopes may solve the puzzle.
 "The combination of coordinated Chandra and NuSTAR observations is extremely powerful for answering questions like this," said Lou Kaluzienski, NuSTAR Program Scientist at NASA Headquarters in Washington. "Now, we can get all sides of the story."
 The observations also revealed a smaller, flaring object that the researchers were able to identify as an "ultraluminous X-ray source," or ULX. ULXs are black holes feeding off material from a partner star. They shine more brightly than typical stellar-mass black holes generated from dying stars, but are fainter and more randomly distributed than the supermassive black holes at the centers of massive galaxies. Astronomers are still working to understand the size, origins and physics of ULXs.
 "These stellar-mass black holes are bumping along near the center of this galaxy," said Hornschemeier. "They tend to be more numerous in areas wh ere there is more star-formation activity."
 If and when the Sculptor's slumbering giant does wake up in the next few years amidst all the commotion, NuSTAR and Chandra will monitor the situation. The team plans to check back on the system periodically.

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http://www.nasa.gov/mission_pages/nustar/news/nustar20130611.html

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Телескоп NuSTAR обнаружил черную дыру, впавшую в "послеобеденный сон"

МОСКВА, 11 июн — РИА Новости. Черная дыра в одной из галактик в созвездии Скульптора, которая ранее активно поглощала межзвездный газ, теперь прекратила активность и впала в "послеобеденный сон", длящийся уже около десяти лет, свидетельствуют данные, полученные астрономами с помощью космического телескопа NuSTAR, говорится в сообщении НАСА.
"Заснувшая" черная дыра массой около 5 миллионов масс Солнца находится в центре активной галактики NGC 253 (известной также как "Серебряная монета"). В этой звездной системе, расположенной в 8 миллионах световых лет от Земли, процессы образования новых звезд идут с очень высокой скоростью.
Прежние наблюдения с рентгеновского телескопа "Чандра", проведенные в 2003 году, показали, что черная дыра активно поглощает газ. "Наши результаты свидетельствуют, что черная дыра уснула за последние десять лет. Периодические наблюдения с помощью телескопов "Чандра" и NuSTAR смогут сказать нам определенно, проснулась ли она вновь. Мы надеемся, что если она проснется в ближайшие несколько лет, мы сможем это увидеть", — сказал Брет Лэмер (Bret Lehmer) из Центра космических полетов имени Годдарда НАСА.
Ученые отмечают, что черные дыры в центрах галактик прекращают поглощать материю и впадают в спячку только тогда, когда в их окрестностях исчерпываются запасы "пищи". Черная дыра в NGC 253 необычна, потому что она "заснула" прямо во время активных процессов звездообразования, которые идут вокруг нее.
Серия одновременных наблюдений с помощью рентгеновского телескопа высокого разрешения NuSTAR и его "старшего коллеги" — "Чандры", проведенная в сентябре и ноябре 2012 года, позволила ученым достоверно установить, что черная дыра в галактике уже не поглощает материю.
Космический телескоп NuSTAR был запущен в июне 2012 года. Он находится на орбите высотой около 630 километров. Как ожидается, 350-килограммовый космический аппарат проработает на орбите как минимум два года. Телескоп работает в диапазоне рентгеновского излучения высокой энергии, причем он имеет чувствительность в 100 раз выше и пространственное разрешение в десять раз лучше, чем все другие рентгеновские телескопы.

http://ria.ru/science/20130611/942860433.html

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The Turbulent, High-Energy Sky Is Keeping NuSTAR Busy

06.17.13

 Status Update
 NuSTAR has been busy studying the most energetic phenomena in the universe. Recently, a few high-energy events have sprung up, akin to "things that go bump in the night." When one telescope catches a sudden outpouring of high-energy light in the sky, NuSTAR and a host of other telescopes stop what they were doing and take a better look.
 For example, in early April, the blazar Markarian 421 had an episode of extreme activity, brightening by more than 50 times its typical level. Blazars are a special class of galaxies with accreting, or "feeding," supermassive black holes at their centers. As the black holes feed, they light up, often ejecting jets of material. When the jets are pointing toward Earth, they are called blazars. By using telescopes sensitive to a range of energies to study how blazars vary, astrophysicists gain insight into black hole feeding processes and the physical conditions near the black hole.
 NuSTAR got lucky in the case of Markarian 421, because it was already observing the blazar at the time of its eruption, simultaneously with other telescopes, including NASA's Fermi and Swift satellites. The flare-up was the brightest ever observed for this object. In fact, it was so bright that NuSTAR and other telescopes changed their observing cadence to spend more time studying this galaxy. More on these findings will be available after the scientists have analyzed the data and published papers.
 Just a few weeks after this event, towards the end of April, NASA's Swift satellite noticed the region around the center of our own Milky Way galaxy had suddenly lit up. Flares lasting from a few minutes to three hours are not uncommon for the black hole in the center of the Milky Way, known as Sagittarius A*. In fact, NuSTAR observed such a flare last July (http://www.nasa.gov/mission_pages/nustar/news/nustar20121023.html). However, this new event had lasted tens of hours and got the whole high-energy community excited. NuSTAR was one of the first "on the scene," observing the galactic center less than 50 hours after the initial Swift discovery. The NuSTAR findings revealed that the brightening was due to a type of neutron star called a magnetar, and not Sagittarius A* itself. The results were written up and accepted in the Astrophysical Journal Letters.
 Yet another event popped up in the sky just a few days later, surprising astronomers. Swift found an extremely bright gamma-ray burst, brighter than any event it had previously identified during its nearly 10 years in orbit. A gamma-ray burst is a huge release of energy from a distant galaxy, thought to be triggered by the collapse of a massive star.
 The astronomical community, including NuSTAR, quickly reacted to the blast. NuSTAR provided the first focused, high-quality observations of a gamma-ray burst in high-energy X-rays.
 Beginning in April, the NuSTAR spacecraft gained use of the Kongsberg Satellite Services' Singapore tracking station for extra command uplinks and data downlinks. The spacecraft's primary tracking coverage is provided by the Italian Space Agency and uses antennas located in Malindi, Kenya, while data uplinks are provided by NASA's Tracking and Data Relay Satellite System (TDRSS) antennas. The back-up Singapore tracking station is helpful for periods when additional coverage is needed either due to high data-rate targets, such as bright objects, or when the Malindi antennas are unavailable. Additional coverage has also been provided by the Universal Space Network's Hawaii antenna.

http://www.nasa.gov/mission_pages/nustar/news/nustar20130617.html

[Andrey Samoilov]

February 19, 2014 - С помощью NuSTAR астрономы уточнили модели формирования сверхновых.
Были получены данные о распределении частиц изотопа титана-44, содержащегося в останках сверхновой Cassiopeia A. Вещество присутствует в центре формирования. Также "полосы" этого материала "торчат" в разные стороны.
http://www.nasa.gov/jpl/nustar/supernova-explosion-20140219/#.UwmwC4XQS4U
Снимки «NuSTAR» позволили исследователям поставить под сомнение те модели взрывов сверхновых, которые утверждают, что скорость вращения звезды перед «гибелью» увеличивается и что "спусковым механизмом" взрыва являются струи материи (джеты), выбрасываемые в пространство умирающей звездой.
"Результаты наблюдений за звездой Cas A позволяют предположить, что она, прежде чем взорваться, достаточно долго "хлюпала", вторично возбуждая и подпитывая энергией стоячие ударные волны, что в конце концов привело к отрыву внешних слоев от ядра звезды", - говорят ученые НАСА.

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NuSTAR's First Five Years in Space
https://www.jpl.nasa.gov/news/news.php?feature=6872