From The National Aeronautics and Space Administration Chandra X-ray telescope: “NGC 4424:: NASA Telescopes Capture Stellar Delivery Service for Black Hole” 

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Credit: A. Graham et al./X-ray: NASA/CXC/Swinburne Univ. of Technology/; Optical: NASA/ESA/STScI.

NGC 4424 is a spiral galaxy in the Virgo galaxy cluster that is absorbing the collision of a smaller one.

Data from NASA’s Chandra X-ray Observatory provides evidence for a supermassive black hole in the smaller galaxy.

The smaller galaxy has likely acted as a black hole “delivery service” for NGC 4424.

A cluster of stars remaining after the smaller galaxy has had most of its stars stripped away has been nicknamed “Nikhuli,” a name relating to the Tulini festival for the harvest..


Astronomers may have witnessed a galaxy’s black hole delivery system in action. A new study using data from NASA’s Chandra X-ray Observatory and Hubble Space Telescope outlines how a large black hole may have been delivered to the spiral galaxy NGC 4424 by another, smaller galaxy.

NGC 4424 is located about 54 million light-years from Earth in the Virgo galaxy cluster.

The main panel of this image, which has been previously released, shows a wide-field view of this galaxy in optical light from Hubble. The image is about 45,000 light-years wide. The center of this galaxy is expected to host a large black hole estimated to contain a mass between about 60,000 and 100,000 Suns. There are also likely to be millions of stellar-mass black holes, which contain between about 5 and 30 solar masses, spread throughout the galaxy.

The inset features a close-up view of NGC 4424 that shows Chandra X-ray data (blue), plus infrared data from Hubble (red) that has had infrared light from a model of NGC 4424 subtracted from the image to show other faint features. This inset image is about 1,160 light-years across. The elongated red object is a cluster of stars that the authors of the new study have nicknamed “Nikhuli,” a name relating to the Tulini festive period of celebrating and wishing for a rich harvest. This name is taken from the Sumi language from the Indian state of Nagaland. The Chandra data shows a point source of X-rays.

Close-up view of NGC 4424 (Credit: A. Graham et al./X-ray: NASA/CXC/Swinburne Univ. of Technology/; Optical: NASA/ESA/STScI).

The researchers determined Nikhuli is likely the center of a small galaxy that has had most of its stars stripped away as it collides with the larger galaxy NGC 4424. Nikhuli has also been stretched out by gravitational forces as it falls towards the center of NGC 4424, giving it an elongated shape. Currently, Nikhuli is about 1,300 light-years from the center of NGC 4424, or about 20 times closer than the Earth is to the Milky Way’s giant black hole.

One possible explanation for the Chandra X-ray source in the inset is that matter from Nikhuli is falling rapidly into a stellar-mass black hole. However, because these smaller black holes are expected to be rare in a cluster the size of Nikhuli, the authors argue it is more likely from material falling slowly onto a more massive black hole weighing between about 40,000 and 150,000 Suns. This is similar to the expected size of the black hole in the center of NGC 4424. These results imply that Nikhuli is likely acting as a delivery system for NGC 4424’s supply of black holes, in this case bringing along a massive one. If the center of NGC 4424 contains a massive black hole, Nikhuli’s massive black hole should end up orbiting it. The distance separating the pair should then shrink until gravitational waves are produced and the two massive black holes merge with each other.

A paper describing these results appeared in the December 2021 issue of The Astrophysical Journal [below]. The authors of the study are Alister Graham (Swinburne Astronomy Online, Australia), Roberto Soria (University of the Chinese Academy of Sciences in Beijing, China), Bogdan Ciambur (The Paris Observatory, France), Benjamin Davis (New York University in Abu Dhabi, United Arab Emirates), and Douglas Swartz (NASA’s Marshall Space Flight Center in Huntsville, Alabama).

Quick Look: NASA Telescopes Capture Stellar Delivery Service for Black Hole.

Science paper:
The Astrophysical Journal

See the full article here .


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NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.
In 1976 the Chandra X-ray Observatory (called AXAF at the time) was proposed to National Aeronautics and Space Administration by Riccardo Giacconi and Harvey Tananbaum. Preliminary work began the following year at NASA’s Marshall Space Flight Center and the Harvard Smithsonian Center for Astrophysics. In the meantime, in 1978, NASA launched the first imaging X-ray telescope, Einstein (HEAO-2), into orbit. Work continued on the AXAF project throughout the 1980s and 1990s. In 1992, to reduce costs, the spacecraft was redesigned. Four of the twelve planned mirrors were eliminated, as were two of the six scientific instruments. AXAF’s planned orbit was changed to an elliptical one, reaching one third of the way to the Moon’s at its farthest point. This eliminated the possibility of improvement or repair by the space shuttle but put the observatory above the Earth’s radiation belts for most of its orbit. AXAF was assembled and tested by TRW (now Northrop Grumman Aerospace Systems) in Redondo Beach, California.

AXAF was renamed Chandra as part of a contest held by NASA in 1998, which drew more than 6,000 submissions worldwide. The contest winners, Jatila van der Veen and Tyrel Johnson (then a high school teacher and high school student, respectively), suggested the name in honor of Nobel Prize–winning Indian-American astrophysicist Subrahmanyan Chandrasekhar. He is known for his work in determining the maximum mass of white dwarf stars, leading to greater understanding of high energy astronomical phenomena such as neutron stars and black holes. Fittingly, the name Chandra means “moon” in Sanskrit.

Originally scheduled to be launched in December 1998, the spacecraft was delayed several months, eventually being launched on July 23, 1999, at 04:31 UTC by Space Shuttle Columbia during STS-93. Chandra was deployed from Columbia at 11:47 UTC. The Inertial Upper Stage’s first stage motor ignited at 12:48 UTC, and after burning for 125 seconds and separating, the second stage ignited at 12:51 UTC and burned for 117 seconds. At 22,753 kilograms (50,162 lb), it was the heaviest payload ever launched by the shuttle, a consequence of the two-stage Inertial Upper Stage booster rocket system needed to transport the spacecraft to its high orbit.

Chandra has been returning data since the month after it launched. It is operated by the SAO at the Chandra X-ray Center in Cambridge, Massachusetts, with assistance from Massachusetts Institute of Technology and Northrop Grumman Space Technology. The ACIS CCDs suffered particle damage during early radiation belt passages. To prevent further damage, the instrument is now removed from the telescope’s focal plane during passages.

Although Chandra was initially given an expected lifetime of 5 years, on September 4, 2001, NASA extended its lifetime to 10 years “based on the observatory’s outstanding results.” Physically Chandra could last much longer. A 2004 study performed at the Chandra X-ray Center indicated that the observatory could last at least 15 years.

In July 2008, the International X-ray Observatory, a joint project between European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU), NASA and Japan Aerospace Exploration Agency (JAXA) (国立研究開発法人宇宙航空研究開発機構], was proposed as the next major X-ray observatory but was later cancelled. ESA later resurrected a downsized version of the project as the Advanced Telescope for High Energy Astrophysics (ATHENA), with a proposed launch in 2028.

European Space Agency [La Agencia Espacial Europea] [Agence spatiale européenne][Europäische Weltraumorganisation](EU) Athena spacecraft depiction

On October 10, 2018, Chandra entered safe mode operations, due to a gyroscope glitch. NASA reported that all science instruments were safe. Within days, the 3-second error in data from one gyro was understood, and plans were made to return Chandra to full service. The gyroscope that experienced the glitch was placed in reserve and is otherwise healthy.

The National Aeronautics and Space Administration (NASA) is the agency of the United States government that is responsible for the nation’s civilian space program and for aeronautics and aerospace research.

President Dwight D. Eisenhower established the National Aeronautics and Space Administration (NASA) in 1958 with a distinctly civilian (rather than military) orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29, 1958, disestablishing NASA’s predecessor, the National Advisory Committee for Aeronautics (NACA). The new agency became operational on October 1, 1958.

Since that time, most U.S. space exploration efforts have been led by NASA, including the Apollo moon-landing missions, the Skylab space station, and later the Space Shuttle. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle and Commercial Crew vehicles. The agency is also responsible for the Launch Services Program (LSP) which provides oversight of launch operations and countdown management for unmanned NASA launches. Most recently, NASA announced a new Space Launch System that it said would take the agency’s astronauts farther into space than ever before and lay the cornerstone for future human space exploration efforts by the U.S.

NASA science is focused on better understanding Earth through the Earth Observing System, advancing heliophysics through the efforts of the Science Mission Directorate’s Heliophysics Research Program, exploring bodies throughout the Solar System with advanced robotic missions such as New Horizons, and researching astrophysics topics, such as the Big Bang, through the Great Observatories [NASA/ESA Hubble, NASA Chandra, NASA Spitzer, and associated programs.] NASA shares data with various national and international organizations such as from [JAXA]Greenhouse Gases Observing Satellite.