Galactic Center
The Galactic Center is the rotational center and the
There are around 10 million stars within one parsec of the Galactic Center, dominated by red giants, with a significant population of massive supergiants and Wolf–Rayet stars from star formation in the region around 1 million years ago. The core stars are a small part within the much wider galactic bulge.
Discovery
Because of interstellar dust along the line of sight, the Galactic Center cannot be studied at visible, ultraviolet, or soft (low-energy) X-ray wavelengths. The available information about the Galactic Center comes from observations at gamma ray, hard (high-energy) X-ray, infrared, submillimetre, and radio wavelengths.
At
In 1958 the
In July 2022, astronomers reported the discovery of massive amounts of
Distance to the Galactic Center
The exact distance between the Solar System and the Galactic Center is not certain,[14] although estimates since 2000 have remained within the range 24–28.4 kilolight-years (7.4–8.7 kiloparsecs).[15] The latest estimates from geometric-based methods and standard candles yield the following distances to the Galactic Center:
- 7.4±0.2(stat) ± 0.2(syst) or 7.4±0.3 kpc (≈24±1 kly)[15]
- 7.62±0.32 kpc (≈24.8±1 kly)[16]
- 7.7±0.7 kpc (≈25.1±2.3 kly)[17]
- 7.94 or 8.0±0.5 kpc (≈26±1.6 kly)[18][19][20]
- 7.98±0.15(stat) ± 0.20(syst) or 8.0±0.25 kpc (≈26±0.8 kly)[21]
- 8.33±0.35 kpc (≈27±1.1 kly)[5]
- 8.0±0.3 kpc (≈25.96±0.98 kly)[22]
- 8.7±0.5 kpc (≈28.4±1.6 kly)[23]
- 8.122±0.031 kpc (≈26.49±0.1 kly)[24]
- 8.178±0.013(stat) ± 0.022(syst) kpc (≈26.67±0.1 kly)[3]
An accurate determination of the distance to the Galactic Center as established from
The nature of the Milky Way's
Supermassive black hole
The complex astronomical radio source Sagittarius A appears to be located almost exactly at the Galactic Center and contains an intense compact radio source, Sagittarius A*, which coincides with a supermassive black hole at the center of the Milky Way. Accretion of gas onto the black hole, probably involving an accretion disk around it, would release energy to power the radio source, itself much larger than the black hole.
A study in 2008 which linked
Scientists at the Max Planck Institute for Extraterrestrial Physics in Germany using Chilean telescopes have confirmed the existence of a supermassive black hole at the Galactic Center, on the order of 4.3 million solar masses.[5] Later studies have estimated a mass of 3.7 million[34][35] or 4.1 million solar masses.[24]
On 5 January 2015, NASA reported observing an
Gamma- and X-ray emitting Fermi bubbles
In November 2010, it was announced that two large elliptical lobe structures of energetic
The origin of the bubbles is being researched.[40][41] The bubbles are connected and seemingly coupled, via energy transport, to the galactic core by columnar structures of energetic plasma termed chimneys.[42] In 2020, for the first time, the lobes were seen in visible light[43] and optical measurements were made.[44] By 2022, detailed computer simulations further confirmed that the bubbles were caused by the Sagittarius A* black hole.[45][38]
Stellar population
The central cubic
Star formation does not seem to be occurring currently at the Galactic Center, although the Circumnuclear Disk of molecular gas that orbits the Galactic Center at two parsecs seems a fairly favorable site for star formation. Work presented in 2002 by Antony Stark and Chris Martin mapping the gas density in a 400-
In addition to the paradox of youth, there is also a "conundrum of old age" associated with the distribution of the old stars at the Galactic Center. Theoretical models had predicted that the old stars—which far outnumber young stars—should have a steeply-rising density near the black hole, a so-called Bahcall–Wolf cusp. Instead, it was discovered in 2009 that the density of the old stars peaks at a distance of roughly 0.5 parsec from Sgr A*, then falls inward: instead of a dense cluster, there is a "hole", or core, around the black hole.[51] Several suggestions have been put forward to explain this puzzling observation, but none is completely satisfactory.[52][53] For instance, although the black hole would eat stars near it, creating a region of low density, this region would be much smaller than a parsec. Because the observed stars are a fraction of the total number, it is theoretically possible that the overall stellar distribution is different from what is observed, although no plausible models of this sort have been proposed yet.
Gallery
In May 2021 NASA published new images of the Galactic Center, based on surveys from Chandra X-ray Observatory and other telescopes.[54] Images are about 2.2 degrees (1,000 light years) across and 4.2 degrees (2,000 light years) long.
-
A small portion of a gigapixel color mosaic of the Milky Way's heart.[55]
-
Red giant stars coexist with white, Sun-like stars.[56]
-
White Dwarfs in Milky Way's Central Hub.[57]
-
The center of the Milky Way – image taken by ISAAC, the VLT's near- and mid-infrared spectrometer and camera.
-
Infrared image from Spitzer Space Telescope.
-
A view of the night sky near Sagittarius, enhanced to show better contrast and detail in the dust lanes. The principal stars in Sagittarius are indicated in red.
-
The central parts of the Milky Way, as observed in the near-infrared with the NACO instrument onESO's Very Large Telescope.
-
Infra-red image of the center of the Milky Way revealing a new population of massive stars.
-
Detection of an unusually bright X-ray flare from Sagittarius A*, a supermassive black hole in the center of the Milky Way galaxy.[36]
-
The center of the Milky Way, as imaged by 64 radio telescopes of the South African MeerKAT array.
See also
Notes and references
- ^ Overbye, Dennis (31 January 2022). "An Electrifying View of the Heart of the Milky Way – A new radio-wave image of the center of our galaxy reveals all the forms of frenzy that a hundred million or so stars can get up to". The New York Times. Retrieved 1 February 2022.
- S2CID 246275657.
- ^ S2CID 119190574.
- ^ S2CID 4424735.
- ^ S2CID 1431308.
- ^ Ley, Willy (August 1965). "The Galactic Giants". For Your Information. Galaxy Science Fiction. pp. 130–142.
- doi:10.1086/142423.
- doi:10.1086/125835.
- Bibcode:1996A&A...310..771N.
- doi:10.1086/145957.
- .
- ^ Starr, Michelle (8 July 2022). "Loads of Precursors For RNA Have Been Detected in The Center of Our Galaxy". ScienceAlert. Retrieved 9 July 2022.
- .
- .
- ^ S2CID 119235554.
- S2CID 122485461.
- S2CID 14316644.
- .
- S2CID 16425333.
- doi:10.1002/asna.200310181. Archived from the original(PDF) on 21 June 2007.
- arXiv:1202.6128 [astro-ph.GA].
- S2CID 118936491.
- ^ S2CID 125177722.
- ^ S2CID 118891445.
- ^ Bibcode:2010AcA....60...55M.
- ^ Vovk, Olga (27 April 2011). "Milky Way: Distance to the Galactic Centre". Universe at a glance (blog). Retrieved 23 March 2019.
- S2CID 15040792.
- S2CID 399710.
- S2CID 16244436.
- S2CID 16046532.
- ^ Staff (12 September 2005). "Introduction: Galactic Ring Survey". Boston University. Retrieved 10 May 2007.
- ^ "Astronomers reveal first image of the black hole at the heart of our galaxy". Event Horizon Telescope. Archived from the original on 12 May 2022. Retrieved 12 May 2022.
- S2CID 205040663.
- S2CID 8656531.
- S2CID 4302128.
- ^ a b Chou, Felicia; Anderson, Janet; Watzke, Megan (5 January 2015). "Release 15-001 – NASA's Chandra Detects Record-Breaking Outburst from Milky Way's Black Hole". NASA.
- ^ a b c Aguilar, David A.; Pulliam, Christine (9 November 2010). "Astronomers Find Giant, Previously Unseen Structure in our Galaxy". Harvard-Smithsonian Center for Astrophysics. Release No. 2010-22.
- ^ S2CID 247292361.
- ^ "2014 Rossi prize awarded to Douglas Finkbeiner, Tracy Slatyer, and Meng Su". Harvard University. 8 January 2014.
- S2CID 56443272.
- ^ Liu, Jia (15 May 2020). "Researchers reveal common origin of Fermi bubbles and galactic center X-ray outflows". Phys.org. Science X Network.
- PMID 30894730.
- S2CID 220969030.
- ^ "236th Meeting of the American Astronomical Society". www.abstractsonline.com. Retrieved 8 June 2020.
- ^ University of Michigan (8 March 2022). "Massive bubbles at center of Milky Way caused by supermassive black hole". Phys.org. Science X Network.
- ^ "Lecture 31: The Center of Our Galaxy".
- S2CID 20968628.
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- ^ "UCLA Galactic Center Group". Archived from the original on 26 June 2017. Retrieved 9 November 2007.
- ^ "Galactic Center".
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- ^ "Lights out in the galactic centre". www.eso.org. Retrieved 30 April 2018.
- ^ "Hubble captures glittering crowded hub of our Milky Way". www.spacetelescope.org. Retrieved 15 January 2018.
- ^ "Hubble Spots White Dwarfs in Milky Way's Central Hub". Retrieved 9 November 2015.
Further reading
- Eckart, A.; Schödel, R.; Straubmeier, C. (2005). The Black Hole at the Center of the Milky Way. London: Imperial College Press. ISBN 978-1-86094-567-0.
- ISBN 978-0-691-09505-9.
- Melia, Fulvio (2007). The Galactic Supermassive Black Hole. Princeton: Princeton University Press. ISBN 978-0-691-13129-0.
Press
- "New MeerKAT radio image reveals complex heart of the Milky Way – SARAO". 26 January 2022.
External links
- UCLA Galactic Center Group Archived 26 June 2017 at the Wayback Machine
- Max Planck Institute for Extraterrestrial Physics Galactic Center Group
- The Galactic Supermassive Black Hole
- The Black Hole at the Center of the Milky Way
- The dark heart of the Milky Way
- Animation showing orbits of stars near the center of the Milky Way galaxy
- Zooming in on the center of the Milky Way
- Dramatic Increase in Supernova Explosions Looms
- APOD:
- A simulation of the stars orbiting the Milky Way's central massive black hole
- Galactic Center on arxiv.org