NGC 931

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NGC 931
NGC 931 -HST-606.png
NGC 931 by Hubble Space Telescope
Observation data (J2000 epoch)
Constellation Triangulum
Right ascension 02h 28m 14.5s [1]
Declination +31° 18′ 42″ [1]
Redshift 0.016652 ± 0.000020 [1]
Heliocentric radial velocity 4,992 ± 6 km/s [1]
Distance 159 ± 30 Mly (48.7 ± 9.3 Mpc) [1]
Apparent magnitude  (V)13.5 [2]
Characteristics
Type Sbc [1]
Apparent size  (V)3.9′ × 0.8′ [1]
Notable features Seyfert galaxy
Other designations
UGC 1935, Mrk 1040, KUG 0225+310, CGCG 504-089, MCG +05-06-049, PGC 9399 [1]

NGC 931 is a spiral galaxy located in the constellation Triangulum. It is located at a distance of circa 200 million light-years from Earth, which, given its apparent dimensions, means that NGC 931 is about 200,000 light years across. It was discovered by Heinrich d'Arrest on September 26, 1865. [3] It is classified as a Seyfert galaxy.

Contents

Characteristics

The nucleus of NGC 931 has been found to be active and it has been categorised as a type I Seyfert galaxy due to its narrow H-beta emission line. [4] [5] The most accepted theory for the energy source of active galactic nuclei is the presence of an accretion disk around a supermassive black hole. The mass of the black hole in the centre of NGC 931 is estimated to be 107.64 ± 0.40 (17- 110 million) M☉ based on the stellar velocity dispersion. [6] [7]

NGC 931 has been found to emit radiowaves, ultraviolet and X-rays. Observations by ASCA revealed the X-ray spectrum was composed of soft and hard emission. The hard element was identified as a strong and wide fluorescent FeKa line, which is created when X-rays meet an optically cold thick material. [8] The soft element has been identified as warm absorbing material. The galaxy was further observed by XMM-Newton, where it was observed that there were significant fluctuations and time lags in the flux changes observed both in the soft and hard elements. [9]

A detail X-ray spectrum of NGC 931 was obtained by Chandra X-ray Observatory. It revealed the presence of many absorption lines from neon, magnesium, and silicon, with a variety of ionisation states. These lines were attributed to low ionisation gases surrounding the nuclear X-ray source. No significant outflowing gas was detected in the large scale. [10]

Supernova

One supernova has been observed in NGC 931, SN 2009lw. The supernova was discovered by W. Li, S. B. Cenko, and A. V. Filippenko during the Lick Observatory Supernova Search on 24.24 November 2009, when it had an apparent magnitude of 18.8. [11] It was identified as a type-Ib or possibly a type-IIb supernova a few months past maximum light. [12]

Nearby galaxies

NGC 931 has been identified as a member of the NGC 973 group, one of the largest galaxy groups of the Perseus–Pisces Supercluster, [13] with at least 39 galaxies identified as its members. Other members of the group include NGC 917, NGC 940, NGC 969, NGC 973, NGC 974, NGC 978, NGC 987, NGC 983, NGC 1060, NGC 1066, NGC 1067, and UGC 2105. [14] On the other hand, Garcia recognised NGC 931 as the largest galaxy in a galaxy group known as the NGC 931 group, which also included NGC 940. [15]

A smaller companion galaxy, measuring 0.2 by 0.1 arcminutes, is superimposed on the galaxy, lying about 0.35 arcminutes towards the north. [16]

See also

Related Research Articles

An active galactic nucleus (AGN) is a compact region at the center of a galaxy that emits a significant amount of energy across the electromagnetic spectrum, with characteristics indicating that this luminosity is not produced by the stars. Such excess, non-stellar emissions have been observed in the radio, microwave, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an active galaxy. The non-stellar radiation from an AGN is theorized to result from the accretion of matter by a supermassive black hole at the center of its host galaxy.

<span class="mw-page-title-main">Seyfert galaxy</span> Class of active galaxies with very bright nuclei

Seyfert galaxies are one of the two largest groups of active galaxies, along with quasar host galaxies. They have quasar-like nuclei with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, their host galaxies are clearly detectable.

<span class="mw-page-title-main">NGC 3227</span> Galaxy in the constellation Leo

NGC 3227 is an intermediate spiral galaxy that is interacting with the dwarf elliptical galaxy NGC 3226. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies. Both galaxies may be found in the constellation Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.

<span class="mw-page-title-main">NGC 3226</span> Dwarf elliptical galaxy in the constellation Leo

NGC 3226 is a dwarf elliptical galaxy that is interacting with the spiral galaxy NGC 3227. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies. Both galaxies may be found in the constellation Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.

<span class="mw-page-title-main">NGC 5005</span> Galaxy in the constellation Canes Venatici

NGC 5005, also known as Caldwell 29, is an inclined spiral galaxy in the constellation Canes Venatici. The galaxy has a relatively bright nucleus and a bright disk that contains multiple dust lanes. The galaxy's high surface brightness makes it an object that is visible to amateur astronomers using large amateur telescopes.

<span class="mw-page-title-main">NGC 5643</span> Galaxy in the constellation Lupus

NGC 5643 is an intermediate spiral galaxy in the constellation Lupus. Based on the tip of the red-giant branch distance indicator, it is located at a distance of about 40 million light-years. NGC 5643 has an active galactic nucleus and is a type II Seyfert galaxy.

<span class="mw-page-title-main">NGC 7469</span> Galaxy located in the constellation Pegasus

NGC 7469 is an intermediate spiral galaxy in the constellation of Pegasus. NGC 7469 is located about 200 million light-years away from Earth, which means, given its apparent dimensions, that NGC 7469 is approximately 90,000 light-years across. It was discovered by William Herschel on November 12, 1784.

<span class="mw-page-title-main">NGC 3367</span> Spiral galaxy in the constellation Leo

NGC 3367 is a barred spiral galaxy located in the constellation Leo. It is located at a distance of about 120 million light years from Earth, which, given its apparent dimensions, means that NGC 3367 is about 85,000 light years across. It was discovered by William Herschel on March 19, 1784.

<span class="mw-page-title-main">NGC 7213</span> Galaxy in the constellation Grus

NGC 7213 is a lenticular galaxy located in the constellation Grus. It is located at a distance of circa 70 million light-years from Earth, which, given its apparent dimensions, means that NGC 7213 is about 75,000 light-years across. It was discovered by John Herschel on September 30, 1834. It is an active galaxy with characteristics between a type I Seyfert galaxy and LINER.

<span class="mw-page-title-main">NGC 7130</span> Galaxy in the constellation Piscis Austrinus

NGC 7130 is a spiral galaxy located in the constellation Piscis Austrinus. It is located at a distance of about 220 million light years from Earth, which, given its apparent dimensions, means that NGC 7130 is about 100,000 light years across. It was discovered by John Herschel on September 25, 1834, and discovered independently by Lewis Swift on September 17, 1897. The location of the galaxy given in the New General Catalogue was off by 30 arcminutes in declination from the location of the galaxy.

<span class="mw-page-title-main">NGC 985</span> Ring galaxy in the constellation Cetus

NGC 985 is a ring galaxy in the constellation of Cetus. It is located about 550 million light years away from Earth, which means, given its apparent dimensions, that NGC 985 is approximately 160,000 light years across. It was discovered by Francis Leavenworth in 1886. It is a type 1 Seyfert galaxy.

<span class="mw-page-title-main">NGC 1386</span> Galaxy in the constellation Eridanus

NGC 1386 is a spiral galaxy located in the constellation Eridanus. It is located at a distance of circa 53 million light years from Earth, which, given its apparent dimensions, means that NGC 1386 is about 50,000 light years across. It is a Seyfert galaxy, the only one in Fornax Cluster.

<span class="mw-page-title-main">NGC 4278</span> Galaxy in the constellation Coma Berenices

NGC 4278 is an elliptical galaxy located in the constellation Coma Berenices. It is located at a distance of circa 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4278 is about 65,000 light years across. It was discovered by William Herschel on March 13, 1785. NGC 4278 is part of the Herschel 400 Catalogue and can be found about one and 3/4 of a degree northwest of Gamma Comae Berenices even with a small telescope.

<span class="mw-page-title-main">NGC 5363</span> Galaxy in the constellation Virgo

NGC 5363 is a lenticular galaxy located in the constellation Virgo. It is located at a distance of circa 65 million light years from Earth, which, given its apparent dimensions, means that NGC 5363 is about 100,000 light years across. It was discovered by William Herschel on January 19, 1784. It is a member of the NGC 5364 Group of galaxies, itself one of the Virgo III Groups strung out to the east of the Virgo Supercluster of galaxies.

<span class="mw-page-title-main">NGC 2273</span> Galaxy in the constellation Lynx

NGC 2273 is a barred spiral galaxy located in the constellation Lynx. It is located at a distance of circa 95 million light years from Earth, which, given its apparent dimensions, means that NGC 2273 is about 100,000 light years across. It was discovered by Nils Dunér on September 15, 1867.

<span class="mw-page-title-main">NGC 3393</span> Galaxy in the constellation Hydra

NGC 3393 is a barred spiral galaxy located in the constellation Hydra. It is located at a distance of circa 180 million light-years from Earth, which, given its apparent dimensions, means that NGC 3393 is about 140,000 light-years across. It was discovered by John Herschel on March 24, 1835. It is a Type II Seyfert galaxy, known to host two supermassive black holes, which are the nearest known pair of supermassive black holes to Earth.

<span class="mw-page-title-main">NGC 5252</span> Galaxy in the constellation of Virgo

NGC 5252 is a lenticular galaxy located in the constellation Virgo. It is located at a distance of about 220 to 320 million light years from Earth, which, given its apparent dimensions, means that NGC 5252 is about 100,000 light years across. It was discovered by William Herschel on February 2, 1786.

<span class="mw-page-title-main">Markarian 590</span> Galaxy in the constellation of Cetus

Markarian 590, also known as NGC 863, NGC 866, and NGC 885, is a spiral galaxy located in the constellation Cetus. It is located at a distance of about 300 million light years from Earth, which, given its apparent dimensions, means that NGC 863 is about 110,000 light years across. It is a change looking Seyfert galaxy.

<span class="mw-page-title-main">NGC 4253</span> Galaxy in the constellation of Coma Berenices

NGC 4253 is a barred spiral galaxy located in the constellation Coma Berenices. It is located at a distance of about 185 million light years from Earth, which, given its apparent dimensions, means that NGC 4253 is about 65,000 light years across. It was discovered by William Herschel on February 3, 1788. It is a Seyfert galaxy.

<span class="mw-page-title-main">NGC 5683</span> Galaxy in the constellation Boötes

NGC 5683 is a type S0-a lenticular galaxy with a bar located in the Boötes constellation. It is 513 million light-years away from the Solar System and has an approximate diameter of 256,000 light-years meaning it is larger compared to the Milky Way. NGC 5683 was discovered by George Johnstone Stoney on April 13, 1850.

References

  1. 1 2 3 4 5 6 7 8 "NASA/IPAC Extragalactic Database". Results for NGC 931. Retrieved 2019-01-18.
  2. ↑ "Revised NGC Data for NGC 931". spider.seds.org. Retrieved 25 November 2018.
  3. ↑ Seligman, Courtney. "NGC 931 (= PGC 9399)". Celestial Atlas. Retrieved 19 November 2018.
  4. ↑ Osterbrock, D. E.; Shuder, J. M. (May 1982). "Emission-line profiles in Seyfert 1 galaxies". The Astrophysical Journal Supplement Series. 49: 149. Bibcode:1982ApJS...49..149O. doi:10.1086/190793.
  5. ↑ Osterbrock, D. E.; Dahari, O. (October 1983). "Spectra of Seyfert galaxies and Seyfert galaxy candidates". The Astrophysical Journal. 273: 478. Bibcode:1983ApJ...273..478O. doi: 10.1086/161385 .
  6. ↑ Zhou, Xin-Lin; Zhang, Shuang-Nan; Wang, Ding-Xiong; Zhu, Ling (10 February 2010). "Calibrating the Correlation Between Black Hole Mass and X-Ray Variability Amplitude: X-Ray Only Black Hole Mass Estimates for Active Galactic Nuclei and Ultra-Luminous X-Ray Sources". The Astrophysical Journal. 710 (1): 16–23. arXiv: 0912.2636 . Bibcode:2010ApJ...710...16Z. doi:10.1088/0004-637X/710/1/16. S2CID   118336945.
  7. ↑ De Marco, B.; Ponti, G.; Cappi, M.; Dadina, M.; Uttley, P.; Cackett, E. M.; Fabian, A. C.; Miniutti, G. (21 May 2013). "Discovery of a relation between black hole mass and soft X-ray time lags in active galactic nuclei". Monthly Notices of the Royal Astronomical Society. 431 (3): 2441–2452. arXiv: 1201.0196 . Bibcode:2013MNRAS.431.2441D. doi: 10.1093/mnras/stt339 . S2CID   18276159.
  8. ↑ Reynolds, C. S.; Fabian, A. C.; Inoue, H. (15 October 1995). "ASCA observations of the Seyfert 1 galaxies Mrk 1040 and MS 0225.5 + 3121". Monthly Notices of the Royal Astronomical Society. 276 (4): 1311–1319. arXiv: astro-ph/9504095 . Bibcode:1995MNRAS.276.1311R. doi: 10.1093/mnras/276.4.1311 .
  9. ↑ Tripathi, Shruti; Misra, Ranjeev; Dewangan, Gulab; Rastogi, Shantanu (1 August 2011). "Soft time lags in the X-ray emission of Mrk 1040". The Astrophysical Journal. 736 (2): L37. arXiv: 1106.6139 . Bibcode:2011ApJ...736L..37T. doi:10.1088/2041-8205/736/2/L37. S2CID   44236594.
  10. ↑ Reeves, J. N.; Braito, V.; Behar, E.; Fischer, T. C.; Kraemer, S. B.; Lobban, A.; Nardini, E.; Porquet, D.; Turner, T. J. (28 February 2017). "High-resolution X-Ray Spectroscopy of the Seyfert 1 Galaxy Mrk 1040. Revealing the Failed Nuclear Wind with Chandra". The Astrophysical Journal. 837 (1): 23. arXiv: 1702.00461 . Bibcode:2017ApJ...837...23R. doi: 10.3847/1538-4357/aa5da1 . hdl: 2381/45349 . S2CID   118860247.
  11. ↑ "Electronic Telegram No. 2175: Supernova 2009lw in NGC 931". Central Bureau for Astronomical Telegrams. 15 February 2010. Retrieved 3 July 2019.
  12. ↑ W. Li, S. B. Cenko, and A. V. Filippenko (25 November 2009). "Electronic Telegram No. 2047: Silverman, J. M.; Cenko, S. B.; Filippenko, A. V." Central Bureau for Astronomical Telegrams. Retrieved 3 July 2019.{{cite web}}: CS1 maint: multiple names: authors list (link)
  13. ↑ "The Perseus-Pisces Supercluster". www.atlasoftheuniverse.com.
  14. ↑ Crook, Aidan C.; Huchra, John P.; Martimbeau, Nathalie; Masters, Karen L.; Jarrett, Tom; Macri, Lucas M. (October 2008). "Erratum: "Groups of Galaxies in the Two Micron All Sky Redshift Survey" (ApJ, 655, 790 [2007])". The Astrophysical Journal. 685 (2): 1320–1323. Bibcode:2008ApJ...685.1320C. doi: 10.1086/590385 .
  15. ↑ Garcia, A. M. (1993). "General study of group membership. II - Determination of nearby groups". Astronomy and Astrophysics Supplement Series. 100 (1): 47–90. Bibcode:1993A&AS..100...47G. ISSN   0365-0138.
  16. ↑ Nilson, P. (1973) Uppsala General Catalogue of Galaxies, Acta Universitatis Upsalienis, Nova Regiae Societatis Upsaliensis, Series V: A Vol. 1
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