NGC 4494

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NGC 4494
NGC 4494 2MASS.jpg
NGC 4494 by 2MASS
Observation data (J2000 epoch)
Constellation Coma Berenices
Right ascension 12h 31m 24.1s [1]
Declination +25° 46′ 31″ [1]
Redshift 1342 ± 5 km/s [1]
Distance 45 ± 10 Mly (13.7 ± 3.2 Mpc) [1]
Apparent magnitude  (V)9.7 [2]
Characteristics
Type E1-2 [1]
Apparent size  (V)4.8′ × 3.5′ [1]
Other designations
UGC 7662, MCG +04-30-002, PGC 41441 [1]

NGC 4494 is an elliptical galaxy located in the constellation Coma Berenices. It is located at a distance of circa 45 million light years from Earth, which, given its apparent dimensions, means that NGC 4494 is about 60,000 light years across. It was discovered by William Herschel in 1785.

Contents

Characteristics

The galaxy hosts a supermassive black hole with estimated mass 26.9 ± 20.4 millions M⊙, based on velocity dispersion. [3] A nuclear dust ring has been detected in NGC 4494, based on observations by the Hubble Space Telescope. It has semimajor axis 0.6 arcseconds, which corresponds to 60 parsec at the distance of NGC 4494. [4] Its ring is symmetric, implying that the dust has settled in this galaxy, [5] after the galaxy merger with a relatively gas rich galaxy that led to its creation. [6] The core of NGC 4494 is kinematically decoupled, as with many elliptical galaxies, probably a result of a galaxy merger. [7]

Dark matter

In observations by XMM-Newton observatory, the galaxy was quite faint in X-rays, nearly two orders of magnitude fainter than galaxies with similar optical luminosities. This fact has been attributed to lack of dark matter and hot gas of the galaxy. [8]

The amount of dark matter existing in the halo of NGC 4494 has been debated. [9] The galaxy is characterised as "naked" by Romanowsky et al., [10] Napolitano et al. found that the dark matter halo has unexpectedly low central density [11] and the analysis by Deason et al. revealed an unusually low dark matter fraction, 0.32 ± 0.12 at 5Re. [12] Rodionov and Athanassoula tried to set strict constraint to the halo mass, but with only partial success. [7] On the other hand, Morganti et al. found the dark matter fraction to be about 0.6 ± 0.1 at 5Re, with particularly high dark matter fraction inside ~ 3Re. [9]

Nearby galaxies

NGC 4494 belongs to the NGC 4565 group, named after the spiral galaxy NGC 4565. Other members of the group are NGC 4525, NGC 4562, NGC 4570, NGC 4725 and NGC 4747. [13] NGC 4494 is also a member of the Coma I Group [14] [15] [16] [17] which is part of the Virgo Supercluster. [18]

Related Research Articles

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<span class="mw-page-title-main">Virgo Supercluster</span> Galactic supercluster containing the Virgo Cluster

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<span class="mw-page-title-main">Galaxy rotation curve</span> Observed discrepancy in galactic angular momenta

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<span class="mw-page-title-main">Messier 84</span> Galaxy in the constellation Virgo

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<span class="mw-page-title-main">Galaxy merger</span> Merger whereby at least two galaxies collide

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<span class="mw-page-title-main">Quasi-star</span> Hypothetical early-universe star with a black hole core

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<span class="mw-page-title-main">NGC 5929</span> Seyfert galaxy in the constellation Boötes

NGC 5929 is a well-studied Seyfert galaxy in the constellation Boötes. It was discovered by English astronomer John Herschel on May 13, 1828. In the revised New General Catalogue it is described as "elongated, brighter toward the middle, with a slightly diffuse halo". This galaxy is located at an estimated distance of 133 million light-years. It forms an interacting pair with NGC 5930 at an angular separation of 0.5′; together they form entry number 90 in Halton Arp's 1966 Atlas of Peculiar Galaxies. A dust streak from NGC 5930 appears to lie in front of NGC 5929, suggesting that the former galaxy is the closer member of this pair.

<span class="mw-page-title-main">NGC 1052</span> Elliptical galaxy in the constellation Cetus

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<span class="mw-page-title-main">NGC 988</span> Galaxy in the constellation Cetus

NGC 988 is a spiral galaxy located in the constellation Cetus. It lies at a distance of 50 million light years from Earth, which, given its apparent dimensions, means that NGC 988 is about 75,000 light years across. Magnitude 7.1 HD 16152 is superposed 52" northwest of the center of NGC 988. The galaxy was discovered by Édouard Jean-Marie Stephan in 1879. One ultraluminous X-ray source has been detected in NGC 988.

<span class="mw-page-title-main">NGC 3941</span> Galaxy in the constellation Ursa Major

NGC 3941 is a barred lenticular galaxy located in the constellation Ursa Major. It is located at a distance of circa 40 million light years from Earth, which, given its apparent dimensions, means that NGC 3941 is about 40,000 light years across. It was discovered by William Herschel in 1787.

<span class="mw-page-title-main">NGC 720</span> Galaxy in the constellation Cetus

NGC 720 is an elliptical galaxy located in the constellation Cetus. It is located at a distance of circa 80 million light years from Earth, which, given its apparent dimensions, means that NGC 720 is about 110,000 light years across. It was discovered by William Herschel on October 3, 1785. The galaxy is included in the Herschel 400 Catalogue. It lies about three and a half degrees south and slightly east from zeta Ceti.

<span class="mw-page-title-main">NGC 5982</span> Galaxy in the constellation Draco

NGC 5982 is an elliptical galaxy located in the constellation Draco. It is located at a distance of circa 130 million light years from Earth, which, given its apparent dimensions, means that NGC 5982 is about 100,000 light years across. It was discovered by William Herschel on May 25, 1788.

<span class="mw-page-title-main">NGC 4665</span> Galaxy in the constellation of Virgo

NGC 4665, also catalogued as NGC 4624 and NGC 4664, is a barred lenticular or spiral galaxy located in the constellation Virgo. It is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster. It is located at a distance of circa 60 million light years from Earth, which, given its apparent dimensions, means that NGC 4665 is about 75,000 light years across. NGC 4665 lies 2 and 3/4 degrees east-south east of Delta Virginis and 50 arcminutes southwest of 35 Virginis. It can be viewed through a moderately sized telescope with 23x magnification, forming a pair with an 11th magnitude star 1.5 arcminutes southwest. It is part of the Herschel 400 Catalogue.

<span class="mw-page-title-main">NGC 4636</span> Galaxy in the constellation Virgo

NGC 4636 is an elliptical galaxy located in the constellation Virgo. It is a member of the NGC 4753 Group of galaxies, which is a member of the Virgo II Groups, a series of galaxies and galaxy clusters strung out from the southern edge of the Virgo Supercluster. It is located at a distance of about 55 million light years from Earth, which, given its apparent dimensions, means that NGC 4636 is about 105,000 light years across.

<span class="mw-page-title-main">IC 1459</span> Elliptical galaxy in the constellation of Grus

IC 1459 is an elliptical galaxy located in the constellation Grus. It is located at a distance of circa 85 million light-years from Earth, which, given its apparent dimensions, means that IC 1459 is about 130,000 light-years across. It was discovered by Edward Emerson Barnard in 1892.

<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 2974</span> Galaxy in the constellation Sextans

NGC 2974 is a lenticular galaxy located in the constellation Sextans. It is located at a distance of circa 90 million light years from Earth, which, given its apparent dimensions, means that NGC 2974 is about 90,000 light years across. It was discovered by William Herschel on January 6, 1785. NGC 2974 is located in the sky about 2 and a half degrees south-south east of Iota Hydrae and more than 6 degrees northeast of Alphard. A 10th magnitude star lies next to the galaxy, thus making it a challenging object at low magnifications. NGC 2974 is part of the Herschel 400 Catalogue.

<span class="mw-page-title-main">NGC 3741</span> Galaxy in the constellation Ursa Major

NGC 3741 is an irregular galaxy in the constellation Ursa Major. It was discovered by John Herschel on March 19, 1828. At a distance of about 10 million light-years, it is located in the M94 Group. It is relatively undisturbed by other galaxies.

<span class="mw-page-title-main">NGC 4365</span> Elliptical galaxy in the constellation Virgo

NGC 4365 is an elliptical galaxy located in the constellation Virgo. It was discovered by William Herschel on April 13, 1784.

<span class="mw-page-title-main">NGC 7513</span> Galaxy in the constellation Sculptor

NGC 7513 is a barred spiral galaxy located in the constellation Sculptor. It is located at a distance of circa 62.5 million light years from Earth, which, given its apparent dimensions, means that NGC 7513 is about 75,000 light years across. It was discovered by Albert Marth on September 24, 1864.

References

  1. 1 2 3 4 5 6 7 "NASA/IPAC Extragalactic Database". Results for NGC 4494. Retrieved 2016-01-18.
  2. ↑ "NGC 4494". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2017-06-19.
  3. ↑ Sadoun, Raphael; Colin, Jacques (11 October 2012). "-σ relation between supermassive black holes and the velocity dispersion of globular cluster systems". Monthly Notices of the Royal Astronomical Society: Letters. 426 (1): L51–L55. arXiv: 1204.0144 . Bibcode:2012MNRAS.426L..51S. doi: 10.1111/j.1745-3933.2012.01321.x . S2CID   117185846.
  4. ↑ Comerón, S.; Knapen, J. H.; Beckman, J. E.; Laurikainen, E.; Salo, H.; Martínez-Valpuesta, I.; Buta, R. J. (March 2010). "AINUR: Atlas of Images of NUclear Rings". Monthly Notices of the Royal Astronomical Society. 402 (4): 2462–2490. arXiv: 0908.0272 . Bibcode:2010MNRAS.402.2462C. doi: 10.1111/j.1365-2966.2009.16057.x . S2CID   18376628.
  5. ↑ Lauer, Tod R.; Faber, S. M.; Gebhardt, Karl; Richstone, Douglas; Tremaine, Scott; Ajhar, Edward A.; Aller, M. C.; Bender, Ralf; Dressler, Alan; Filippenko, Alexei V.; Green, Richard; Grillmair, Carl J.; Ho, Luis C.; Kormendy, John; Magorrian, John; Pinkney, Jason; Siopis, Christos (May 2005). "The Centers of Early-Type Galaxies with Hubble Space Telescope. V. New WFPC2 Photometry". The Astronomical Journal. 129 (5): 2138–2185. arXiv: astro-ph/0412040 . Bibcode:2005AJ....129.2138L. doi:10.1086/429565. S2CID   15473461.
  6. ↑ Foster, Caroline; Spitler, Lee R.; Romanowsky, Aaron J.; Forbes, Duncan A.; Pota, Vincenzo; Bekki, Kenji; Strader, Jay; Proctor, Robert N.; Arnold, Jacob A.; Brodie, Jean P. (21 August 2011). "Global properties of 'ordinary' early-type galaxies: photometry and spectroscopy of stars and globular clusters in NGC 4494". Monthly Notices of the Royal Astronomical Society. 415 (4): 3393–3416. arXiv: 1104.5503 . Bibcode:2011MNRAS.415.3393F. doi: 10.1111/j.1365-2966.2011.18965.x . S2CID   54172134.
  7. 1 2 Rodionov, S. A.; Athanassoula, E. (1 January 2011). "Dynamical models of the elliptical galaxy NGC 4494". Monthly Notices of the Royal Astronomical Society. 410 (1): 111–126. arXiv: 1007.5200 . Bibcode:2011MNRAS.410..111R. doi: 10.1111/j.1365-2966.2010.17429.x . S2CID   119122130.
  8. ↑ O'Sullivan, E.; Ponman, T. J. (April 2004). "XMM-Newton and Chandra observations of three X-ray-faint early-type galaxies". Monthly Notices of the Royal Astronomical Society. 349 (2): 535–546. arXiv: astro-ph/0312266 . Bibcode:2004MNRAS.349..535O. doi: 10.1111/j.1365-2966.2004.07518.x . S2CID   17208484.
  9. 1 2 Morganti, L.; Gerhard, O.; Coccato, L.; Martinez-Valpuesta, I.; Arnaboldi, M. (11 April 2013). "Elliptical galaxies with rapidly decreasing velocity dispersion profiles: NMAGIC models and dark halo parameter estimates for NGC 4494". Monthly Notices of the Royal Astronomical Society. 431 (4): 3570–3588. arXiv: 1303.2688 . Bibcode:2013MNRAS.431.3570M. doi: 10.1093/mnras/stt442 . S2CID   56274333.
  10. ↑ Romanowsky, A. J. (19 September 2003). "A Dearth of Dark Matter in Ordinary Elliptical Galaxies". Science. 301 (5640): 1696–1698. arXiv: astro-ph/0308518 . Bibcode:2003Sci...301.1696R. doi:10.1126/science.1087441. PMID   12947033. S2CID   120137872.
  11. ↑ Napolitano, N. R.; Romanowsky, A. J.; Coccato, L.; Capaccioli, M.; Douglas, N. G.; Noordermeer, E.; Gerhard, O.; Arnaboldi, M.; De Lorenzi, F.; Kuijken, K.; Merrifield, M. R.; O'Sullivan, E.; Cortesi, A.; Das, P.; Freeman, K. C. (21 February 2009). "The Planetary Nebula Spectrograph elliptical galaxy survey: the dark matter in NGC 4494". Monthly Notices of the Royal Astronomical Society. 393 (2): 329–353. arXiv: 0810.1291 . Bibcode:2009MNRAS.393..329N. doi: 10.1111/j.1365-2966.2008.14053.x . S2CID   54039999.
  12. ↑ Deason, A. J; Belokurov, V.; Evans, N. W.; McCarthy, I. G. (20 March 2012). "Elliptical Galaxy Masses Out to Five Effective Radii: The Realm of Dark Matter". The Astrophysical Journal. 748 (1): 2. arXiv: 1110.0833 . Bibcode:2012ApJ...748....2D. doi:10.1088/0004-637X/748/1/2. S2CID   119109261.
  13. ↑ Makarov, Dmitry; Karachentsev, Igor (21 April 2011). "Galaxy groups and clouds in the local (z~ 0.01) Universe". Monthly Notices of the Royal Astronomical Society. 412 (4): 2498–2520. arXiv: 1011.6277 . Bibcode:2011MNRAS.412.2498M. doi: 10.1111/j.1365-2966.2010.18071.x . S2CID   119194025.
  14. ↑ "Nearby Groups of Galaxies". ned.ipac.caltech.edu. Retrieved 2018-05-20.
  15. ↑ R. B. Tully (1988). Nearby Galaxies Catalog. Cambridge: Cambridge University Press. ISBN   978-0-521-35299-4.
  16. ↑ A. Garcia (1993). "General study of group membership. II - Determination of nearby groups". Astronomy and Astrophysics Supplement . 100: 47–90. Bibcode:1993A&AS..100...47G.
  17. ↑ Giuricin, Giuliano; Marinoni, Christian; Ceriani, Lorenzo; Pisani, Armando (2000). "Nearby Optical Galaxies: Selection of the Sample and Identification of Groups". The Astrophysical Journal. 543 (1): 178. arXiv: astro-ph/0001140 . Bibcode:2000ApJ...543..178G. doi:10.1086/317070. ISSN   0004-637X. S2CID   9618325.
  18. ↑ Gregory, Stephen A.; Thompson, Laird A. (April 1977). "The Coma i Galaxy Cloud". The Astrophysical Journal. 213: 345–350. Bibcode:1977ApJ...213..345G. doi:10.1086/155160. ISSN   0004-637X.


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