| NGC 4395 | |
|---|---|
 NGC 4395 imaged by Mount Lemmon SkyCenter | |
| Observation data (J2000 epoch) | |
| Constellation | Canes Venatici[1] |
| Right ascension | 12h 25m 48.8599s[2] |
| Declination | +33° 32′ 48.711″[2] |
| Redshift | 0.001064 |
| Heliocentric radial velocity | 319±1 km/s[2] |
| Distance | 13.90 ± 0.86 Mly (4.261 ± 0.264 Mpc)[2] |
| Group or cluster | NGC 4631 Group (LGG 291) |
| Apparent magnitude (V) | 10.6[2] |
| Characteristics | |
| Type | SA(s)m[2] |
| Size | ~64,700 ly (19.83 kpc) (estimated)[2] |
| Apparent size (V) | 13.2′ × 11.0′[2] |
| Other designations | |
| IRAS 12233+3348, UGC 7542, MCG +06-27-053, PGC 40596, CGCG 187-042[2] | |
NGC 4395 is a nearby low surface brightness spiral galaxy located about 14 million light-years (or 4.3 Mpc) from Earth in the constellation Canes Venatici.[1] It was discovered by German-British astronomer William Herschel on 2 January 1786.[3] The nucleus of NGC 4395 is active and the galaxy is classified as a Seyfert Type I, known for its very low-mass supermassive black hole.[4]
Physical characteristics
NGC 4395 has a halo that is about 8′ in diameter. It has several patches of greater brightness running northwest to southeast. The one furthest southeast is the brightest. Three of the patches have their own NGC numbers: 4401, 4400, and 4399 running east to west.[5]
The galaxy is highly unusual for Seyfert galaxies, because it does not have a bulge and is considered to be a dwarf galaxy.[4]
Observational history
NGC 4395 was imaged and classified as a "spiral nebula" in a 1920 paper by astronomer Francis G. Pease.[6] Now, it is known to be a galaxy distinct from the Milky Way (see Great Debate). Along with several other nearby galaxies, resolved stars in NGC 4395 were used to measure the expansion rate of the Universe by Allan Sandage and Gustav Andreas Tammann in their 1974 paper.[7] More recently, NGC 4395 was discovered to contain a very low-luminosity active galactic nucleus.[8] Since then, its nucleus has been the subject of several academic papers and attempts to measure the mass of its central black hole.
Nucleus
NGC 4395 is one of the least luminous and nearest Seyfert galaxies known.[4] The nucleus of NGC 4395 is notable for containing one of the smallest supermassive black holes with a well-measured mass.[9] The central black hole has a mass of "only" 300,000 M☉.[10] However, more recent studies found a black hole mass of just 4,000 M☉ to 20,000 M☉.[11][12][13] The low-mass black hole in NGC 4395 would make it a so-called "intermediate-mass black hole".[14] The black hole may have a truncated disk. [15]
NGC 4631 Group
According to A.M. Garcia, NGC 4395 is part of the NGC 4631 group (also known as LGG 291) that has at least 14 members. The other members are NGC 4150, NGC 4163, NGC 4190, NGC 4214, NGC 4244, NGC 4308, NGC 4631, NGC 4656, IC 779, UGC 7605, UGC 7698, UGCA 276, and UGCA 292.[16]
See also
References
- ^ a b Thim, F.; Hoessel, J. G.; Saha, A.; Claver, J.; Dolphin, A.; Tammann, G. A. (April 2004). "Cepheids and Long-Period Variables in NGC 4395". The Astronomical Journal. 127 (4): 2322–2343. arXiv:astro-ph/0401558. Bibcode:2004AJ....127.2322T. doi:10.1086/382244. ISSN 0004-6256. S2CID 14631171.
- ^ a b c d e f g h i "Results for object NGC 4395". NASA/IPAC Extragalactic Database. NASA and Caltech. Retrieved 2006-11-04.
- ^ Seligman, Courtney. "New General Catalogue Objects: NGC 4395 (=PGC 40596)". Celestial Atlas. Retrieved 24 May 2025.
- ^ a b c Filippenko, Alexei V.; Ho, Luis C. (May 2003). "A Low-Mass Central Black Hole in the Bulgeless Seyfert 1 Galaxy NGC 4395". The Astrophysical Journal. 588 (1): L13–L16. arXiv:astro-ph/0303429. Bibcode:2003ApJ...588L..13F. doi:10.1086/375361. ISSN 0004-637X. S2CID 14411746.
- ^ Kepple, George Robert; Sanner, Glen W. (1998). The night sky observers guide. Vol. 2. Richmond (Va.): Willmann-Bell. p. 48. ISBN 978-0-943396-60-6.
- ^ Pease, F. G. (June 1920). "Photographs of nebulae with the 60-inch reflector, 1917-1919". The Astrophysical Journal. 51: 276. Bibcode:1920ApJ....51..276P. doi:10.1086/142552. ISSN 0004-637X.
- ^ Sandage, A.; Tammann, G. A. (December 1974). "Steps toward the Hubble constant. IV - Distances to 39 galaxies in the general field leading to a calibration of the galaxy luminosity classes and a first hint of the value of H sub 0". The Astrophysical Journal. 194: 559. Bibcode:1974ApJ...194..559S. doi:10.1086/153275. ISSN 0004-637X.
- ^ Filippenko, Alexei V.; Sargent, Wallace L. W. (July 1989). "Discovery of an extremely low luminosity Seyfert 1 nucleus in the dwarf galaxy NGC 4395". The Astrophysical Journal. 342: L11. Bibcode:1989ApJ...342L..11F. doi:10.1086/185472. ISSN 0004-637X.
- ^ Merritt, David (2013). Dynamics and evolution of galactic nuclei. Princeton series in astrophysics. Princeton: Princeton University Press. ISBN 978-0-691-15860-0.
- ^ Peterson, Bradley M.; et al. (20 October 2005). "Multiwavelength Monitoring of the Dwarf Seyfert 1 Galaxy NGC 4395. I. A Reverberation-based Measurement of the Black Hole Mass". The Astrophysical Journal. 632 (2): 799–808. arXiv:astro-ph/0506665. Bibcode:2005ApJ...632..799P. doi:10.1086/444494. ISSN 0004-637X. S2CID 13886279.
- ^ Woo, Jong-Hak; et al. (10 July 2019). "A 10,000-solar-mass black hole in the nucleus of a bulgeless dwarf galaxy". Nature Astronomy. 3 (8): 755–759. arXiv:1905.00145. Bibcode:2019NatAs...3..755W. doi:10.1038/s41550-019-0790-3. ISSN 2397-3366. S2CID 189762554.
- ^ Huapeng, Gu; Xue-Bing, Wu; Yuhan, Wen; Qinchun, Ma; Hengxiao, Guo (June 2024). "H α reverberation mapping from broad-band photometry of dwarf type 1 Seyfert galaxy NGC 4395". Monthly Notices of the Royal Astronomical Society. 530 (4): 3578. arXiv:2404.11495. Bibcode:2024MNRAS.530.3578G. doi:10.1093/mnras/stae1063. ISSN 0035-8711. Archived from the original on 2024-11-15. Retrieved 2025-05-01.
- ^ Cho, Hojin; Woo, Jong-Hak; Treu, Tommaso; Williams, Peter R.; Armen, Stephen F.; Barth, Aaron J.; Bennert, Vardha N.; Cho, Wanjin; Filippenko, Alexei V.; Gallo, Elena; Geum, Jaehyuk; González-Buitrago, Diego; Gültekin, Kayhan; Hodges-Kluck, Edmund; Horst, John C. (2021-11-01). "Hα Reverberation Mapping of the Intermediate-mass Active Galactic Nucleus in NGC 4395". The Astrophysical Journal. 921 (2): 98. arXiv:2108.07756. Bibcode:2021ApJ...921...98C. doi:10.3847/1538-4357/ac1e92. ISSN 0004-637X.
- ^ Shih, D. C.; Iwasawa, K.; Fabian, A. C. (21 May 2003). "Evidence for an intermediate-mass black hole and a multi-zone warm absorber in NGC 4395". Monthly Notices of the Royal Astronomical Society. 341 (3): 973–980. arXiv:astro-ph/0302108. Bibcode:2003MNRAS.341..973S. doi:10.1046/j.1365-8711.2003.06482.x. ISSN 0035-8711.
- ^ McHardy, I M; et al. (9 January 2023). "First detection of the outer edge of an AGN accretion disc: very fast multiband optical variability of NGC 4395 with GTC/HiPERCAM and LT/IO:O". Monthly Notices of the Royal Astronomical Society. 519 (3): 3366–3382. arXiv:2212.08015. doi:10.1093/mnras/stac3651. ISSN 0035-8711.
- ^ Garcia, A. M. (1993). "General study of group membership. II. Determination of nearby groups". Astronomy and Astrophysics Supplement Series. 100: 47. Bibcode:1993A&AS..100...47G.
