Markarian galaxies

The Markarian galaxies are a class of galaxies that have nuclei with excessive amounts of ultraviolet emissions compared with other galaxies. Benjamin Markarian drew attention to these types of galaxies starting in 1963. The nuclei of the galaxies had a blue colour, associated to stars in the classes from O to A. This blue core did not match the rest of the galaxy. The spectrum in detail tends to show a continuum that Markarian concluded was produced non-thermally. Most of these have emission lines and are characterized by highly energetic activity.[1][2] Markarian Catalogue entries are of the form "Markarian ####", and can frequently use the abbreviations Mrk, Mkr, Mkn; and rarely Ma, Mk, Mark.[3]

Aladin2011.04.13-21-28-34.268
Sky plot showing locations of Markarian galaxies. White band is due to the Milky Way.

History

In 1964 Markarian decided to search for this kind of galaxy.[4] The First Byurakan Survey commenced in 1965 using the Schmidt telescope at the Byurakan Astrophysical Observatory. The telescope used a 132 cm mirror and 102 cm correcting plate. When this started it was the largest telescope to have a full aperture objective prism. The purpose of the survey was to find galaxies with an ultraviolet excess.[5] The optics used were corrected for blue violet. Prisms in this had a low dispersion of 180 nm/mm in order not to spread out the galactic core spectrum too much and confuse it with other objects. This permitted classification of galaxies with magnitudes down to 17.5.[4] Seventy galaxies with UV-continuum appeared on lists, and the term "Markarian galaxies" came into use.[4][6][7] Two more lists brought the number of galaxies up to 302 in 1969.[8][9] The FBS continued observations till 1978 with a full spectra survey at high galactic latitudes. 1980 saw the completion of plate analysis and picking the objects that would be included. Twelve more papers with objects from the First Byurakan Survey brought the list up to 1500 galaxies.[4][10][11][12][13][14][15][16][17][18][19][20][21]

A list titled "First Byurakan Survey" circulated in 1986, including the original 1500 galaxies and 32 extras numbered from 9001 to 9032.[22] In 1989 an extended list numbering up to 1515 was published.[4][23]

In 2005, the "Second Byurakan Survey" (SBS, SBSSS, BSS, MrkII, Markarian II) was carried out, extending the MrkI survey to fainter objects, making a catalogue of 3563 objects of 1863 galaxies (SBSG) and 1700 stars (SBSS); 761 of the galaxies are AGN (155 Seyferts, 596 quasars, 10 blazars).[24][25][26]

Characteristics

The catalogues of galaxies included a name, coordinates, spectral type, visible size and morphological type of galaxy.[4] A custom designator for the galaxy core of s for star-like or d for diffuse was used, with hybrids of ds or sd. A digit 1,2 or 3 indicated strong, moderate or weak UV emission. And a letter "e" was appended if emission lines were apparent. Eleven galaxies had a blue star in the foreground creating the ultraviolet excess, so these galaxies do not really fall into the class.[27] Another problem is duplicate entries where Mrk 107 is Mrk 20, Mrk 1318 is Mrk 49, and Mrk 890 is Mrk 503.[28]

The various objects in this catalogue include Seyfert galaxies, starburst galaxies, H II regions, active galactic nuclei, BL Lac objects and quasars.[27] Some objects are actually giant glowing regions of ionized hydrogen in a galaxy including Mrk 59, 71, 86b, 94, 256b, 404, 489b, 1039, 1236, 1315, and 1379a.[27] Other galaxies have black holes shooting hot gas in energetic jets. Many are variable, showing the brightness comes from a small region.

Publications listing the Markarian galaxies

I 1-70 Markaryan, B. E. (1967). "Galaxies with an ultraviolet continuum. I". Astrofizika. 3: 24-3. Bibcode:1967Afz.....3...24M. [29]
II 71-200 Markaryan, B. E. (1971). "Galaxies with an ultraviolet continuum. II". Astrophysics. 5 (3): 206. Bibcode:1969Ap......5..206M. doi:10.1007/BF01004709. [30]
III 201-302 Markaryan, B. E. (1972). "Galaxies with ultraviolet continuum. III". Astrophysics. 5 (4): 286. Bibcode:1969Ap......5..286M. doi:10.1007/BF01003911. [31]
IV 303-401 Markaryan, B. E.; Lipovetskii, V. A. (1974). "Galaxies with an ultraviolet continuum. IV". Astrophysics. 7 (4): 299. Bibcode:1971Ap......7..299M. doi:10.1007/BF01003012. [32]
V 402-507 Markaryan, B. E.; Lipovetskii, V. A. (1974). "Galaxies with ultraviolet continuum V". Astrophysics. 8 (2): 89. Bibcode:1972Ap......8...89M. doi:10.1007/BF01002156. [33]
VI 508-604 Markaryan, B. E.; Lipovetskii, V. A. (1975). "Galaxies with ultraviolet continuum. VI". Astrophysics. 9 (4): 283. Bibcode:1973Ap......9..283M. doi:10.1007/BF01002512. [34]
VII 605-700 Markaryan, B. E.; Lipovetskii, V. A. (1975). "Galaxies with ultraviolet continuum. VII". Astrophysics. 10 (3): 185. Bibcode:1974Ap.....10..185M. doi:10.1007/BF01001549. [35]
VIII 701-797 Markaryan, B. E.; Lipovetskii, V. A. (1977). "Galaxies with an ultraviolet continuum. VIII". Astrophysics. 12 (3): 241. Bibcode:1976Ap.....12..241M. doi:10.1007/BF01003320. [36]
IX 798-895 Markaryan, B. E.; Lipovetskii, V. A. (1977). "Galaxies with an ultraviolet continuum. IX". Astrophysics. 12 (4): 429. Bibcode:1976Ap.....12..429M. doi:10.1007/BF01000934. [37]
X 896-995 Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1978). "Galaxies with ultraviolet continuum. X". Astrophysics. 13 (2): 116. Bibcode:1977Ap.....13..116M. doi:10.1007/BF01005701. [38]
XI 996-1095 Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1978). "Galaxies with ultraviolet continuum. XI". Astrophysics. 13 (3): 215. Bibcode:1977Ap.....13..215M. doi:10.1007/BF01001214. [39]
XII 1096-1194 Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1979). "Galaxies with ultraviolet continuum. XII". Astrophysics. 15 (2): 130. Bibcode:1979Ap.....15..130M. doi:10.1007/BF01006033. [40]
XIII 1195-1302 Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1980). "Galaxies with ultraviolet continuum. XIII". Astrophysics. 15 (3): 235. Bibcode:1979Ap.....15..235M. doi:10.1007/BF01004367. [41]
XIV 1303-1399 Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1980). "Galaxies with ultraviolet continuum. XIV". Astrophysics. 15 (4): 363. Bibcode:1979Ap.....15..363M. doi:10.1007/BF01005372. [42]
XV 1400-1500 Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1982). "Galaxies with ultraviolet continuum. XV". Astrophysics. 17 (4): 321. Bibcode:1981Ap.....17..321M. doi:10.1007/BF01004228. [43]

Gallery

Hubble Interacting Galaxy NGC 3690 (2008-04-24)

171

NGC 4319 I HST2002

205

Markarian 209

209

Hubble Interacting Galaxy UGC 8058 (2008-04-24)

231

Hubble Interacting Galaxy NGC 5256 (2008-04-24)

266

Hubble Interacting Galaxy Mrk 273 (2008-04-24)

273

Hubble Interacting Galaxy UGC 12812 (2008-04-24)

331

Mark421-U3WS2701M

421

MRK 0501 2MASS

501

Markarian 509 (HST).tiff

509

Hubble Interacting Galaxy NGC 7674 (2008-04-24)

533

Markarian 817 (captured by the Hubble Space Telescope)

817

Hubble Interacting Galaxy VV 705 (2008-04-24)

848

Further reading

  • Petrosian, A.; McLean, B.; Allen, R. J.; MacKenty, J. W. (May 2007). "Markarian Galaxies. I. The Optical Database and Atlas". The Astrophysical Journal Supplement Series. 170 (1): 33–70. Bibcode:2007ApJS..170...33P. doi:10.1086/511333.
    • Petrosian, A.; McLean, B.; Allen, R. J.; MacKenty, J. W. (August 2008). "Erratum: 'Markarian Galaxies. I. The Optical Database and Atlas'". The Astrophysical Journal Supplement Series. 177 (2): 645–646. Bibcode:2008ApJS..177..645P. doi:10.1086/588098.

References

  1. ^ Koioian, Gabriel; Dickinson, D. F.; Tovmassian, H.; Purton, C. R.; Sramek, R. A. (15 January 1976). "The Radio Spectra of Markarian Galaxies". Astrophysical Journal. 203 (1): 323–328. Bibcode:1976ApJ...203..323K. doi:10.1086/154082.
  2. ^ Markarian, Benjamin Y. (1963). "NASA Extragalactic Database". Soobshcheniya Byurakan Observatory. 34: 3. Bibcode:1963SoByu..34....3M.
  3. ^ "info cati Mrk$". Dictionary of Nomenclature of Celestial Objects. SIMBAD. 7 November 2014. Retrieved 7 November 2014.
  4. ^ a b c d e f Markarian, B. E.; Lipovetskii, V. A.; Stepanian, J. A.; Erastova, L. K.; Shapovalova, A. I. (1989). The First Byurkan Survey: A Catalogue of Galaxies with UV-Continuum. Soobshcheniya Spetsial'noj Astrofizicheskoj Observatorii. 62. p. 5. Bibcode:1989SoSAO..62....5M.
  5. ^ Massaro, E.; Mickaelian, A.; Nesci, R.; Weedman, D. (2008). The Digitized First Byurakan Survey (PDF). ISBN 978-88-548-2421-8. Archived from the original (PDF) on 2012-04-26.
  6. ^ Markarian, B. E. (1967). "Galaxies with an ultraviolet continuum". Astrofizika. 3: 55. Bibcode:1967Afz.....3...55M.
  7. ^ Markarian, B. E. (1968). Non-stable Phenomena in Galaxies. IAU Symposium No. 29. Yerevan: Publishing House of the Academy of Sciences of Armenian SSR.
  8. ^ Markarian, Benjamin E. (1969). "Galaxies with ultraviolet continuum. I". Astrofizika. 5: 443. Bibcode:1969Afz.....5..443M.
  9. ^ Markarian, B. E. (1969). "Galaxies with ultraviolet continuum. II". Astrofizika. 5: 581. Bibcode:1969Afz.....5..581M.
  10. ^ Markarian, B. E.; Lipovetskii, V. A.; Lipovetskii, V. A. (1971). "Galaxies with ultraviolet continuum. IV". Astrofizika. 7: 511. Bibcode:1971Afz.....7..511M.
  11. ^ Markarian, B. E.; Lipovetskii, V. A. (1972). "Galaxies with ultraviolet continuum. V". Astrofizika. 8: 155. Bibcode:1972Afz.....8..155M.
  12. ^ Markarian, B. E.; Lipovetskii, V. A. (1973). "Galaxies with ultraviolet continuum. VI". Astrofizika. 9: 487. Bibcode:1973Afz.....9..487M.
  13. ^ Markarian, B. E.; Lipovetskii, V. A. (1974). "Galaxies with Ultraviolet continuum. VII". Astrofizika. 10: 307. Bibcode:1974Afz....10..307M.
  14. ^ Markarian, B. E.; Lipovetskii, V. A. (1976). "Galaxies with ultraviolet continuum. VIII". Astrofizika. 12: 389. Bibcode:1976Afz....12..389M.
  15. ^ Markarian, B. E.; Lipovetskii, V. A. (1976). "Galaxies with ultraviolet continuum. IX". Astrofizika. 12: 657. Bibcode:1976Afz....12..657M.
  16. ^ Markarian, B. E.; Lipovetskii, V. A.; Stepanian, J. A. (1977). "Galaxies with ultraviolet continua. X". Astrofizika. 13: 225. Bibcode:1977Afz....13..225M.
  17. ^ Markarian, B. E.; Lipovetskii, V. A.; Stepanian, J. A. (1977). "Galaxies with ultraviolet continuum. XI". Astrofizika. 13: 397. Bibcode:1977Afz....13..397M.
  18. ^ Markarian, B. E.; Lipovetskii, V. A.; Stepanian, J. A. (1979). "Galaxies with ultraviolet continuum. XII". Astrofizika. 15: 201. Bibcode:1979Afz....15..201M.
  19. ^ Markarian, B. E.; Lipovetskii, V. A.; Stepanian, J. A. (1979). "Galaxies with ultraviolet continuum. XIII". Astrofizika. 15: 363. Bibcode:1979Afz....15..363M.
  20. ^ Markarian, B. E.; Lipovetskii, V. A.; Stepanian, J. A. (1979). "Galaxies with ultraviolet continuum. XIV". Astrofizika. 15: 549. Bibcode:1979Afz....15..549M.
  21. ^ Markarian, B. E.; Lipovetskii, V. A.; Stepanian, J. A. (1981). "Galaxies with ultraviolet continuum. XV". Astrofizika. 17: 619. Bibcode:1981Afz....17..619M.
  22. ^ Lipovetskii, V. A.; Stepanian, J. A. (1986). "First Byurakan Survey". unpublished.
  23. ^ "Frequently Asked Questions: NED and other catalogs". 29 May 2009. Retrieved 10 December 2011.
  24. ^ Stepanian, J. A. (2005). "The Second Byurakan Survey. General Catalogue". Revista Mexicana de Astronomía y Astrofísica (published April 2005). 41: 155–368. Bibcode:2005RMxAA..41..155S.
  25. ^ "info cati SBSS$". Dictionary of Nomenclature of Celestial Objects. SIMBAD. 7 November 2014. Retrieved 7 November 2014.
  26. ^ "info cati SBSG$". Dictionary of Nomenclature of Celestial Objects. SIMBAD. 7 November 2014. Retrieved 7 November 2014.
  27. ^ a b c "The Data". Atlas and Database of Markarian Galaxies - Petrosian et al. Retrieved 11 December 2011.
  28. ^ Petrosian. "The Optical Database". Retrieved 11 December 2011.
  29. ^ Markaryan, B. E. (1967). "Galaxies with an ultraviolet continuum. I". Astrofizika. 3: 24-3. Bibcode:1967Afz.....3...24M.
  30. ^ Markaryan, B. E. (1971). "Galaxies with an ultraviolet continuum. II". Astrophysics. 5 (3): 206. Bibcode:1969Ap......5..206M. doi:10.1007/BF01004709.
  31. ^ Markaryan, B. E. (1972). "Galaxies with ultraviolet continuum. III". Astrophysics. 5 (4): 286. Bibcode:1969Ap......5..286M. doi:10.1007/BF01003911.
  32. ^ Markaryan, B. E.; Lipovetskii, V. A. (1974). "Galaxies with an ultraviolet continuum. IV". Astrophysics. 7 (4): 299. Bibcode:1971Ap......7..299M. doi:10.1007/BF01003012.
  33. ^ Markaryan, B. E.; Lipovetskii, V. A. (1974). "Galaxies with ultraviolet continuum V". Astrophysics. 8 (2): 89. Bibcode:1972Ap......8...89M. doi:10.1007/BF01002156.
  34. ^ Markaryan, B. E.; Lipovetskii, V. A. (1975). "Galaxies with ultraviolet continuum. VI". Astrophysics. 9 (4): 283. Bibcode:1973Ap......9..283M. doi:10.1007/BF01002512.
  35. ^ Markaryan, B. E.; Lipovetskii, V. A. (1975). "Galaxies with ultraviolet continuum. VII". Astrophysics. 10 (3): 185. Bibcode:1974Ap.....10..185M. doi:10.1007/BF01001549.
  36. ^ Markaryan, B. E.; Lipovetskii, V. A. (1977). "Galaxies with an ultraviolet continuum. VIII". Astrophysics. 12 (3): 241. Bibcode:1976Ap.....12..241M. doi:10.1007/BF01003320.
  37. ^ Markaryan, B. E.; Lipovetskii, V. A. (1977). "Galaxies with an ultraviolet continuum. IX". Astrophysics. 12 (4): 429. Bibcode:1976Ap.....12..429M. doi:10.1007/BF01000934.
  38. ^ Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1978). "Galaxies with ultraviolet continuum. X". Astrophysics. 13 (2): 116. Bibcode:1977Ap.....13..116M. doi:10.1007/BF01005701.
  39. ^ Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1978). "Galaxies with ultraviolet continuum. XI". Astrophysics. 13 (3): 215. Bibcode:1977Ap.....13..215M. doi:10.1007/BF01001214.
  40. ^ Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1979). "Galaxies with ultraviolet continuum. XII". Astrophysics. 15 (2): 130. Bibcode:1979Ap.....15..130M. doi:10.1007/BF01006033.
  41. ^ Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1980). "Galaxies with ultraviolet continuum. XIII". Astrophysics. 15 (3): 235. Bibcode:1979Ap.....15..235M. doi:10.1007/BF01004367.
  42. ^ Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1980). "Galaxies with ultraviolet continuum. XIV". Astrophysics. 15 (4): 363. Bibcode:1979Ap.....15..363M. doi:10.1007/BF01005372.
  43. ^ Markaryan, B. E.; Lipovetskii, V. A.; Stepanyan, Dzh A. (1982). "Galaxies with ultraviolet continuum. XV". Astrophysics. 17 (4): 321. Bibcode:1981Ap.....17..321M. doi:10.1007/BF01004228.

External links

Benjamin Markarian

Benjamin "Benik" Egishevitch Markarian (Armenian: Բենիամին Եղիշեի Մարգարյան; born on 29 November, 1913 in Shulaver, Tiflis Governorate; died on 29 September, 1985 in Yerevan, Armenian SSR) was an Armenian astrophysicist. Markarian's Chain (of galaxies) was named after him when he discovered that this string of galaxies moves with a common motion. He is also the namesake of a catalog of compact, optically bright galaxies (including both starbursts and AGNs) known as Markarian galaxies.

Coma Filament

Coma Filament is a galaxy filament. The filament contains the Coma Supercluster of galaxies and forms a part of the CfA2 Great Wall.

List of galaxies named after people

A small number of galaxies or galaxy groups have been named after individual people. In most cases, the named individual was the person who discovered the object, who first brought attention to it, or who first studied it scientifically.

Many of the brighter galaxies visible from the Northern Hemisphere have Messier numbers, named after Charles Messier. For instance, the Andromeda Galaxy is Messier 31 and the Whirlpool Galaxy is Messier 51. There are a few other comprehensive catalogs that assign the cataloguer's name to galaxies. For instance, Markarian galaxies, named after Benjamin Markarian, are galaxies with excess blue and ultraviolet emission; galaxies in the Atlas of Peculiar Galaxies are assigned an Arp number after Halton Arp who produced the catalog; etc. Objects in these catalogs are excluded below, except in cases where they carry the name of an additional person.

MKN

MKN, Mkn or mkn may represent:

Macedonian denar

Markarian galaxies are often abbreviated "Mkn" (also Mrk, Mkr, Ma, Mk, Mark), followed by their four-digit number

the ISO 639:m language code for Malay

the ICAO airline code for Mekong Airlines

Markarian 177

Markarian 177 is a blue compact dwarf galaxy located 90,000,000 ly (28 Mpc) away, at the constellation of Ursa Major, in the bowl of the Big Dipper asterism. It was discovered by the astronomer Benjamin Markarian.

Markarian 177 is a peculiar galaxy that is receding from us at a rate of 2425 km/s. It has a visual apparent size of 0.41×0.34 arcmin.

Markarian 231

Markarian 231 (UGC 8058) is a Type-1 Seyfert galaxy that was discovered in 1969 as part of a search of galaxies with strong ultraviolet radiation. It contains the nearest known quasar, and in 2015 it was shown that the powerful active galactic nucleus present in the center of the galaxy may in fact be a supermassive binary black hole. It is located about 581 million light years away from Earth.

Markarian 335

Markarian 335 is a Seyfert galaxy containing a supermassive black hole, located 324 million light-years away in the constellation of Pegasus.

The central black hole in this active galaxy nucleus is notable for its corona's spinning rate (at about 20 percent the speed of light) and its change in brightness from 2007 to 2014. The geometry of the corona has been deduced from relativistic blurring of the reflection of the accretion disc. An x-ray flare in 2013 is interpreted as an aborted jet.

Markarian 421

Markarian 421 (Mrk 421, Mkn 421) is a blazar located in the constellation Ursa Major. The object is an active galaxy and a BL Lacertae object, and is a strong source of gamma rays. It is about 397 million light-years (redshift: z=0.0308 eq. 122Mpc) to 434 million light-years (133Mpc) from the Earth. It is one of the closest blazars to Earth, making it one of the brightest quasars in the night sky. It is suspected to have a supermassive black hole (SMBH) at its center due to its active nature. An early-type high inclination spiral galaxy (Markarian 421-5) is located 14 arc-seconds northeast of Markarian 421.

It was first determined to be a very high energy gamma ray emitter in 1992 by M. Punch at the Whipple Observatory, and an extremely rapid outburst in very-high-energy gamma rays (15-minute rise-time) was measured in 1996 by J. Gaidos at Whipple Observatory Markarian 421 also had an outburst in 2001 and is monitored by the Whole Earth Blazar Telescope project.Due to its brightness (around 13.3 magnitude, max. 11.6 mag. and min. 16 mag.) the object can also be viewed by amateurs in smaller telescopes.

Markarian 501

Markarian 501 (or Mrk 501) is a galaxy with a spectrum extending to the highest energy gamma rays. It is a blazar or BL Lac object, which is an active galactic nucleus with a jet that is shooting towards the Earth.

In the very-high-energy gamma ray region of the spectrum, at energies above 1011 eV (0.1 TeV), it is the brightest object in the sky. The object has a redshift of z = 0.034.The galaxy hosting the blazar was studied and catalogued by Benjamin Markarian in 1974. It was first determined to be a very high energy gamma ray emitter in 1996 by J. Quinn at the Whipple Observatory.

NGC 1614

NGC 1614 is the New General Catalogue identifier for a spiral galaxy in the equatorial constellation of Eridanus. It was discovered on December 29, 1885 by American astronomer Lewis Swift, who described it in a shorthand notation as: pretty faint, small, round, a little brighter middle. The nebula was then catalogued by Danish-Irish astronomer J. L. E. Drayer in 1888. When direct photography became available, it was noted that this galaxy displayed some conspicuous peculiarities. American astronomer Halton Arp included it in his 1966 Atlas of Peculiar Galaxies. In 1971, Swiss astronomer Fritz Zwicky described it as a "blue post-eruptive galaxy, compact patchy core, spiral plumes, long blue jet SSW".In the De Vaucouleurs system for classifying galaxies, NGC 1614 has a galaxy morphological classification of SB(s)c pec. The SB indicates this is a barred spiral galaxy, while the '(s)' means it lacks a ring-like structure around the nucleus. The trailing 'c' describes the spiral arm structure as being loosely wound. The peculiar nature of the galaxy is noted with the 'pec.' abbreviation. The galaxy is bright at the center, with two nearly symmetrical inner spiral arms. It is a luminous infrared source, with total infrared luminosity is 1011.60 L☉, ranking 55th in the 2003 IRAS Revised Bright Galaxy Sample, and is the second most luminous galaxy within 75 Mpc.This galaxy is undergoing a minor merger event with a gas-rich, low-mass companion galaxy, located in a tidal tail to the southwest of the nucleus. The main galaxy is estimated to be around 3−5 times as massive as the merging object. The interaction between the two galaxies is triggering a burst of star formation in NGC 1614, although not apparently an active galactic nucleus. It is described as "one of the most extreme nearby starbursts".In the core region, a 230 pc radius ring feature has formed around the nucleus within the last 5−10 million years from an inflow of gas caused by the merger event, and this structure is the site of the intense star forming activity known as a starburst region. This activity is bright enough that it is masking whatever weak nuclear emission there is coming from the core. The nucleus itself displays evidence of an older starburst event. The starburst activity is presumed to be driving an observed outflow of cold molecular gas that has a combined mass of around 32 million times the mass of the Sun.

NGC 2273

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 οn September 15, 1867.

NGC 262

NGC 262 (also known as Markarian 348) is a huge spiral galaxy in the cluster LGG 14. It is a Seyfert 2 spiral galaxy located 287 million light years away in the constellation Andromeda. It was discovered on September 17, 1885 by Lewis A. Swift.

NGC 5256

NGC 5256 is a galaxy that contains two disc galaxies, that are colliding into each other. It is located in the constellation Ursa Major, and was discovered by William Herschel on 12 May 1787. The two nuclei of the galaxies are separated by about 13046.3 light years. NGC 5256 is located at about 350 million light years away from the earth.

NGC 5548

NGC 5548 is a Type I Seyfert galaxy with a bright, active nucleus. This activity is caused by matter flowing onto a 65 million solar mass (M☉) supermassive black hole at the core. Morphologically, this is an unbarred lenticular galaxy with tightly-wound spiral arms, while shell and tidal tail features suggest that it has undergone a cosmologically-recent merger or interaction event. NGC 5548 is approximately 245 million light years away and appears in the constellation Boötes. The apparent visual magnitude of NGC 5548 is approximately 13.3 in the V band.In 1943, this galaxy was one of twelve nebulae listed by American astronomer Carl Keenan Seyfert that showed broad emission lines in their nuclei. Members of this class of objects became known as Seyfert galaxies, and they were noted to have a higher than normal surface brightness in their nuclei. Observation of NGC 5548 during the 1960s with radio telescopes showed an enhanced level of radio emission. Spectrograms of the nucleus made in 1966 showed that the energized region was confined to a volume a few parsecs across, where temperature were around 14000 K and the plasma had a dispersion velocity of ±450 km/s.Among astronomers, the accepted explanation for the active nucleus in NGC 5548 is the accretion of matter onto a supermassive black hole (SMBH) at the core. This object is surrounded by an orbiting disk of accreted matter drawn in from the surroundings. As material is drawn into the outer parts of this disk, it becomes photoionized, producing broad emission lines in the optical and ultraviolet bands of the electromagnetic spectrum. A wind of ionized matter, organized in filamentary structures at distances of 1–14 light days from the center, is flowing outward in the direction perpendicular to the accretion disk plane.The mass of the central black hole can be estimated based on the properties of the emission lines in the core region. Combined measurements yield an estimated mass of 6.54+0.26−0.25×107 M☉. In other words, it is some 65 million times the mass of the Sun. This result is consistent with other methods of estimating the mass of the SMBH in the nucleus of NGC 5548. Matter is falling onto this black hole at the estimated rate of 0.03 M☉ per year, whereas mass is flowing outward from the core at or above the rate of 0.92 M☉ each year. The inner part of the accretion disk surrounding the SMBH forms a thick, hot corona spanning several light hours that is emitting X-rays. When this radiation reaches the optically thick part of the accretion disk at a radius of around 1–2 light days, the X-rays are converted into heat.

NGC 732

NGC 732 is a lenticular galaxy located 250 million light-years away in the constellation Andromeda. It was discovered by astronomer Édouard Stephan on December 5, 1883 and is member of Abell 262.

NGC 7469

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.NGC 7469 is a type I Seyfert galaxy, characterised by its bright nucleus. It is also a luminous infrared source with a powerful starburst embedded into its circumnuclear region. The coexistence of a circumnuclear starburst ring and an active galactic nucleus have turned NGC 7469 into a key target for studying their relation. NGC 7469 interacts with its smaller companion IC 5283, forming a pair collectively known in the Atlas of Peculiar Galaxies as Arp 298.

NGC 7674

NGC 7674 is a spiral galaxy located in the constellation Pegasus. It is located at a distance of circa 350 million light years from Earth, which, given its apparent dimensions, means that NGC 7674 is about 125,000 light years across. It was discovered by John Herschel on August 16, 1830.

NGC 985

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.NGC 985 is characterised by its ring shape. It is believed it was formed as a result of a galaxy merger. Further evidence supporting this theory is the observation of a second nucleus in NGC 985. When observed in infrared light, a second nucleus was found 3.8 arcseconds northwest of the active nucleus. It is much redder than the rest of the galaxy, indicating the presence of old stars. It has been suggested that the collision between a disk galaxy with another galaxy caused the formation of the ring and displaced the nucleus of the galaxy, creating an empty ring. Based on the kinematics of the galaxy, the secondary nucleus belonged to the intruder galaxy, while the active nucleus is associated with the main stellar component.As is common with merger remnants, NGC 985 has increased star formation rate, and as a result shines bright in the infrared. The total infrared luminosity of NGC 985 is 1.8×1011 L☉ and it is characterised as a luminous infrared galaxy. The total molecular gas mass of the galaxy is estimated to be 2×1010 M☉. Very large molecular clouds exist near the nuclei. They may be clouds gathering around the nucleus in the process of forming a disk around the two nuclei or molecular clouds disrupted by an outflow from the nucleus of the galaxy.NGC 985 is a powerful X-ray source, detected by ROSAT. It is a complex X-ray source, whose spectrum cannot be accounted for by a simple power law at 0.6 keV and suggests the presence of a warm absorber. The hard X-ray emission on the other hand is characterised by a simple power law. The X-ray flux, especially soft X-rays, diminished in NGC 985 in 2013. The variability of the X-ray and ultraviolet emission from the nucleus was observed using the XMM-Newton and Hubble Space Telescope respectively. These observations revealed the presence of outflowing wind from an accretion disk formed around a supermassive black hole that obstructed the nucleus in soft X-rays and UV. The nucleus is otherwise seen unobstructed.

Ursa Major Filament

Ursa Major Filament is a galaxy filament. The filament is connected to the CfA Homunculus, a portion of the filament forms a portion of the "leg" of the Homunculus.

Morphology
Structure
Active nuclei
Energetic galaxies
Low activity
Interaction
Lists
See also

This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.