Hen 2-10

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Hen 2-10
Henize 2-10 (Chandra & Hubble).jpg
A composite image of Hen 2-10. Visual data comes from the Hubble Space Telescope, X-ray data comes from the Chandra X-Ray Observatory, and radio data comes from the Very Large Array.
Observation data (J2000 epoch)
Constellation Pyxis
Right ascension 08h 36m 15s [1]
Declination −26° 24′ 34″ [1]
Redshift 0.002912 [1]
Heliocentric radial velocity 873 km/s [1]
Galactocentric velocity657 km/s [1]
Distance 34.24 Mly [1]
Apparent magnitude  (V)11.09 (R Band) [1]
Characteristics
Type dwarf
Mass ~1×1010 [2]   M☉
Apparent size  (V)1.8' [1]
Other designations
ESO 495-21, MCG-04-21-005, PGC 24171/24175 [1]

Hen 2-10, also known as He 2-10 and Henize 2-10, is a dwarf starburst galaxy located 34 million light years away in the constellation of Pyxis. [1] The galaxy is believed to be an early stage starburst galaxy. A black hole was later discovered near the center of the dwarf galaxy, suggesting that the black holes found at the center of most large galaxies may have formed before the galaxies themselves. [3] Recent estimates have placed the mass of this black hole around 3×106  M☉, and the mass of the entire dwarf galaxy at about 1×1010 M☉. [2]

Contents

History

Henize 2-10 draws its name from a catalog of planetary nebulae assembled by astronomer Karl Henize. Henize additionally noted that the object was identified in an unpublished paper by Rudolph Minkowski. The object was likely misidentified as a planetary nebula due to the galaxy's strong emission lines, a feature common of planetary nebulas. [4]

It was not until the 1970s when observations of Hen 2-10 indicated that the center of the object was a strong source of radio waves that it was shown that Hen 2-10 was a dwarf galaxy rather than a planetary nebula. Supporting evidence for the reclassification came in the form of excess infrared emission and a higher than usual density of neutral hydrogen. [5]

Structure

Hen 2-10 is a starburst galaxy featuring at least two star-forming regions near the center of the galaxy. [6] These regions feature a variety of different substances, and multiple super star clusters. A study of some of these SSCs estimates their age to be between 4 and 5 megayears. [7] The galaxy also features emission typical of that in a Wolf–Rayet star, further providing evidence for the starburst region of the galaxy. It was one of the first galaxies found to feature this emission. [5] The strong prevalence of this emission has led to its classification as a Wolf–Rayet galaxy, a special subclass of starburst galaxy that features a higher than normal number of Wolf–Rayet stars. [6]

Furthermore, observations have shown irregularities in the southeast portion of the galaxy which could be interpreted as a tidal tail. This tidal tail suggests that Hen 2-10 may have had past interactions with other galaxies, possibly even a merger event. [8]

Central black hole

In 2011, a team of researchers studied the non-thermal emission of the galaxy center and indicated that the source strengths of radio waves are too strong to come from x-ray binaries while the source strengths of x-rays are too strong to be supernova remnants. However, these sources do align with known data for black holes. [9] This original paper postulated the mass of the black hole to be ~1×106 M☉, but a newer study has refined the estimate to 3×106 M☉. [2]

The presence of SSCs near the center of the galaxy, and not a singular nuclear star cluster (NSC) has led some[ who? ] to believe that Hen 2-10 is a galaxy in its early years. The presence of the black hole is seen to be evidence of the dissipationless model of NSC formation. [10] In this model, the SSCs will move to the center and form a singular NSC. Due to the black hole's relatively small mass, it is not believed to have a major effect on the timescale of this motion, although it is not yet understood how the black hole will affect the NSC formation. Ignoring the black hole indicates that the NSC should be fully formed in a few hundred million years. [11]

Related Research Articles

<span class="mw-page-title-main">H II region</span> Large, low-density interstellar cloud of partially ionized gas

An H II region or HII region is a region of interstellar atomic hydrogen that is ionized. It is typically in a molecular cloud of partially ionized gas in which star formation has recently taken place, with a size ranging from one to hundreds of light years, and density from a few to about a million particles per cubic centimetre. The Orion Nebula, now known to be an H II region, was observed in 1610 by Nicolas-Claude Fabri de Peiresc by telescope, the first such object discovered.

<span class="mw-page-title-main">Messier 87</span> Elliptical galaxy in the Virgo Galaxy Cluster

Messier 87 is a supergiant elliptical galaxy in the constellation Virgo that contains several trillion stars. One of the largest and most massive galaxies in the local universe, it has a large population of globular clusters—about 15,000 compared with the 150–200 orbiting the Milky Way—and a jet of energetic plasma that originates at the core and extends at least 1,500 parsecs, traveling at a relativistic speed. It is one of the brightest radio sources in the sky and a popular target for both amateur and professional astronomers.

<span class="mw-page-title-main">Wolf–Rayet star</span> Heterogeneous class of stars with unusual spectra

Wolf–Rayet stars, often abbreviated as WR stars, are a rare heterogeneous set of stars with unusual spectra showing prominent broad emission lines of ionised helium and highly ionised nitrogen or carbon. The spectra indicate very high surface enhancement of heavy elements, depletion of hydrogen, and strong stellar winds. The surface temperatures of known Wolf–Rayet stars range from 20,000 K to around 210,000 K, hotter than almost all other kinds of stars. They were previously called W-type stars referring to their spectral classification.

<span class="mw-page-title-main">IC 10</span> Irregular starburst galaxy in the constellation Cassiopeia

IC 10 is an irregular galaxy in the constellation Cassiopeia. It was discovered by Lewis Swift in 1887 and in 1935 Nicholas Mayall became the first to suggest that the object is extragalactic. Edwin Hubble suspected it might belong to the Local Group of galaxies, but its status remained uncertain for decades. The radial velocity of IC 10 was measured in 1962, and it was found to be approaching the Milky Way at approximately 350 km/s, strengthening the evidence for its membership in the Local Group. Its membership in the group was finally confirmed in 1996 by direct measurements of its distance based on observations of Cepheids; most estimates place the galaxy 2–3 million light years from Earth, with some estimates ranging from 1.5–4.5 million light years. Despite its closeness, the galaxy is rather difficult to study because it lies near the plane of the Milky Way and is therefore heavily obscured by interstellar matter.

<span class="mw-page-title-main">Starburst galaxy</span> Galaxy undergoing an exceptionally high rate of star formation

A starburst galaxy is one undergoing an exceptionally high rate of star formation, as compared to the long-term average rate of star formation in the galaxy, or the star formation rate observed in most other galaxies.

<span class="mw-page-title-main">Stingray Nebula</span> Planetary nebula in the constellation Ara

The Stingray Nebula is the youngest-known planetary nebula, having appeared in the 1980s. The nebula is located in the direction of the southern constellation Ara, and is located 18,000 light-years away. Although it is some 130 times the size of the Solar System, the Stingray Nebula is only about one tenth the size of most other known planetary nebulae. The central star of the nebula is the fast-evolving star SAO 244567. Until the early 1970s, it was observed on Earth as a preplanetary nebula in which the gas had not yet become hot and ionized.

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

The Sombrero Galaxy is a peculiar galaxy of unclear classification in the constellation borders of Virgo and Corvus, being about 9.55 megaparsecs from the Milky Way galaxy. 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 has an isophotal diameter of approximately 29.09 to 32.32 kiloparsecs, making it slightly bigger in size than the Milky Way.

<span class="mw-page-title-main">NGC 3603</span> Open cluster in the constellation Carina

NGC 3603 is a nebula situated in the Carina–Sagittarius Arm of the Milky Way around 20,000 light-years away from the Solar System. It is a massive H II region containing a very compact open cluster HD 97950.

<span class="mw-page-title-main">HD 97950</span> Multiple star system in the constellation Carina

HD 97950, is the central core of a super star cluster within the NGC 3603 H II region. It was catalogued as a single star, but has now been resolved into one of the densest clusterings of stars in the galaxy.

<span class="mw-page-title-main">R136a1</span> Wolf–Rayet star with one of the highest mass and luminosity of any known star

R136a1 is one of the most massive and luminous stars known, at nearly 200 M☉ and nearly 4.7 million L☉, and is also one of the hottest, at around 46,000 K. It is a Wolf–Rayet star at the center of R136, the central concentration of stars of the large NGC 2070 open cluster in the Tarantula Nebula in the Large Magellanic Cloud. The cluster can be seen in the far southern celestial hemisphere with binoculars or a small telescope, at magnitude 7.25. R136a1 itself is 100 times fainter than the cluster and can only be resolved using speckle interferometry.

<span class="mw-page-title-main">AB7</span> Binary star in the Small Magellanic Cloud in the constellation Tucana

AB7, also known as SMC WR7, is a binary star in the Small Magellanic Cloud. A Wolf–Rayet star and a supergiant companion of spectral type O orbit in a period of 19.56 days. The system is surrounded by a ring-shaped nebula known as a bubble nebula.

WR 142 is a Wolf-Rayet star in the constellation Cygnus, an extremely rare star on the WO oxygen sequence. It is a luminous and very hot star, highly evolved and close to exploding as a supernova. It is suspected to be a binary star with a companion orbiting about 1 AU away.

<span class="mw-page-title-main">WR 102</span> Star in the constellation Sagittarius

WR 102 is a Wolf–Rayet star in the constellation Sagittarius, an extremely rare star on the WO oxygen sequence. It is a luminous and very hot star, highly evolved and close to exploding as a supernova.

<span class="mw-page-title-main">NGC 6905</span> Planetary nebula in the constellation Delphinus

NGC 6905, also known as the Blue Flash Nebula, is a planetary nebula in the constellation Delphinus. It was discovered by William Herschel in 1784. The central star is 14.0 mag. The distance of the nebula, as with most planetary nebulae, is not well determined and estimates range between 1.7 and 2.6 kpc.

<span class="mw-page-title-main">WR 31a</span> Wolf Rayet star in the constellation Carina

WR 31a, commonly referred to as Hen 3-519, is a Wolf–Rayet (WR) star in the southern constellation of Carina that is surrounded by an expanding Wolf–Rayet nebula. It is not a classical old stripped-envelope WR star, but a young massive star which still has some hydrogen left in its atmosphere.

<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 541</span> Galaxy in the constellation Cetus

NGC 541 is a lenticular galaxy located in the constellation Cetus. It is located at a distance of about 230 million light years from Earth, which, given its apparent dimensions, means that NGC 541 is about 130,000 light years across. It was discovered by Heinrich d'Arrest on October 30, 1864. It is a member of the Abell 194 galaxy cluster and is included in the Atlas of Peculiar Galaxies in the category galaxies with nearby fragments. NGC 541 is a radio galaxy of Fanaroff–Riley class I, also known as 3C 40A.

<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.

NGC 6822-WR 12 is a WN-type Wolf-Rayet star located in the galaxy NGC 6822, about 1.54 million light years away in the constellation of Sagittarius. NGC 6822-WR 12 was the first Wolf-Rayet star to be discovered in the galaxy, and is one of only four known in the galaxy.

References

  1. 1 2 3 4 5 6 7 8 9 10 "NED entry for HE 2-10" . Retrieved 1 June 2011.
  2. 1 2 3 Reines, Amy E.; Reynolds, Mark T.; Miller, Jon M.; Sivakoff, Gregory R.; Greene, Jenny E.; Hickox, Ryan C.; Johnson, Kelsey E. (2016). "Deep Chandra Observations of the Compact Starburst Galaxy Henize 2-10: X-rays from the Massive Black Hole". The Astrophysical Journal Letters. 830 (2): L35. arXiv: 1610.01598 . Bibcode:2016ApJ...830L..35R. doi: 10.3847/2041-8205/830/2/L35 . S2CID   118419430.
  3. ↑ Grossman, Lisa (10 January 2011). "Baby Galaxy Hosts Monster Black Hole". Wired News . Retrieved 3 July 2011.
  4. ↑ Henize, Karl (April 1967). "Observations of Southern Planetary Nebulae". Astrophysical Journal Supplement. 14: 127–128. Bibcode:1967ApJS...14..125H. doi:10.1086/190151.
  5. 1 2 Allen, David A.; Wright, Alan E.; Goss, W. Miller (October 1976). "The Dwarf Emission Galaxy He2-10". Monthly Notices of the Royal Astronomical Society. 176: 91–97. Bibcode:1976MNRAS.177...91A. doi: 10.1093/mnras/177.1.91 .
  6. 1 2 Beck, Sara C.; Kelly, Dennis M.; Lacy, John H. (August 1997). "The Infrared Nucleus of the Wolf-Rayet Galaxy Henize 2-10". Astronomical Journal. 114: 585–591. arXiv: astro-ph/9705227 . Bibcode:1997AJ....114..585B. doi:10.1086/118495. S2CID   35229182.
  7. ↑ Chandar, Rupali; Leitherer, Claus; Tremonti, Christy; Calzetti, Daniela (April 2003). "The Stellar Content of Henize 2-10 from Space Telescope Imaging Spectrograph Ultraviolet Spectroscopy". The Astrophysical Journal. 586 (2): 939–958. Bibcode:2003ApJ...586..939C. doi: 10.1086/367956 . S2CID   120212135.
  8. ↑ Kobulnicky, Henry A.; Dickey, John M.; Sargent, Anneila I.; Hogg, David E.; Conti, Peter S. (July 1995). "Aperture Synthesis Observations of Molecular and Atomic Gas in the Wolf- Rayet Starburst Galaxy". The Astronomical Journal. 110: 116. Bibcode:1995AJ....110..116K. doi:10.1086/117500. ISSN   0004-6256.
  9. ↑ Reines, Amy E.; Sivakoff, Gregory R.; Johnson, Kelsey E.; Brogan, Crystal L. (February 2011). "An Actively Accreting Massive Black Hole in the Dwarf Starburst Galaxy Henize 2-10". Nature. 470 (7332): 66–68. arXiv: 1101.1309 . Bibcode:2011Natur.470...66R. doi:10.1038/nature09724. PMID   21217688. S2CID   4316728.
  10. ↑ Arca Sedda, Manuel; Capuzzo-Dolcetta, Roberto; Antonini, Fabio; Seth, Anil C. (June 2015). "Henize 2-10: The Ongoing Formation of a Nuclear Star Cluster around a Massive Black Hole". The Astrophysical Journal. 806 (2): 220. arXiv: 1501.04567 . Bibcode:2015ApJ...806..220A. doi:10.1088/0004-637X/806/2/220. S2CID   118864739.
  11. ↑ Nguyen, Dieu D.; Seth, Anil C.; Reines, Amy E.; den Brok, Mark; Sand, David; McLeod, Brian (August 2014). "Extended Structure and Fate of the Nucleus in Henize 2-10". The Astrophysical Journal. 794 (1): 34. arXiv: 1408.4446 . Bibcode:2014ApJ...794...34N. doi:10.1088/0004-637X/794/1/34. S2CID   118490716.
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