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The earliest identification of Hen 2-10 is from an unpublished paper by [[Rudolph Minkowski]] who discovered it while looking for planetary nebulae.The galaxy's strong [[Hα]] emission lines mean that it appeared similarly to a planetary nebula when its spectral lines were observed. [[Karl Henize]] would later include the galaxy in his catalog of planetary nebulae, giving it the designation 2-10.<ref name="Henize">{{cite journal|last1=Henize|first1=Karl|title=Observations of Southern Planetary Nebulae|journal=Astrophysical Journal Supplement|date=April 1967|volume=14|pages=127-128|doi=10.1086/190151|accessdate=March 5, 2017}}</ref> |
The earliest identification of Hen 2-10 is from an unpublished paper by [[Rudolph Minkowski]] who discovered it while looking for planetary nebulae.The galaxy's strong [[Hα]] emission lines mean that it appeared similarly to a planetary nebula when its spectral lines were observed. [[Karl Henize]] would later include the galaxy in his catalog of planetary nebulae, giving it the designation 2-10.<ref name="Henize">{{cite journal|last1=Henize|first1=Karl|title=Observations of Southern Planetary Nebulae|journal=Astrophysical Journal Supplement|date=April 1967|volume=14|pages=127-128|doi=10.1086/190151|accessdate=March 5, 2017}}</ref> |
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It was not until the 1970's 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.<ref name="Wright et al. 1976">{{cite journal|last1=Allen|first1=David A.|last2=Wright|first2=Alan E.|last3=Goss|first3=W. Miller|title=The Dwarf Emission Galaxy He2-10|journal=Monthly Notices of the Royal Astronomical Society|date=October 1976|volume=176|pages=91-97|doi=10.1093/mnras/177.1.91}}</ref> |
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In 2011 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.<ref name = "Reines et al 2011">{{ |
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cite journal|last1=Reines|first1=Amy E.|last2=Sivakoff|first2=Gregory R.|last3=Johnson |first3=Kelsey E.|last4=Brogan| first4=Crystal L.|title=An Actively Accreting Massive Black Hole in the Dwarf Starburst Galaxy Henize 2-10|journal=Nature|date=February 2011|volume=470|issue=7332|pages=66-68|arxiv=1101.1309|doi=10.1038/nature09724}} |
cite journal|last1=Reines|first1=Amy E.|last2=Sivakoff|first2=Gregory R.|last3=Johnson |first3=Kelsey E.|last4=Brogan| first4=Crystal L.|title=An Actively Accreting Massive Black Hole in the Dwarf Starburst Galaxy Henize 2-10|journal=Nature|date=February 2011|volume=470|issue=7332|pages=66-68|arxiv=1101.1309|doi=10.1038/nature09724}} |
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</ref> This original paper postulated the mass of the black hole to be ~{{Solar mass|1{{e|6}}}}, but a newer |
</ref> This original paper postulated the mass of the black hole to be ~{{Solar mass|1{{e|6}}}}, but a newer study has refined the estimate to {{Solar mass|3{{e|6}}}}.<ref name = "Reines et al 2016"/> |
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== Structure == |
== Structure == |
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Hen 2-10 is a [[starburst galaxy]] featuring at least two star clusters near the center of the galaxy. <ref name="Beck et al 1997">{{cite journal|last1=Beck|first1=Sara C.|last2=Kelly|first2=Dennis M.|last3=Lacy|first3=John H.|title=The Infrared Nucleus of the Wolf-Rayet Galaxy Henize 2-10.|journal=Astronomical Journal|date=August 1997|volume=114|pages=585-591|arxiv=astro-ph/9705227|doi=10.1086/118495|accessdate=5 March 2017}}</ref> The galaxy also features [[Wolf-Rayet star|Wolf-Rayet]] emission, usually found in planetary nebulas. It was one of the first galaxies found to feature this emission.<ref name = "Wright et al. 1976"/> |
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===Central black hole=== |
===Central black hole=== |
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Revision as of 03:19, 6 March 2017
Anywhere wiith [Cite] needs to be cited, I know, it's just a note to self to do them later.
| Hen 2-10 | |
|---|---|
.jpg) A composite image of Hen 2-10. Visual data comes from Hubble, 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 velocity | 657 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 galaxy located 34 million light years away in the constellation of Pyxis.[1] It is the first dwarf galaxy discovered that contains, at its center, a supermassive black hole.[3] This discovery was surprising since the black hole was about one quarter of the size of the black hole at the center of the Milky Way Galaxy, despite the fact that the galaxy is roughly one thousandth the size of the Milky Way. This discovery suggests that the black holes found at the center of most large galaxies may have formed before the galaxies themselves.[4] 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]
History
The earliest identification of Hen 2-10 is from an unpublished paper by Rudolph Minkowski who discovered it while looking for planetary nebulae.The galaxy's strong Hα emission lines mean that it appeared similarly to a planetary nebula when its spectral lines were observed. Karl Henize would later include the galaxy in his catalog of planetary nebulae, giving it the designation 2-10.[5]
It was not until the 1970's 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.[6]
In 2011 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.[7] 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]
Structure
Hen 2-10 is a starburst galaxy featuring at least two star clusters near the center of the galaxy. [8] The galaxy also features Wolf-Rayet emission, usually found in planetary nebulas. It was one of the first galaxies found to feature this emission.[6]
Central black hole
References
- ^ a b c d e f g h i j "NED entry for HE 2-10". Retrieved 1 June 2011.
- ^ a b c 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. arXiv:1610.01598. doi:10.3847/2041-8205/830/2/L35.
{{cite journal}}: CS1 maint: extra punctuation (link) CS1 maint: unflagged free DOI (link) - ^ Kaufman, Rachel (10 January 2011). "Huge Black Hole Found in Dwarf Galaxy". National Geographic. Retrieved 1 June 2011.
- ^ Grossman, Lisa (10 January 2011). "Baby Galaxy Hosts Monster Black Hole". Wired News. Retrieved 3 July 2011.
- ^ Henize, Karl (April 1967). "Observations of Southern Planetary Nebulae". Astrophysical Journal Supplement. 14: 127–128. doi:10.1086/190151.
{{cite journal}}:|access-date=requires|url=(help) - ^ a b 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. doi:10.1093/mnras/177.1.91.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - ^ 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. doi:10.1038/nature09724.
- ^ 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. doi:10.1086/118495.
{{cite journal}}:|access-date=requires|url=(help)
]