CHXR 73

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Star
CHXR 73
Hubble image of CHXR 73 and its companion CHXR 73 b (false colors)
Hubble image of CHXR 73 and its companion CHXR 73 b (false colors)
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation chameleon
Right ascension 11 h 06 m 28.76 s
declination -77 ° 37 ′ 33.1 ″
Typing
Known exoplanets ≧ 1
Spectral class M3
Astrometry
parallax 5.2343 ± 0.1759  mas
distance 620 ± 20  ly
191 ± 6  pc
Visual absolute brightness M vis 0.09 ± 0.07 mag
Proper movement 
Rec. Share: −22,193 ± 0.233  mas / a
Dec. portion: 0.215 ± 0.206  mas / a
Physical Properties
Dimensions 0.32 ± 0.11  M ☉
radius 0.83 ± 0.04  R ☉
Luminosity

0.09 ± 0.07  L ☉

Effective temperature 3490 ± 180  K
Age 8 (+70 -5) million  a
Other names
and catalog entries
2MASS catalog 2MASS J11062877-7737331 [1]

CHXR 73 is a star in the constellation Chameleon . It is located in the Cha I molecular cloud, about 620 light years away from Earth . With a temperature of 3490 K and a mass of 0.32 M ☉, it lies in the typical spectrum of red dwarfs , but its radius of 0.83 R ☉ is relatively large, which can be explained by its young age of only 8 million years.

In 2006, the companion CHXR 73 b was discovered in the star's system through direct imaging . It orbits the central star at a distance of about 200 AU . A special feature of CHXR 73 b is that with 12 +8 −5 Jupiter masses ( M J ) it can be categorized as both a planet and a brown dwarf of planetary mass ( Sub-Brown-Dwarf ), according to an ongoing controversy over the definition of planets . Although this mass range does not allow a nuclear fusion to occur and the celestial body does not shine, a (temporary) fusion of deuterium can occur with the corresponding metallicity .

According to experts, the large distance between the celestial body and its central star speaks for the theory of the categorization of CHXR 73 b as a brown dwarf . According to the current standard theory of planet formation, the satellites are formed by clumping within the gas disk of a star. According to model calculations, the maximum probable distance of such a formation in the vicinity of a red dwarf would be around 31.3 billion km (approx. 107 AU), for large, Jupiter-like objects ( gas giants ) even significantly less (<4.8 billion km / 32 AU) . At the observed distance of 200 AU there would simply be too little matter for a planet formation of this dimension. vor The astronomer Kevin Luhman , a member of the international team that discovered CHXR 73 b, considers a local gravitational collapse within a molecular cloud to be the likely origin of the companion. The history of the creation of a celestial body should be preferred to the pure consideration of mass in questions of categorization. A final classification is only possible through high-resolution observation. This is probably already possible with the James Webb space telescope , which is due to start in 2021. The direct observation of a possibly existing accretion disk CHXR 73 b would strengthen the theory of the brown dwarf and explain the two objects to the binary star system .

Animated representation of the CHXR 73 system

Individual evidence

  1. ↑ https://arxiv.org/abs/1804.09365
  2. ↑ http://exoplanet.eu/catalog/chxr_73_b/
  3. ↑ https://arxiv.org/abs/1804.09365
  4. ↑ https://ui.adsabs.harvard.edu/abs/2013A%26A...554A..43D/abstract
  5. ↑ https://ui.adsabs.harvard.edu/abs/2013A%26A...554A..43D/abstract
  6. ↑ https://ui.adsabs.harvard.edu/abs/2013A%26A...554A..43D/abstract
  7. ↑ https://ui.adsabs.harvard.edu/abs/2013A%26A...554A..43D/abstract
  8. ↑ https://ui.adsabs.harvard.edu/abs/2013A%26A...554A..43D/abstract
  9. ↑ Ker Than 2006-09-07T17: 00: 00Z: Newfound Object Further Blurs Planet Definition. Retrieved January 9, 2020 .
  10. ↑ Gaia Collaboration, AGA Brown, A. Vallenari, T. Prusti, JHJ de Bruijne: Gaia Data Release 2. Summary of the contents and survey properties . In: A&A . tape 616 , August 2018, ISSN  0004-6361 , p. A1 , doi : 10.1051 / 0004-6361 / 201833051 ( harvard.edu [accessed January 9, 2020]).
  11. ↑ S. Daemgen, MG Petr-Gotzens, S. Correia, PS Teixeira, W. Brandner: Protoplanetary disk evolution and stellar parameters of T Tauri binaries in Chamaeleon I . In: Astronomy & Astrophysics . tape 554 , June 1, 2013, ISSN  0004-6361 , p. A43 , doi : 10.1051 / 0004-6361 / 201321220 ( aanda.org [accessed January 9, 2020]).
  12. ^ KL Luhman, JC Wilson, W. Brandner, MF Skrutskie, MJ Nelson: Discovery of a Young Substellar Companion in Chamaeleon . In: ApJ . tape 649 , no. 2 , October 2006, ISSN  0004-637X , p. 894–899 , doi : 10.1086 / 506517 ( harvard.edu [accessed January 9, 2020]).
  13. ^ Newfound Object Further Blurs Planet Definition , Space.com. Retrieved November 13, 2016. 
  14. ↑ David S. Spiegel, Adam Burrows, John A. Milsom: THE DEUTERIUM-BURNING MASS LIMIT FOR BROWN DWARFS AND GIANT PLANETS . In: The Astrophysical Journal . tape 727 , no. 1 , January 3, 2011, ISSN  0004-637X , p. 57 , doi : 10.1088 / 0004-637x / 727/1/57 ( iop.org [accessed January 9, 2020]).
  15. ↑ Planet Or Failed Star? NASA's Hubble Telescope Photographs One of Smallest Stellar Companions Ever Seen. Retrieved January 18, 2020 .
  16. ↑ Ker Than 2006-09-07T17: 00: 00Z: Newfound Object Further Blurs Planet Definition. Retrieved January 10, 2020 .