Astronomy:HD 28185 b

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Short description: Gas giant orbiting HD 28185
HD 28185 b
Jkv.HD28185.b.png
An artist's impression of HD28185 b
Discovery
Discovered bySantos et al.
Discovery siteLa Silla Observatory
Discovery dateApril 4, 2001[1]
Radial velocity (CORALIE)
Orbital characteristics[2]
1.035+0.042
−0.046 astronomical unit|AU
Eccentricity0.055+0.004
−0.003
Orbital period1.056 ± 0.0002 years (385.704 ± 0.073 d)
astron|astron|helion}}2452262.394+3.714
−3.315
356.596°+3.495°
−3.155°
Semi-amplitude163.657+0.653
−0.533
StarHD 28185
Physical characteristics[2]
Mass≥5.837+0.486
−0.510 Jupiter mass


HD 28185 b is an extrasolar planet 128 light-years away from Earth in the constellation of Eridanus. The planet was discovered orbiting the Sun-like star HD 28185 in April 2001 as a part of the CORALIE survey for southern extrasolar planets, and its existence was independently confirmed by the Magellan Planet Search Survey in 2008.[3] HD 28185 b orbits its sun in a circular orbit that is at the inner edge of its star's habitable zone.[4]

Discovery

HD 28185 b was discovered by detecting small periodic variations in the radial velocity of its parent star caused by the gravitational attraction of the planet. This was achieved by measuring the Doppler shift of the star's spectrum. In 2001 it was announced that HD 28185 exhibited a wobble along the line-of-sight with a period of 383 days, with an amplitude indicating a minimum mass 5.72 times that of Jupiter.[1][5]

Orbit and mass

HD 28185 b takes 1.04 years to orbit its parent star. Unlike most known long-period planets, the orbit of HD 28185 b has a low eccentricity, comparable to that of Mars in the Solar System.[6] The orbit lies entirely within its star's habitable zone.[4]

The amplitude of the radial velocity oscillations means that the planet has a mass at least 5.7 times that of Jupiter in the Solar System. However, the radial velocity method only yields a minimum value on the planet's mass, depending on the orbital inclination to our line-of-sight. Therefore, the true mass of the planet may be much greater than this lower limit.

Characteristics

Given the planet's high mass, it is most likely to be a gas giant with no solid surface. Since the planet has only been detected indirectly through observations of the star, properties such as its radius, composition, and temperature are unknown. Periastron (0.959 AU), semimajor axis (1.031 AU) and apastron (1.102 AU) irradiances are 112%, 96.6% and 84.5% that of the Earth. [note 1]

Since HD 28185 b orbits in its star's habitable zone, some have speculated on the possibility of life on worlds in the HD 28185 system.[7] While it is unknown whether gas giants can support life, simulations of tidal interactions suggest that HD 28185 b could harbor Earth-mass satellites in orbit around it for many billions of years.[8] Such moons, if they exist, may be able to provide a habitable environment, though it is unclear whether such satellites would form in the first place.[9] Additionally, a small planet in one of the gas giant's Trojan points could survive in a habitable orbit for long periods.[10] The high mass of HD 28185 b, of over six Jupiter masses, actually makes either of these scenarios more likely than if the planet was about Jupiter's mass or less.

See also

Notes

  1. ↑ From [math]\displaystyle{ \frac{f}{f_\oplus}=\left(\frac{R_\ast}{R_\odot}\right)^2 \left(\frac{T_\ast}{t_\odot}\right)^4 \left(\frac{d}{\mathrm{1\ AU}}\right)^{-2} }[/math] Star radius is 1.15 times solar, temperature is 5609 K compared to the sun 5777 K. Irradiance is given by bolometric luminosity divided by square of distance, flux divided by Solar Constant, ratio relative to Earth.

References

  1. ↑ 1.0 1.1 "Exoplanets: The Hunt Continues!" (Press release). Garching, Germany: European Southern Observatory. April 4, 2001. Retrieved December 27, 2012.
  2. ↑ 2.0 2.1 Feng, Fabo et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series 262 (21): 21. doi:10.3847/1538-4365/ac7e57. Bibcode: 2022ApJS..262...21F. 
  3. ↑ Minniti, Dante et al. (2009). "Low-Mass Companions for Five Solar-Type Stars From the Magellan Planet Search Program". The Astrophysical Journal 693 (2): 1424–1430. doi:10.1088/0004-637X/693/2/1424. Bibcode: 2009ApJ...693.1424M. 
  4. ↑ 4.0 4.1 Jones, Barrie W.; Sleep, P. Nick; Underwood, David R. (2006). "Habitability of Known Exoplanetary Systems Based on Measured Stellar Properties". The Astrophysical Journal 649 (2): 1010–1019. doi:10.1086/506557. Bibcode: 2006ApJ...649.1010J. 
  5. ↑ Santos, N. (2001). "The CORALIE survey for southern extra-solar planets VI. New long-period giant planets around HD 28185 and HD 213240". Astronomy and Astrophysics 379 (3): 999–1004. doi:10.1051/0004-6361:20011366. Bibcode: 2001A&A...379..999S. http://www.edpsciences.org/articles/aa/abs/2001/45/aah3054/aah3054.html. 
  6. ↑ Butler, R. P. et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646 (1): 505–522. doi:10.1086/504701. Bibcode: 2006ApJ...646..505B. 
  7. ↑ Mullen, L. (2001). "Extrasolar Planets with Earth-like Orbits". http://nai.nasa.gov/news_stories/news_detail.cfm?ID=126. 
  8. ↑ Barnes, J., O'Brien, D. (2002). "Stability of Satellites around Close-in Extrasolar Giant Planets". Astrophysical Journal 575 (2): 1087–1093. doi:10.1086/341477. Bibcode: 2002ApJ...575.1087B. 
  9. ↑ Canup, R.; Ward, W. (2006). "A common mass scaling for satellite systems of gaseous planets". Nature 441 (7095): 834–839. doi:10.1038/nature04860. PMID 16778883. Bibcode: 2006Natur.441..834C. 
  10. ↑ Schwarz, R.; Dvorak, R.; Süli, Á.; Érdi, B. (2007). "Survey of the stability region of hypothetical habitable Trojan planets". Astronomy and Astrophysics 474 (3): 1023–1029. doi:10.1051/0004-6361:20077994. Bibcode: 2007A&A...474.1023S. 

External links

Coordinates: Sky map 04h 26m 26.3205s, −10° 33′ 02.955″



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