54 Piscium

Starbox begin
name = 54 PisciumStarbox image


caption = 54 Piscium A and the brown dwarf 54 Piscium B (circled).Starbox observe
epoch = J2000.0
constell = Pisces
ra = RA|00|39|21.8
dec = DEC|+21|15|01.7
appmag_v = 5.80Starbox character
class = K0V / T7.5V
b-v = 0.85
u-b = 0.57
variable = "Suspected"Starbox astrometry
radial_v = −34.2
prop_mo_ra = −461.09
prop_mo_dec = −370.90
parallax = 90.03
p_error = 0.72
dist_ly =
dist_pc =
absmag_v = 5.65Starbox detail
mass = 0.78 / 0.051
radius = 0.86
luminosity = 0.48
metal = 110%Starbox catalog
names = BD+20°85, GCTP 110.00, Gliese 27, HD 3651, HIP 3093, HR 166, LHS 1116, LTT 10224, SAO 74175Starbox reference
Simbad = HD+3651
ARICNS =

54 Piscium is an orange dwarf star approximately 36 light-years away in the constellation of Pisces. As of 2002, an extrasolar planet was confirmed to be orbiting the star. In 2006, a brown dwarf was discovered orbiting the star, making the system somewhat a "binary star".

Stellar components

54 Piscium is an orange dwarf star of the spectral type "K0V". It has been calculated that the star may have 79 percent of the Sun's mass, along with 86 percent of the radius and 46 percent of the luminosity. The rotational period of 54 Piscium is about 48 days. It is though that the star is about 5.1 billion years old (based on chromospheric activity and isochronal analysis). The star appears to be about 1.1 times more enriched with elements heavier than hydrogen (based on its abundance of iron).

In 2006, a direct image of 54 Piscium showed that there was a brown dwarf companion to 54 Piscium A. [cite journal | url=http://www3.interscience.wiley.com/journal/118593359/abstract | author=Mugrauer "et al." | title=HD 3651 B: the first directly imaged brown dwarf companion of an exoplanet host star | journal=Monthly Notices of the Royal Astronomical Society: Letters | volume=373 | issue=1 | pages=L31–L35 | year=2006 | doi=10.1111/j.1745-3933.2006.00237.x | format=abstract [http://arxiv.org/abs/astro-ph/0608484 web preprint] ] 54 Piscium B is though to be a "methane brown dwarf" of the spectral type "T7.5V". A comparison of its luminosity suggests that the substellar object has a mass of 0.051 that of the Sun (50 times the mass of Jupiter), along. Similar to Gliese 570 D, this brown dwarf is though to have a surface temperature between 500 and 600 degrees Celsius.

When 54 Piscium B was directly imaged by NASA's Spitzer Space Telescope, it was shown that the brown dwarf had a projected separation of around 476 astronomical units from the primary star. [cite journal | url=http://www.journals.uchicago.edu/doi/abs/10.1086/509073 | author=Luhman "et al." | title=Discovery of Two T Dwarf Companions with the Spitzer Space Telescope | journal=The Astrophysical Journal | volume=654 | issue=1 | pages=570–579 | year=2007 | doi=10.1086/509073 | format=abstract [http://fr.arxiv.org/abs/astro-ph/0609464 web preprint] ] 54 Piscium B was the first brown dwarf to be detected around a star with an already known extrasolar planet (based on radial velocity surveys).

Planetary system

On January 16 2002, a team of astronomers (lead by Geoff Marcy) announced the discovery of an extrasolar planet (named 54 Piscium b) around 54 Piscium. [cite journal | url=http://www.journals.uchicago.edu/doi/full/10.1086/375027 | author=Fischer "et al." | title=A Sub-Saturn Mass Planet Orbiting HD 3651 | journal=The Astrophysical Journal | volume=590 | issue=2 | year=2003 | pages=1081–1087 | doi=10.1086/375027 ] [cite journal | url=http://www.journals.uchicago.edu/doi/full/10.1086/504701 | author=Butler "et al." | title=Catalog of Nearby Exoplanets | journal=The Astrophysical Journal | volume=646 | issue=1 | pages=505–522 | year=2006 | doi=10.1086/504701] The planet has been estimated to have a mass of only 20 percent that of Jupiter (making the planet around the same size and mass of Saturn).

The planet orbits its sun at a distance of 0.28 astronomical units (which would be within the orbit of Mercury), which takes approximately 62 days to complete. The planet has a high eccentricity of about 0.63. The highly elliptical orbit, however, suggested that the gravity of an unseen object farther away from the star was pulling the planet outward. The eccentric orbit became clear with the discovery of the brown dwarf within the system.

The orbit of an Earth-like planet would need to be centered within 0.68 AU [square root of luminosity] (around the orbital distance of Venus), which in a Keplerian system means a 240 day orbital period. In a later simulation with the brown dwarf, 54 Piscium b's orbit "sweeps clean" most test particles within 0.5 AU, leaving only asteroids "in low-eccentricity orbits near the known planet’s apastron distance, near the 1:2 mean-motion resonance". Also, observation has ruled out Neptune-class or heavier planets with a period of one year or less; which still allows for Earth-sized planets at 0.6 AU or more. [cite journal | url=http://www.iop.org/EJ/abstract/1538-3881/134/3/1276 | author=Wittenmyer "et al" | year=2007 | title=Dynamical and Observational Constraints on Additional Planets in Highly Eccentric Planetary Systems | journal=The Astronomical Journal | volume=134 | issue=3 | page=1276–1284 | doi=10.1086/520880 [http://arxiv.org/abs/0706.1962v1 web preprint] ]

OrbitboxPlanet
exoplanet = b
mass = >0.227±0.023
semimajor = 0.296±0.017
period = 62.206±0.021
eccentricity = 0.618±0.051

See also

* 107 Piscium
* 109 Piscium
* Delta Trianguli
* Upsilon Andromedae

References

External links

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