Gliese 876 c

Coordinates: Sky map 22h 53m 16.7s, −14° 15′ 49″
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Gliese 876 c
Keck Observatories
Discovery dateJanuary 9, 2001
Doppler spectroscopy
Orbital characteristics[3]
Epoch 2,450,602.09311 BJD
0.136044+0.000021
−0.000022 AU
Eccentricity0.2571±0.0019
30.0972+0.0071
−0.0073 d
292.55+1
−0.99 º
Inclination53.06±0.85 º[note 1]
51.09+0.77
−0.78 º
Semi-amplitude87.46+0.3
−0.29 m/s
StarGliese 876
Physical characteristics[3]
Mass265.6±2.7 M🜨[note 2]

Gliese 876 c is an exoplanet orbiting the red dwarf Gliese 876, taking about 30 days to complete an orbit. The planet was discovered in April 2001 and is the second planet in order of increasing distance from its star.

Discovery

At the time of discovery, Gliese 876 was already known to host an extrasolar planet designated

eccentricity
of the orbit of Gliese 876 b.

Host star

Main article: Gliese 876

The planet orbits a (M-type) star named Gliese 876. The star has a mass of 0.33 M☉ and a radius of around 0.36 R☉. It has a surface temperature of 3350 K and is 2.55 billion years old. In comparison, the Sun is about 4.6 billion years old[4] and has a surface temperature of 5778 K.[5]

Orbit and mass

The orbits of the planets of Gliese 876. Gliese 876 c is the second planet from the star Gliese 876.

Gliese 876 c is in a 1:2:4

moons Io, Europa and Ganymede
.

The orbital

semimajor axis is only 0.13 AU, around a third of the average distance between Mercury and the Sun, and is more eccentric than the orbit of any of the major planets of the Sun's Solar System.[6] Despite this, it is located in the inner regions of the system's habitable zone, since Gliese 876 is such an intrinsically faint star.[9]

A limitation of the radial velocity method used to detect Gliese 876 c is that only a lower limit on the planet's

inclination of the orbit, which is not determined by the radial velocity measurements. However, in a resonant system such as Gliese 876, gravitational interactions between the planets can be used to determine the true masses. Using this method, the inclination of the orbit can be determined, revealing the planet's true mass to be 0.72 times that of Jupiter.[6]

Characteristics

Based on its high mass, Gliese 876 c is likely to be a gas giant with no solid surface. Since it was detected indirectly through its gravitational effects on the star, properties such as its radius, composition, and temperature are unknown. Assuming a composition similar to Jupiter and an environment close to chemical equilibrium, the planet is predicted to have a cloudless upper atmosphere.[10]

Gliese 876 c lies at the inner edge of the system's habitable zone. While the prospects for life on gas giants are unknown, it might be possible for a large moon of the planet to provide a habitable environment. Unfortunately tidal interactions between a hypothetical moon, the planet, and the star could destroy moons massive enough to be habitable over the lifetime of the system.[11] In addition it is unclear whether such moons could form in the first place.[12]

This planet, like b and e, has likely migrated inward.[13]

See also

Notes

  1. ^ The inclination assumes the planets in the system are coplanar, long-term orbital stability simulations strongly favor low mutual inclinations.
  2. ^ Uncertainties in the planetary masses and semimajor axes do not take into account the uncertainty in the mass of the star.

References

  1. ^
    doi:10.1086/321552
    .
  2. ^ a b "Two new planetary systems discovered" (Press release). Kamuela, Hawaii: W. M. Keck Observatory. January 9, 2001. Archived from the original on August 13, 2019. Retrieved August 13, 2019.
  3. ^
    doi:10.3847/1538-3881/aaa894
    .
  4. ^ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Archived from the original on 18 August 2010. Retrieved 19 February 2011.
  5. ^ Fraser Cain (September 15, 2008). "Temperature of the Sun". Universe Today. Archived from the original on 29 August 2010. Retrieved 19 February 2011.
  6. ^
    S2CID 118707953
    .
  7. S2CID 122255962
    .
  8. S2CID 119067572
    .
  9. S2CID 121585653
    .
  10. S2CID 16004653
    .
  11. S2CID 14508244
    . (paper incorrectly refers to Gliese 876 b as GJ876c)
  12. S2CID 4327454
    .
  13. S2CID 254381557
    .

External links

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