Extrasolar Visions - Gliese 876 d

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Clarified Neptunian

Object Type:

Clarified Neptunian

Parent Star:

Gliese 876 (M4 V)

Discovery Status:

Confirmed

Current Planet

Habitability Zone

Mass ( M sin i ):

7.314 ± 0.954 Earths

Mean Distance:

0.02 ± 0.0000005 AU

Orbital Period:

1.93776 ± 0.00007 Days

Eccentricity:

Argument of Perihelion (omega):

0 °

Planet Appearance:

Blue and cloudless

Estimated Mean Temp:

642 Kelvin

Mean Angular Star Size:

11.17°

Gravitational Influence
(Hill Sphere):

< 0.001 AU / 80000 km

Tidally locked if older than:

0 Myr

Estimated Bond Albedo:

~ 0.01 ¹

Notes:
¹ from Sudarsky et al. 2000

Year Discovered:

2005

Detection Method:

Doppler Spectroscopy

Discovered By:

Rivera et al.

Click image below to enlarge

Given an orbital inclination of 50 degrees, the mass of this planet would be 7.5 Earths, making it the lightest exoplanet discovered around a main sequence star.

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Gliese 876 d
Superearth Gliese 876 d is only 7.5 Earth masses, making it as of mid 2005 the smallest extrasolar planet known around a normal star. At such a low mass, it must be composed primarily of rock, although its rocky surface may lie beneath a thick layer of super condensed volatiles and a dense atmosphere. If, on the other hand, most of the planet's volatiles have been lost to early bombardment or were never present in large quantities, the rocky surface of Gliese 876 d may be visible from space. Baked both internally by the heat of radioactive decay and externally by its close proximity to its star, such a massive terrestrial world have a thin crust riddled with tectonic rifts and possibly even oceans of magma exposed on the surface.

Lava Oceans of Gliese 876 d
Oceans of lava glow red on the nightside of Gliese 876 d. The dayside of the planet broils in the yellowish light of the planet's host red dwarf star. In the distance glow two bright "stars", planets c and b of Gliese 876.