Gliese 710

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**Gliese 710**
Observation data Equinox J2000
Constellation	Serpens
Right ascension	18^h 19^m 51^s
Declination	-01° 56.4′
Apparent magnitude (V)	9.65-9.69(var)
Characteristics
Spectral type	K7V
U-B color index	1.23
B-V color index	1.36
Variable type	Suspected
Astrometry
Radial velocity (R_v)	-24.0 km/s
Proper motion (μ)	RA: -130 mas/yr Dec.: -50 mas/yr
Parallax (π)	65.8 ± 7.1 mas
Distance	approx. 50 ly (approx. 15 pc)
Absolute magnitude (M_V)	8.7 ± 0.3
Details
Mass	0.42 M_☉
Radius	0.1 R_☉
Luminosity	(bolometric)0.042 L_☉
Temperature	4000k K
Metallicity	?
Rotation	>14 km/s.
Age	? years
Other designations
Gliese 710, BD-01 3474, Gl 710, Hip 89825, BD-01 3474, HD 168442, HD 168442, U449, Vys/McC 63, NSV 10635

Gliese 710 is a red dwarf star in the constellation Serpens Cauda, with visual magnitude 9.66 and a mass of 0.4–0.6 solar masses.

It is about 63.0 light years from Earth, but is notable because its proper motion, distance, and radial velocity indicate that it will approach within 1.1 light years (70,000 AU) from Earth within 1.4 million years, based on the latest Hipparcos data. At closest approach it will be a first-magnitude star about as bright as Antares. As one can reference from the data on the right, the proper motion of this star is very small for its distance, meaning it is travelling nearly directly in our line of sight; Compare for example with Arcturus.

In a time interval of ±10 million years from the present, Gliese 710 is the star whose combination of mass and close approach distance will cause the greatest gravitational perturbation of our solar system. Specifically, it has the potential to perturb the Oort cloud enough to send a shower of comets into the inner solar system, possibly causing an impact event. However, recent dynamic models by García-Sánchez, et al. indicate that the net increase in cratering rate due to the passage of Gliese 710 will be no more than 5%.

Interestingly, the star with the second greatest perturbational effect in the past or future 10 million years was Algol, a triple star system that passed no closer than 9.8 light years, 7.3 million years ago, but with a considerably larger total mass of 5.8 solar masses. Algol (also known as the Demon Star) was traditionally considered the unluckiest star in the sky, which is reflected in its name (Al-ghol means 'the ghoul' in Arabic)