# Gliese 710

Gliese 710
Observation data
Epoch J2000      Equinox J2000
Constellation Serpens
Right ascension 18h 19m 50.84215s[1]
Declination –01° 56′ 18.9841″[1]
Apparent magnitude (V) 9.69[2] (9.65–9.69)[3]
Characteristics
Spectral type K7 Vk[4]
U−B color index +1.23[2]
B−V color index +1.36[2]
Variable type Suspected[3]
Astrometry
Proper motion (μ) RA: +1.15[1] mas/yr
Dec.: +1.99[1] mas/yr
Parallax (π) 51.12 ± 1.63 mas
Distance 64 ± 2 ly
(19.6 ± 0.6 pc)
Absolute magnitude (MV) 8.23 (8.19-8.23)[note 1][citation needed]
Details
Mass 0.6[6] M
Luminosity (bolometric) 0.084[note 2][citation needed] L
Luminosity (visual, LV) 0.044[note 3] L
Temperature 4,250[6] K
Rotational velocity (v sin i) 6.42 ± 0.78[10] km/s
Other designations
GJ 710, Gl 710, BD-01 3474, HIP 89825, HD 168442, U449, Vys/McC 63, NSV 10635[2]

Gliese 710 is a star in the constellation Serpens Cauda with an apparent visual magnitude of 9.69. It has a stellar classification of K7 Vk,[4] which means it is a main sequence star that is generating energy through the thermonuclear fusion of hydrogen at its core. (The suffix 'k' indicates that the spectrum shows absorption lines from interstellar matter.) The mass of this star is about 60%[6] of the Sun's mass and it has an estimated 67% of the Sun's radius.[7] It is a suspected variable star that may vary in magnitude from 9.65–9.69.

This star is currently about 63.8 light-years (19.6 parsecs) from Earth, but its proper motion, distance, and radial velocity[11] indicate that it will approach within a very small distance—perhaps under one light year—from the Sun within 1.4 million years, based on past and current Hipparcos data.[5] At closest approach it will be a first-magnitude star about as bright as Antares. The proper motion of Gliese 710 is very small for its distance, meaning it is traveling nearly directly in our line of sight.

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 the Solar System.

## Computing and details of the closest approach

Gliese 710 has the potential to perturb the hypothetical Oort cloud enough to send a shower of comets into the inner Solar System, possibly causing an impact event. However, dynamic models by García-Sánchez, et al. in 1999 indicate that the net increase in cratering rate due to the passage of Gliese 710 will be no more than 5%.[6] They estimate that the closest approach will happen in 1,360,000 years when the star will approach within 0.337 ± 0.177 parsecs (1.100 ± 0.577 light years) of the Sun.[12]

An artist's rendering of the Oort cloud and the Kuiper belt (inset)

More recent calculations by Bobylev in 2010 suggest Gliese 710 has an 86% chance of passing through the Oort cloud, considering the Oort cloud to be a spheroid around the Sun with semiminor and semimajor axes of 80,000 and 100,000 astronomical units. The distance of closest approach of Gliese 710 is difficult to compute precisely as it depends sensitively on its current position and velocity; Bobylev estimates that it will pass within 0.311 ± 0.167 pc (1.014 ± 0.545 light years) of the Sun.[5] There is even a 1/10,000 chance of the star penetrating into the region (d < 1,000 AU) where the influence of the passing star on Kuiper belt objects is significant.[5] Gliese 710 would have an apparent magnitude at the time of its closest approach of about 0.5

The star with the second greatest perturbational effect in the past or future 10 million years was Algol,[6] 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.

## Notes

1. ^ From apparent magnitude and parallax: $\scriptstyle M_V = m_V - 5 \log_{10} \left( \frac{100}{\mathrm{parallax\ in\ milliarcseconds}} \right)$
2. ^ Using the absolute visual magnitude of Gliese 710 $\scriptstyle M_{V_{\ast}}=8.23$ with a bolometric correction of $\scriptstyle BC=-0.814$[8] the bolometric magnitude can be calculated as $\scriptstyle M_{bol_{\ast}}=7.416$, the bolometric magnitude of the Sun $\scriptstyle M_{bol_{\odot}}=4.73$,[9] therefore the bolometric luminosity can be calculated by $\scriptstyle \frac{L_{bol_{\ast}}}{L_{bol_{\odot}}}=10^{0.4\left(M_{bol_{\odot}} - M_{bol_{\ast}}\right)}$
3. ^ Using the absolute visual magnitude of Gliese 710 $\scriptstyle M_{V_{\ast}}=8.23$ and the absolute visual magnitude of the Sun $\scriptstyle M_{V_{\odot}}=4.83$, the visual luminosity can be calculated by $\scriptstyle \frac{L_{V_{\ast}}}{L_{V_{\odot}}}=10^{0.4\left(M_{V_{\odot}} - M_{V_{\ast}}\right)}$

## References

1. ^ a b c d van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
2. ^ a b c d "Gliese 710". SIMBAD Astronomical Database. Centre de Données astronomiques de Strasbourg. Retrieved 2010-03-18.
3. ^ a b Kukarkin, B. V. et al. (1971), "The third edition containing information on 20437 variable stars discovered and designated till 1968", General Catalogue of Variable Stars (3rd ed.), Bibcode:1971GCVS3.C......0K
4. ^ a b Gray, R. O. et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I". The Astronomical Journal 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637.
5. ^ a b c d Bobylev, Vadim V. (March 2010). "Searching for Stars Closely Encountering with the Solar System". Astronomy Letters 36 (3): 220–226. arXiv:1003.2160. Bibcode:2010AstL...36..220B. doi:10.1134/S1063773710030060.
6. García-Sánchez, Joan et al. (February 1999). "Stellar Encounters with the Oort Cloud Based on HIPPARCOS Data". The Astronomical Journal 117 (2): 1042–1055. Bibcode:1999AJ....117.1042G. doi:10.1086/300723.
7. ^ a b Johnson, H. M.; Wright, C. D. (November 1983). "Predicted infrared brightness of stars within 25 parsecs of the sun". The Astrophysical Journal Supplement Series 53: 643–711. Bibcode:1983ApJS...53..643J. doi:10.1086/190905.
8. ^
9. ^ Torres, Guillermo (November 2010). "On the Use of Empirical Bolometric Corrections for Stars". The Astronomical Journal 140 (5): 1158–1162. arXiv:1008.3913. Bibcode:2010AJ....140.1158T. doi:10.1088/0004-6256/140/5/1158. Lay summary.
10. ^ López-Santiago, J. et al. (May 2010), "A high-resolution spectroscopic survey of late-type stars: chromospheric activity, rotation, kinematics, and age", Astronomy and Astrophysics 514: A97, arXiv:1002.1663, Bibcode:2010A&A...514A..97L, doi:10.1051/0004-6361/200913437