# Gliese 710

Gliese 710, or HIP 89825, is an orange 0.6 M star in the constellation Serpens Cauda. It is projected to pass near the Sun in a timeframe well within the parameters of current models which cover the next 15 million years. The predicted minimum distance will occur in about 1.281 million years, with Gaia DR2 suggesting a distance (slightly closer than the previous estimates) of 0.0676 parsecs—0.221 light-years (14,000 astronomical units)[11]—a distance about 20 times closer than the current distance of Proxima Centauri, although the approach could be even closer.[12] Such a distance would make for a similar brightness to the brightest planets, optimally reaching an apparent visual magnitude of about −2.7 (brighter than Mars at opposition). The star's proper motion will peak around one arcminute per year,[13][14] a rate of apparent motion that would be noticeable over a human lifespan.

Gliese 710
Observation data
Epoch J2000      Equinox J2000
Constellation Serpens
Right ascension 18h 19m 50.8412s[1]
Declination –01° 56′ 19.003″[1]
9.66[2] (9.65–9.69)[3]
Characteristics
Spectral type K7 Vk[4]
U−B color index +1.26[2]
B−V color index +1.37[2]
Variable type Suspected[3]
Astrometry
Radial velocity (Rv) –14.525 ± 0.435 km/s
Proper motion (μ) RA: -0.460 ± 0.084[5] mas/yr
Dec.: -0.028 ± 0.074[5] mas/yr
Parallax (π)52.519 ± 0.048[6] mas
Distance62.10 ± 0.06 ly
(19.04 ± 0.02 pc)
Absolute magnitude (MV)8.20[7] (8.19-8.23)[note 1]
Details
Mass0.6[8] M
Luminosity (bolometric)0.100+0
−0.001
[6] L
Luminosity (visual, LV)0.045[note 2] L
Temperature4,250[8] K
Rotational velocity (v sin i)6.42 ± 0.78[10] km/s
Other designations
Gliese 710, BD–01° 3474, HIP 89825, HD 168442, NSV 10635[2]
Database references
ARICNSdata

## Description

Gliese 710 currently is 63.8 light-years (19.6 parsecs) from Earth in the constellation Serpens and has a below naked-eye visual magnitude of 9.69. A stellar classification of K7 Vk[4] means it is a small main-sequence star mostly generating energy through the thermonuclear fusion of hydrogen at its core. (The suffix 'k' indicates that the spectrum shows absorption lines from interstellar matter.) Stellar mass is about 60%[8] of the Sun's mass with an estimated 67% of the Sun's radius.[9] It is suspected to be a variable star that may vary in magnitude from 9.65 to 9.69. As of 2020, no planets have been detected orbiting it.

## Computing and details of the closest approach

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

Gliese 710 has the potential to perturb the Oort cloud in the outer Solar System, exerting enough force to send showers of comets into the inner Solar System for millions of years, triggering visibility of about ten naked-eye comets per year,[14] and possibly causing an impact event. According to Filip Berski and Piotr Dybczyński, this event will be "the strongest disrupting encounter in the future and history of the Solar System".[15] Earlier dynamic models indicated that the net increase in cratering rate due to the passage of Gliese 710 would be no more than 5%.[8] They had originally estimated that the closest approach would 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.[16] Gaia DR2 now finds the minimum perihelion distance is 0.0676 ± 0.0157 parsecs or 13,900 ± 3,200 AU about 1.281 million years from now.[11]

Bobylev in 2010 further suggested Gliese 710 has an 86% chance of passing through the Oort cloud, assuming the Oort cloud to be a spheroid around the Sun with semiminor and semimajor axes of 80,000 and 100,000 AU. The distance of closest approach of Gliese 710 is difficult to compute precisely as it depends sensitively on its current position and velocity; Bobylev estimated that it would pass within 0.311 ± 0.167 parsecs (1.014 ± 0.545 light-years) of the Sun.[17] There is even a 1 in 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.

Results from new calculations that include input data from Gaia EDR3 indicate that the flyby of Gliese 710 to the Solar System will be slightly closer at 0.051 ± 0.003 pc in 1.29 ± 0.04 Myr time.[18] The effects of such an encounter on the orbit of the Pluto–Charon system (and therefore, on the classical trans-Neptunian belt) are negligible, but Gliese 710 will traverse the outer Oort cloud (inside 100,000 AU or 0.48 pc) and reach the outskirts of the inner Oort cloud (inward of 20,000 AU).

Table of parameters of predictions of Gliese 710 encounter with Sun

Source Date Encounter distance, pc Encounter time, Myr
[8] 1999 0.34 ± 0.18 pc (1.11 ± 0.59 ly) 1.36 ± 0.04
[17] March 2010 0.311 ± 0.167 pc (1.01 ± 0.54 ly) 1.45 ± 0.06
[12] May 2018 0.052 ± 0.01 pc (0.170 ± 0.033 ly) 1.28 ± 0.05
[11] May 2018 0.0676 ± 0.0157 pc (0.220 ± 0.051 ly) 1.281
[18] December 2020 0.051 ± 0.003 pc (0.1663 ± 0.0098 ly) 1.29 ± 0.04

## Notes

1. ^ From apparent magnitude and parallax: ${\displaystyle \scriptstyle M_{V}=m_{V}+5+5\log _{10}\left({\frac {\mathrm {parallax\ in\ milliarcseconds} }{1000}}\right)}$
2. ^ Using the absolute visual magnitude of Gliese 710 ${\displaystyle \scriptstyle M_{V_{\ast }}=8.20}$  and the absolute visual magnitude of the Sun ${\displaystyle \scriptstyle M_{V_{\odot }}=4.83}$ , the visual luminosity can be calculated by ${\displaystyle \scriptstyle {\frac {L_{V_{\ast }}}{L_{V_{\odot }}}}=10^{0.4\left(M_{V_{\odot }}-M_{V_{\ast }}\right)}}$

## References

1. ^ a b Gaia Collaboration; Brown, A. G. A.; Vallenari, A.; Prusti, T.; De Bruijne, J. H. J.; Mignard, F.; Drimmel, R.; Babusiaux, C.; Bailer-Jones, C. A. L.; Bastian, U.; Biermann, M.; Evans, D. W.; Eyer, L.; Jansen, F.; Jordi, C.; Katz, D.; Klioner, S. A.; Lammers, U.; Lindegren, L.; Luri, X.; O'Mullane, W.; Panem, C.; Pourbaix, D.; Randich, S.; Sartoretti, P.; Siddiqui, H. I.; Soubiran, C.; Valette, V.; Van Leeuwen, F.; et al. (2016). "Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties". Astronomy & Astrophysics. 595: A2. arXiv:1609.04172. Bibcode:2016A&A...595A...2G. doi:10.1051/0004-6361/201629512.
2. ^ a b c d "GJ 710". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-07-06.
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. 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 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.
6. ^ a b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
7. ^ Koen, C.; Kilkenny, D.; Van Wyk, F.; Marang, F. (2010). "UBV(RI)C JHK observations of Hipparcos-selected nearby stars". Monthly Notices of the Royal Astronomical Society. 403 (4): 1949. Bibcode:2010MNRAS.403.1949K. doi:10.1111/j.1365-2966.2009.16182.x.
8. García-Sánchez, J.; et al. (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.
9. ^ 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.
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.
11. ^ a b c Bailer-Jones, C.A.L.; Rybizki, J; Andrae, R.; Fouesnea, M. (2018). "New stellar encounters discovered in the second Gaia data release". Astronomy & Astrophysics. 616: A37. arXiv:1805.07581. Bibcode:2018A&A...616A..37B. doi:10.1051/0004-6361/201833456.
12. ^ a b de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (10 May 2018). "An Independent Confirmation of the Future Flyby of Gliese 710 to the Solar System Using Gaia". Research Notes of the AAS. 2 (2): 30. arXiv:1805.02644. Bibcode:2018RNAAS...2b..30D. doi:10.3847/2515-5172/aac2d0.
13. ^ Berski, Filip; Dybczyński, Piotr A. (2016-11-01). "Gliese 710 will pass the Sun even closer". Astronomy & Astrophysics. 595: L10. Bibcode:2016A&A...595L..10B. doi:10.1051/0004-6361/201629835. ISSN 0004-6361.
14. ^ a b Dorminey, Bruce. "Solar System's Next Close Encounter Will Be With Gliese 710, Say Astronomers". Forbes. Retrieved 2016-12-24.
15. ^ Dvorsky, George. "Incoming Star Could Spawn Swarms of Comets When It Passes Our Sun". Gizmodo. Retrieved 2016-12-24.
16. ^ García-Sánchez, J.; Weissman, P. R.; Preston, R. A.; Jones, D. L.; Lestrade, J.-F.; Latham, D. W.; Stefanik, R. P.; Paredes, J. M. (2001). "Stellar encounters with the solar system". Astronomy and Astrophysics. 379 (2): 634–659. Bibcode:2001A&A...379..634G. doi:10.1051/0004-6361:20011330.
17. ^ a b 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.
18. ^ a b de la Fuente Marcos, Carlos; de la Fuente Marcos, Raúl (10 December 2020). "An Update on the Future Flyby of Gliese 710 to the Solar System Using Gaia EDR3: Slightly Closer and a Tad Later than Previous Estimates". Research Notes of the AAS. 4 (12): 222. Bibcode:2020RNAAS...4b.222D. doi:10.3847/2515-5172/abd18d.