Gliese 710


Gliese 710, or HIP 89825, is an orange 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 slightly closer distance to the previous estimates of 0.0676 parsecs——a distance about 20 times closer than the current distance of Proxima Centauri. Such a distance would make for a similar brightness to the brightest planets, optimally reaching an apparent visual magnitude of about −2.7. The star's proper motion will peak around one arcminute per year, a rate of apparent motion that would be noticeable over a human lifespan.

Description

Gliese 710 currently is from Earth in the constellation Serpens and has a below naked-eye visual magnitude of 9.69. A stellar classification of K7 Vk means it is a small main-sequence star mostly generating energy through the thermonuclear fusion of hydrogen at its core. Stellar mass is about 60% of the Sun's mass with an estimated 67% of the Sun's radius. 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

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, 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". Earlier dynamic models indicated that the net increase in cratering rate due to the passage of Gliese 710 would be no more than 5%. 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 of the Sun. 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.
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 of the Sun. There is even a 1 in 10,000 chance of the star penetrating into the region where the influence of the passing star on Kuiper belt objects is significant.
Table of parameters of predictions of Gliese 710 encounter with Sun
SourceDateEncounter distance, pcEncounter time, Myr
19991.36 ± 0.04
March 20101.45 ± 0.06
May 20181.28 ± 0.05
May 20181.281