61 Virginis

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NASA

61 Virginis is a yellow-orange star
like our Sun, Sol. (See a Digitized
Sky Survey image of 61 Virginis
from the Nearby Stars Database.)

System Summary

61 Virginis is located about 27.8 light-years from Sol. It lies at the southern edge (13:18:24.31-18:18:40.31, ICRS 2000.0) of Constellation Virgo, the Maiden -- southwest of Spica (Alpha Virginis). As 61 Virginis has become one of the top 100 target stars for NASA's planned Terrestrial Planet Finder (TPF), images of this star and its position relative to the Milky Way in Earth's night sky are now available from the TPF-C team.

JPL, CalTech, NASA

Larger illustration

Astronomers have identified 61
Virginis as a prime target for the
Terrestrial Planet Finder (TPF),
now planned for launch between
2014 and 2020.

The Star

61 Virginis is a yellow-orange main sequence dwarf of spectral and luminosity type G5-6 V, with about 96 percent of Sol's mass, 94 percent of its diameter (Johnson and Wright, 1983, page 677), and around 78 percent of its luminosity. The star may be almost (93 to 95 percent) as enriched as Sol with elements heavier than hydrogen ("metallicity"), based on its abundance of iron (Cayrel de Strobel et al, 1991, page 295). Useful star catalogue numbers for the star include: 61 Vir, HR 5019, Gl 506, Hip 64924, HD 115617, BD-17 3813, SAO 157844, FK5 1345, LHS 349, LTT 5111, LPM 467, LFT 990, and GC 18007.

Hunt for Substellar Companions

Small but significant variations in radial velocity have been detected which may be caused by a substellar companion of one to nine Jupiter masses with an orbital period of 50 years of less (Campbell et al, 1988, pages 904, 906, and 919). A subsequent radial velocity study also failed to detect a brown dwarf sized companion (with 20 to 80 times the mass of Jupiter) within 10 AUs of 61 Virginis (Murdoch et al, 1993). However, the failure, thus far, to find large substellar objects like brown dwarfs or a Jupiter- or Saturn-class planet in a "torch" orbit (closer than the Mercury to Sun distance) around 61 Virginis -- with even the highly sensitive radial-velocity technique of Geoffrey R. Marcy and R. Paul Butler -- bodes well for the possibility of Earth-type terrestrial planets around this star (Cumming et al, 1999).

The orbit of an Earth-like planet (with liquid water) around this star would be centered around 0.9 AU -- inside the orbital distance of Earth in the Solar System -- with an orbital period of almost 317 days, or about 87 percent of an Earth year. Astronomers are hoping to use NASA's Terrestrial Planet Finder (TPF) and the ESA's Darwin planned groups of observatories to search for a rocky inner planet in the so-called "habitable zone" (HZ) around 61 Virginis. As currently planned, the TPF will include two complementary observatory groups: a visible-light coronagraph to launch around 2014; and a "formation-flying" infrared interferometer to launch before 2020, while Darwin will launch a flotilla of three mid-infrared telescopes and a fourth communications hub beginning in 2015.

Closest Neighbors

The following star systems are located within 10 light-years of 61 Virginis.

Star System	Spectra & Luminosity	Distance (light-years)
L 763-63	K2 V	4.6
Ross 695	M4 V	6.4
LP 734-32	M V	8.9

Other Information

Up-to-date technical summaries on these stars can be found at: the Astronomiches Rechen-Institut at Heidelberg's ARICNS, the Near Stars Database, and the Research Consortium on Nearby Stars (RECONS). Additional information may be available at Roger Wilcox's Internet Stellar Database.

Translated into Latin by the Romans from the Greek Goddess Demeter, the Earth-Goddess, Virgo, is associated with the arrival of spring and bringer of the growing season. For more information about the stars and objects in this constellation and an illustration, go to Christine Kronberg's Virgo. For another illustration, see David Haworth's Virgo.

For more information about stars including spectral and luminosity class codes, go to ChView's webpage on The Stars of the Milky Way.