70 Virginis |
Home | Stars | Orbits | Habitability | Life | |
NASA
70 Virginis is a yellow-orange star
like our Sun, Sol. (See a Digitized
Sky Survey
image
of 70 Virginis
from NASA's
NStars Database.)
System Summary
70 Virginis is located about 50.1 light-years from Sol. It lies at the north central edge (13:28:25.8+13:46:43.6, ICRS 2000.0) of Constellation Virgo, the Virgin -- northeast of Vindemiatrix (Epsilon Virginis -- see chart with 70 Virginis labelled). In 1996, astronomers announced the discovery of a Jupiter-like planet around this Sun-like star (Marcy and Butler, 1996 -- details below), with indications of an even larger planet in an outer orbit. (See an animation of the planetary and potentially habitable zone orbits of this system, with a table of basic orbital and physical characteristics.)
© James
B. Kaler, UIUC -- more
information
(Photo from
Stars,
Planet Project,
and
70 Virginis;
used with permission)
70 Virginis is a yellow-orange main sequence dwarf star of spectral and luminosity type G5 Va, but has been previously classified from G2.5 to G4. The star has about 1.10 percent of Sol's mass (70 Virginis at exoplanets.org), 2.0 to 2.5 times its diameter (Henry et al, 1997), and 2.9 times its luminosity. The star may be less enriched (92 percent) than Sol with elements heavier than hydrogen ("metallicity"), based on its abundance of iron (J.B. Heanshaw, 1974). It appears to be more highly evolved than Sol, perhaps as much as nine billion years old (Henry et al, 1997). Useful catalogue numbers and designations for the star include: 70 Vir, HR 5072*, Gl 512.1, Hip 65721, HD 117176, BD+14 2621, SAO 100582, FK5 1349, Wo 9446, LHS 2740, LTT 13918, and LFT 1009.
© Walter Myers --
larger image
(Artwork from
Computergraphic
Vistas, permission being sought)
View of a ringed, planetary candidate "b" from
a rocky moon, as imagined by Myers
(more).
In 1996, a team of astronomers led by Geoffrey W. Marcy and R. Paul Butler announced the discovery of a Jupiter-class planet around 70 Virginis using highly sensitive radial-velocity methods (Marcy and Butler, 1996). Planet b has at least 7.4 times Jupiter's mass, with an upper mass limit of 38 Jupiter masses from analysis of HIPPARCOS astrometric data (Perryman et al. 1996). It moves around 70 Virginis at an average distance of only 0.48 AUs (a semi-major axis around Mercury's orbital distance) in a highly elliptical orbit (e=0.40) that takes almost 167 days to complete.
© Lynette Cook --
larger image
Artwork from
Extrasolar
Planets - Collection II
(permission being sought).
70 Virginis "b" may be massive enough to
glow with internal heat and to have a moon
with an atmosphere, as imagined by Cook.
Subsequent astrometric analysis, however, suggests that planet b may have as much as 27 times the mass of Jupiter with an inclination of 16.1° from Earth's line of sight (Han et al, 2000). Thus, planet is probably an extremely dim brown dwarf, substellar companion of 70 Virginis. The authors consider their analysis to be preliminary, needing confirmation with additional astrometric as well as other observations.
© John Whatmough
-- larger image
(Artwork from
Extrasolar
Visions, permission being sought)
After the initial discovery of b, some hoped that water
could exist on a large moon, as imagined by Whatmough.
The orbit of an Earth-like planet (with liquid water) around Star A may be centered around 1.7 AU -- between the orbital distances of Mars and the Main Asteroid Belt in the Solar System -- with an orbital period around 2.1 years. However, the presence of planet b at its orbital distance of nearly 0.5 AU may have disrupted the development of an Earth-type planet in the water zone. Astronomers would find it very difficult to detect an Earth-sized planet of this star using present methods. (See an animation of the planetary and potentially habitable zone orbits of this system, with a table of basic orbital and physical characteristics.)
© Christoph Kulmann --
larger image
Artwork from
Exoplaneten.de
(permission being sought).
Later, some speculated that surface
water might exist temporarily on a
large, tidally-locked moon of b, as
imagined by Kulmann
(more).
Closest Neighbors
The following table includes all star systems known to be located within 10 light-years (ly), plus more bright stars within 10 to 20 ly, of 70 Virginis.
Star System | Spectra & Luminosity | Distance (light-years) |
L 1194-26 | M5 V | 4.5 |
59 Virginis | G0 Vs | 5.4 |
BD+09 2776 | K0 V | 5.7 |
LTT 18350 | M V | 7.5 |
G 63-54 | DA7 /VII | 8.1 |
LTT 13826 | M V | 8.1 |
Wolf 515 | M2 V | 8.3 |
Tau Boötis AB | F6-7 V-IV V ? M2 V | 9.9 |
V 150 | M0.5 V | 9.9 |
* plus bright stars * | . . . | |
HR 5273 A | G8 V | 10 |
BD+03 2766 | G5 V | 12 |
BD+3 2765 AB | G5 V ? | 13 |
Diadem 3 | F5 V ? F5 V | 13 |
HR 4864 | G7 V | 15 |
Hip 63383 | G V | 18 |
HR 5384 | G1 V | 19 |
Other Information
Try Professor Jim Kaler's Stars site for other information about 70 Virginis at the University of Illinois' Department of Astronomy. John Whatmough developed illustrated web pages on this system in Extrasolar Visions. For another illustrated discussion, see Christoph Kulmann's web page on 70 Virginis.
Up-to-date technical summaries on these stars can be found at: Jean Schneiders's Extrasolar Planets Encyclopaedia; the Astronomiches Rechen-Institut at Heidelberg's ARICNS, NASA's NStar 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 -- as the bringer of the growing season for farmers. 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.
© 1998-2001 Sol Company. All Rights Reserved. |