82 Eridani

Starbox begin
name=82 Eridani Starbox observe
epoch=J2000
constell=Eridanus
ra=RA|03|19|55.6505cite web
url=http://simbad3.u-strasbg.fr/sim-id.pl?protocol=html&Ident=HD+20794
title=SIMBAD Query Result: HD 20794 -- High proper-motion Star
publisher=Centre de Données astronomiques de Strasbourg
accessdate=2007-07-26 ]
dec=DEC|−43|04|11.221
appmag_v=4.27 Starbox character
class=G8 V
b-v=+0.71
u-b=+0.21
variable=None Starbox astrometry
radial_v=+87.3
prop_mo_ra=3037.21
prop_mo_dec=726.52
parallax=165.00
p_error=0.55
parallax_footnote=
absmag_v=5.35cite web
author=Staff | date=2007-06-08
url=http://www.chara.gsu.edu/RECONS/
title=List of the Nearest 100 Stellar Systems
publisher =Research Consortium on Nearby Stars (RECONS), Georgia State University
accessdate = 2007-07-26 ] Starbox detail
age=1.3 ±0.3 × 10¹⁰cite journal
last=Hearnshaw | first=J. B.
title=The iron abundance of 82 Eridani
journal=Astronomy and Astrophysics
year=1973 | volume=29 | pages=165–170
url=http://adsabs.harvard.edu/abs/1973A&A....29..165H
accessdate=2007-07-26 ]
metal= [Fe/H] = -0.54cite journal
last = Gratton | first = R. G.
title=Abundance of manganese in metal-poor stars
journal=Astronomy and Astrophysics
year=1989 | volume=208 | issue=1-2 | pages=171–178
url=http://adsabs.harvard.edu/abs/1989A&A...208..171G
accessdate=2007-07-26 ]
mass=0.97
radius=0.92 [cite journal
author=Johnson, H. M.; Wright, C. D.
title=Predicted infrared brightness of stars within 25 parsecs of the sun
journal=Astrophysical Journal Supplement Series
year=1983 | volume=53 | pages=643–711
url=http://adsabs.harvard.edu/abs/1998RPPh...61...77K
accessdate=2007-07-26 | doi=10.1086/190905 — See the table on p. 653.]
rotation=0.52 km/scite journal
author=Santos, N. C. "et al"
title=Are beryllium abundances anomalous in stars with giant planets?
journal=Astronomy and Astrophysics
year=2004 | volume=427 | pages=1085–1096
url=http://adsabs.harvard.edu/abs/2004astro.ph..8108S
accessdate=2007-07-26 | doi=10.1051/0004-6361:20040509]
luminosity=0.62 [Based upon::$frac\{L\}\{L\_\{sun$ = left ( frac{R}{R_{sun ight )^2 left ( frac{T_{eff{T_{sun ight )^4where "L" is luminosity, "R" is radius and "T_eff" is the effective temperature.] [cite web
last = Krimm
first = Hans
date =August 19, 1997
url =http://ceres.hsc.edu/homepages/classes/astronomy/spring99/Mathematics/sec20.html
title =Luminosity, Radius and Temperature
publisher = Hampden-Sydney College
accessdate = 2007-05-16 ]
gravity=4.17
temperature=5,338 Starbox catalog
names=e Eri, HD 20794, CD-43°1028, GCTP 703, GJ 139, LHS 19, LTT 1583, HR 1008, SAO 216263, FK5 119, and HIP 15510.

82 Eridani is a star about 20 light years away from Earth. It is in constellation Eridanus. It is a main sequence star of spectral type G5.

Observation

82 G. Eridani (often abbreviated "82 Eridani") is the 82nd star in Eridanus in the now-obscure catalog "Uranometria Argentina". The Argentina catalog, compiled by the 19th-century astronomer Benjamin Gould, is a southern celestial hemisphere analog of the more famous Flamsteed catalog, and used a similar numbering scheme. 82 G. Eridani is one of the very few "G." stars still referred to as such.

Properties

In terms of luminosity, 82 G. Eridani is marginally dimmer than the Sun; about half as luminous as Tau Ceti or Alpha Centauri B. The projected equatorial rotation rate ($v\; sin\; i$) is a leisurely 0.52 km/s, compared to 2 km/s for the Sun.

82 G. Eridani is a high-velocity star—it is moving relatively quickly compared to the average—and hence is probably a member of Population II, generally older stars whose motions take them well outside the plane of the Milky Way. Like many other Population II stars, 82 G. Eridani is somewhat metal-deficient (though much less deficient than many), and is older than the Sun. It has a relatively high orbital eccentricity of 0.40 about the galaxy, ranging between 4.6 and 10.8 kiloparsecs from the core. The estimated age of this star is close to the age of the universe, so it was likely formed early in the history of the Milky Way.

This star is located in a region of low-density interstellar matter (ISM), so it is believed to have a large astropause that subtends an angle of 6″ across the sky. Relative to the Sun, this star is moving at a space velocity of 101 km/s, with the bow shock advancing at more than Mach 3 through the ISM. [cite journal
last = Frisch | first = P. C.
title=G-star astropauses - A test for interstellar pressure
journal=Astrophysical Journal
year=1993 | volume=407 | issue=1 | pages=198–206
url=http://adsabs.harvard.edu/abs/1993ApJ...407..198F
accessdate=2007-07-26
doi=10.1086/172505 ]

Habitability

In his book "Habitable Planets for Man", [cite book | first=Stephen H. | last=Dole | title=Habitable Planets for Man | publisher=American Elsevier Pub. Co | location=London | edition=2nd | year=1970 | url=http://www.rand.org/pubs/commercial_books/CB179-1/ | id=0444000925 ] Stephen Dole gave 82 G. Eridani his highest estimate for habitability: 5.7%. Four other stars had this figure: Alpha Centauri B, 70 Ophiuchi A, Eta Cassiopeiae A, and Delta Pavonis. 82 Eridani (GJ 139) was also picked as a Tier 1 target star for NASA's proposed Space Interferometry Mission (SIM) mission to search for Terrestrial-sized or larger planets. [cite web
first=Chris | last=McCarthy | year=2005
url=http://tauceti.sfsu.edu/~chris/SIM/
title=SIM Planet Search Tier 1 Target Stars
publisher =San Francisco State University
accessdate = 2007-07-26 ]

References

External links

* cite web
title=82 Eridani | work=SolStation
url=http://www.solstation.com/stars/82erida2.htm
accessdate=2005-11-03