S2 (star)

Starbox begin
name= S 2 Starbox observe
epoch=J2000.0 (ICRS)
ra=RA|17|45|40.044SIMBAD link|%5BEG97%5D+S2|PGM2006 E1 -- Star in double system, database entry, SIMBAD. Accessed on line July 15, 2008.]
dec=DEC|−29|00|28
constell=Sagittarius Starbox character
class=B1V
variable=None Starbox astrometry
dist_pc = 7940 ± 420
dist_ly = 25900 ± 1400Starbox visbin
reference=A Geometric Determination of the Distance to the Galactic Center, F. Eisenhauer et al., "Astrophysical Journal" 597, #2 (November 2003), pp. L121–L124, bibcode|2003ApJ...597L.121E, doi|10.1086/380188.]
name=Sagittarius A*
period=15.56 ± 0.35
axis=0.1203 ± 0.0027
eccentricity=0.881 ± 0.007
inclination=−48.1 ± 1.3
node=45.0 ± 1.6
periastron=2002.331 ± 0.012
periarg = 245.4 ± 1.7 Starbox catalog
names= [CRG2004] 13, [GKM98] S0-2, [PGM2006] E1, [EG97] S2, [GPE2000] 0.15, [SOG2003] 1, S0—2. Starbox reference
Simbad=%5BEG97%5D+S2

S2 (also known as S0—2) is a star that is located close to the radio source Sagittarius A*, orbiting it with an orbital period of 15.56 ± 0.35 years and a pericenter distance of 17 light hours. Given a recent estimate of 3.7 million M_sun for the mass of Sagittarius A*, the maximum gravitational acceleration experienced by S2 at the pericenter of its orbit would be about 1.5 m/s² or almost one-sixth of Earth's surface gravity.

Its changing apparent position has been monitored since 1995 as part of an effort to gather evidence for the existence of a supermassive black hole in the center of the Milky Way galaxy. The accumulating evidence points to Sagittarius A* as being the black hole. A large part of one orbit had been observed as of 2004.

A team of astronomers mainly from the Max Planck Institute for Extraterrestrial Physics used observations of S2's orbital dynamics around Sgr A* to measure the distance from the Earth to the galactic center. They determined the distance to be 7.94 ± 0.42 kiloparsecs, in close agreement with prior determinations of the distance by other methods. [ [http://www.mpe.mpg.de/ir/GC/index.php Max-Planck-Institut für extraterrestrische Physik—Infrared/Submillimeter Astronomy—Galactic Center Research] ]

The 'S' in 'S2' simply stands for 'star'.

External links

* [http://www.eso.org/outreach/press-rel/pr-2002/pr-17-02.html Star Orbiting Massive Milky Way Centre Approaches to within 17 Light-Hours] ESO Press Release, October 16 2002
* [http://www.eso.org/outreach/press-rel/pr-2002/video/vid-02-02.mpg ESO video clip of orbiting star] (533 KB MPEG Video)
* [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=%5BEG97%5D+S2 S2 page on the SIMBAD database]
* [http://www.eso.org/public/outreach/press-rel/pr-2002/phot-23c-02-preview.jpgPhoto] in ESO press release

Component

References