Gamma Microscopii

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Star
Gamma Microscopii
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation microscope
Right ascension 21 h 01 m 17.47 s
declination -32 ° 15 ′ 27.8 ″
Apparent brightness (4.68) mag
Typing
B − V color index +0.575 
U − B color index +0.882 
R − I index +0.32 
Spectral class G6 III
Astrometry
Radial velocity (17.50 ± 0.36) km / s
parallax (14.6428 ± 0.4966)  mas
distance (220)  Ly
(68)  pc
Proper movement 
Rec. Share: (-11.3)  mas / a
Dec. portion: (-13.7)  mas / a
Physical Properties
Dimensions 2.5  M ☉
radius 10  R ☉
Luminosity

64  L ☉

Effective temperature 5050  K
Other names
and catalog entries
Cordoba Survey CD-32 16 353
Bright Star Catalog HR 8039 [1]
Henry Draper Catalog HD 199951 [2]
Hipparcos catalog HIP 103738 [3]
SAO catalog SAO 212636 [4]
Tycho catalog TYC 7475-1129-1 [5]
2MASS catalog 2MASS J21011746-3215281 [6]
Other names FK5 1550

Gamma Microscopii (γ Microscopii, γ Mic) is the brightest star in the southern constellation Microscope . It has an apparent brightness of 4.68 which is too weak to be seen in the urban night sky. The distance to the sun was determined by the parallax method during the Hipparcos mission to be about 229 light years (with about 2% error). This value agrees well with the Gaia data ( Gaia DR2 ).

Based on its spectral class of G6III, it is a giant star . A helium fusion takes place in its core , which classifies it as a "red lump star" . However, its metallicity , i.e. the proportion of elements other than hydrogen and helium, is unusually low for a star of this class. The effective temperature of its outer shell is around 5050 Kelvin, which gives it the yellow light color typical of G stars.

In the galactic coordinate system this star has a movement of [U, V, W] = [+13.75, +3.47, –10.50] km / s. The peculiar speed relative to its neighboring stars is 1.2 km / s, therefore it is listed as a member of the Ursa Major movement group . Backward calculations have shown that Gamma Microscopii passed the solar system about 3.8 million years ago at a distance of about 6 light years. It should have had an apparent brightness of -3 back then and would then have been brighter than Sirius today.

Gamma Microscopii has a visible companion CCDM J21013-3215B at a distance of 26 arc seconds at a position angle of 94 ° and with an apparent magnitude of about 13.7. Probably this is not gravitationally bound to Gamma Microscopii.

Gamma Microscopii is a later name of 1 Piscis Austrini.

Individual evidence

  1. ↑ a b c d Simbad
  2. ↑ a b c Gamma Mic , Stars , Jim Kaler. Accessed on line March 19, 2015.
  3. ↑ Jennens, PA; Helfer, HL (September 1975), "A new photometric metal abundance and luminosity calibration for field G and K giants.", Monthly Notices of the Royal Astronomical Society, 172: 667-679, bibcode : 1975MNRAS.172..667J , doi : 10.1093 / mnras / 172.3.667
  4. ^ Van Leeuwen, F. (November 2007), "Validation of the new Hipparcos reduction", Astronomy and Astrophysics, 474 (2): 653-664, bibcode : 2007A & A ... 474..653V doi : 10.1051 / 0004-6361 : 20078357 arxiv : 0708.1752
  5. ↑ Montes, D .; et al. (November 2001), "Late-type members of young stellar kinematic groups - I. Single stars", Monthly Notices of the Royal Astronomical Society, 328 (1): 45-63, arxiv : astro-ph / 0106537 , bibcode : 2001MNRAS .328 ... 45M , doi : 10.1046 / j.1365-8711.2001.04781.x
  6. ↑ Kubiak, M .; et al. (June 2002), "Metal Abundance of Red Clump Stars in Baade's Window", Acta Astronomica, 52: 159-175, bibcode : 2002AcA .... 52..159K
  7. ↑ McWilliam, Andrew (December 1990), “High-resolution spectroscopic survey of 671 GK giants. I - Stellar atmosphere parameters and abundances”, Astrophysical Journal Supplement Series, 74: 1075-1128, bibcode : 1990ApJS ... 74.1075M , doi : 10.1086 / 191527
  8. ^ "The Color of Stars" , Australia Telescope, Outreach and Education, Commonwealth Scientific and Industrial Research Organization, December 21, 2004, archived from the original on 2012-03-10, retrieved 2012-01-16
  9. ↑ King, Jeremy R .; et al. (April 2003), "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group", The Astronomical Journal, 125 (4): 1980-2017, bibcode : 2003AJ .... 125.1980 K , doi : 10.1086 / 368241
  10. ↑ García-Sánchez, J .; Weissman, PR; Preston, RA; Jones, DL; Lestrade, J.-F .; Latham, DW; Stefanik, RP; Paredes, JM (2001), "Stellar encounters with the solar system", Astronomy and Astrophysics, 379 (2): 634-659, bibcode : 2001A & A ... 379..634G , doi : 10.1051 / 0004-6361: 20011330
  11. ↑ Entry 21013-3215, The Washington Double Star Catalog , United States Naval Observatory . Accessed on line November 20, 2008.
  12. ↑ Eggleton, PP; Tokovinin, AA (September 2008). "A catalog of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869-879. arxiv : 0806.2878 . bibcode : 2008MNRAS.389..869E , doi : 10.1111 / j.1365-2966.2008.13596.x
  13. ↑ M. Wagman: Flamsteed's Missing Stars . In: Journal for the History of Astronomy, Vol.18, NO. 3 / AUG, P. 209, 1987 . August 18, 1987, p. 220. bibcode : 1987JHA .... 18..209W . doi : 10.1177 / 002182868701800305 .