Theta2 Microscopii

Theta2 Microscopii (θ2 Mic) is a class A0III[3] (white giant) star in the constellation Microscopium. Its apparent magnitude is 5.76[2] and it is approximately 390 light years away based on parallax.[1] It is an Ap star, a chemically peculiar star with unusually strong metallic spectral lines.[9]

For other stars with the name θ Microscopii, see Theta Microscopii.
θ2 Microscopii
Location of θ2 Microscopii (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Microscopium
Right ascension 21h 24m 24.81796s[1]
Declination −41° 00′ 24.1033″[1]
Apparent magnitude (V) 5.76[2]
Characteristics
Spectral type A0IIIpSi[3]
U−B color index -0.21[4]
B−V color index -0.04[5]
Astrometry
Radial velocity (Rv)+8.00[6] km/s
Proper motion (μ) RA: +24.64[1] mas/yr
Dec.: −0.25[1] mas/yr
Parallax (π)8.35 ± 0.70 mas[1]
Distance390 ± 30 ly
(120 ± 10 pc)
Absolute magnitude (MV)0.39[2]
Orbit[7]
Period (P)464.66 yr
Semi-major axis (a)0.836″
Eccentricity (e)0.210
Inclination (i)111.8°
Details
Luminosity78.22[2] L☉
Temperature10,378[8] K
Other designations
CD−41 14503, CCDM J21245-4100AB, GC 29950, HIP 105696, HR 8180, HD 203585, SAO 230667, WDS J21244-4100AB
Database references
SIMBADdata

The main star is known to be a binary, with two components A (6.24 mag) and B (6.88 mag) orbiting with a semimajor axis of 0.836" and eccentricity 0.201, with a period 464.66 years.[10] A more distant companion, C, has a separation around 78.4" and magnitude 10.3.[11]

References
  1. Van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Vizier catalog entry
  2. Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644. Vizier catalog entry
  3. Hoffleit, D.; Warren, W. H. (1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR On-line Data Catalog: V/50. Originally Published in: 1964BS....C......0H. 5050. Bibcode:1995yCat.5050....0H.
  4. Mermilliod, J. C. (2006). "VizieR Online Data Catalog: Homogeneous Means in the UBV System (Mermilliod 1991)". VizieR On-line Data Catalog: II/168. Originally Published in: Institut d'Astronomie. 2168. Bibcode:2006yCat.2168....0M.Vizier catalog entry
  5. Mallama, A. (2014). "Sloan Magnitudes for the Brightest Stars". The Journal of the American Association of Variable Star Observers. 42 (2): 443. Bibcode:2014JAVSO..42..443M.Vizier catalog entry
  6. Kharchenko, N.V.; Scholz, R.-D.; Piskunov, A.E.; Röser, S.; Schilbach, E. (2007). "Astrophysical supplements to the ASCC-2.5: Ia. Radial velocities of ~55000 stars and mean radial velocities of 516 Galactic open clusters and associations". Astronomische Nachrichten. 328 (9): 889. arXiv:0705.0878. Bibcode:2007AN....328..889K. doi:10.1002/asna.200710776. S2CID 119323941.
  7. Marco Scardia; Jean-Louis Prieur; Luigi Pansecchi; Robert W. Argyle. "Orbital elements of double stars: ADS 11468, 13850 and 16057". IAU Circular. International Astronomical Union. Retrieved 2022-12-27.
  8. McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (2012). "Fundamental parameters and infrared excesses of Hipparcos stars". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. S2CID 118665352. Vizier catalog entry
  9. Renson, P.; Manfroid, J. (2009). "Catalogue of Ap, HGMN and Am stars". Astronomy and Astrophysics. 498 (3): 961. Bibcode:2009A&A...498..961R. doi:10.1051/0004-6361/200810788.
  10. Malkov, O. Yu.; Tamazian, V. S.; Docobo, J. A.; Chulkov, D. A. (2012). "Dynamical masses of a selected sample of orbital binaries". Astronomy & Astrophysics. 546: A69. Bibcode:2012A&A...546A..69M. doi:10.1051/0004-6361/201219774. Vizier catalog entry
  11. Mason, Brian D.; Wycoff, Gary L.; Hartkopf, William I.; Douglass, Geoffrey G.; Worley, Charles E. (2001). "The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog". The Astronomical Journal. 122 (6): 3466. Bibcode:2001AJ....122.3466M. doi:10.1086/323920. Vizier catalog entry
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