38 Geminorum

38 Geminorum is a binary star system in the northern zodiac constellation of Gemini. It has the Bayer designation e Geminorum, while 38 Geminorum is the Flamsteed designation. This system is visible to the naked eye as a faint, white-hued point of light with an apparent visual magnitude of 4.71. The primary component is a magnitude 4.75 star, while the secondary is magnitude 7.80.[2] The system is located about 98 light years away from the Sun based on parallax, and is drifting further away with a radial velocity of +16 km/s.[14] It is a potential member of the Tucana–Horologium stellar kinematic group.[15]

This article is about e Geminorum. It is not to be confused with ε (epsilon) Geminorum.
38 Geminorum
Observation data
Epoch J2000      Equinox J2000
Constellation Gemini
Right ascension  06h 54m 38.63478s[1]
Declination +13° 10′ 40.2207″[1]
Apparent magnitude (V) 4.75 + 7.80[2]
Characteristics
Spectral type A8V[3] + G6V[4]
U−B color index +0.07[5]
B−V color index +0.30[5]
Variable type Suspected δ Sct[6]
Astrometry
A
Radial velocity (Rv)+24±5[7] km/s
Proper motion (μ) RA: 68.745[8] mas/yr
Dec.: −86.832[8] mas/yr
Parallax (π)33.9184 ± 0.8248[8] mas
Distance96 ± 2 ly
(29.5 ± 0.7 pc)
B
Radial velocity (Rv)+22.6±2[7] km/s
Proper motion (μ) RA: 89.235[9] mas/yr
Dec.: −77.171[9] mas/yr
Parallax (π)33.3308 ± 0.0847[9] mas
Distance97.9 ± 0.2 ly
(30.00 ± 0.08 pc)
Details
38 Gem A
Mass1.55[10] M☉
Surface gravity (log g)4.23[11] cgs
Temperature7,410±252[11] K
Metallicity [Fe/H]−0.08±0.06[12] dex
Rotational velocity (v sin i)147.5±10.5[13] km/s
Age1.179[11] Gyr
38 Gem B
Mass0.89[10] M☉
Radius0.89[9] R☉
Luminosity0.694[9] L☉
Temperature5,583[9] K
Other designations
e Gem, 38 Gem, NSV 3266, BD+13°1462, GJ 9220, HD 50635, HIP 33202, HR 2564, SAO 96265, WDS J06546+1311
Database references
SIMBADdata
A
B

This is a wide binary system with a projected separation of 184.3 AU.[10] Two sets of low quality orbital elements have been computed for this system, yielding periods of 1,943.8 years and 3,190 years, and eccentricities of 0.150 and 0.485, respectively.[16] As of 2018, the pair had an angular separation of 7.4″ along a position angle of 143°.[2]

Abt and Morrell (1995) classified the primary component as an A-type main-sequence star with a stellar classification of A8V.[3] It is a suspected chemically peculiar star of subtype CP1 (an Am star),[13] which Slettebak (1955) classified as kA8mF0Vp.[17] This notation indicates the star displays the calcium K line of an A8 star and the metal lines of an F0V star. In 1949, J. Hopmann catalogued it as a suspected Delta Scuti variable.[6] The secondary is a G-type main-sequence star with a class of G6V.[4]

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.
  2. Mason, B. D.; et al. (2014), The Washington Visual Double Star Catalog, Bibcode:2001AJ....122.3466M, doi:10.1086/323920
  3. Abt, Helmut A.; Morrell, Nidia I. (1995). "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars". The Astrophysical Journal Supplement Series. 99: 135. Bibcode:1995ApJS...99..135A. doi:10.1086/192182.
  4. Adams, Walter S.; et al. (1935). "The Spectroscopic Absolute Magnitudes and Parallaxes of 4179 Stars". Astrophysical Journal. 81: 187. Bibcode:1935ApJ....81..187A. doi:10.1086/143628.
  5. Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory. 4: 99. Bibcode:1966CoLPL...4...99J.
  6. Starikova, G. A. (July 1979). "Absolute magnitudes and masses for three types of variable stars". Soviet Astronomy Letters. 5: 188–192. Bibcode:1979SvAL....5..188S.
  7. Evans, D. S. (1967). "The Revision of the General Catalogue of Radial Velocities". Determination of Radial Velocities and Their Applications. 30: 57. Bibcode:1967IAUS...30...57E.
  8. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  9. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  10. Tokovinin, A.; Kiyaeva, O. (February 2016). "Eccentricity distribution of wide binaries". Monthly Notices of the Royal Astronomical Society. 456 (2): 2070–2079. arXiv:1512.00278. Bibcode:2016MNRAS.456.2070T. doi:10.1093/mnras/stv2825.
  11. David, Trevor J.; Hillenbrand, Lynne A. (2015). "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets". The Astrophysical Journal. 804 (2): 146. arXiv:1501.03154. Bibcode:2015ApJ...804..146D. doi:10.1088/0004-637X/804/2/146.
  12. Gáspár, András; et al. (2016). "The Correlation between Metallicity and Debris Disk Mass". The Astrophysical Journal. 826 (2): 171. arXiv:1604.07403. Bibcode:2016ApJ...826..171G. doi:10.3847/0004-637X/826/2/171.
  13. Paunzen, E.; et al. (February 2013). "A photometric study of chemically peculiar stars with the STEREO satellites - II. Non-magnetic chemically peculiar stars". Monthly Notices of the Royal Astronomical Society. 429 (1): 119–125. arXiv:1211.1535. Bibcode:2013MNRAS.429..119P. doi:10.1093/mnras/sts318.
  14. Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065.
  15. Nakajima, Tadashi; Morino, Jun-Ichi (2012). "Potential Members of Stellar Kinematic Groups within 30 pc of the Sun". The Astronomical Journal. 143 (1): 2. Bibcode:2012AJ....143....2N. doi:10.1088/0004-6256/143/1/2.
  16. Abt, Helmut A. (August 2005). "Observed Orbital Eccentricities". The Astrophysical Journal. 629 (1): 507–511. Bibcode:2005ApJ...629..507A. doi:10.1086/431207.
  17. Slettebak, Arne (May 1955). "The Spectra and Rotational Velocities of the Bright Stars of Draper Types A3-G0". Astrophysical Journal. 121: 653. Bibcode:1955ApJ...121..653S. doi:10.1086/146031.
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