Astronomy:38 Geminorum

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Short description: Quadruple star system in the constellation Gemini
38 Geminorum
Location of 38 Cassiopeiae (circled in red)
Observation data
Equinox J2000.0]] (ICRS)
Constellation Gemini
Right ascension  06h 54m 38.63478s[1]
Declination +13° 10′ 40.2207″[1]
Apparent magnitude (V) 4.75 + 7.80[2] + 15.1[3]
Characteristics
A
Evolutionary stage main sequence[4]
Spectral type A8V[5]
U−B color index +0.07[6]
B−V color index +0.30[6]
Variable type Suspected δ Sct[7]
B
Evolutionary stage main sequence[8]
Spectral type G6V[9]
UPM J0654+1310
Evolutionary stage main sequence[8]
Spectral type dMp3.5[10]
Astrometry
A
Radial velocity (Rv)+24±5[11] km/s
Proper motion (μ) RA: +68.745[12] mas/yr
Dec.: −86.832[12] mas/yr
Parallax (π)33.9184 ± 0.8248[12] mas
Distance96 ± 2 ly
(29.5 ± 0.7 pc)
Absolute magnitude (MV)+2.50[13]
B
Radial velocity (Rv)+22.6±2[11] km/s
Proper motion (μ) RA: +89.235[14] mas/yr
Dec.: −77.171[14] mas/yr
Parallax (π)33.3308 ± 0.0847[14] mas
Distance97.9 ± 0.2 ly
(30.00 ± 0.08 pc)
UPM J0654+1310
Radial velocity (Rv)+25.59±3.25[15] km/s
Proper motion (μ) RA: +71.706[15] mas/yr
Dec.: −85.515[15] mas/yr
Parallax (π)33.2912 ± 0.0248[15] mas
Distance97.97 ± 0.07 ly
(30.04 ± 0.02 pc)
Details
38 Gem Aa
Mass1.61[16] M☉
Radius1.97[16] R☉
Surface gravity (log g)4.23[17] cgs
Temperature7,150[16] K
Metallicity [Fe/H]−0.08±0.06[18] dex
Rotational velocity (v sin i)147.5±10.5[19] km/s
Age1.3[16] Gyr
38 Gem Ab
Mass1.17[16] M☉
Radius1.16[16] R☉
Temperature6,300[16] K
Age1.3[16] Gyr
38 Gem B
Mass0.89[20] M☉
Radius0.89[14] R☉
Luminosity0.694[14] L☉
Temperature5,583[14] K
Age1.3[16] Gyr
UPM J0654+1310
Mass0.25[8] M☉
Radius0.29[15] R☉
Luminosity0.0064[15] L☉
Surface gravity (log g)4.46[15] cgs
Temperature3,000[15] K
Age1.3[16] Gyr
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
B
UPM J0654+1310

38 Geminorum is a quadruple 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 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.[21] It is a potential member of the Tucana–Horologium stellar kinematic group.[22]

Characteristics

Light curve for 38 Geminorum plotted from TESS data[23]

The primary component, e Geminorum Aa, is an A-type main-sequence star which has about 1.61 times the mass of the Sun, 1.97 times the radius of the Sun and an effective temperature of 7,150 K.[16] It is a suspected chemically peculiar star of subtype CP1 (an Am star),[19] which Slettebak (1955) classified as kA8mF0Vp.[24] 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.[7]

The primary is closely orbited by companion e Geminorum Ab, which is a smaller F-type main-sequence star with 1.16 times the radius of the Sun and a temperature of 6,300 K. It can explain the X-ray emission coming from the system. The system has been resolved using interferometry, which obtained an projected separation of 0.44 astronomical units (66×10^6 km). Combined with the masses, this results in an estimated orbital period of about two months.[16]

The Aa-Ab system is orbited by the component B, which has a projected separation of 184.3 astronomical unit|AU.[20] 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.[25] As of 2018, the pair had an angular separation of 7.4″ (implying a projected separation of 220 au[16]) along a position angle of 143°.[2] Star B is a G-type main-sequence star with a class of G6V,[9] 0.95 times the Sun's mass, 0.89 times the Sun's radius and an estimated effective temperature of 5,583 K.[14]

The most distant component, UPM J0654+1310, has a projected separation of 4,560 au and is believed to be a red dwarf with a mass of just 0.3 M☉.[16]

References

  1. ↑ 1.0 1.1 van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics 474 (2): 653–664. doi:10.1051/0004-6361:20078357. Bibcode: 2007A&A...474..653V. 
  2. ↑ 2.0 2.1 Mason, B. D. et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal 122 (6): 3466, doi:10.1086/323920, Bibcode: 2001AJ....122.3466M 
  3. ↑ Muirhead, Philip S.; Dressing, Courtney D.; Mann, Andrew W.; Rojas-Ayala, Bárbara; Lépine, Sébastien; Paegert, Martin; De Lee, Nathan; Oelkers, Ryan (2018). "A Catalog of Cool Dwarf Targets for the Transiting Exoplanet Survey Satellite". The Astronomical Journal 155 (4): 180. doi:10.3847/1538-3881/aab710. Bibcode: 2018AJ....155..180M. 
  4. ↑ Zorec, J.; Royer, F. (2012). "Rotational velocities of A-type stars. IV. Evolution of rotational velocities". Astronomy and Astrophysics 537: A120. doi:10.1051/0004-6361/201117691. Bibcode: 2012A&A...537A.120Z. 
  5. ↑ 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. doi:10.1086/192182. Bibcode: 1995ApJS...99..135A. 
  6. ↑ 6.0 6.1 Johnson, H. L. (1966). "UBVRIJKL Photometry of the Bright Stars". Communications of the Lunar and Planetary Laboratory 4: 99. Bibcode: 1966CoLPL...4...99J. 
  7. ↑ 7.0 7.1 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. 
  8. ↑ 8.0 8.1 8.2 Hardegree-Ullman, Kevin K.; Apai, Dániel; Bergsten, Galen J.; Pascucci, Ilaria; López-Morales, Mercedes (2023). "Bioverse: A Comprehensive Assessment of the Capabilities of Extremely Large Telescopes to Probe Earth-like O2 Levels in Nearby Transiting Habitable-zone Exoplanets". The Astronomical Journal 165 (6): 267. doi:10.3847/1538-3881/acd1ec. Bibcode: 2023AJ....165..267H. 
  9. ↑ 9.0 9.1 Adams, Walter S. et al. (1935). "The Spectroscopic Absolute Magnitudes and Parallaxes of 4179 Stars". Astrophysical Journal 81: 187. doi:10.1086/143628. Bibcode: 1935ApJ....81..187A. 
  10. ↑ Zhong, Jing; Li, Jing; Carlin, Jeffrey L.; Chen, Li; Mendez, Rene A.; Hou, Jinliang (2019). "Value-added Catalogs of M-type Stars in LAMOST DR5". The Astrophysical Journal Supplement Series 244 (1): 8. doi:10.3847/1538-4365/ab3859. Bibcode: 2019ApJS..244....8Z. 
  11. ↑ 11.0 11.1 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. 
  12. ↑ 12.0 12.1 12.2 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  13. ↑ Allende Prieto, C.; Lambert, D. L. (1999). "Fundamental parameters of nearby stars from the comparison with evolutionary calculations: Masses, radii and effective temperatures". Astronomy and Astrophysics 352: 555. Bibcode: 1999A&A...352..555A. 
  14. ↑ 14.0 14.1 14.2 14.3 14.4 14.5 14.6 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  15. ↑ 15.0 15.1 15.2 15.3 15.4 15.5 15.6 15.7 Vallenari, A. et al. (2022). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy & Astrophysics. doi:10.1051/0004-6361/202243940  Gaia DR3 record for this source at VizieR.
  16. ↑ 16.00 16.01 16.02 16.03 16.04 16.05 16.06 16.07 16.08 16.09 16.10 16.11 16.12 16.13 Waisberg, Idel; Klein, Ygal; Katz, Boaz (2025-11-21). "Hidden Companions to Intermediate-mass Stars. Upgraded Multiplicity 3 → 4. XXXII. Discovery of a 1.17M⊙, 0.44 au Companion to e Geminorum A". Research Notes of the AAS 9 (11): 314. doi:10.3847/2515-5172/ae2121. ISSN 2515-5172. 
  17. ↑ 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. doi:10.1088/0004-637X/804/2/146. Bibcode: 2015ApJ...804..146D. 
  18. ↑ Gáspár, András et al. (2016). "The Correlation between Metallicity and Debris Disk Mass". The Astrophysical Journal 826 (2): 171. doi:10.3847/0004-637X/826/2/171. Bibcode: 2016ApJ...826..171G. 
  19. ↑ 19.0 19.1 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. doi:10.1093/mnras/sts318. Bibcode: 2013MNRAS.429..119P. 
  20. ↑ 20.0 20.1 Tokovinin, A.; Kiyaeva, O. (February 2016). "Eccentricity distribution of wide binaries". Monthly Notices of the Royal Astronomical Society 456 (2): 2070–2079. doi:10.1093/mnras/stv2825. Bibcode: 2016MNRAS.456.2070T. 
  21. ↑ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters 32 (11): 759–771. doi:10.1134/S1063773706110065. Bibcode: 2006AstL...32..759G. 
  22. ↑ Nakajima, Tadashi; Morino, Jun-Ichi (2012). "Potential Members of Stellar Kinematic Groups within 30 pc of the Sun". The Astronomical Journal 143 (1): 2. doi:10.1088/0004-6256/143/1/2. Bibcode: 2012AJ....143....2N. 
  23. ↑ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. https://mast.stsci.edu/portal/Mashup/Clients/Mast/Portal.html. 
  24. ↑ Slettebak, Arne (May 1955). "The Spectra and Rotational Velocities of the Bright Stars of Draper Types A3-G0.". Astrophysical Journal 121: 653. doi:10.1086/146031. Bibcode: 1955ApJ...121..653S. 
  25. ↑ Abt, Helmut A. (August 2005). "Observed Orbital Eccentricities". The Astrophysical Journal 629 (1): 507–511. doi:10.1086/431207. Bibcode: 2005ApJ...629..507A. 



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