HD 136138

Last updated
HD 136138
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Serpens [1]
Right ascension 15h 18m 24.507s [2]
Declination +20° 34′ 21.95″ [2]
Apparent magnitude  (V)5.68 [1] + 15.3 [3]
Characteristics
Evolutionary stage Horizontal branch + white dwarf
Spectral type G8IIIa [4] + DA1.7 [3]
B−V color index 0.972±0.004 [1]
Variable type Constant [5] [6]
Astrometry
Radial velocity (Rv)−7.74±0.07 [1] km/s
Proper motion (μ)RA: −12.993 mas/yr [2]
Dec.: −22.380 mas/yr [2]
Parallax (π)7.7902±0.2193  mas [2]
Distance 420 ± 10  ly
(128 ± 4  pc)
Absolute magnitude  (MV)0.65±0.15 [7]
Orbit [7]
Period (P)506.45±0.18 d
Semi-major axis (a)4.14±0.52"
(≥ 41.76±0.34 Gm [5] )
Eccentricity (e)0.3353±0.0056
Inclination (i)42.9±6.7°
Longitude of the node (Ω)207.0±7.4°
Periastron epoch (T)2,453,240.3±1.3  MJD
Argument of periastron (ω)
(secondary)		35.0±1.4°
Semi-amplitude (K1)
(primary)		6.340±0.044 km/s
Details [7]
A
Mass 1.84±0.40  M☉
Radius 10.3  R☉
Luminosity 56.2  L☉
Surface gravity (log g)2.68  cgs
Temperature 4,960±100  K
Metallicity [Fe/H]−0.08±0.09 [8]   dex
Age 1.45  Gyr
B
Mass 0.59±0.12 or 0.79±0.09  M☉
Surface gravity (log g)8.25±0.15  cgs
Temperature 30,400±780  K
Other designations
BD+21°2755, FK5 1400, GC 20575, HD 136138, HIP 74896, HR 5692, SAO 83755, [9] WD 1516+207 [3]
Database references
SIMBAD data

HD 136138, or HR 5692, is a binary star system in the Serpens Caput segment of the Serpens constellation. It has a golden hue like the Sun and is dimly visible to the naked eye with an apparent visual magnitude of 5.68; [1] the light contribution from the companion is effectively negligible. [8] This system is located at a distance of approximately 420  light years from the Sun based on parallax. [2] It is drifting closer with a radial velocity of −7.7 km/s [1] and has a proper motion of 23.5  mas ·yr−1. [8]

The radial velocity variation of this star was reported by J. R. de Medeiros and M. Mayor in 1999, [5] and it was confirmed as a binary by A. Frankowski and colleagues in 2007 using proper motion measurements. [3] It is an unresolved, single-lined spectroscopic binary system with an orbital period of 1.39 years and an eccentricity (ovalness) of 0.335. Proper motion measurements allow an estimate of the orbital inclination angle as ~43°. [7] Their semimajor axis is around 2.0  AU , or double the distance from the Earth to the Sun. [8]

The stellar classification of the primary component is G8IIIa, [4] indicating this is a evolved G-type giant star that has exhausted the supply of hydrogen at its core. It is a red clump giant that is generating energy through core helium fusion. There is some ambiguous evidence for this being a mild barium star [7] of class Ba0.3, [8] with the spectra showing marginal overabundances of s-process elements. [8] A low level of X-ray emission has been detected, which appears to be coming from the star's corona. [6]

The high level of ultraviolet flux coming from this system strongly suggests the companion is a compact white dwarf. Mass estimates put it in the range of 0.6 to 0.8 times the mass of the Sun, and the temperature is around 30,400 K. [7] It is possible that the earlier evolution of this component contaminated its partner with s-process elements, although the resulting interaction should have circularized the orbit to some degree. [5] The dwarf has a visual magnitude of 15.3 and a hydrogen-dominated atmospheric class of DA1.7. [3]

References

  1. 1 2 3 4 5 6 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.
  2. 1 2 3 4 5 6 Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR.
  3. 1 2 3 4 5 Holberg, J. B.; et al. (2013). "Where are all the Sirius-like binary systems?". Monthly Notices of the Royal Astronomical Society. 435 (3): 2077. arXiv: 1307.8047 . Bibcode:2013MNRAS.435.2077H. doi: 10.1093/mnras/stt1433 .
  4. 1 2 Keenan, Philip C.; McNeil, Raymond C. (1989). "The Perkins catalog of revised MK types for the cooler stars". The Astrophysical Journal Supplement Series. 71: 245. Bibcode:1989ApJS...71..245K. doi:10.1086/191373.
  5. 1 2 3 4 Griffin, R. F. (February 2009). "Spectroscopic binary orbits from photoelectric radial velocities. Paper 204: HR 738, HR 831, HR 5692, and HR 7252". The Observatory. 129: 6–28. Bibcode:2009Obs...129....6G.
  6. 1 2 Jorissen, A.; et al. (February 1996). "New X-ray sources detected among mild barium and S stars". Astronomy and Astrophysics. 306: 467. Bibcode:1996A&A...306..467J.
  7. 1 2 3 4 5 6 Stefanik, Robert P.; et al. (May 2011). "Observations and Orbital Analysis of the Giant White Dwarf Binary System HR 5692". The Astronomical Journal. 141 (5): 9. Bibcode:2011AJ....141..144S. doi:10.1088/0004-6256/141/5/144. S2CID   56137377. 144.
  8. 1 2 3 4 5 6 Merle, T.; et al. (February 2016). "To Ba or not to Ba: Enrichment in s-process elements in binary systems with WD companions of various masses". Astronomy & Astrophysics. 586: 16. arXiv: 1510.05908 . Bibcode:2016A&A...586A.151M. doi:10.1051/0004-6361/201526944. S2CID   119224869. A151.
  9. ↑ "HD 136138". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2020-12-22.{{cite web}}: CS1 maint: postscript (link)
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