Astronomy:HD 72945

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Short description: Binary star system in the constellation of Cancer
HD 72945 & HD 72946
Observation data
{{#ifeq:J2000.0|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| [[History:Epoch|Epoch J2000.0]]      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000.0}}
Constellation Cancer
HD 72945
Right ascension  08h 35m 50.978s[1]
Declination 06° 37′ 12.77″[1]
Apparent magnitude (V) 5.91[2]
HD 72946
Right ascension  08h 35m 51.267s[3]
Declination 06° 37′ 21.95″[3]
Apparent magnitude (V) 7.25[2]
Characteristics
HD 72945
Evolutionary stage Main sequence[4]
Spectral type F8 V[5]
B−V color index 0.530±0.007[2]
HD 72946
Spectral type G5V[6]
B−V color index 0.710±0.015[2]
Astrometry
HD 72945
Radial velocity (Rv)26.61±0.15[7] km/s
Proper motion (μ) RA: −130.308[1] mas/yr
Dec.: −133.119[1] mas/yr
Parallax (π)38.4212 ± 0.1515[1] mas
Distance84.9 ± 0.3 ly
(26.0 ± 0.1 pc)
Absolute magnitude (MV)3.91[2]
HD 72946
Radial velocity (Rv)28.75±0.14[8] km/s
Proper motion (μ) RA: −136.593 mas/yr
Dec.: −137.148 mas/yr
Parallax (π)38.9809 ± 0.0412[3] mas
Distance83.67 ± 0.09 ly
(25.65 ± 0.03 pc)
Absolute magnitude (MV)5.16[2]
Orbit[7]
PrimaryHD 72945 A
Period (P)14.2995±0.0001 d
Semi-major axis (a)≥4.07 ± 0.05 Gm (5.850 ± 0.072 R☉)
Eccentricity (e)0.332±0.008
Periastron epoch (T)2,446,781.30±0.12 JD
Argument of periastron (ω)
(secondary)		227.1±3.0°
Semi-amplitude (K1)
(primary)		21.95±0.15 km/s
Details
HD 72945
Mass1.245±0.030[9] M☉
Radius1.358[10] R☉
Luminosity2.372[10] L☉
Surface gravity (log g)4.32[11] cgs
Temperature6,222[11] K
Metallicity [Fe/H]0.05[11] dex
Rotational velocity (v sin i)7.1[11] km/s
Age1.584±0.952[9] Gyr
HD 72946
Mass1.02±0.04[12] M☉
Radius0.97±0.02[12] R☉
Luminosity0.84[2] L☉
Surface gravity (log g)4.69[13] cgs
Temperature5,670[12] K
Metallicity [Fe/H]0.16[12] dex
Rotational velocity (v sin i)4.14[9] km/s
Age1.9+0.6−0.5[6] Gyr
Other designations
BD+07 1997, GJ 9271, 310.1, ADS 6886, WDS J08358+0637[14][15]
HD 72945: Boss 2285[16], GC 11781, HIP 42172, HR 3395, SAO 116929, PPM 154707, NLTT 19856[14]
HD 72946: Boss 2286[16], GC 16412, HIP 42173, HR 3396, SAO 116931, PPM 154708, NLTT 19851[15]
Database references
SIMBADHD 72945
HD 72946

HD 72945 and HD 72946 form a co-moving star system in the northern constellation of Cancer.[17] HD 72945 is a binary star that is dimly visible to the naked eye as a point of light with an apparent visual magnitude of 5.91.[2] At an angular separation of 10.10″ (as of 2020)[18] is the fainter companion star HD 72946 at magnitude 7.25.[2] It is being orbited by a brown dwarf.[9] The system as a whole is located at a distance of approximately 84 light years from the Sun based on parallax measurements.[1][3]

The discovery of this double star was announced by F. G. W. Struve in 1782, and later given the discovery code STF 1245.[18] Their common proper motion was confirmed by A. van Maanen in 1916, and this suggested they are physically associated.[16] The projected separation of the two systems is 258.9 astronomical unit|AU.[19] Based on astrometric measurements from the Gaia spacecraft, the semimajor axis of this system is 200+52
−41 astronomical unit|AU.[6] Assuming they are gravitationally bound, they would have an orbital period of around 2,500 years.[20]

There is an additional candidate stellar companion at an angular separation of ~130″, which would make this a four star system. (This object has the 2MASS designation J08354678+0635294.)[9] Three additional faint companions detected by Struve are most likely background stars.[7]

HD 72945

The binary nature of HD 72945 was announced in 1919 by A. H. Joy and G. Abetti at the Mount Wilson Observatory. Observed variations in the radial velocity of the primary component inferred an orbiting stellar companion.[16] This is a single-lined spectroscopic binary system with a period of 14.3 days and an orbital eccentricity of 0.33.[7] The minimum value for the semimajor axis is only 5.9 times the radius of the Sun, although the actual value is uncertain because the orbital inclination is unknown.[7]

The visible component of this system has a stellar classification of F8 V,[5] matching an ordinary F-type main-sequence star. It has 1.25[9] times the mass of the Sun and 1.4[10] times the Sun's radius. The star is radiating 2.4[10] times the luminosity of the Sun from its photosphere at an effective temperature of 6,222 K.[11] It has an estimated age of approximately 1.6 billion years.[9] The derived minimum mass for the secondary component is 0.34 M☉.[9]

HD 72946

This is a G-type main-sequence star with a class of G5V.[6] It has about the same size and mass as the Sun.[12] However, the star is slightly more active than the Sun, and thus probably younger.[6] It is metal-rich, showing a higher abundance of elements other than hydrogen and helium compared to the Sun.[21]

In 2016, a candidate brown dwarf companion in orbit around HD 72946 was announced. It was discovered based on radial velocity monitoring over a twenty-year period.[22] The companion was confirmed in 2020.[9] It has a classification of L5.0±1.5, a derived temperature of 1,700±90 K, and a mass near the hydrogen-burning limit.[6] The orbit lies just outside the ice line of the host star, with a semimajor axis of 6.48 AU.[9] It is orbiting with a period of 16 years and an eccentricity of 0.49.[6]

The HD 72945 planetary system[6]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
B 72.5±1.3 MJ 6.48[9] 5,815 ± 37 0.489±0.007 59.5+1.2−1.1° —

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters 38 (5): 331, doi:10.1134/S1063773712050015, Bibcode: 2012AstL...38..331A. 
  3. ↑ 3.0 3.1 3.2 3.3 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  4. ↑ Schröder, C. et al. (January 2009), "Ca II HK emission in rapidly rotating stars. Evidence for an onset of the solar-type dynamo", Astronomy and Astrophysics 493 (3): 1099–1107, doi:10.1051/0004-6361:200810377, Bibcode: 2009A&A...493.1099S. 
  5. ↑ 5.0 5.1 Abt, Helmut A. (December 23, 2008), "Mk Classifications of Spectroscopic Binaries", The Astrophysical Journal Supplement Series 180 (1): 117–118, doi:10.1088/0067-0049/180/1/117, ISSN 0067-0049, Bibcode: 2009ApJS..180..117A. 
  6. ↑ 6.0 6.1 6.2 6.3 6.4 6.5 6.6 6.7 Brandt, G. Mirek et al. (December 2021), "Improved Dynamical Masses for Six Brown Dwarf Companions Using Hipparcos and Gaia EDR3", The Astronomical Journal 162 (6): 28, doi:10.3847/1538-3881/ac273e, 301, Bibcode: 2021AJ....162..301B. 
  7. ↑ 7.0 7.1 7.2 7.3 7.4 Duquennoy, A.; Mayor, M. (1991), "Multiplicity among solar-type stars in the solar neighbourhood. II – Distribution of the orbital elements in an unbiased sample", Astronomy & Astrophysics 248 (2): 485–524, Bibcode: 1991A&A...248..485D. 
  8. ↑ 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.
  9. ↑ 9.00 9.01 9.02 9.03 9.04 9.05 9.06 9.07 9.08 9.09 9.10 Maire, A. -L. et al. (January 2020), "A dusty benchmark brown dwarf near the ice line of HD 72946", Astronomy & Astrophysics 633: 10, doi:10.1051/0004-6361/201937134, L2, Bibcode: 2020A&A...633L...2M. 
  10. ↑ 10.0 10.1 10.2 10.3 Schofield, Mathew et al. (2019), "The Asteroseismic Target List for Solar-like Oscillators Observed in 2 minute Cadence with the Transiting Exoplanet Survey Satellite", The Astrophysical Journal Supplement Series 241 (1): 12, doi:10.3847/1538-4365/ab04f5, Bibcode: 2019ApJS..241...12S. 
  11. ↑ 11.0 11.1 11.2 11.3 11.4 Luck, R. Earle (January 2017), "Abundances in the Local Region II: F, G, and K Dwarfs and Subgiants", The Astronomical Journal 153 (1): 19, doi:10.3847/1538-3881/153/1/21, 21, Bibcode: 2017AJ....153...21L. 
  12. ↑ 12.0 12.1 12.2 12.3 12.4 Hirsch, Lea A. et al. (2021), "Understanding the Impacts of Stellar Companions on Planet Formation and Evolution: A Survey of Stellar and Planetary Companions within 25 pc", The Astronomical Journal 161 (3): 134, doi:10.3847/1538-3881/abd639, Bibcode: 2021AJ....161..134H. 
  13. ↑ Gray, R. O. et al. (2003), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 Parsecs: The Northern Sample. I", The Astronomical Journal 126 (4): 2048, doi:10.1086/378365, Bibcode: 2003AJ....126.2048G. 
  14. ↑ 14.0 14.1 "HD 72945". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+72945. 
  15. ↑ 15.0 15.1 "HD 72946". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+72946. 
  16. ↑ 16.0 16.1 16.2 16.3 Joy, A. H.; Abetti, G. (December 1919), "The orbit of the spectroscopic binary Boss 2285", Astrophysical Journal 50: 391–393, doi:10.1086/142515, Bibcode: 1919ApJ....50..391J. 
  17. ↑ Sinnott, Roger W.; Perryman, Michael A. C. (1997), Millennium Star Atlas, 2, Sky Publishing Corporation and the European Space Agency, p. 761, ISBN 0-933346-83-2. 
  18. ↑ 18.0 18.1 Mason, B. D. et al. (2014), "The Washington Visual Double Star Catalog", The Astronomical Journal 122 (6): 3466–71, doi:10.1086/323920, Bibcode: 2001AJ....122.3466M, http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=B/wds. 
  19. ↑ 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. 
  20. ↑ Tokovinin, Andrei (2014), "From Binaries to Multiples. II. Hierarchical Multiplicity of F and G Dwarfs", The Astronomical Journal 147 (4): 87, doi:10.1088/0004-6256/147/4/87, Bibcode: 2014AJ....147...87T. 
  21. ↑ Feltzing, S.; Gustafsson, B. (April 1998), "Abundances in metal-rich stars. Detailed abundance analysis of 47 G and K dwarf stars with [Me/H] > 0.10 dex", Astronomy and Astrophysics Supplement 129: 237–266, doi:10.1051/aas:1998400, Bibcode: 1998A&AS..129..237F. 
  22. ↑ Bouchy, F. et al. (January 2016), "The SOPHIE search for northern extrasolar planets. VIII. Follow-up of ELODIE candidates: long-period brown-dwarf companions", Astronomy & Astrophysics 585: 8, doi:10.1051/0004-6361/201526347, A46, Bibcode: 2016A&A...585A..46B. 



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