Astronomy:HR 4098

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Short description: Binary star system in the constelaltion Ursa Major

Coordinates: Sky map 10h 28m 03.8821s, +48° 47′ 05.6554″

HR 4098
Observation data
Equinox J2000.0]] (ICRS)
Constellation Ursa Major
Right ascension  10h 28m 03.8821s[1]
Declination +48° 47′ 05.6554″[1]
Apparent magnitude (V) 6.45[2]
Characteristics
HD 90508A
Spectral type G0V[1]
Apparent magnitude (g) 6.28[3]
HD 90508B
Apparent magnitude (g) 11.72[4]
Astrometry
HD 90508A
Radial velocity (Rv)-7.2±0.2[3] km/s
Proper motion (μ) RA: 83.79±0.03[3] mas/yr
Dec.: -896.055±0.04[3] mas/yr
Parallax (π)43.4944 ± 0.0386[3] mas
Distance74.99 ± 0.07 ly
(22.99 ± 0.02 pc)
HD 90508B
Proper motion (μ) RA: 81.80±0.03 mas/yr
Dec.: -880.66±0.03 mas/yr
Parallax (π)43.4822 ± 0.0452[4] mas
Distance75.01 ± 0.08 ly
(23.00 ± 0.02 pc)
Orbit[5]
PrimaryHD 90508A
CompanionHD 90508B
Period (P)590±208 yr
Semi-major axis (a)4.67±0.12"
(107 AU)
Eccentricity (e)0
Inclination (i)81.4±3.5°
Longitude of the node (Ω)16.5±1.9°
Periastron epoch (T)1958.6±16.8
Details[6]
HD 95508A
Mass0.86±0.03 M
Radius1.12±0.03 R
Surface gravity (log g)4.3±0.1 cgs
Temperature5720±100 K
Metallicity [Fe/H]-0.23[7] dex
Rotation18.0±2.7 d[8]
Rotational velocity (v sin i)1.0[8] km/s
Age10.5±2[9] Gyr
HD 95508B
Mass0.25±0.01 M
Other designations
BD+49 1961, GJ 392, HD 90508, HIP 51248, HR 4098, WDS J10281+4847AB, GSC 08176-00283, 2MASS J10280388+4847067[1]
HD 90508A: Gliese 392A, TYC 8176-283-1, LHS 2267,LTT 12795, NLTT 24398, Gaia DR2 834571523535702528
HD 90508B: Gliese 392B, LHS 2266, NLTT 24397, Gaia DR2 834571523535693184
Database references
SIMBADdata

HR 4098, also known as HD 90508, is a binary star system in the northern constellation of Ursa Major at a distance of 75 light years. This object is barely visible to the naked eye as a dim, yellow star with an apparent visual magnitude of 6.45. It is approaching the Earth with a heliocentric radial velocity of 7.2±0.2 km/s.[3]

The star system is a visual binary with a 3.466″ projected separation,[10] identified as such in 1994–1997.[5][10] The orbit of the binary is wide and highly uncertain[10] due to the long period and high inclination.[5]

The larger star, HD 90508A, is a very old main-sequence star approaching a turn-off from the main sequence.[11] Very little dust remains in the stellar system, therefore the starlight of HR 4098 is one of the standards for non-polarized emission, polarization being below 0.2% in all bands.[12] Unlike the majority of G-class stars, HD 90508A has a direct correlation between brightness and stellar activity. This behavior is shared with HD 88986 and the Sun.[13]

Very little is known about the companion, which could be a K-class or M-class dwarf star.[6]

References

  1. 1.0 1.1 1.2 1.3 "HD 90508". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HD+90508. 
  2. Hall, Jeffrey C.; Lockwood, G. W.; Skiff, Brian A. (23 January 2007). "The Activity and Variability of the Sun and Sun-like Stars. I. Synoptic Ca II H and K Observations". The Astronomical Journal 133 (3): 862–881. doi:10.1086/510356. ISSN 0004-6256. Bibcode2007AJ....133..862H. 
  3. 3.0 3.1 3.2 3.3 3.4 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. Bibcode2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  4. 4.0 4.1 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. Bibcode2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  5. 5.0 5.1 5.2 Drummond, Jack D. (11 February 2014). "Binary Stars Observed with Adaptive Optics at the Starfire Optical Range". The Astronomical Journal 147 (3): 65. doi:10.1088/0004-6256/147/3/65. ISSN 0004-6256. Bibcode2014AJ....147...65D. 
  6. 6.0 6.1 Hirsch, Lea A.; Rosenthal, Lee; Fulton, Benjamin J.; Howard, Andrew W.; Ciardi, David R.; Marcy, Geoffrey W.; Nielsen, Eric; Petigura, Erik A. et al. (22 February 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. ISSN 0004-6256. Bibcode2021AJ....161..134H. 
  7. CLOSE BINARY MASS ANOMALIES AND METALLICITY
  8. 8.0 8.1 Justesen, A. B.; Albrecht, S. (2020), "The spin-orbit alignment of visual binaries", Astronomy & Astrophysics 642: A212, doi:10.1051/0004-6361/202039138, Bibcode2020A&A...642A.212J 
  9. Loyd, R. O. Parke; France, Kevin (2014), "Fluctuations and Flares in the Ultraviolet Line Emission of Cool Stars: Implications for Exoplanet Transit Observations", The Astrophysical Journal Supplement Series 211 (1): 9, doi:10.1088/0067-0049/211/1/9, Bibcode2014ApJS..211....9L 
  10. 10.0 10.1 10.2 CCD MEASUREMENTS OF DOUBLE AND MULTIPLE STARS AT NAO ROZHEN. III
  11. ON THE AGE OF GLIESE 86
  12. Goswami, A.; Karinkuzhi, D. (2012), "Polarimetric studies of carbon stars at high Galactic latitude", Astronomy & Astrophysics 549: A68, doi:10.1051/0004-6361/201219911 
  13. THE ACTIVITY AND VARIABILITY OF THE SUN AND SUN-LIKE STARS. II. CONTEMPORANEOUS PHOTOMETRY AND SPECTROSCOPY OF BRIGHT SOLAR ANALOGS