HD 90508
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.
The star system is a visual binary with a 3.466″ projected separation, identified as such in 1994–1997. The orbit of the binary is wide and highly uncertain due to the long period and high inclination.
The larger star, HD 90508A, is a very old main-sequence star approaching a turn-off from the main sequence. 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. 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.
Very little is known about the companion, which could be a K-class or M-class dwarf star.
References
- ^ "HD 90508". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved December 20, 2021.
- ^ 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. Bibcode:2007AJ....133..862H. doi:10.1086/510356. eISSN 1538-3881. ISSN 0004-6256. S2CID 121460023.
- ^ 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.
- ^ 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.
- ^ Drummond, Jack D. (11 February 2014). "Binary Stars Observed with Adaptive Optics at the Starfire Optical Range". The Astronomical Journal. 147 (3): 65. Bibcode:2014AJ....147...65D. doi:10.1088/0004-6256/147/3/65. eISSN 1538-3881. ISSN 0004-6256.
- ^ Hirsch, Lea A.; Rosenthal, Lee; Fulton, Benjamin J.; Howard, Andrew W.; Ciardi, David R.; Marcy, Geoffrey W.; Nielsen, Eric; Petigura, Erik A.; de Rosa, Robert J.; Isaacson, Howard; Weiss, Lauren M.; Sinukoff, Evan; Macintosh, Bruce (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. arXiv:2012.09190. Bibcode:2021AJ....161..134H. doi:10.3847/1538-3881/abd639. eISSN 1538-3881. ISSN 0004-6256.
- ^ CLOSE BINARY MASS ANOMALIES AND METALLICITY
- ^ Justesen, A. B.; Albrecht, S. (2020), "The spin-orbit alignment of visual binaries", Astronomy & Astrophysics, 642: A212, arXiv:2008.12068, Bibcode:2020A&A...642A.212J, doi:10.1051/0004-6361/202039138, S2CID 221340982
- ^ 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, arXiv:1402.0073, Bibcode:2014ApJS..211....9L, doi:10.1088/0067-0049/211/1/9, S2CID 118394892
- ^ CCD MEASUREMENTS OF DOUBLE AND MULTIPLE STARS AT NAO ROZHEN. III
- ^ ON THE AGE OF GLIESE 86
- ^ Goswami, A.; Karinkuzhi, D. (2012), "Polarimetric studies of carbon stars at high Galactic latitude", Astronomy & Astrophysics, 549: A68, arXiv:1212.4276, doi:10.1051/0004-6361/201219911, S2CID 118393046
- ^ THE ACTIVITY AND VARIABILITY OF THE SUN AND SUN-LIKE STARS. II. CONTEMPORANEOUS PHOTOMETRY AND SPECTROSCOPY OF BRIGHT SOLAR ANALOGS
