Astronomy:HR 4098
Coordinates: 
10h 28m 03.8821s, +48° 47′ 05.6554″
| 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 |
| Distance | 74.99 ± 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 |
| Distance | 75.01 ± 0.08 ly (23.00 ± 0.02 pc) |
| Orbit[5] | |
| Primary | HD 90508A |
| Companion | HD 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 | |
| Mass | 0.86±0.03 M☉ |
| Radius | 1.12±0.03 R☉ |
| Surface gravity (log g) | 4.3±0.1 cgs |
| Temperature | 5720±100 K |
| Metallicity [Fe/H] | -0.23[7] dex |
| Rotation | 18.0±2.7 d[8] |
| Rotational velocity (v sin i) | 1.0[8] km/s |
| Age | 10.5±2[9] Gyr |
| HD 95508B | |
| Mass | 0.25±0.01 M☉ |
| Other designations | |
| 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 | |
| SIMBAD | data |
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
- ↑ 1.0 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.
- ↑ 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. Bibcode: 2007AJ....133..862H.
- ↑ 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. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ 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. Bibcode: 2021A&A...649A...1G. Gaia EDR3 record for this source at VizieR.
- ↑ 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. Bibcode: 2014AJ....147...65D.
- ↑ 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. Bibcode: 2021AJ....161..134H.
- ↑ CLOSE BINARY MASS ANOMALIES AND METALLICITY
- ↑ 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, Bibcode: 2020A&A...642A.212J
- ↑ 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, Bibcode: 2014ApJS..211....9L
- ↑ 10.0 10.1 10.2 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, doi:10.1051/0004-6361/201219911
- ↑ THE ACTIVITY AND VARIABILITY OF THE SUN AND SUN-LIKE STARS. II. CONTEMPORANEOUS PHOTOMETRY AND SPECTROSCOPY OF BRIGHT SOLAR ANALOGS
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