HD 89744

HD 89744 is a star in the northern circumpolar constellation of Ursa Major, positioned about 0.4° due south of the bright star Tania Australis (μ UMa).[11] This object has a yellow-white hue and is dimly visible to the naked eye with an apparent visual magnitude of 5.73.[2] The distance to this star has been measured using the patallax method, which locates it 126 light years from the Sun. It is drifting closer with a radial velocity of −4.4 km/s.[2] There are two known exoplanets orbiting this star.

HD 89744
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Ursa Major
Right ascension 10h 22m 10.5623s[1]
Declination +41° 13′ 46.3088″[1]
Apparent magnitude (V) 5.73[2]
Characteristics
Evolutionary stage Main sequence
Spectral type F7V[3] or F8IV[4]
B−V color index 0.531±0.003[2]
Astrometry
Radial velocity (Rv)−4.35±0.12[2] km/s
Proper motion (μ) RA: −120.573±0.111[1] mas/yr
Dec.: −138.144±0.131[1] mas/yr
Parallax (π)25.8537 ± 0.0716 mas[1]
Distance126.2 ± 0.3 ly
(38.7 ± 0.1 pc)
Absolute magnitude (MV)2.83[5]
Details
A
Mass1.37±0.09[6] M☉
Radius2.16+0.06
−0.01[1] R☉
Luminosity6.38±0.02[7] L☉
Surface gravity (log g)4.27±0.05[6] cgs
Temperature6,381±43[6] K
Metallicity [Fe/H]0.30±0.03[6] dex
Rotation~9 days[7]
Rotational velocity (v sin i)9.3[8] km/s
Age8.4[7] Gyr
B
Mass0.076[9] M☉
Other designations
BD+41°2076, GJ 9326, HD 89744, HIP 50786, HR 4067, SAO 43309, NLTT 24128[10]
Database references
SIMBADThe star
planet b
Exoplanet Archivedata
ARICNSdata

At various times the star HD 89744 has been assigned a stellar classification of F7V,[3][12] F7IV-V,[13] and F8IV,[4][2] suggesting it is an F-type main-sequence star that is evolving onto the subgiant branch. It is ~8.4[7] billion years old with an inactive chromosphere[13] and is spinning with a projected rotational velocity of 9.3 km/s.[8] The star is 2.16[1] times the size of the Sun with 1.4[6] times the Sun's radius. It is a high metallicity star, showing a greater abundance of heavier elements than in the Sun. The star is radiating 6.4[7] times the luminosity of the Sun from its photosphere at an effective temperature of 6,381 K.[6]

In 2001, a faint co-moving companion was identified at an angular separation of 63.1″ from the primary.[14] This is equivalent to a linear projected separation of 2,456 AU (0.04 ly).[9] The companion, designated component B, is an L-class (~L0.5)[3] brown dwarf[14] with a mass of ~0.076 M☉.[9]

Planetary system

In April 2000, a planet was discovered using radial velocity measurements taken at Fred Lawrence Whipple Observatory and Lick Observatory.[12] The orbital parameters were updated in 2006 and 2007 using additional measurements.[15][16] A second planet with a much longer period was discovered in 2019.[17]

The HD 89744 planetary system[17]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >8.35±0.18 MJ 0.917±0.009 256.78±0.02 0.677±0.003 — —
c (unconfirmed) >5.36±4.57 MJ 8.3±1.8 6,974±2,161 0.29±0.12 — —

See also

References
  1. Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. 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.
  3. Scholz, R. -D. (March 2016). "Overlooked wide companions of nearby F stars". Astronomy & Astrophysics. 587: 8. arXiv:1601.01896. Bibcode:2016A&A...587A..51S. doi:10.1051/0004-6361/201527965. S2CID 118348424. A51.
  4. Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 parsecs: The Northern Sample I". The Astronomical Journal. 132 (1): 161–170. arXiv:astro-ph/0603770. Bibcode:2006AJ....132..161G. doi:10.1086/504637. S2CID 119476992.
  5. Pizzolato, N.; et al. (September 2000). "Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases". Astronomy and Astrophysics. 361: 614–628. Bibcode:2000A&A...361..614P.
  6. Sousa, S. G.; et al. (November 2018). "SWEET-Cat updated. New homogenous spectroscopic parameters". Astronomy & Astrophysics. 620: 13. arXiv:1810.08108. Bibcode:2018A&A...620A..58S. doi:10.1051/0004-6361/201833350. S2CID 119374557. A58.
  7. Metcalfe, Travis S.; Egeland, Ricky (January 2019). "Understanding the Limitations of Gyrochronology for Old Field Stars". The Astrophysical Journal. 871 (1): 6. arXiv:1811.11905. Bibcode:2019ApJ...871...39M. doi:10.3847/1538-4357/aaf575. S2CID 119405127. 39.
  8. Morris, Brett M.; et al. (September 2019). "Stellar Properties of Active G and K Stars: Exploring the Connection between Starspots and Chromospheric Activity". The Astronomical Journal. 158 (3): 16. arXiv:1907.00423. Bibcode:2019AJ....158..101M. doi:10.3847/1538-3881/ab2e04. S2CID 195767281. 101.
  9. Mugrauer, M.; et al. (2005). "Four new wide binaries among exoplanet host stars". Astronomy and Astrophysics. 440 (3): 1051–1060. arXiv:astro-ph/0507101. Bibcode:2005A&A...440.1051M. doi:10.1051/0004-6361:20042297.
  10. "HD 89744". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-10-14.
  11. Sinnott, Roger W.; Perryman, Michael A. C. (1997). Millennium Star Atlas. Vol. 2. Sky Publishing Corporation and the European Space Agency. p. 617. ISBN 0-933346-83-2.
  12. Korzennik, Sylvain G.; et al. (2000). "A High-Eccentricity Low-Mass Companion to HD 89744". The Astrophysical Journal Letters. 533 (2): L147–L150. arXiv:astro-ph/0003045. Bibcode:2000ApJ...533L.147K. doi:10.1086/312611. PMID 10770711.
  13. Wright, J. T. (September 2004). "Do We Know of Any Maunder Minimum Stars?". The Astronomical Journal. 128 (3): 1273–1278. arXiv:astro-ph/0406338. Bibcode:2004AJ....128.1273W. doi:10.1086/423221. S2CID 118975831.
  14. Wilson, J. C.; et al. (October 2001). "Three Wide-Separation L Dwarf Companions from the Two Micron All Sky Survey: Gliese 337C, Gliese 618.1B, and HD 89744B". The Astronomical Journal. 122 (4): 1989–2000. arXiv:astro-ph/0108424. Bibcode:2001AJ....122.1989W. doi:10.1086/323134. S2CID 17789028.
  15. Butler, R. P.; et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal. 646 (1): 505–522. arXiv:astro-ph/0607493. Bibcode:2006ApJ...646..505B. doi:10.1086/504701.
  16. Wittenmyer, Robert A.; et al. (2007). "Dynamical and Observational Constraints on Additional Planets in Highly Eccentric Planetary Systems". The Astronomical Journal. 134 (3): 1276–1284. arXiv:0706.1962. Bibcode:2007AJ....134.1276W. doi:10.1086/520880.
  17. Wittenmyer, Robert A.; et al. (2019). "Truly eccentric – I. Revisiting eight single-eccentric planetary systems". Monthly Notices of the Royal Astronomical Society. 484 (4): 5859–5867. arXiv:1901.08471. Bibcode:2019MNRAS.484.5859W. doi:10.1093/mnras/stz290.
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