24 Boötis

24 Boötis or g Boötis is a single,^[6] yellow-hued star in the constellation Boötes. It is faintly visible to the naked eye with an apparent visual magnitude of +5.59.^[2] Based upon an annual parallax shift of 10.59 mas,^[1] it is located around 308 light years from the Sun. The star is moving closer to the Sun with a radial velocity of −8 km/s.^[2] It is a thick disk star with a high galactic space velocity and an orbital eccentricity of 0.47±0.01 that carries it as close as 3.30±0.05 kpc to the Galactic Center, and as far away as 9.15±0.02 kpc.^[7] An extrasolar planet was discovered orbiting this star in 2018.^[8]

24 Boötis

Observation data Epoch J2000      Equinox J2000
Constellation	Boötes
Right ascension	14h 28m 37.81288s[1]
Declination	+49° 50′ 41.4615″[1]
Apparent magnitude (V)	+5.59[2]
Characteristics
Spectral type	G4 III-IV Fe-1[3]
B−V color index	0.85±0.02[2]
Astrometry
Radial velocity (Rv)	−8.116±0.024[2] km/s
Proper motion (μ)	RA: −303.943 mas/yr[1] Dec.: −46.836 mas/yr[1]
Parallax (π)	10.5895 ± 0.0421 mas[1]
Distance	308 ± 1 ly (94.4 ± 0.4 pc)
Absolute magnitude (MV)	+0.59[2]
Details[4]
Mass	1.46±0.15 M☉
Radius	10.045±0.098 R☉
Luminosity	54.97±0.90 L☉
Surface gravity (log g)	2.599±0.047 cgs
Temperature	4,959±21 K
Metallicity [Fe/H]	−0.71±0.06 dex
Rotational velocity (v sin i)	2.57±0.73[2] km/s
Other designations
g Boötis, 24 Boo, BD+50° 2084, GC 19532, HD 127243, HIP 70791, HR 5420, SAO 29165[5]
Database references
SIMBAD	data

This is an evolving red giant^[7] star with a stellar classification of G4 III-IV Fe-1,^[3] with the notation indicating the spectrum shows blended characteristics of a subgiant and giant star with an underabundance of iron. It has 1.46 times the mass of the Sun but has expanded to ten times the Sun's radius. The star is radiating 55 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 4,959 K.^[4]

Planetary system

24 Boötis b was discovered by Takuya Takarada and collaborators using the Doppler Spectroscopy method, during the Okayama Planet Search radial velocity survey of G and K giants at Okayama Astrophysical Observatory. The preprint announcing the discovery was published on the arXiv eprint repository on April 11, 2018.^[8]

The 24 Boötis planetary system^[8]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥0.91+0.13 −0.10 MJ	0.190+0.012 −0.009	30.3506+0.0078 −0.0077	0.042+0.048 −0.029	—	—

References

1. Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
2. Niedzielski, A.; et al. (January 2016), "The Penn State - Toruń Centre for Astronomy Planet Search stars", Astronomy & Astrophysics, 585: 14, arXiv:1407.4956, Bibcode:2016A&A...585A..73N, doi:10.1051/0004-6361/201527362, A73
3. Keenan, Philip C.; McNeil, Raymond C. (1989), "The Perkins catalog of revised MK types for the cooler stars", Astrophysical Journal Supplement Series, 71: 245, Bibcode:1989ApJS...71..245K, doi:10.1086/191373.
4. Karovicova, I.; White, T. R.; Nordlander, T.; Casagrande, L.; Ireland, M.; Huber, D.; Jofré, P. (2020-08-01). "Fundamental stellar parameters of benchmark stars from CHARA interferometry - I. Metal-poor stars". Astronomy & Astrophysics. 640: A25. arXiv:2006.05411. Bibcode:2020A&A...640A..25K. doi:10.1051/0004-6361/202037590. ISSN 0004-6361.
5. "g Boo". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-02-09.
6. Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
7. Pakhomov, Yu. V. (February 2012), "Chemical composition of the atmospheres of red giants with high space velocities", Astronomy Letters, 38 (2): 101−116, arXiv:1312.3195, Bibcode:2012AstL...38..101P, doi:10.1134/S1063773712020053, S2CID 119161642.
8. Takarada, Takuya; et al. (2018). "Planets around the evolved stars 24 Booties and γ Libra: A 30d-period planet and a double giant-planet system in possible 7:3 MMR". Publications of the Astronomical Society of Japan. 70 (4). arXiv:1804.04008. doi:10.1093/pasj/psy052. S2CID 119027104.

External links

• HR 5420
• Image 24 Boötis