HD 130458

HD 130458 (HR 5520) is a double star^[17] in the southern circumpolar constellation of Apus. The pair has a combined apparent magnitude of 5.8,^[6] making it faintly visible to the naked eye under ideal conditions. Parallax measurements place the system 310-24 light years away^[1] and it is receding with a heliocentric radial velocity of 31.4 km/s.^[7]

HD 130458

Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Apus
A
Right ascension	14h 53m 13.6598s[1]
Declination	−73° 11′ 23.837″[1]
Apparent magnitude (V)	5.77±0.01[2]
B
Right ascension	14h 53m 14.0752s[3]
Declination	−73° 11′ 25.2484″[3]
Apparent magnitude (V)	7.54±0.01[2]
Characteristics
A
Evolutionary stage	Horizontal branch[4]
Spectral type	G7 IIIa[5] (G8 IIb)[4]
U−B color index	+0.42[6]
B−V color index	+0.82[6]
B
Spectral type	F9 IV[5]
Astrometry
Radial velocity (Rv)	+31.4 ± 2.5[7] km/s
Absolute magnitude (MV)	+0.58[8]
A
Proper motion (μ)	RA: +15.901[1] mas/yr Dec.: +28.871[1] mas/yr
Parallax (π)	10.5077 ± 0.3522 mas[1]
Distance	310 ± 10 ly (95 ± 3 pc)
B
Proper motion (μ)	RA: +20.669[3] mas/yr Dec.: +19.875[3] mas/yr
Parallax (π)	10.0654 ± 0.0476 mas[3]
Distance	324 ± 2 ly (99.4 ± 0.5 pc)
Details
A
Mass	1.5[9] M☉
Radius	8.87[10] R☉
Luminosity	54.7[11] L☉
Surface gravity (log g)	2.65[9] cgs
Temperature	5194±124[10] K
Metallicity [Fe/H]	−0.17[9] dex
Rotational velocity (v sin i)	3.6±1[12] km/s
B
Mass	1.41[9] M☉
Radius	2.8[13] R☉
Luminosity	7.5[14] L☉
Surface gravity (log g)	3.96[9] cgs
Temperature	6,601[9] K
Metallicity [Fe/H]	−0.18[9] dex
Other designations
17 G. Apodis[15], CPD−72°1604, GC 19976, HD 130458, HIP 72833, HR 5520, SAO 257206, WDS J14532-7311AB[16]
Database references
SIMBAD	data

The primary is a red giant with a stellar classification of G7 IIIa. It was earlier classified as G8 IIb, indicating a bright giant.The dimmer component has a stellar classification of F9 IV, indicating that it is an F-type subgiant evolving onto the red giant branch. As of 2008, the pair has an angular separation of 2.167″.^[17]

At present the primary has 1.5 times the mass of the Sun^[9] but has expanded to 8.9^[10] times its girth. It radiates at 55^[11] times the luminosity of the Sun from its enlarged photosphere at an effective temperature 5,194 K,^[10] which gives it a yellow glow. Currently it spins leisurely with a projected rotational velocity of 3.6 km/s,^[12] common for giants. HD 130458A is believed to be on the horizontal branch.^[4]

As for the secondary component, it has 1.4 times the mass of the Sun and an effective temperature of 6,601 K, giving a yellowish white hue.^[9]

References

1. 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.
2. Fabricius, C.; Høg, E.; Makarov, V. V.; Mason, B. D.; Wycoff, G. L.; Urban, S. E. (March 2002). "The Tycho double star catalogue". Astronomy & Astrophysics. 384 (1): 180–189. Bibcode:2002A&A...384..180F. doi:10.1051/0004-6361:20011822. ISSN 0004-6361.
3. 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.
4. Corbally, C. J.; Garrison, R. F. (August 1980). "New Spectral Classifications on the MK System for Visual Double Stars". Publications of the Astronomical Society of the Pacific. 92: 493. Bibcode:1980PASP...92..493C. doi:10.1086/130700. eISSN 1538-3873. ISSN 0004-6280.
5. Corbally, C. J. (August 1984). "Close visual binaries. I - MK classifications". The Astrophysical Journal Supplement Series. 55: 657. Bibcode:1984ApJS...55..657C. doi:10.1086/190973. eISSN 1538-4365. ISSN 0067-0049.
6. Johnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars", Communications of the Lunar and Planetary Laboratory, 4 (99): 99, Bibcode:1966CoLPL...4...99J
7. Gontcharov, G. A. (November 2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. arXiv:1606.08053. Bibcode:2006AstL...32..759G. doi:10.1134/S1063773706110065. ISSN 1063-7737. S2CID 119231169.
8. Anderson, E.; Francis, Ch. (May 2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331–346. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. ISSN 1063-7737. S2CID 255204555.
9. Anders, F.; et al. (August 2019). "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18". Astronomy & Astrophysics. 628: A94. arXiv:1904.11302. Bibcode:2019A&A...628A..94A. doi:10.1051/0004-6361/201935765. ISSN 0004-6361.
10. Stassun, Keivan G.; et al. (9 September 2019). "The Revised TESS Input Catalog and Candidate Target List". The Astronomical Journal. 158 (4): 138. arXiv:1905.10694. Bibcode:2019AJ....158..138S. doi:10.3847/1538-3881/ab3467. ISSN 0004-6256.
11. McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (21 November 2012). "Fundamental parameters and infrared excesses of Hipparcos stars: Parameters and IR excesses from Hipparcos". Monthly Notices of the Royal Astronomical Society. 427 (1): 343–357. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x. ISSN 0035-8711.
12. De Medeiros, J. R.; Da Silva, J. R. P.; Maia, M. R. G. (20 October 2002). "The Rotation of Binary Systems with Evolved Components". The Astrophysical Journal. 578 (2): 943–950. arXiv:astro-ph/0207288. Bibcode:2002ApJ...578..943D. doi:10.1086/342613. eISSN 1538-4357. ISSN 0004-637X.
13. Montalto, M.; et al. (2021). "The all-sky PLATO input catalogue". Astronomy and Astrophysics. 653: A98. arXiv:2108.13712. Bibcode:2021A&A...653A..98M. doi:10.1051/0004-6361/202140717. S2CID 237363915.
14. 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.
15. Gould, Benjamin Apthorp (1878). "Uranometria Argentina : brillantez y posicion de las estrellas fijas, hasta la septima magnitud, comprendidas dentro de cien grados del polo austral : con atlas". Resultados del Observatorio Nacional Argentino. 1. Bibcode:1879RNAO....1.....G.
16. "HR+5520". SIMBAD. Centre de données astronomiques de Strasbourg.
17. 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.

External links

• Image HD 130458