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HD 130948

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HD 130948

The visual band light curve of HP Boötis, plotted from data published by Gaidos et al. (2000)[1]
Observation data
Epoch J2000      Equinox ICRS
Constellation Boötes[2]
Right ascension 14h 50m 15.8110s[3]
Declination +23° 54′ 42.634″[3]
Apparent magnitude (V) 5.99[4]
Characteristics
Evolutionary stage main sequence[3]
Spectral type F9 IV-V[5]
U−B color index +0.01[6]
B−V color index +0.576[4]
Variable type BY Dra[7]
Astrometry
Radial velocity (Rv)−1.5[8] km/s
Proper motion (μ) RA: +144.396 mas/yr[3]
Dec.: +31.661 mas/yr[3]
Parallax (π)54.9502±0.0343 mas[3]
Distance59.35 ± 0.04 ly
(18.20 ± 0.01 pc)
Absolute magnitude (MV)+4.56[2]
Orbit[9][a]
PrimaryHD 130948 A
NameHD 130948 BC
Period (P)308.3 (155.2–35,116.2) yr
Semi-major axis (a)47.2 (30.2–1,110) au
Eccentricity (e)0.83 (0–0.96)
Inclination (i)92.1 or 96.0, 91.0–105.1°
Longitude of the node (Ω)0, 103.0, 173.3, 87.2–124.0, 47.9–129.4°
Periastron epoch (T)2000 (41620 BC–87648)
Argument of periastron (ω)
(secondary)		0, 61.5, 295.1, 360, 0–360°
Orbit
PrimaryHD 130948 B
NameHD 130948 C
Period (P)10.010 ± 0.011[10] yr
Semi-major axis (a)2.226+0.014
−0.013 au[10]
Eccentricity (e)0.1627±0.0017[10]
Inclination (i)95.7±0.2[11]°
Longitude of the node (Ω)313.39±0.12[11]°
Periastron epoch (T)54,613±22 MJD[11]
Argument of periastron (ω)
(secondary)		244±3[11]°
Details
HD 130948 A
Mass1.02±0.05[12] M☉
Radius1.113±0.022[13] R☉
Luminosity1.273±0.007[13] L☉
Surface gravity (log g)4.33±0.03[13] cgs
Temperature5,812±57[13] K
Metallicity [Fe/H]−0.01±0.02[13] dex
Rotation8.1±0.4[14] days
Rotational velocity (v sin i)6.8±0.9[14] km/s
Age0.50±0.07[15] Gyr
HD 130948 B
Mass59.8±0.6[15] MJup
Radius1.00±0.01[15] RJup
Luminosity(1.349±0.031)×10−4[15] L☉
Surface gravity (log g)5.18±0.01[15] cgs
Temperature1,950±30[15] K
Age0.50±0.07[15] Gyr
HD 130948 C
Mass56.3±0.5[15] MJup
Radius0.98±0.02[15] RJup
Luminosity1.096+0.026
−0.024×10−4[15] L☉
Surface gravity (log g)5.16±0.01[15] cgs
Temperature1,870±30[15] K
Age0.50±0.07[15] Gyr
Other designations
HP Boötis, GJ 564, BD+24°2786, HD 130948, FK5 3172, HIP 72567, HR 5534, SAO 83553[6]
Database references
SIMBADdata

HD 130948 or HP Boötis is a variable star with 2 brown dwarfs in the constellation Boötes. With an apparent magnitude of 6.0, it is faintly visible to the naked eye under very good observing conditions. It has a stellar classification of G1V, which means it is a main sequence star with a mass and surface temperature that are similar to the Sun.

The estimated age of HD 130948 is similar to the Sun at 4.7 billion years (Gyr) old, but it has a lower proportion of elements (63%) other than hydrogen or helium. However, a separate study in 2009 gave a much younger age of 0.5±0.3 Gyr and a higher metallicity that is very similar to the Sun.[16] The younger age was favored in a 2019 study, based on coevality with the brown dwarf companions.[13] Evolutionary models suggest that it is just reaching the end of its main sequence life.[3]

Eric J. Gaidos et al. observed the star in 1998 and 1999, and discovered that it is a variable star.[17] It was given its variable star designation, HP Boötis, in 2006.[7]

In 2002, a pair of co-orbiting brown dwarfs were discovered in orbit around this star, named HD 130948 B and HD 130948 C. They were found using an adaptive optics instrument on the Gemini North 8m telescope in Hawaii.[18] The brown dwarfs are similar to each other, with masses of 59.8±0.6 MJ and 56.3±0.5 MJ, radii of 1.00±0.01 RJ and 0.98±0.03 RJ, and temperatures of 1,950±30 K and 1,870±30 K for HD 130948 B and HD 130948 C, respectively.[15] They orbit around each other with a period of 3,656 ± 4 days (10.010 ± 0.011 years), and the orbit around the primary star is poorly constrained due to insufficient orbital coverage, with an period in the order of centuries to dozens of thousand of years.[9]

The space velocity components of this star through the Milky Way galaxy are (U, V, W) = (−14.0, 14.7, −0.1).[19]

Notes

[edit]
  1. ↑ Values not shown as range represent the peak value(s). The three best-fitting orbits are given in Table 5 of the paper.

References

[edit]
  1. ↑ Gaidos, E. J.; Henry, G. W.; Henry, S. M. (August 2000). "Spectroscopy and Photometry of Nearby Young Solar Analogs". The Astronomical Journal. 120 (2): 1006–1013. Bibcode:2000AJ....120.1006G. doi:10.1086/301488. S2CID 16930014.
  2. 1 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.
  3. 1 2 3 4 5 6 7 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.
  4. 1 2 van Leeuwen, F. (November 2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.
  5. ↑ Gray, R. O.; Napier, M. G.; Winkler, L. I. (2001). "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars". The Astronomical Journal. 121 (4): 2148. Bibcode:2001AJ....121.2148G. doi:10.1086/319956.
  6. 1 2 "V* HP Boo -- Variable of BY Dra type". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2010-10-03.
  7. 1 2 Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (August 2006). "The 78th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 5721: 1–45. Bibcode:2006IBVS.5721....1K. Retrieved 6 December 2024.
  8. ↑ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". In Batten, Alan Henry; Heard, John Frederick (eds.). Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: International Astronomical Union. Bibcode:1967IAUS...30...57E.
  9. 1 2 Ginski, C.; Neuhäuser, R.; Mugrauer, M.; Schmidt, T. O. B.; Adam, C. (2013-07-03). "Orbital motion of the binary brown dwarf companions HD 130948 BC around their host star". Monthly Notices of the Royal Astronomical Society. 434 (1): 671–683. Bibcode:2013MNRAS.434..671G. doi:10.1093/mnras/stt1059. ISSN 0035-8711.
  10. 1 2 3 Dupuy, Trent J.; Liu, Michael C. (2017-08-01). "Individual Dynamical Masses of Ultracool Dwarfs". The Astrophysical Journal Supplement Series. 231 (2): 15. arXiv:1703.05775. Bibcode:2017ApJS..231...15D. doi:10.3847/1538-4365/aa5e4c. ISSN 0067-0049.
  11. 1 2 3 4 Dupuy, Trent J.; Liu, Michael C. (2011-06-01). "On the Distribution of Orbital Eccentricities for Very Low-mass Binaries". The Astrophysical Journal. 733 (2): 122. arXiv:1103.5744. Bibcode:2011ApJ...733..122D. doi:10.1088/0004-637X/733/2/122. ISSN 0004-637X.
  12. ↑ Llorente de Andrés, F.; Chavero, C.; de la Reza, R.; Roca-Fàbrega, S.; Cifuentes, C. (October 2021). "The evolution of lithium in FGK dwarf stars: The lithium-rotation connection and the Li desert". Astronomy & Astrophysics. 654: A137. arXiv:2108.05852. Bibcode:2021A&A...654A.137L. doi:10.1051/0004-6361/202141339. ISSN 0004-6361.
  13. 1 2 3 4 5 6 Soubiran, C.; Creevey, O. L.; Lagarde, N.; Brouillet, N.; Jofré, P.; Casamiquela, L.; Heiter, U.; Aguilera-Gómez, C.; Vitali, S.; Worley, C.; de Brito Silva, D. (February 2024). "Gaia FGK benchmark stars: Fundamental Teff and log g of the third version". Astronomy & Astrophysics. 682: A145. arXiv:2310.11302. Bibcode:2024A&A...682A.145S. doi:10.1051/0004-6361/202347136. ISSN 0004-6361.
  14. 1 2 Bowler, Brendan P.; Tran, Quang H.; Zhang, Zhoujian; Morgan, Marvin; Ashok, Katelyn B.; Blunt, Sarah; Bryan, Marta L.; Evans, Analis E.; Franson, Kyle; Huber, Daniel; Nagpal, Vighnesh; Wu, Ya-Lin; Zhou, Yifan (2023). "Rotation Periods, Inclinations, and Obliquities of Cool Stars Hosting Directly Imaged Substellar Companions: Spin-Orbit Misalignments Are Common". The Astronomical Journal. 165 (4): 164. arXiv:2301.04692. Bibcode:2023AJ....165..164B. doi:10.3847/1538-3881/acbd34.
  15. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Briesemeister, Zackery W.; Skemer, Andrew J.; Stone, Jordan M.; Barman, Travis S.; Hinz, Philip; Leisenring, Jarron; Skrutskie, Michael F.; Woodward, Charles E.; Spalding, Eckhart (2019-05-30). "High Spatial Resolution Thermal Infrared Spectroscopy with ALES: Resolved Spectra of the Benchmark Brown Dwarf Binary HD 130948BC". The Astronomical Journal. 157 (6): 244. arXiv:1904.07892. Bibcode:2019AJ....157..244B. doi:10.3847/1538-3881/ab1901. ISSN 1538-3881.
  16. ↑ Dupuy, Trent J.; Liu, Michael C.; Ireland, Michael J. (February 2009). "Dynamical Mass of the Substellar Benchmark Binary HD 130948BC". The Astrophysical Journal. 692 (1): 729–752. arXiv:0807.2450. Bibcode:2009ApJ...692..729D. doi:10.1088/0004-637X/692/1/729. S2CID 119237470.
  17. ↑ Gaidos, E. J.; Henry, G. W.; Henry, S. M. (August 2000). "Spectroscopy and Photometry of Nearby Young Solar Analogs". The Astronomical Journal. 120 (2): 1006–1013. Bibcode:2000AJ....120.1006G. doi:10.1086/301488.
  18. ↑ Potter, Daniel; Martín, Eduardo L.; Cushing, Michael C.; Baudoz, Pierre; Brandner, Wolfgang; Guyon, Olivier; Neuhäuser, Ralph (March 2002). "Hokupa'a-Gemini Discovery of Two Ultracool Companions to the Young Star HD 130948". The Astrophysical Journal. 567 (2): L133–L136. arXiv:astro-ph/0201431. Bibcode:2002ApJ...567L.133P. doi:10.1086/339999. S2CID 16249194.
  19. ↑ Chen, Y. Q.; Nissen, P. E.; Zhao, G.; Zhang, H. W.; Benoni, T. (February 2000). "Chemical composition of 90 F and G disk dwarfs". Astronomy and Astrophysics Supplement. 141 (3): 491–506. arXiv:astro-ph/9912342. Bibcode:2000A&AS..141..491C. doi:10.1051/aas:2000124. S2CID 16273589.
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