| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lupus[1] |
| Right ascension | 15h 20m 13.3930s[2] |
| Declination | −34° 55′ 31.574″[2] |
| Apparent magnitude (V) | +7.76±0.01[3] |
| Characteristics | |
| Spectral type | A2V (A)[4] M6-L2 (Ab)[5] |
| B−V color index | 0.175±0.015[1] |
| Astrometry | |
| Proper motion (μ) | RA: −22.631 mas/yr[2] Dec.: −25.861 mas/yr[2] |
| Parallax (π) | 8.2024±0.0401 mas[2] |
| Distance | 398 ± 2 ly (121.9 ± 0.6 pc) |
| Absolute magnitude (MV) | +2.05[1] |
| Position (relative to A)[5] | |
| Component | B |
| Angular distance | 5.159±0.003″ |
| Position angle | 33.0±0.2° |
| Projected separation | 650 AU |
| Orbit[6] | |
| Primary | A |
| Companion | Ab |
| Period (P) | 130[5] yr |
| Semi-major axis (a) | 22.48+1.15 −1.03 au |
| Eccentricity (e) | 0.44±0.03 |
| Inclination (i) | 11.5+4.6 −5.2° |
| Longitude of the node (Ω) | 75+27 −25° |
| Periastron epoch (T) | 2023.67+0.36 −0.21 |
| Argument of periastron (ω) (secondary) | 128+25 −30° |
| Details | |
| A | |
| Mass | 1.87±0.07[6] M☉ |
| Radius | 1.66+0.13 −0.15[7] R☉ |
| Luminosity | 12.65[1] L☉ |
| Surface gravity (log g) | 4.2[6] cgs |
| Temperature | 8,100[6] K |
| Metallicity [Fe/H] | −0.07+0.11 −0.13[7] dex |
| Age | 16±2[6] Myr |
| Ab | |
| Mass | 35±10[6] MJup |
| Radius | 1.9[6] RJup |
| Luminosity | 2.09+0.42 −0.23×10−3[6] L☉ |
| Surface gravity (log g) | 4.35[6] cgs |
| Temperature | 2,640[6] K |
| Metallicity [Fe/H] | +0.39[6] dex |
| Age | 16±2[6] Myr |
| B | |
| Mass | 0.30[8] M☉ |
| Age | 16±2[6] Myr |
| Other designations | |
| CD−34°10322, HD 136164, HIP 75056, TYC 7321-201-1[9] | |
| Database references | |
| SIMBAD | data |
HD 136164, also known as HIP 75056, is a binary star system in the constellation Lupus. At an apparent magnitude of +7.76, it is far too faint to be visible to the naked eye. Parallax measurements give a distance of 398 light-years (121.9 parsecs). The primary is orbited by a brown dwarf.
Characteristics
[edit]This is a visual binary system whose components, as of 2015[update], are separated by 5.195" in the sky, translating to a projected separation of 650 astronomical units. The orbital period is estimated at 8,000 years.[5] The system is 16 million years old and is part of the Upper–Centaurus–Lupus stellar association.[6]
The primary component, HD 136164 A, has a spectrum matching a spectral class of A2V,[4] with the luminosity class 'V' indicating it is a main sequence star fusing atoms of hydrogen into helium at its core. The star has 1.87 times the mass[6] and 1.66 times the radius of the Sun.[7] It radiates 12.65 times the Sun's luminosity from its photosphere[1] at an effective temperature of 8,100 K.[6] This temperature gives it the white hue typical of an A-type stars.[10]
The secondary has a mass of 0.30 M☉.[8]
Substellar companion
[edit]The primary star is orbited by a brown dwarf named HD 136164 Ab or HIP 75056 Ab. It was first discovered in 2020 through direct imaging.[5] The companion orbits at a semi-major axis of 22.5 astronomical units, has a mild eccentricity,[6] and takes roughly 130 years to circle the host star.[5] Relative to Earth, the orbit is nearly face-on, with an inclination less than 35°.[6]
Based on observations of the brown dwarf's orbit using both relative and absolute astrometry, its mass is measured at 35±10 Jupiter masses. Comparing its spectrum to atmospheric models retrieve a radius of 1.9 RJ and an effective temperature of 2,640 K. The luminosity is estimated at 10−2.68+0.08
−0.05 L☉ from evolutionary models. The carbon-to-oxygen abundance ratio and relatively high eccentricity of the orbit suggest that the companion formed like a failed star, either via fragmentation of the circumstellar disk or via fragmentation of a molecular cloud.[6]
References
[edit]- ^ a b c d e 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. XHIP record for this object at VizieR.
- ^ a b c d 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.
- ^ Høg, E.; Fabricius, C.; Makarov, V. V.; Urban, S.; Corbin, T.; Wycoff, G.; Bastian, U.; Schwekendiek, P.; Wicenec, A. (March 2000). "The Tycho-2 catalogue of the 2.5 million brightest stars". Astronomy and Astrophysics. 355: L27–L30. Bibcode:2000A&A...355L..27H. ISSN 0004-6361.
- ^ a b Houk, N. (1982). Michigan Catalogue of Two-dimensional Spectral Types for the HD stars. Volume_3. Declinations -40_ƒ0 to -26_ƒ0. Bibcode:1982mcts.book.....H.
- ^ a b c d e f Wagner, Kevin; Apai, Dániel; Kasper, Markus; McClure, Melissa; Robberto, Massimo; Currie, Thayne (2020-10-01). "Direct Imaging Discovery of a Young Brown Dwarf Companion to an A2V Star". The Astrophysical Journal Letters. 902 (1): L6. Bibcode:2020ApJ...902L...6W. doi:10.3847/2041-8213/abb94e. ISSN 2041-8205.
- ^ a b c d e f g h i j k l m n o p q r s =Balmer, William O.; Pueyo, L.; Lacour, S.; Wang, J. J.; Stolker, T.; Kammerer, J.; Pourré, N.; Nowak, M.; Rickman, E.; Blunt, S.; Sivaramakrishnan, A.; Sing, D.; Wagner, K.; Marleau, G.-D.; Lagrange, A.-M. (2024-02-01). "VLTI/GRAVITY Provides Evidence the Young, Substellar Companion HD 136164 Ab Formed Like a "Failed Star"". The Astronomical Journal. 167 (2): 64. Bibcode:2024AJ....167...64B. doi:10.3847/1538-3881/ad1689. ISSN 0004-6256.
- ^ a b c Bochanski, John J.; Faherty, Jacqueline K.; Gagné, Jonathan; Nelson, Olivia; Coker, Kristina; Smithka, Iliya; Desir, Deion; Vasquez, Chelsea (April 2018). "Fundamental Properties of Co-moving Stars Observed by Gaia". The Astronomical Journal. 155 (4): 149. arXiv:1801.00537. Bibcode:2018AJ....155..149B. doi:10.3847/1538-3881/aaaebe. ISSN 0004-6256.
- ^ a b Kouwenhoven, M. B. N.; Brown, A. G. A.; Portegies Zwart, S. F.; Kaper, L. (October 2007). "The primordial binary population. II.: Recovering the binary population for intermediate mass stars in Scorpius OB2". Astronomy & Astrophysics. 474 (1): 77–104. Bibcode:2007A&A...474...77K. doi:10.1051/0004-6361:20077719. ISSN 0004-6361.
- ^ "HIP 75056". SIMBAD. Centre de données astronomiques de Strasbourg.
- ^ "The Colour of Stars". Australia Telescope, Outreach and Education. Commonwealth Scientific and Industrial Research Organisation. December 21, 2004. Archived from the original on 2013-12-03. Retrieved 2012-01-16.
