HD 148427, formally named Timir,[2] is a 7th-magnitude K-type subgiant star approximately 193 light years away in the constellation Ophiuchus. Its mass is 45% greater than the Sun, and it is three times the size and six times more luminous, although its age is 2½ billion years.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 16h 28m 28.151s[1] |
| Declination | –13° 23′ 58.69″[1] |
| Apparent magnitude (V) | 6.903 |
| Characteristics | |
| Spectral type | K0IV |
| Apparent magnitude (B) | 7.839 |
| Apparent magnitude (J) | 5.299 |
| Apparent magnitude (H) | 4.875 |
| Apparent magnitude (K) | 4.682 |
| B−V color index | 0.936 |
| Astrometry | |
| Proper motion (μ) | RA: –37.74 ± 0.76[1] mas/yr Dec.: 2.81 ± 0.51[1] mas/yr |
| Parallax (π) | 16.94 ± 0.60 mas[1] |
| Distance | 193 ± 7 ly (59 ± 2 pc) |
| Absolute magnitude (MV) | 3.039 |
| Orbit | |
| Primary | HD 148427 |
| Companion | HD 148427 b |
| Period (P) | 331.5 ± 3.0 d (0.9076 yr) |
| Semi-major axis (a) | 0.93 ± 0.01 AU |
| Eccentricity (e) | 0.16 ± 0.08 |
| Inclination (i) | 0.5120+0.1635 −0.1082° |
| Details | |
| HD 148427 | |
| Mass | 1.45 ± 0.06 M☉ |
| Radius | 3.22 ± 0.2 R☉ |
| Luminosity | 6.06 L☉ |
| Surface gravity (log g) | 3.75 cgs |
| Temperature | 5052 ± 44 K |
| Metallicity [Fe/H] | 0.154 ± 0.04 dex |
| Age | 2.5 Gyr |
| HD 148427 b | |
| Mass | 136.5+37.2 −33.7 MJup |
| Other designations | |
| HD 148427: Timir | |
| HD 148427 b: Tondra | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Brown dwarf/red dwarf companion
editIn August 2009, it was found to have a companion in orbit (HD 148427 b or Tondra) with a minimum mass of 0.96 MJ and an orbital period of 331.5 days.[3] In 2020, this object's inclination was measured, revealing its true mass to be between 27 and 345 MJ. This makes it either a brown dwarf or a low-mass red dwarf star.[4]
Naming
editHD 148427, and HD 148427 b (thought at the time to be an exoplanet), were chosen as part of the 2019 NameExoWorlds campaign organised by the International Astronomical Union, which assigned each country a star and planet to be named. HD 148427 was assigned to Bangladesh. The winning name for the star was Timir meaning darkness in the Bengali language, alluding to the star being far away in the darkness of space. The winning name for the companion was Tondra meaning nap in the Bengali language, alluding to the symbolic notion that the object was asleep until discovered.[5]
See also
editReferences
edit- ^ a b c d e van Leeuwen, F. (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.Vizier catalog entry
- ^ "Naming of exoplanets". IAU. International Astronomical Union. Retrieved 26 January 2022.
- ^ Fischer, Debra; et al. (2009). "Five planets and an independent confirmation of HD 196885 Ab from Lick Observatory". The Astrophysical Journal. 703 (2): 1545–1556. arXiv:0908.1596. Bibcode:2009ApJ...703.1545F. doi:10.1088/0004-637X/703/2/1545. S2CID 15524804.
- ^ Kiefer, F.; et al. (January 2021). "Determining the true mass of radial-velocity exoplanets with Gaia. Nine planet candidates in the brown dwarf or stellar regime and 27 confirmed planets". Astronomy & Astrophysics. 645 A7. arXiv:2009.14164. Bibcode:2021A&A...645A...7K. doi:10.1051/0004-6361/202039168. S2CID 221995447.
- ^ "Naming of Exoplanets". IAU. International Astronomical Union. Retrieved 26 January 2022.
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