HD 148427
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Ophiuchus[1] |
| Right ascension | 16h 28m 28.1512s[2] |
| Declination | −13° 23′ 58.690″[2] |
| Apparent magnitude (V) | 6.89[1] |
| Characteristics | |
| Spectral type | K0III/IV[1] |
| Apparent magnitude (B) | 7.840[1] |
| Apparent magnitude (J) | 5.299[1] |
| Apparent magnitude (H) | 4.875[1] |
| Apparent magnitude (K) | 4.682[1] |
| B−V color index | 0.950[1] |
| Astrometry | |
| Radial velocity (Rv) | −34.76±0.12[2] km/s |
| Proper motion (μ) | RA: −37.413 mas/yr[2] Dec.: +3.049 mas/yr[2] |
| Parallax (π) | 14.2059±0.0206 mas[2] |
| Distance | 229.6 ± 0.3 ly (70.4 ± 0.1 pc) |
| Absolute magnitude (MV) | 3.04[1] |
| Details[3] | |
| Mass | 1.45±0.06 M☉ |
| Radius | 3.22±0.2 R☉ |
| Luminosity | 6.09±0.75 L☉ |
| Surface gravity (log g) | 3.59±0.10 cgs |
| Temperature | 5052±44 K |
| Metallicity [Fe/H] | +0.154±0.04 dex |
| Rotation | 55.7 days |
| Rotational velocity (v sin i) | 2.13±0.5 km/s |
| Age | 2.5 Gyr |
| Other designations | |
| Timir, BD−13°4437, HD 148427, HIP 80687, SAO 159932, PPM 231736 | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
HD 148427, formally named Timir,[4] is a 7th-magnitude star approximately 230 light-years away in the constellation Ophiuchus. It has a spectral type of K0III/IV, indicating a K-type star that is close to becoming a red giant. While some sources describe it as a subgiant,[3] stellar evolution models suggest it is already on the red giant branch.[2] Its mass is 45% greater than the Sun, and it is three times the size and six times more luminous, although its age is 2.5 billion years, younger than the Sun.[3]
Companion
In August 2009, it was found to have a companion in orbit (HD 148427 b or Tondra) with a minimum mass of 0.96 MJ, suggesting it is a gas giant planet, and an orbital period of 331.5 days.[3] An astrometric study in 2020 suggested that this object has a nearly face-on orbit, with a true mass between 27 and 345 MJ. This would make it either a brown dwarf or a low-mass red dwarf star, rather than a planet.[5] However, a 2026 study instead found an edge-on orbit, indicating a planetary mass. While this study's measurements are uncertain, they suggest the companion is likely substellar.[6]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b / Tondra | 1.2+0.2 −0.3 MJ |
1.11±0.06 | 331.9+1.9 −2.2 |
0.12+0.09 −0.08 |
90.2+30.5 −30.7° |
— |
Naming
HD 148427 and HD 148427 b 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.[7]
See also
References
- ^ a b c d e f g h i 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 e f 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.
- ^ a b c d 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.
- ^ "Naming of exoplanets". IAU. International Astronomical Union. Archived from the original on 11 April 2020. Retrieved 26 January 2022.
- ^ 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.
- ^ a b Piccinini, G.; Petralia, A.; et al. (January 2026). "True Masses using RV data with Hipparcos and Gaia Astrometry". Astronomy & Astrophysics. arXiv:2601.09401.
- ^ "Naming of Exoplanets". IAU. International Astronomical Union. Archived from the original on 10 January 2020. Retrieved 26 January 2022.
