HD 240237
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cassiopeia |
| Right ascension | 23h 15m 42.22441s[1] |
| Declination | +58° 02′ 35.6705″[1] |
| Apparent magnitude (V) | 8.19[2] |
| Characteristics | |
| Spectral type | K2III[3] |
| B−V color index | 1.682±0.029[2] |
| Astrometry | |
| Radial velocity (Rv) | −24.82±0.04[1] km/s |
| Proper motion (μ) | RA: −0.203[1] mas/yr Dec.: −4.290[1] mas/yr |
| Parallax (π) | 1.0437 ± 0.0364 mas[1] |
| Distance | 3,100 ± 100 ly (960 ± 30 pc) |
| Details | |
| Mass | 1.69±0.42[3] or 0.61[4] M☉ |
| Radius | 78.13+7.31 −5.66[1] R☉ |
| Luminosity | 1,244±65[1] L☉ |
| Temperature | 3,878+148 −170[1] K |
| Metallicity [Fe/H] | −0.26±0.07[3] dex |
| Rotation | ≥ 1010 d[3] |
| Age | 270[3] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
HD 240237 is a star in the northern constellation of Cassiopeia.[5] It is an orange star that can be viewed with binoculars or a small telescope, but is too faint to be seen with the naked eye at an apparent visual magnitude of 8.19.[2] This object is located at a distance of approximately 3,100 light years away from the Sun based on parallax, but is drifting closer with a radial velocity of −25 km/s.[1]
This is an aging giant star with a stellar classification of K2III;[3] a star that has exhausted the supply of hydrogen at its core and expanded to 78 times the radius of the Sun.[1] S. Gettel and associates (2011) estimate the star is around 270 million years old with 1.7 times the mass of the Sun.[3] However, S. G. Sousa and associates found a much lower mass of 0.61 times the mass of the Sun.[4] It is radiating 1,244 times the Sun's luminosity from its enlarged photosphere at an effective temperature of 3,878 K.[1]
Planetary system
[edit]In 2011, Gettel et al. announced the discovery of a planet orbiting this star. They estimated a mass around 5 times that of Jupiter, with an orbital period of 2.042 years and a moderate eccentricity. Sousa et al. (2015) gave a much lower estimate of 1.53 MJ.[4] The designation b for this object, derives from the order of discovery. The designation of b is given to the first planet orbiting a given star, followed by the other lowercase letters of the alphabet.[6] In the case of HD 240237, there was only one planet, so only the letter b is used.
| Companion (in order from star) | Mass | Semimajor axis (AU) | Orbital period (days) | Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 5.3 MJ | 1.9 | 745.7±13.8 | 0.4±0.1 | — | — |
References
[edit]- ^ a b c d e f g h i j k l 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.
- ^ a b c 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. S2CID 119257644.
- ^ a b c d e f g h Gettel, S.; et al. (2011). "Substellar-Mass Companions to the K-Giants HD 240237, BD +48 738 and HD 96127". The Astrophysical Journal. 745 (1): 28. arXiv:1110.1641. Bibcode:2012ApJ...745...28G. doi:10.1088/0004-637X/745/1/28. S2CID 119116402.
- ^ a b c Sousa, S. G.; et al. (April 2015). "Homogeneous spectroscopic parameters for bright planet host stars from the northern hemisphere . The impact on stellar and planetary mass". Astronomy & Astrophysics. 576: 8. arXiv:1503.02443. Bibcode:2015A&A...576A..94S. doi:10.1051/0004-6361/201425227. S2CID 73575554. A94.
- ^ a b "HD 240237". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 7 June 2014.
- ^ Hessman, F. V.; et al. (2010). "On the naming convention used for multiple star systems and extrasolar planets". arXiv:1012.0707 [astro-ph.SR].
