HD 15115
F-type subgiant star in the constellation Cetus
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HD 15115 is a single[12] star in the equatorial constellation of Cetus. It is readily visible in binoculars or a small telescope, but is considered too dim to be seen with the naked eye at an apparent visual magnitude of 6.76.[3] The distance to this object is 159 light years based on parallax,[2] and it is slowly drifting further away at the rate of about 1 km/s.[6] It has been proposed as a member of the Beta Pictoris moving group[13] or the Tucana-Horologium association of co-moving stars; there is some ambiguity as to its true membership.[14]
Debris disk surrounding young star HD 15115 Credit: NASA, ESA, G. Schneider (University of Arizona), and the HST/GO 12228 Team | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cetus[1] |
| Right ascension | 02h 26m 16.24578s[2] |
| Declination | +06° 17′ 33.1865″[2] |
| Apparent magnitude (V) | 6.76[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | F4IV[4] or F2V[5] |
| U−B color index | −0.03[3] |
| B−V color index | +0.39[3] |
| Astrometry | |
| Radial velocity (Rv) | 0.81±0.12[6] km/s |
| Proper motion (μ) | RA: +88.013[2] mas/yr Dec.: −50.419[2] mas/yr |
| Parallax (π) | 20.5026±0.0293 mas[2] |
| Distance | 159.1 ± 0.2 ly (48.77 ± 0.07 pc) |
| Absolute magnitude (MV) | +3.52[1] |
| Details | |
| Mass | 1.19[7] M☉ |
| Radius | 1.39±0.06[8] R☉ |
| Luminosity | 3.74±0.01[8] L☉ |
| Surface gravity (log g) | 4.30[7] cgs |
| Temperature | 6,811+148 −152[8] K |
| Metallicity [Fe/H] | 0.96[7] dex |
| Rotational velocity (v sin i) | 89.8[9] km/s |
| Age | 500[10] Myr |
| Other designations | |
| BD+05°338, HD 15115, HIP 11360, SAO 110532, WDS J02263+0618A[11] | |
| Database references | |
| SIMBAD | data |
This object has a stellar classification of F4IV,[4] suggesting it is an aging subgiant star that has exhausted the supply of hydrogen at its core. MacGregor and associates (2015) instead classify it as a young F-type main-sequence star with a class of F2V.[5] Age estimates give a value of 500[10] million years, while membership in the β Pictoris moving group would indicate an age of around 21±4 million.[5] It has 1.19[7] times the mass of the Sun, 1.39[8] times the Sun's radius, and has a relatively high rate of spin with a projected rotational velocity of 90 km/s.[9] The star is radiating 3.74[8] times the luminosity of the Sun from its photosphere at an effective temperature of 6,811 K.[8] Its metallicity – the abundance of elements other than hydrogen and helium – is nearly the same as in the Sun.[7]
HD 15115 was shown to have an asymmetric debris disk surrounding it, which is being viewed nearly edge-on. The reason for the asymmetry is thought to be either the gravitational pull of a passing star (HIP 12545), an exoplanet, or interaction with the local interstellar medium.[15] A magnitude 11.35 visual companion lies at an angular separation of 12.6″ along a position angle of 195°, as of 2015.[13]