HD 83953
Star in the constellation Hydra
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HD 83953 (I Hydrae) is a single,[10] blue-white hued star in the equatorial constellation of Hydra. It is visible to the naked eye, having an apparent visual magnitude of 4.76.[1] Based upon an annual parallax shift of 6.6 mas,[2] the distance to this star is estimated as 500 light years. It is moving further from Earth with a heliocentric radial velocity of +16 km/s.[5]
 | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra[1] |
| Right ascension | 09h 41m 17.00785s[2] |
| Declination | −23° 35′ 29.4325″[2] |
| Apparent magnitude (V) | 4.76[1] |
| Characteristics | |
| Evolutionary stage | main sequence[3] |
| Spectral type | B5 V[4] |
| B−V color index | −0.117±0.015[1] |
| Astrometry | |
| Radial velocity (Rv) | +16.05±1.5[5] km/s |
| Proper motion (μ) | RA: −29.969[2] mas/yr Dec.: +1.914[2] mas/yr |
| Parallax (π) | 6.5733±0.2851 mas[2] |
| Distance | 500 ± 20 ly (152 ± 7 pc) |
| Absolute magnitude (MV) | −1.19[1] |
| Details | |
| Mass | 4.57±0.08[6] M☉ |
| Radius | 4.00±0.08[7] R☉ |
| Luminosity | 708+60 −55[6] L☉ |
| Surface gravity (log g) | 2.54±0.03[7] cgs |
| Temperature | 15,000±150[7] K |
| Rotational velocity (v sin i) | 315[6][8] km/s |
| Other designations | |
| I Hya, BD−22°2684, HD 83953, HIP 47522, HR 3858, SAO 177840[9] | |
| Database references | |
| SIMBAD | data |
This is a B-type main-sequence star with a stellar classification of B5 V.[4] It has been known to be a Be star since 1926, when an Hβ emission line was discovered in the stellar spectrum by Mount Wilson Observatory.[11] This energy is coming from a circumstellar envelope of heated gas that has been expelled from the central star and formed a thin orbiting disk.[12] HD 83953 is spinning rapidly with a projected rotational velocity of 315 km/s, giving the star an oblate shape with an equatorial bulge that is 18% larger than the polar radius.[8]
HD 83953 has 4.6[6] times the mass of the Sun and 4.0[7] times the Sun's radius. It is radiating 708[6] times the Sun's luminosity from its photosphere at an effective temperature of 15,000 K.[7]