| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Ophiuchus |
| Right ascension | 17h 31m 24.95413s[1] |
| Declination | −23° 57′ 45.5136″[1] |
| Apparent magnitude (V) | 4.81[2] |
| Characteristics | |
| Spectral type | B9.5IIIe[3] |
| U−Bcolor index | –0.06[2] |
| B−Vcolor index | +0.00[2] |
| Astrometry | |
| Radial velocity (Rv) | –12[4] km/s |
| Proper motion (μ) | RA: 5.24[1]mas/yr Dec.: −25.72[1]mas/yr |
| Parallax (π) | 8.04±0.24 mas[1] |
| Distance | 410 ± 10 ly (124 ± 4 pc) |
| Details | |
| Mass | 3.3±0.1[5] M☉ |
| Radius | 5.66±0.23[5] R☉ |
| Luminosity | 3.12[6] L☉ |
| Temperature | 9,772[6] K |
| Metallicity [Fe/H] | –0.25[6] dex |
| Rotational velocity (v sin i) | 267 ± 5[7] km/s |
| Age | 0.3[8] Myr |
| Other designations | |
| c Oph,51 Oph,CD–23° 13412,GC 23320,HD 158643,HIP 85755,HR 6519,SAO 185470[9] | |
| Database references | |
| SIMBAD | data |
51 Ophiuchi is a single[8]star located approximately 410[1] light years away from the Sun in theequatorialconstellation ofOphiuchus, northwest of the center of theMilky Way. It is visible to the naked eye as a faint, blue-white point of light with anapparent visual magnitude of 4.81.[2] The star is moving closer to the Earth with a heliocentricradial velocity of –12 km/s.[4]
This object is notable for being "a rare, nearby example of a young planetary system just entering the last phase of planet formation".[10] There is uncertainty about thestellar classification of this star. It has the nominal classification of B9.5IIIe, a B-type giant star withemission lines. However, it has also been classified as an A0 II-IIIe star and as aHerbig Ae/Be star.[11] 51 Ophiuchi is about 300,000[8] years old with 3.3 times themass of the Sun and a polar radius 5.7 times theSun's radius.[5] It is radiating three[6] times theSun's luminosity from itsphotosphere at aneffective temperature of 9,772 K.[6] The star is spinning rapidly with aprojected rotational velocity of 267 km/s,[7] close to the critical rotation rate.[5]
51 Ophiuchi has a disk of dust and gas that appears to be a youngdebris disk and is probably a planetary system in the late stages of formation. This system resemblesBeta Pictoris, a well known star with a large debris disk, in several ways: spectral type, the presence of an edge-on disk with both gas and dust, and the presence of variableblue-shifted absorption lines suggesting in-falling comets.[10][12]
The distance to 51 Ophiuchi is much greater than the distance toBeta Pictoris, and its debris disk is relatively compact. As a consequence, the disk around 51 Ophiuchi requires aninterferometer to resolve, in contrast to that of Beta Pictoris, which has been observed using visual spectrum imaging.[13] Recent observations of 51 Ophiuchi made with the Keck Interferometer Nuller at theW. M. Keck Observatory show that the disk has two components: a central cloud of large particles (exozodiacal dust) surrounded by a much larger cloud of smallsilicate particles extending to about 1,000astronomical units.[12] The inner disk has a radius approximately four times the distance between the sun and the Earth, with a density of around 100,000 times that of the dust in the Solar System.[10]
The spectra taken by 2020 have indicated the circumstellar disc is similar in composition to interstellar medium. The dominant species in atomic numbers are hydrogen, helium, oxygen, nitrogen, silicon and iron. Surprisingly, the disk was found to be strongly depleted of carbon and carbon monoxide.[14]
