56 Arietis
Star in the constellation Aries
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56 Arietis is a single,[13] variable star in the northern zodiac constellation of Aries. It has the variable star designation SX Arietis, while 56 Arietis is the Flamsteed designation. This object is visible to the naked eye as a faint, blue-white hued point of light with an apparent visual magnitude of about 5.8. The estimated distance to this star is approximately 415 light-years (127 parsecs), based on parallax,[2] and it is drifting further away with a radial velocity of +18 km/s.[6]
| Observation data Epoch J2000 Equinox ICRS | |
|---|---|
| Constellation | Aries |
| Right ascension | 03h 12m 14.2461s[2] |
| Declination | +27° 15′ 25.086″[2] |
| Apparent magnitude (V) | 5.75 – 5.81[3] |
| Characteristics | |
| Evolutionary stage | main sequence[2] |
| Spectral type | B9pSi[4] |
| U−B color index | −0.42[5] |
| B−V color index | −0.12[5] |
| Variable type | SX Ari[3] |
| Astrometry | |
| Radial velocity (Rv) | +18.0[6] km/s |
| Proper motion (μ) | RA: +11.899(94) mas/yr[2] Dec.: −18.294(88) mas/yr[2] |
| Parallax (π) | 7.8671±0.0651 mas[2] |
| Distance | 415 ± 3 ly (127 ± 1 pc) |
| Absolute magnitude (MV) | +0.25[7] |
| Details | |
| Mass | 3.2±0.3[8] M☉ |
| Radius | 2.38±0.20[8] R☉ |
| Luminosity | 138+24 −20[8] L☉ |
| Surface gravity (log g) | 3.97[9] cgs |
| Temperature | 12,800±300[8] K |
| Metallicity [Fe/H] | +0.45[10] dex |
| Rotation | 0.7278972 days[7] |
| Rotational velocity (v sin i) | 165±5[8] km/s |
| Age | 174[11] Myr |
| Other designations | |
| 56 Ari, SX Ari, BD+26°523, HD 19832, HIP 14893, HR 954, SAO 75788[12] | |
| Database references | |
| SIMBAD | data |
This is a magnetic, chemically peculiar star of the silicon type with a stellar classification of B9pSi,[4] and it has a rapid rotation period of 17.5 hours.[14] This period is increasing by about two seconds every hundred years.[15] The star displays evidence of a five year period for procession of its axis.[16] Sanford S. Provin discovered that 56 Arietis is a variable star in 1952, and reported the discovery in 1953.[17] It is the prototype of a class of variable stars known as SX Arietis variables, which are rotationally variable stars with strong magnetic fields. It ranges in brightness from 5.75 down to 5.81 with a cyclical period matching its rotation rate.[3]