ET Andromedae is a binary star system star in the northern constellation of Andromeda.[14] It has an apparent visual magnitude of 6.48,[3] placing it at the nominal limit for visibility with the naked eye. The distance to this system can be estimated from its annual parallax shift of 5.42 mas,[2] which yields a value of 602 light years.
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Andromeda |
Right ascension | 23h 17m 56.011185s[2] |
Declination | +45° 29′ 20.1197″[2] |
Apparent magnitude (V) | 6.48[3] |
Characteristics | |
Spectral type | A0 Vp SiSr[4] or B9p SI[5] |
B−V color index | −0.037±0.006[3] |
Variable type | α2 CVn |
Astrometry | |
Radial velocity (Rv) | −0.30±4.10[3] km/s |
Proper motion (μ) | RA: +24.740[2] mas/yr Dec.: −11.038[2] mas/yr |
Parallax (π) | 5.4200 ± 0.0572 mas[2] |
Distance | 602 ± 6 ly (185 ± 2 pc) |
Absolute magnitude (MV) | 0.58[6] |
Orbit[7] | |
Period (P) | 48.304±0.007 d |
Eccentricity (e) | 0.50±0.05 |
Periastron epoch (T) | 2443720.11±0.64 JD |
Argument of periastron (ω) (secondary) | 49.8±6.0° |
Semi-amplitude (K1) (primary) | 25.7±2.0 km/s |
Details | |
Mass | 3.25[8] M☉ |
Radius | 2.7[9] R☉ |
Luminosity | 91.06[3] L☉ |
Surface gravity (log g) | 3.81[10] cgs |
Temperature | 11,444[10] K |
Rotation | 1.62 d[11] |
Rotational velocity (v sin i) | 65[12] km/s |
Age | 284[6] Myr |
Other designations | |
Database references | |
SIMBAD | data |
Variations in the radial velocity of this star suggest it is a single-lined spectroscopic binary system. This yields orbital elements with a period of 48.3 days and an eccentricity of 0.50. The a sin i value for the primary is 14.8 Gm (0.099 AU), where a is the semimajor axis and i is the (unknown) orbital inclination.[7]
The visible component is a well-studied magnetic chemically peculiar star[15] with a stellar classification of A0 Vp SiSr.[4] The SiSr notation indicates unusual abundances of silicon and strontium in the spectrum. It has a magnetic field with an average surface value of 3.2 kT.[16] The abundance of silicon varies depending on the viewing angle.[15] The star is an Alpha2 Canum Venaticorum variable with a period of 1.618875 days.[17]