MY Camelopardalis
Binary star system in the constellation Camelopardalis
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MY Camelopardalis (MY Cam) is a binary star system located in the Alicante 1 open cluster, some 13 kly (4.0 kpc) away in the constellation Camelopardalis. It is one of the most massive known binary star systems and a leading candidate for a massive star merger. MY Cam is the brightest star in Alicante 1.[1]
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Camelopardalis |
| Right ascension | 03h 59m 18.2863s[2] |
| Declination | +57° 14′ 13.673″[2] |
| Apparent magnitude (V) | 9.80 - 10.15[3] |
| Characteristics | |
| Spectral type | O6nn[4] (O6V((f)) + O6V((f))[5]) |
| U−B color index | −0.66[4] |
| B−V color index | +0.28[4] |
| Variable type | Ellipsoidal[3] |
| Astrometry | |
| Radial velocity (Rv) | −47[1] km/s |
| Proper motion (μ) | RA: −2.3[6] mas/yr Dec.: −0.3[6] mas/yr |
| Parallax (π) | 0.1333±0.0789 mas[7] |
| Distance | ~4,000[1] pc |
| Absolute magnitude (MV) | −4.1[4] |
| Orbit[1] | |
| Period (P) | 1.175 days |
| Semi-major axis (a) | 19.24 R☉ |
| Eccentricity (e) | 0 |
| Inclination (i) | 62.59° |
| Argument of periastron (ω) (secondary) | 90° |
| Argument of periastron (ω) (primary) | 270° |
| Semi-amplitude (K1) (primary) | 335 km/s |
| Semi-amplitude (K2) (secondary) | 400 km/s |
| Details[1] | |
| A | |
| Mass | 37.7 M☉ |
| Radius | 7.60 R☉ |
| Surface gravity (log g) | 4.251 cgs |
| Temperature | 42,000 ± 1,500 K |
| Rotational velocity (v sin i) | 290 km/s |
| B | |
| Mass | 31.6 M☉ |
| Radius | 7.01 R☉ |
| Surface gravity (log g) | 4.245 cgs |
| Temperature | 39,000 ± 1,500 K |
| Rotational velocity (v sin i) | 268 km/s |
| Other designations | |
| MY Camelopardalis, BD+56°864, Alicante 1 NM 693, 2MASS J03591829+5714137, Gaia DR2 469715181320008960, TYC 3725-498-1 | |
| Database references | |
| SIMBAD | data |
The system consists of two hot blue O-type stars with one component having a mass of 32 solar masses and the other 38 solar masses.
In 1998, the star was included in a list of suspected variable stars.[8] John Greaves and Patrick Wils proved that it is variable, in 2004.[9] It was given its variable star designation, MY Camelopardalis, in 2008.[10] MY Cam is a contact binary and eclipsing binary, with an orbital period of 1.2 days, and an orbital velocity of 1,000,000 km/h (280 km/s; 620,000 mph).[1] Both stars share a common envelope.[1]