M33-013406.63, also known as B416 or UIT301,[4] is a O-type blue evolved supergiant star in the constellation of Triangulum. It is located within the Triangulum Galaxy, which is approximately 2,380,000–3,070,000 light years away from Earth.
M33-013406.63 (brightest star at the center) by Pan-STARRS Data Release 1 in blue, g, and r filters. Credit: NASA/UH-IfA | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Triangulum |
| Right ascension | 01h 34m 06.63s[1] |
| Declination | +30° 41′ 37.60″[1] |
| Apparent magnitude (V) | 16.1[2] |
| Characteristics | |
| Evolutionary stage | Late O supergiant or candidate LBV[3] |
| Spectral type | O[3] |
| Variable type | cLBV?[3] |
| Astrometry | |
| Absolute magnitude (MV) | –9.1 – –9.6[3] |
| Absolute bolometric magnitude (Mbol) | –12.2 – –12.7[3] |
| Details[2] | |
| A | |
| Radius | 80[a] R☉ |
| Luminosity | 4.68×106 L☉ |
| Temperature | ~30,000 K |
| Rotational velocity (v sin i) | 75±5 km/s |
| B | |
| Radius | 210[b] R☉ |
| Luminosity | 407,380 L☉ |
| Temperature | 10,000 K |
| Other designations | |
LGGS J013406.63+304147.8, B416 | |
| Database references | |
| SIMBAD | data |
It is potentially one of the most luminous stars ever discovered, estimated to be approximately between 3 and 10 million times more luminous than the Sun, although it is thought likely to be a multiple star system.[3] Modelling of the spectrum based on some assumptions about the relative sizes of the two stars suggests a secondary around half a million times as luminous as the Sun and the primary over four million times as luminous as the Sun.[2]
M33-013406.3 is embbed within a prominent ring shaped H II region, large regions of Ionized hydrogen clouds with lots of star formation occurring in them.[5][6] It is also near the center of the H II region its in and possible associated with the nebula's origin.[7]