Ross 248
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Andromeda |
| Right ascension | 23h 41m 54.99s |
| Declination | +44° 10′ 40.8″ |
| Apparent magnitude (V) | 12.29 |
| Characteristics | |
| Spectral type | M6 V |
| Apparent magnitude (J) | 12.3 |
| U−B color index | +1.48 |
| B−V color index | +1.92 |
| Variable type | Flare star |
| Astrometry | |
| Radial velocity (Rv) | –81 km/s |
| Proper motion (μ) |
RA: +111 mas/yr Dec.: –1,584 mas/yr |
| Parallax (π) | 316.72 ± 0.72mas |
| Distance | 10.30 ± 0.02 ly (3.157 ± 0.007 pc) |
| Absolute magnitude (MV) | 14.79 |
| Details | |
| Mass | 0.136 M☉ |
| Radius | 0.16 R☉ |
| Luminosity | 0.0018 L☉ |
| Surface gravity (log g) | 5.12 cgs |
| Temperature | 2,799 K |
| Rotational velocity (v sin i) | 1.2 km/s |
| Other designations | |
| Database references | |
| SIMBAD | data |
Ross 248, also called HH Andromedae or Gliese 905, is a small star located approximately 10.30 light-years (3.16 parsecs) from Earth in the northern constellation of Andromeda. Despite its proximity to the Earth, this star is too dim to be seen with the naked eye. Ross 248 was first catalogued by Frank Elmore Ross in 1926 with his second list of proper motion stars.
This star has about 12% of the Sun's mass and 16% of the Sun's radius, but only 0.2% of the Sun's luminosity. It has a stellar classification of M6 V, which indicates it is a type of main sequence star known as a red dwarf. This is a flare star that occasionally increases in luminosity. With high probability there appears to be a long-term cycle of variability with a period of 4.20 years. This variability causes the star to range in visual magnitude from 12.23 to 12.34. In 1950, this became the first star to have a small variation in magnitude attributed to spots on its photosphere.
Long term observations of this star by the Sproul Observatory show no astrometric perturbations by an unseen companion. The proper motion of this star was examined for a brown dwarf or stellar companion orbiting at a wide separation (between 100–1400 AU) but none was found. A search for a faint companion using the Hubble Space Telescope Wide Field Planetary Camera revealed nothing, nor did a search with near-infrared speckle interferometry.
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