 Artist's conception of a flare explosion on EV Lacertae. | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lacerta |
| Right ascension | 22h 46m 49.73126s[1] |
| Declination | +44° 20′ 02.3744″[1] |
| Apparent magnitude (V) | 10.26[2] |
| Characteristics | |
| Spectral type | M3.5[3] |
| U−Bcolor index | +0.83[4] |
| B−Vcolor index | +1.36[4] |
| Variable type | Flare star |
| Astrometry | |
| Radial velocity (Rv) | −0.23±0.17[1] km/s |
| Proper motion (μ) | RA: –706.216mas/yr[1] Dec.: –458.920mas/yr[1] |
| Parallax (π) | 197.9573±0.0220 mas[1] |
| Distance | 16.476 ± 0.002 ly (5.0516 ± 0.0006 pc) |
| Details | |
| Mass | 0.32±0.008[5] M☉ |
| Radius | 0.331±0.013[5] R☉ |
| Temperature | 3370+75 −71[5] K |
| Metallicity [Fe/H] | –0.01 ± 0.17[6] dex |
| Rotation | 4.3715±0.0006 d[7] |
| Rotational velocity (v sin i) | 4.5[8] km/s |
| Other designations | |
| EV Lac,BD+43 4305,GJ 873,HIP 112460,LHS 3853,LTT 16695,PLX 5520[2] | |
| Database references | |
| SIMBAD | data |
  EV Location of EV Lacertae in the constellationLacerta | |
EV Lacertae (EV Lac, Gliese 873, HIP 112460) is a faintred dwarfstar 16.48light-years away in the constellationLacerta. It is the nearest star to theSun in that region of the sky, although with anapparent magnitude of 10, it is only barely visible withbinoculars. EV Lacertae is aspectral type M3.5flare star that emitsX-rays.[9]
On 25 April 2008,NASA'sSwift satellite picked up a record-settingflare from EV Lacertae.[11] This flare was thousands of times more powerful than the largest observed solar flare. Because EV Lacertae is much farther fromEarth than the Sun, the flare did not appear as bright as a solar flare. The flare would have been visible to the naked eye if the star had been in an observable part of the night sky at the time. It was the brightest flare ever seen from a star other than the Sun.
EV Lacertae is muchyounger than that of the Sun. Its age is estimated at 300 million years, and it is still spinning rapidly. The fastspin, together with itsconvective interior, produces amagnetic field much more powerful than that of the Sun. This strong magnetic field is believed to play a role in the star's ability to produce such bright flares.
In October 2022, another stellar flare was observed in EV Lacertae by a group of scientists led by Shun Inoue ofKyoto University, after observing the star innear-ultraviolet andwhite-light curves.[12] The finding was announced and detailed on December 31, 2023, in the pre-print serverarXiv.[12]
