G 117-B15A
File:RYLMiLightCurve.png A light curve for RY Leonis Minoris, plotted from data published by Chote et al. (2014)[1] | |
| Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
|---|---|
| Constellation | Leo Minor |
| Right ascension | Template:RA[2] |
| Declination | Template:DEC[2] |
| Apparent magnitude (V) | 15.5[3] |
| Characteristics | |
| Spectral type | DAV4[3] |
| U−B Template:Engvar | −0.6[3] |
| B−V Template:Engvar | +0.2[3] |
| Variable type | DAV[3] |
| Astrometry | |
| Proper motion (μ) | RA: −145.181[2] mas/yr Dec.: −0.053[2] mas/yr |
| Parallax (π) | 17.3947±0.0452 mas[2] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | 11.79[4] |
| Details | |
| Mass | 0.69[4] Template:Solar mass |
| Surface gravity (log g) | 8.14[4] cgs |
| Temperature | Script error: No such module "val".[5] K |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist | |
| Database references | |
| SIMBAD | data |
Script error: No such module "Check for unknown parameters".
G117-B15A[6] is a small, well-observed variable white dwarf star of the DAV, or ZZ Ceti, type in the constellation of Leo Minor.
G117-B15A was found to be variable in 1974 by Richer and Ulrych,[7] and this was confirmed in 1976 by McGraw and Robinson.[8] In 1984 it was demonstrated that the star's variability is due to nonradial gravity wave pulsations. As a consequence, its timescale for period change is directly proportional to its cooling timescale, allowing its cooling rate to be measured using astroseismological techniques.[6] Its age is estimated at 400 million years.[9] Its light curve has a dominant period of 215.2 seconds,[6] which is estimated to increase by approximately one second each 14 million years.[10] G117-B15A has been claimed to be the most stable optical clock ever found, much more stable than the ticks of an atomic clock.[11] It is also the first pulsating white dwarf to have its main pulsation mode index identified.[6]
An X-ray source in the constellation Leo Minor is the white dwarf G117-B15A.[12]
Notes
<templatestyles src="Reflist/styles.css" />
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b c d e Template:Cite Gaia DR3
- ↑ a b c d e Script error: No such module "Citation/CS1". CDS ID III/210.
- ↑ a b c Script error: No such module "Citation/CS1".
- ↑ Script error: No such module "Citation/CS1".
- ↑ a b c d Script error: No such module "Citation/CS1".
- ↑ High-frequency optical variables. II. Luminosity-variable white dwarfs and maximum entropy spectral analysis, H. B. Richer and T. J. Ulrych, Astrophysical Journal 192 (September 1974), pp. 719–730.
- ↑ High-speed photometry of luminosity-variable DA dwarfs: R808, GD 99, and G 117-B15A, J. T. McGraw and E. L. Robinson, Astrophysical Journal 205 (May 1976), pp. L155–L158.
- ↑ Script error: No such module "citation/CS1".
- ↑ From Ṗ=2.3·10−15 in Kepler et al.
- ↑ Script error: No such module "citation/CS1".Script error: No such module "Unsubst".
- ↑ Script error: No such module "citation/CS1".
<ref> tag with name "simbad" defined in <references> is not used in prior text.Script error: No such module "Check for unknown parameters".