Eta Cassiopeiae
Binary star system in the constellation Cassiopeia / From Wikipedia, the free encyclopedia
Dear Wikiwand AI, let's keep it short by simply answering these key questions:
Can you list the top facts and stats about Eta Cassiopeiae?
Summarize this article for a 10 year old
SHOW ALL QUESTIONS
Eta Cassiopeiae (η Cassiopeiae, abbreviated Eta Cas, η Cas) is a binary star system in the northern constellation of Cassiopeia. Its binary nature was first discovered by William Herschel in August 1779. Based upon parallax measurements, the distance to this system is 19.42 light-years (5.95 parsecs) from the Sun.[1] The two components are designated Eta Cassiopeiae A (officially named Achird /ˈeɪtʃərd/)[14] and B.
Quick Facts Observation data Epoch J2000 Equinox J2000, Constellation ...
Observation data Epoch J2000 Equinox J2000 | |
---|---|
Constellation | Cassiopeia |
Right ascension | 00h 49m 06.29070s[1] |
Declination | +57° 48′ 54.6758″[1] |
Apparent magnitude (V) | 3.44[2]/7.51[3] |
Characteristics | |
Spectral type | G0 V[4] + K7 V[3] |
U−B color index | +0.02[2]/1.03 |
B−V color index | +0.58[2]/1.39 |
Variable type | RS CVn?[5] |
Astrometry | |
A | |
Radial velocity (Rv) | +10.0 ± 0.1[6] km/s |
Proper motion (μ) | RA: 1,086.59[1] mas/yr Dec.: –559.43[1] mas/yr |
Parallax (π) | 168.8322 ± 0.1663 mas[7] |
Distance | 19.32 ± 0.02 ly (5.923 ± 0.006 pc) |
Absolute magnitude (MV) | 4.57[8] |
B | |
Proper motion (μ) | RA: 1144.693[9] mas/yr Dec.: –469.668[9] mas/yr |
Parallax (π) | 168.7186 ± 0.0216 mas[9] |
Distance | 19.331 ± 0.002 ly (5.9270 ± 0.0008 pc) |
Orbit[10] | |
Companion | Eta Cassiopeiae B |
Period (P) | 480 yr |
Semi-major axis (a) | 11.9939″ |
Eccentricity (e) | 0.497 |
Inclination (i) | 34.76° |
Longitude of the node (Ω) | 98.42° |
Periastron epoch (T) | 1889.6 |
Argument of periastron (ω) (secondary) | 88.59° |
Details | |
η Cas A | |
Mass | 0.972 ± 0.012[11] M☉ |
Radius | 1.0386 ± 0.0038[12] R☉ |
Luminosity | 1.2321 ± 0.0074[12] L☉ |
Temperature | 5,973 ± 8[12] K |
Metallicity [Fe/H] | –0.31[3] dex |
Rotational velocity (v sin i) | 3.15[4] km/s |
Age | 5.4 ± 0.9[11] Gyr |
η Cas B | |
Mass | 0.57 ± 0.07[3] M☉ |
Radius | 0.66[13] R☉ |
Luminosity | 0.06[3] L☉ |
Temperature | 4,036 ± 150[3] K |
Other designations | |
Database references | |
SIMBAD | The system |
A | |
B | |
Location of η Cassiopeiae in the constellation Cassiopeia |
Close