Eta Delphini

Eta Delphini
Diagram showing star positions and boundaries of the Delphinus constellation and its surroundings
Location of η Delphini (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Delphinus
Right ascension 20h 33m 57.04099s[1]
Declination +13° 01′ 38.1437″[1]
Apparent magnitude (V) 5.38[2]
Characteristics
Spectral type A3 IVs[3]
U−B color index +0.05[2]
B−V color index +0.08[2]
Astrometry
Radial velocity (Rv)−25.00±4.2[4] km/s
Proper motion (μ) RA: +73.15[1] mas/yr
Dec.: +24.66[1] mas/yr
Parallax (π)13.81 ± 1.17 mas[1]
Distance240 ± 20 ly
(72 ± 6 pc)
Absolute magnitude (MV)+1.11[5]
Details
Mass2.12[6] M☉
Radius2.2[7] R☉
Luminosity35[8] L☉
Surface gravity (log g)4.38[6] cgs
Temperature9,355±318[6] K
Metallicity [Fe/H]+0.56[5] dex
Rotational velocity (v sin i)65[8] km/s
Age309[6] Myr
Other designations
η Del, 3 Del, BD+12° 4378, GC 28617, HD 195943, HIP 101483, HR 7858, SAO 106248[9]
Database references
SIMBADdata

Eta Delphini, Latinized from η Delphini, is a candidate astrometric binary[10] star system in the northern constellation of Delphinus. It has an apparent magnitude of about 5.4, meaning that it is faintly visible to the naked eye. Based upon a parallax measurement of 13.81[1] mas made by the Hipparcos spacecraft, this star is around 240 light years away from the Sun. It is advancing in general direction of the Earth with a radial velocity of −25 km/s.[4]

The stellar classification of the visible component is A3 IVs,[3] which matches an A-type subgiant star with narrow absorption lines.[11] It is a suspected chemically peculiar star[12] that is about 64.3%±9.2% of the way through its main sequence lifetime.[8] SIMBAD lists this star as a variable star,[9] although it is not catalogued as such in the GCVS.[13] It has more than double the mass[6] and radius[7] of the Sun, and is radiating 35[8] times the Sun's luminosity from its photosphere at an effective temperature of around 9,355 K.[6]

  1. ^ a b c d e f Cite error: The named reference vanLeeuwen2007 was invoked but never defined (see the help page).
  2. ^ a b c Cite error: The named reference Feinstein1974 was invoked but never defined (see the help page).
  3. ^ a b Cite error: The named reference Cowley1969 was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference Gontcharov2006 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  6. ^ a b c d e f Cite error: The named reference David2015 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference PasinettiFracassini2001 was invoked but never defined (see the help page).
  8. ^ a b c d Cite error: The named reference Zorec2012 was invoked but never defined (see the help page).
  9. ^ a b Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  10. ^ Cite error: The named reference Eggleton2008 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference Allen was invoked but never defined (see the help page).
  12. ^ Cite error: The named reference Renson2009 was invoked but never defined (see the help page).
  13. ^ Cite error: The named reference Samus2017 was invoked but never defined (see the help page).