1 Delphini

1 Delphini
Location of 1 Delphini (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Delphinus
A
Right ascension 20h 30m 17.9623s[1]
Declination +10° 53′ 45.335″[1]
Apparent magnitude (V) 6.20±0.01[2]
B
Right ascension 20h 30m 17.9505s[3]
Declination +10° 53′ 46.244″[3]
Apparent magnitude (V) 8.00±0.01[2]
Characteristics
Spectral type A1:III shell[4]
U−B color index −0.11[5]
B−V color index −0.03[5]
Astrometry
Radial velocity (Rv)−15.5 ± 2[6] km/s
Absolute magnitude (MV)−0.69[7]
A
Proper motion (μ) RA: +19.320 mas/yr[1]
Dec.: +4.645 mas/yr[1]
Parallax (π)4.6400 ± 0.0616 mas[1]
Distance703 ± 9 ly
(216 ± 3 pc)
B
Proper motion (μ) RA: +19.545[3] mas/yr
Dec.: +4.710[3] mas/yr
Parallax (π)4.1851 ± 0.1421 mas[3]
Distance780 ± 30 ly
(239 ± 8 pc)
Details
A
Mass3.1±0.3[8] M☉
Surface gravity (log g)3.66±0.77[8] cgs
Temperature10,651+932
−1156[8] K
Metallicity [Fe/H]0.00[9] dex
Rotational velocity (v sin i)217[10] km/s
Age246[9] Myr
B
Surface gravity (log g)4.14+0.19
−0.47[8] cgs
Rotational velocity (v sin i)370[10] km/s
Other designations
1 Delphini, BD+10°4303, HD 195325, HIP 101160, HR 7836, SAO 106172, WDS J20303+1054AB
Database references
SIMBADdata

1 Delphini (1 Del) is the Flamsteed designation for a close binary star in the equatorial constellation Delphinus. With a combined apparent magnitude of 6.08, it is barely visible to the naked eye, even under ideal conditions. Parallax measurements put the components at a distance 703 and 780 light years respectively. However, its approaching the Solar System with a radial velocity of 15 km/s.

1 Del consists of three components. The brightest of them has a magnitude of 6.1; a companion located around 0.9 arcseconds from the primary has an apparent magnitude of 8.1; and a third star, located much farther away at around 17 arcseconds from component A, is the faintest with a magnitude of around 14 and is an unrelated background object.[11]

The entire system has a stellar classification of A1: III sh, indicating that it is a white giant + a shell star. However, there is some uncertainty about the temperature class. When resolved, the secondary has a class of B9. 1 Del A has 3 times the mass of the Sun and an effective temperature of 10,651 K,[8] giving it a bluish white glow. It is estimated to be almost 250 million years old and has a solar metallicity.[9] Both components spin rapidly, with projected rotational velocities of 217 and 370 km/s respectively.[10] As for the peculiarities, the shell star is a primary component; the spectrum of the secondary shows broad absorption lines.[10]

Due to the stability of the emission lines data from 1 Delphini has been used for developing models of shell stars and Be stars.[10]

  1. ^ a b c d Cite error: The named reference EDR3A was invoked but never defined (see the help page).
  2. ^ a b Cite error: The named reference Fabricius2002 was invoked but never defined (see the help page).
  3. ^ a b c d e Cite error: The named reference EDR3B was invoked but never defined (see the help page).
  4. ^ Cite error: The named reference Abt1995 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Ducati was invoked but never defined (see the help page).
  6. ^ Cite error: The named reference GCRV was invoked but never defined (see the help page).
  7. ^ Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
  8. ^ a b c d e Cite error: The named reference Anders2022 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Gontcharov2012 was invoked but never defined (see the help page).
  10. ^ a b c d e Cite error: The named reference kubat2016 was invoked but never defined (see the help page).
  11. ^ Cite error: The named reference EDR3C was invoked but never defined (see the help page).