Eta Delphini

Eta Delphini
	Location of η Delphini (circled)
Observation data; Epoch J2000.0 Equinox J2000.0 (ICRS)
Constellation	Delphinus
Right ascension	20h 33m 57.042s
Declination	+13° 01′ 37.934″
Apparent magnitude (V)	5.38
Characteristics
Evolutionary stage	main sequence
Spectral type	A3 IVs
U−B color index	+0.05
B−V color index	+0.08
Variable type	Constant
Astrometry
Radial velocity (Rv)	−25.00±4.2 km/s
Proper motion (μ)	RA: +69.654 mas/yr ; Dec.: +39.707 mas/yr
Parallax (π)	18.1436±0.4530 mas
Distance	180 ± 4 ly ; (55 ± 1 pc)
Absolute magnitude (MV)	+1.11
Details
Mass	2.12 M☉
Radius	1.43 R☉
Luminosity	11.5 L☉
Surface gravity (log g)	4.38 cgs
Temperature	9,355±318 K
Metallicity [Fe/H]	+0.56 dex
Rotational velocity (v sin i)	65 km/s
Age	309 Myr
Other designations
	η Del, 3 Del, BD+12°4378, GC 28617, HD 195943, HIP 101483, HR 7858, SAO 106248
Database references
SIMBAD	data

Eta Delphini is a candidate astrometric binary star system in the northern constellation of Delphinus. Its name is a Bayer designation that is Latinized from η Delphini and abbreviated η Del or η Del. This system has a combined apparent visual magnitude of about 5.4, meaning that it is faintly visible to the naked eye as a point of light. Based upon a parallax measurement of 18.14 mas, this star is around 180 light-years (55 pc) distance from the Sun. It is drifting closer with a radial velocity of −25 km/s.

The stellar classification of the visible component is A3 IVs, which matches an A-type subgiant star with narrow absorption lines. It is a suspected chemically peculiar star that is about 64.3%±9.2% of the way through its main sequence lifetime. It has more than double the mass and radius of the Sun, and is radiating 11.5 times the Sun's luminosity from its photosphere at an effective temperature of around 9,355 K.

References

1 2 3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.
1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023), "Gaia Data Release 3. Summary of the content and survey properties", Astronomy and Astrophysics, 674: A1, arXiv:2208.00211, Bibcode:2023A&A...674A...1G, doi:10.1051/0004-6361/202243940, S2CID 244398875. Gaia DR3 record for this source at VizieR.
1 2 3 Feinstein, A. (1974), "Photoelectric UBVRI observations of AM stars", Astronomical Journal, 79: 1290, Bibcode:1974AJ.....79.1290F, doi:10.1086/111675.
1 2 3 Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.
1 2 Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.
1 2 Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
1 2 3 4 5 6 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
1 2 3 4 Stassun, Keivan G.; et al. (2019), "The Revised TESS Input Catalog and Candidate Target List", The Astronomical Journal, 158 (4): 138, arXiv:1905.10694, Bibcode:2019AJ....158..138S, doi:10.3847/1538-3881/ab3467.
↑ Erspamer, D.; North, P. (2003), "Automated spectroscopic abundances of a and F-type stars using echelle spectrographs. II. Abundances of 140 A-F stars from ELODIE", Astronomy and Astrophysics, 398 (3): 1121–1136, arXiv:astro-ph/0210065, Bibcode:2003A&A...398.1121E, doi:10.1051/0004-6361:20021711, S2CID 1109164.
↑ "eta Del", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-08-18.
↑ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
↑ Allen, J. S., "The Classification of Stellar Spectra", Department of Physics and Astronomy: Astrophysics Group, University College London, retrieved 1 January 2014.
↑ Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.

[Anderson2012-1] 1 2 3 Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015. XHIP record for this object at VizieR.

[GaiaDR3-2] 1 2 3 4 5 6 Vallenari, A.; et al. (Gaia collaboration) (2023), "Gaia Data Release 3. Summary of the content and survey properties", Astronomy and Astrophysics, 674: A1, arXiv:2208.00211, Bibcode:2023A&A...674A...1G, doi:10.1051/0004-6361/202243940, S2CID 244398875. Gaia DR3 record for this source at VizieR.

[Feinstein1974-3] 1 2 3 Feinstein, A. (1974), "Photoelectric UBVRI observations of AM stars", Astronomical Journal, 79: 1290, Bibcode:1974AJ.....79.1290F, doi:10.1086/111675.

[Zorec2012-4] 1 2 3 Zorec, J.; Royer, F. (January 2012), "Rotational velocities of A-type stars. IV. Evolution of rotational velocities", Astronomy & Astrophysics, 537: A120, arXiv:1201.2052, Bibcode:2012A&A...537A.120Z, doi:10.1051/0004-6361/201117691, S2CID 55586789.

[Cowley1969-5] 1 2 Cowley, A.; et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal, 74: 375–406, Bibcode:1969AJ.....74..375C, doi:10.1086/110819.

[Gontcharov2006-6] 1 2 Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.

[David2015-7] 1 2 3 4 5 6 David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.

[tic-8] 1 2 3 4 Stassun, Keivan G.; et al. (2019), "The Revised TESS Input Catalog and Candidate Target List", The Astronomical Journal, 158 (4): 138, arXiv:1905.10694, Bibcode:2019AJ....158..138S, doi:10.3847/1538-3881/ab3467.

[Erspamer_North_2003-9] Erspamer, D.; North, P. (2003), "Automated spectroscopic abundances of a and F-type stars using echelle spectrographs. II. Abundances of 140 A-F stars from ELODIE", Astronomy and Astrophysics, 398 (3): 1121–1136, arXiv:astro-ph/0210065, Bibcode:2003A&A...398.1121E, doi:10.1051/0004-6361:20021711, S2CID 1109164.

[SIMBAD-10] "eta Del", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2017-08-18.

[Eggleton2008-11] Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.

[Allen-12] Allen, J. S., "The Classification of Stellar Spectra", Department of Physics and Astronomy: Astrophysics Group, University College London, retrieved 1 January 2014.

[Renson2009-13] Renson, P.; Manfroid, J. (May 2009), "Catalogue of Ap, HgMn and Am stars", Astronomy and Astrophysics, 498 (3): 961–966, Bibcode:2009A&A...498..961R, doi:10.1051/0004-6361/200810788.