Iota Delphini

Iota Delphini (ι Del, ι Delphini) is a star in the constellation Delphinus. It has an apparent magnitude of about 5.4, meaning that it is just barely visible to the naked eye. Based upon parallax measurements made by the Hipparcos spacecraft, this star is around 177 light years away from the Sun.[1]

Iota Delphini
Location of ι Delphini (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Delphinus
Right ascension  20h 37m 49.11939s[1]
Declination +11° 22′ 39.6356″[1]
Apparent magnitude (V) 5.428[2]
Characteristics
Spectral type A1IV[2]
U−B color index +0.035[3]
B−V color index +0.035[3]
Astrometry
Radial velocity (Rv)-3.9[2] km/s
Proper motion (μ) RA: 39.15[1] mas/yr
Dec.: -8.26[1] mas/yr
Parallax (π)17.26 ± 0.33[1] mas
Distance189 ± 4 ly
(58 ± 1 pc)
Absolute magnitude (MV)1.62[4]
Orbit[5]
Period (P)11.039 days
Eccentricity (e)0.23
Periastron epoch (T)2422139.862
Argument of periastron (ω)
(secondary)		61.8°
Semi-amplitude (K1)
(primary)		26.0 km/s
Details
Surface gravity (log g)4.29[4] cgs
Temperature9301[4] K
Other designations
ι Del, 5 Del, BD+10° 4339, HD 196544, HIP 101800, SAO 106322, HR 7883, GC 28711[2]
Database references
SIMBADdata

Iota Delphini's spectral type is A1IV, meaning it is an A-type subgiant.[6] Observations of the star's spectrum reveal a periodic Doppler shift. This means that Iota Delphini is a spectroscopic binary with a period of 11 days and an eccentricity of 0.23.[5] However, almost no information is known about the companion star.

Iota Delphini appears to be an Am star,[4] also known as a metallic-line star. These types of stars have spectra indicating varying amounts of metals, like iron.[7] Observations of Iota Delphini's spectrum have showed lower amounts of calcium and higher amounts of iron than usual.[4]

References
  1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  2. "iot Del". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 15 January 2016.
  3. Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Bibcode:1986EgUBV........0M. Cite journal requires |journal= (help)
  4. "Abundance analysis of Am binaries and search for tidally driven abundance anomalies - III. HD 116657, HD 138213, HD 155375, HD 159560, HD 196544 and HD 204188". Monthly Notices of the Royal Astronomical Society. 420 (2): 1207–1216. 2012. arXiv:1111.0978. Bibcode:2012MNRAS.420.1207S. doi:10.1111/j.1365-2966.2011.20108.x.
  5. Pourbaix, D.; et al. (2004). "SB9: The ninth catalogue of spectroscopic binary orbits". Astronomy and Astrophysics. 424 (2): 727. arXiv:astro-ph/0406573. Bibcode:2004A&A...424..727P. doi:10.1051/0004-6361:20041213.
  6. Allen, J. S. "The Classification of Stellar Spectra". UCL Department of Physics and Astronomy: Astrophysics Group. Retrieved 1 January 2014.
  7. Am star, The Internet Encyclopedia of Science, David Darling. Accessed on line August 14, 2008.


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