Psi Phoenicis

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ψ Phoenicis
Location of ψ Phoenicis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Phoenix
Right ascension 01h 53m 38.74103s[1]
Declination −46° 18′ 09.6048″[1]
Apparent magnitude (V) 4.41[2] (4.3 - 4.5[3])
Characteristics
Evolutionary stage asymptotic giant branch[4]
Spectral type M4III[5]
U−B color index +1.71[2]
B−V color index +1.59[2]
Variable type SR[3]
Distance
342 ± 7 ly
(105 ± 2 pc)
Absolute magnitude (MV)−0.71[5]
Details
Gyr
SAO
 215696
Database references
SIMBADdata

Psi Phoenicis (ψ Phoenicis) is a star in the constellation Phoenix. Its apparent magnitude varies from 4.3 to 4.5 with a period of about 30 days[3] and it is approximately 342 light years away based on parallax.[1]

A light curve for Psi Phoenicis, plotted from Hipparcos data[11]

Psi Phoenicis is a

semiregular variable, of no specific subtype.[3]

In 2001, Psi Phoenicis was observed by the

solar radii. From the radius and estimating an effective temperature of 3,550 K, a luminosity of 1,000 times the solar luminosity was calculated.[7] A 2008 study reanalyzed the interferometric data with a new atmospheric model, finding an angular diameter of 10.15±0.15 mas and a radius of 85±1.6 R.[14]

By having directly measured distance, radius and luminosity, Psi Phoenicis was included in a list of 34 well characterized stars to be used as a reference. This program made the first measurement of the metallicity of Psi Phoenicis, showing it is a metal-poor star with only 5% the amount of iron of the Sun ([Fe/H] = −1.24±0.39). This value has a large uncertainty due to the difficulties in modeling the spectra of cool stars, which have strong molecular absorption. The evolutionary state and poorly constrained metallicity result in an uncertain mass of 1.0±0.4 M.[9][15] Assuming a metallicity closer to solar, a mass of 1.3±0.2 M is derived.[7]

Psi Phoenicis is considered a single star, and has no known companions.

Hipparcos Catalogue, which stems from spectroscopic observations in 1919 which showed a possibly variable radial velocity. More recent data, however, showed the velocity to be constant.[7]

References