V399 Carinae
{{Short description|Star in the constellation Carina}}
{{about|P Carinae|p Carinae|PP Carinae}}
{{Starbox begin}}
{{Starbox image
| image=
{{Location mark
|image=Carina constellation map.svg|alt=|float=center|width=300
|label=|position=right
|mark=Red circle.svg|mark_width=8|mark_link=V399 Car
|x=161|y=327
}}
|caption=Location of V399 Carinae (circled)
}}
{{Starbox observe
| epoch = J2000.0
| constell = Carina
| dec = {{DEC|-57|38|19.6984}}
}}
{{Starbox character
| class = A5Iae or F0Ia
| variable=SRd?
}}
{{Starbox astrometry
| radial_v =
| parallax = 0.4976
| p_error = 0.1151
| dist_pc =
}}
{{Starbox detail
| radius = {{solar radius calculator|type=AD|0.954|2.009}}
| rotational_velocity =
}}
{{Starbox catalog
| names = P Carinae, 195 G. Carinae, HR 4110, HD 90772, CP−57°3256, HIP 51192, SAO 238077, GC 14373, IC 2581 1
}}
{{Starbox reference
| Simbad = V399_Carinae
}}
{{Starbox end}}
V399 Carinae (V399 Car, P Carinae, P Car, 195 G. Carinae) is a variable star in the constellation Carina. It is visible to the naked eye.
The spectral type of V399 Carinae has been variously assigned between A5 and F0, being a bright, luminous supergiant. Its spectrum is described as having a non-photospheric continuum and silicon absorption lines, indicative of high mass loss.
File:V399CarLightCurve.png light curve for V399 Carinae, adapted from Berdnikov and Turner (1997)]]
V399 Carinae has long been suspected to be variable. A 1981 study of yellow supergiants fit observations to a Cepheid-like light curve with a period of 58.8 days, although the luminosity and spectral type do not place the star near the Cepheid instability strip. It was listed in the General Catalogue of Variable Stars as a possible δ Cep variable. Further observations refined the period to 47.25 days. The Hipparcos catalogue classified V399 Car as a semiregular variable with a period of 88 days and a mean amplitude of only 0.04 magnitudes. An automated classification from Hipparos photometry suggested it is an α Cygni variable. The observed brightness varies from magnitude +4.63 to +4.72.
V399 Carinae lies amongst the stars of the open cluster IC 2581, by far the brightest member of the cluster. It is about 7,500 light years from Earth assuming it is a member of IC 2581, which is given a 62.9% probability. Its angular diameter has been estimated at {{val|0.954|0.09|u=milliarcseconds}}, which, at the estimated distance of 2009 parsecs, gives it a radius 206 times the solar radius.
References
{{reflist|refs=
{{citation | first1=Kenneth R. | last1=Lang | title=Astrophysical formulae | volume=1 | series=Astronomy and astrophysics library | edition=3 | publisher=Birkhäuser | date=2006 | isbn=978-3-540-29692-8 | url=https://books.google.com/books?id=OvTjLcQ4MCQC&pg=PA41 }}. The radius (R*) is given by:
:
& = \frac{(2009\cdot 0.954\cdot 10^{-3})\ \text{UA}}{0.0046491\ \text{UA}/R_{\bigodot}} \\
& \approx 412.25\cdot R_{\bigodot}
\end{align}
{{cite Gaia DR3|5351701122540337792}}
|last1=Evans|first1=L.
|last2=Francis |first2=Ch.
|date=1969
|title=The open cluster IC 2581
|journal=Monthly Notices of the Royal Astronomical Society
|volume=146 |issue=5 |page=101
|bibcode=1969MNRAS.146..101L
|doi=10.1093/mnras/146.2.101
|doi-access=free
}}
|last1=Baumgardt |first1=H.
|last2=Detbarn |first2=C.
|last3=Wielen |first3=R.
|date=2000
|title=Absolute proper motions of open clusters. I. Observational data
|journal=Astronomy and Astrophysics Supplement
|volume=146 |issue=2
|page=251
|arxiv=astro-ph/0010306
|bibcode=2000A&AS..146..251B
|doi=10.1051/aas:2000362
|s2cid=7180188
}}
| title=Revisiting the absolute-magnitude calibration of F-type supergiants and bright giants as a function of the equivalent width of the OIλ7774Å triplet
| last1=Dambis | first1=A. K.
| journal=Proceedings of the International Astronomical Union
| volume=289 | pages=379−381 | date=February 2013
| doi=10.1017/S1743921312021758 | bibcode=2013IAUS..289..379D | doi-access=free }}
}}
{{Stars of Carina}}
{{DEFAULTSORT:V399 Carinae}}
Category:Carina (constellation)
Category:Semiregular variable stars