HD 166

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Template:Short description

HD 166
File:V439AndLightCurve.png
A light curve for V439 Andromedae, plotted from TESS data,[1] with the 6.23 day rotation period shown in red,
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Andromeda
Right ascension Template:RA[2]
Declination Template:DEC[2]
Apparent magnitude (V) 6.13 – 6.17[3]
Characteristics
Spectral type K0Ve[3][4]
U−B Template:Engvar +0.30[5]
B−V Template:Engvar +0.755[5]
Variable type BY Dra[3]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[4] km/s
Proper motion (μ) RA: Script error: No such module "val".[2] mas/yr
Dec.: Script error: No such module "val".[2] mas/yr
Parallax (π)72.5764±0.0498 mas[2]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)5.41[6]
Details
Mass0.889[7] Template:Solar mass
RadiusScript error: No such module "val".[7] Template:Solar radius
LuminosityScript error: No such module "val".[7] Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val".[8] cgs
TemperatureScript error: No such module "val".[8] K
Metallicity [Fe/H]Script error: No such module "val".[8] dex
RotationScript error: No such module "val". days[9]
Rotational velocity (v sin i)4.1 [9] km/s
AgeScript error: No such module "val".[8] Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
BD+28°4704, GC 95, GSC 01735-02532, GSC 01735-00927, Gliese 5, HD 166, HIP 544, HR 8, SAO 73743, PPM 89410, NSV 33, V439 Andromedae
Database references
SIMBADdata

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HD 166 or V439 Andromedae (ADS 69 A) is a 6th magnitude star in the constellation Andromeda, approximately 45 light years away from Earth. It is a variable star of the BY Draconis type, varying between magnitudes 6.13 and 6.18 with a 6.23 days periodicity.[3] It appears within one degree of the star Alpha Andromedae[10] and is a member of the Hercules-Lyra association moving group.[4] It also happens to be less than 2 degrees from right ascension 00h 00m.

Star characteristics

HD 166 is a K-type main sequence star, cooler and dimmer than the Sun, and has a stellar classification of K0Ve[3] where the e suffix indicates the presence of emission lines in the spectrum. The star has a proper motion of 0.422 arcseconds per year in a direction 114.1° from north. It has an estimated visual luminosity of 61% of the Sun,[7] and is emitting like a blackbody with an effective temperature of 5,327K.[8] It has a diameter that is about 90% the size of the Sun[7] and a radial velocity of −6.9 km/s.[4] Age estimates range from as low as 78 million years old based on its chromospheric activity,[8] up to 9.6 billion years based on a comparison with theoretical evolutionary tracks.[7] X-ray emission has been detected from this star, with an estimated luminosity of Script error: No such module "val"..[11]

An infrared excess has been detected around HD 166, most likely indicating the presence of a circumstellar disk at a radius of 7.5 AU. The temperature of this dust is 90 K.[12]

Variability

Eric J. Gaidos et al. first detected variability in HD 166 in the year 2000.[9] It was given its variable star designation, V439 Andromedae, in 2006.[13] It has been found that the periodicity in the photometric variability of HD 166 is coincident with the rotation period.[9] This leads to its classification as a BY Draconis variable, where brightness variations are caused by the presence of large starspots on the surface and by chromospheric activity.

References

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  1. ↑ Script error: No such module "citation/CS1".
  2. ↑ a b c d e Template:Cite DR2
  3. ↑ a b c d e Script error: No such module "citation/CS1".
  4. ↑ a b c d Script error: No such module "Citation/CS1".
  5. ↑ a b Script error: No such module "citation/CS1".
  6. ↑ Script error: No such module "citation/CS1".
  7. ↑ a b c d e f Script error: No such module "citation/CS1".
  8. ↑ a b c d e f Script error: No such module "Citation/CS1".
  9. ↑ a b c d Script error: No such module "Citation/CS1".
  10. ↑ Autostar Suite Astronomer Edition. CD-ROM. Meade, April 2006.
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".
  13. ↑ Script error: No such module "Citation/CS1".

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External links

Template:Stars of Andromeda

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