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.
 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 | 00h 06m 36.7841s[2] |
| Declination | +29° 01′ 17.4103″[2] |
| Apparent magnitude (V) | 6.13 – 6.17[3] |
| Characteristics | |
| Spectral type | K0Ve[3][4] |
| U−B color index | +0.30[5] |
| B−V color index | +0.755[5] |
| Variable type | BY Dra[3] |
| Astrometry | |
| Radial velocity (Rv) | −6.9±0.2[4] km/s |
| Proper motion (μ) | RA: 380.092±0.060[2] mas/yr Dec.: −177.573±0.037[2] mas/yr |
| Parallax (π) | 72.5764 ± 0.0498 mas[2] |
| Distance | 44.94 ± 0.03 ly (13.779 ± 0.009 pc) |
| Absolute magnitude (MV) | 5.41[6] |
| Details | |
| Mass | 0.889[7] M☉ |
| Radius | 0.9172±0.0090[7] R☉ |
| Luminosity | 0.6078±0.0099[7] L☉ |
| Surface gravity (log g) | 4.49±0.09[8] cgs |
| Temperature | 5509±34[8] K |
| Metallicity [Fe/H] | 0.00±0.03[8] dex |
| Rotation | 6.23±0.01 days[9] |
| Rotational velocity (v sin i) | 4.1 [9] km/s |
| Age | 78±28[8] Myr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Star characteristics
editHD 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 8.5×1028 erg s−1.[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
editEric 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
edit- ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 26 August 2024.
- ^ a b c d e Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
- ^ a b c d e N. N. Samus; O. V. Durlevich; et al. "V439 And database entry". Combined General Catalog of Variable Stars (2017 ed.). CDS. Retrieved 2018-11-12.
- ^ a b c d López-Santiago, J.; Montes, D.; Crespo-Chacón, I.; Fernández-Figueroa, M. J. (2006). "The Nearest Young Moving Groups". The Astrophysical Journal. 643 (2): 1160–1165. arXiv:astro-ph/0601573. Bibcode:2006ApJ...643.1160L. doi:10.1086/503183. S2CID 119520529.
- ^ a b Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data. SIMBAD: 0, Bibcode:1986EgUBV........0M
- ^ Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511.
- ^ a b c d e f Boyajian, Tabetha S.; et al. (July 2013), "Stellar Diameters and Temperatures. III. Main-sequence A, F, G, and K Stars: Additional High-precision Measurements and Empirical Relations", The Astrophysical Journal, 771 (1): 40, arXiv:1306.2974, Bibcode:2013ApJ...771...40B, doi:10.1088/0004-637X/771/1/40, S2CID 14911430.
- ^ a b c d e f Rich, Evan A.; Wisniewski, John P.; McElwain, Michael W.; Hashimoto, Jun; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Okamoto, Yoshiko K.; Abe, Lyu; Akiyama, Eiji; Brandner, Wolfgang; Brandt, Timothy D.; Cargile, Phillip; Carson, Joseph C.; Currie, Thayne M.; Egner, Sebastian; Feldt, Markus; Fukagawa, Misato; Goto, Miwa; Grady, Carol A.; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiko; Hayashi, Saeko S.; Hebb, Leslie; Hełminiak, Krzysztof G.; Henning, Thomas; Hodapp, Klaus W.; Ishii, Miki; Iye, Masanori; et al. (2017). "The fundamental stellar parameters of FGK stars in the SEEDS survey Norman, OK 73071, USA". Monthly Notices of the Royal Astronomical Society. 472 (2): 1736. arXiv:1708.02541. Bibcode:2017MNRAS.472.1736R. doi:10.1093/mnras/stx2051. S2CID 58942857.
- ^ a b c d Gaidos; et al. (2000). "Spectroscopy and Photometry of Nearby Young Solar Analogs". The Astronomical Journal. 120 (2): 1006–1013. Bibcode:2000AJ....120.1006G. CiteSeerX 10.1.1.43.4478. doi:10.1086/301488. S2CID 16930014.
- ^ Autostar Suite Astronomer Edition. CD-ROM. Meade, April 2006.
- ^ Micela, G.; Favata, F.; Sciortino, S. (October 1997), "HIPPARCOS distances of X-ray selected stars: implications on their nature as stellar population", Astronomy and Astrophysics, 326: 221–227, Bibcode:1997A&A...326..221M
- ^ Eiroa, C.; et al. (July 2013). "DUst around NEarby Stars. The survey observational results". Astronomy & Astrophysics. 555: A11. arXiv:1305.0155. Bibcode:2013A&A...555A..11E. doi:10.1051/0004-6361/201321050. S2CID 377244.
- ^ Kazarovets, E. V.; Samus, N. N.; Durlevich, O. V.; Kireeva, N. N.; Pastukhova, E. N. (August 2006). "The 78th Name-List of Variable Stars" (PDF). Information Bulletin on Variable Stars. 5721: 1–45. Bibcode:2006IBVS.5721....1K. Retrieved 6 November 2024.