CM Draconis

CM Draconis

A red band light curve for CM Draconis, adapted from Kozhevnikova et al. (2009)[1]
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Draco
Right ascension 16h 34m 20.33027s[2]
Declination +57° 09′ 44.3689″[2]
Apparent magnitude (V) 12.87[3]
Characteristics
Spectral type M4.5V / M4.5V[4] / DQ8[5]
Variable type BY Draconis variable
Eclipsing binary
Flare star
Astrometry
Radial velocity (Rv)–118.24[3] km/s
Proper motion (μ) RA: –1113.797 mas/yr[2]
Dec.: 1180.977 mas/yr[2]
Parallax (π)67.2876 ± 0.0337 mas[2]
Distance48.47 ± 0.02 ly
(14.862 ± 0.007 pc)
Absolute magnitude (MV)12.1[citation needed]
Orbit[6]
Period (P)1.2683900573(17) d
Semi-major axis (a)0.0173945(64) AU
Eccentricity (e)0.00527(21)
Inclination (i)89.5514±0.0020°
Longitude of the node (Ω)15.79[4]°
Argument of periastron (ω)
(secondary)
107.98±0.70°
Semi-amplitude (K1)
(primary)
72.23[4] km/s
Semi-amplitude (K2)
(secondary)
77.95[4] km/s
Details
A
Mass0.22507(24)[6] M
Radius0.25113(16)[6] R
Luminosity (bolometric)0.00552[4] L
Surface gravity (log g)4.994±0.007[4] cgs
Temperature3130 ± 70[4] K
Metallicity [Fe/H]−0.30±0.12[7] dex
Age4.1 ± 0.8[4] Gyr
B
Mass0.21017(28)[6] M
Radius0.23732(14)[6] R
Luminosity (bolometric)0.00486[4] L
Surface gravity (log g)5.009±0.006[4] cgs
Temperature3120 ± 70[4] K
Metallicity [Fe/H]−0.30±0.12[7] dex
Age4.1 ± 0.8[4] Gyr
Other designations
Eclipsing binary: CM Dra, GJ 630.1A, CCDM J16343+5710A, WDS J16345+5709A, LHS 421, LP 101-15, NLTT 43148, TIC 199574208[3]
White dwarf: GJ 630.1B, CCDM J16343+5710B, WDS J16345+5709B, EGGR 258, LHS 422, LP 101-16, NLTT 43149, WD 1633+57, TIC 199574211[5]
Database references
SIMBADA
B
ARICNSA
B

CM Draconis (GJ 630.1A) is an eclipsing binary star system 48.5 light-years (14.9 parsecs) away in the constellation of Draco (the Dragon). The system consists of two nearly identical red dwarf stars that orbit each other with a period of 1.268 days and a separation of 2.6 million kilometres (0.017 AU).[6] Along with two stars in the triple system KOI-126, the stars in CM Draconis are among the lightest stars with precisely measured masses and radii. Consequently, the system plays an important role in testing stellar structure models for very low mass stars.[4] These comparisons find that models underpredict the stellar radii by approximately 5%. This is attributed to consequences of the stars' strong magnetic activity.[4]

According to the system's entry in the Combined General Catalogue of Variable Stars, at least one of the components is a flare star and at least one is a BY Draconis variable.[8] The white dwarf star GJ 630.1B, located 25.7 arcseconds away shares the same proper motion as the CM Draconis stars and is thus a true companion star of the system.[9] Given the system's distance of 47 light years,[10] this corresponds to a separation of at least 370 astronomical units between CM Draconis and GJ 630.1B.

  1. ^ Cite error: The named reference Kozhevnikova was invoked but never defined (see the help page).
  2. ^ a b c d Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  3. ^ a b c Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  4. ^ a b c d e f g h i j k l m n Cite error: The named reference Morales was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference SIMBAD2 was invoked but never defined (see the help page).
  6. ^ a b c d e f Cite error: The named reference Martin2024 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference Terrien2012 was invoked but never defined (see the help page).
  8. ^ Samus (2004). "CM Dra". Combined General Catalogue of Variable Stars.
  9. ^ Deeg, H. J.; Ocaña, B.; Kozhevnikov, V. P.; Charbonneau, D.; O'Donovan, F. T.; Doyle, L. R. (2008). "Extrasolar planet detection by binary stellar eclipse timing: evidence for a third body around CM Draconis". Astronomy and Astrophysics. 480 (2): 563–571. arXiv:0801.2186. Bibcode:2008A&A...480..563D. doi:10.1051/0004-6361:20079000. S2CID 10252705.
  10. ^ Gliese, W.; Jahreiß, H. (1991). "GJ 630.1A". Preliminary Version of the Third Catalogue of Nearby Stars. Retrieved 2008-10-12.