CM Draconis

Starbox begin
name = CM DraconisStarbox observe
epoch = J2000.0 (ICRS)
constell = Draco
ra = RA|16|34|20.321
dec = DEC|+57|09|44.70
appmag_v = 12.90 Starbox character
class = M4.5V / M4.5V / DB
variable =BY Draconis variable
Eclipsing binary
Flare star Starbox astrometry
radial_v = –118.71
prop_mo_ra = –1109
prop_mo_dec = 1203
parallax = 69.0
p_error = 2.9
parallax_footnote = cite web|url=http://webviz.u-strasbg.fr/viz-bin/VizieR-S?GJ%20630.1%20A|title=GJ 630.1A|work=Preliminary Version of the Third Catalogue of Nearby Stars|author=Gliese, W. and Jahreiss, H.|year=1991|accessdate=2008-10-12]
absmag_v = 12.1Starbox catalog
names = Gliese 630.1A, LHS 421, USNO-B1.0 1471-00307615Starbox reference
Simbad = CM+DRA
ARICNS =

CM Draconis (GJ 630.1A) is an eclipsing binary system approximately 47 light-years away in the constellation of Draco (the Dragon). The system consists of two nearly identical red dwarf stars located in the constellation Draco. The two stars orbit each other with a period of 1.27 days with a separation of 2.7 million kilometres [cite web|url=http://www.iac.es/project/tep/cmdra.html|title=TEP: CM Draconis] . 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. [cite web|url=http://webviz.u-strasbg.fr/viz-bin/VizieR-S?V*%20CM%20Dra|title=CM Dra|work=Combined General Catalogue of Variable Stars|author=Samus|year=2004] 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.cite journal|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2008A%26A...480..563D&db_key=AST&nosetcookie=1 |title=Extrasolar planet detection by binary stellar eclipse timing: evidence for a third body around CM Draconis|author=Deeg, H. J.; Ocaña, B.; Kozhevnikov, V. P.; Charbonneau, D.; O'Donovan, F. T.; Doyle, L. R.|journal=Astronomy and Astrophysics|volume=480|issue=2|pages=563–571|year=2008] Given the system's distance of 47 light years, this corresponds to a separation of at least 370 astronomical units between CM Draconis and GJ 630.1B.

Possible planetary system

The system was the subject of a dedicated search for transiting extrasolar planets in orbit around the binary from 1994–1999. In the end, the existence of all of the transiting planet candidates suggested by the project was ruled out.cite web|url=http://www.iac.es/project/tep/tephome.html|title=The TEP network] [cite journal|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2000ApJ...535..338D&db_key=AST&nosetcookie=1|title=Observational Limits on Terrestrial-sized Inner Planets around the CM Draconis System Using the Photometric Transit Method with a Matched-Filter Algorithm|author=Doyle, Laurance R.; Deeg, Hans J.; Kozhevnikov, Valerij P.; Oetiker, Brian; Martín, Eduardo L.; Blue, J. Ellen; Rottler, Lee; Stone, Remington P. S.; Ninkov, Zoran; Jenkins, Jon M.; Schneider, Jean; Dunham, Edward W.; Doyle, Moira F.; Paleologou, Efthimious|journal=The Astrophysical Journal|volume=535|issue=1|pages=338–349|year=2000]

Based on variations in the timing of the system's eclipses, it has been suggested that there may be an object in a circumbinary orbit around the two red dwarf stars. In 2000, it was proposed that a Jovian planet is orbiting the system with a period of 750–1050 days. [cite journal|url=http://cdsads.u-strasbg.fr/cgi-bin/nph-bib_query?2000A%26A...358L...5D&db_key=AST&nosetcookie=1|title=A search for Jovian-mass planets around CM Draconis using eclipse minima timing.|author=Deeg, H. J.; Doyle, L. R.; Kozhevnikov, V. P.; Blue, J. E.; Martín, E. L.; Schneider, J.|journal=Astronomy and Astrophysics|volume=358|pages=L5–L8|year=2000] More recent eclipse measurements suggest there may be a planet with a mass similar to Jupiter in an 18.5-year orbit, or instead a more massive object located further out. The variations are inconsistent with being caused by the white dwarf companion star. No further evidence for the 750–1050 day planet was found and it is considered unlikely that it exists.

References

External links

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