CM Draconis#CM Draconis b

{{Starbox begin

| name = CM Draconis

}}

{{Starbox image

| image = 250px

| caption = A red band light curve for CM Draconis, adapted from Kozhevnikova et al. (2009)

}}

{{Starbox observe

| epoch = J2000.0 (ICRS)

| constell = Draco

| ra = {{RA|16|34|20.33027}}

| dec = {{DEC|+57|09|44.3689}}

| appmag_v = 12.87

}}

{{Starbox character

| class = M4.5V / M4.5V / DQ8

| variable =BY Draconis variable
Eclipsing binary
Flare star

}}

{{Starbox astrometry

| radial_v = –118.24

| prop_mo_ra = –1113.797

| prop_mo_dec = 1180.977

| pm_footnote =

| parallax = 67.2876

| p_error = 0.0337

| parallax_footnote =

| absmag_v = 12.1{{cn|date=May 2024}}

}}

{{Starbox orbit

|reference=

|period_unitless={{val|1.2683900573|(17)|ul=d}}

|axis_unitless={{val|0.0173945|(64)|ul=AU}}

|eccentricity={{val|0.00527|(21)}}

|inclination={{val|89.5514|0.0020}}

|node=15.79

|periarg={{val|107.98|0.70}}

|k1=72.23

|k2=77.95

}}

{{Starbox detail

|source=

|component1=Aa

|mass={{val|0.22507|(24)}}

|radius={{val|0.25113|(16)}}

|luminosity_bolometric=0.00552

|gravity={{val|4.994|0.007}}

|temperature=3130 ± 70

|metal_fe={{val|−0.30|0.12}}

|age_gyr=4.1 ± 0.8

|component2=Ab

|mass2={{val|0.21017|(28)}}

|radius2={{val|0.23732|(14)}}

|luminosity_bolometric2=0.00486

|gravity2={{val|5.009|0.006}}

|temperature2=3120 ± 70

|metal_fe2={{val|−0.30|0.12}}

|age_gyr2=4.1 ± 0.8

}}

{{Starbox catalog

|component1=Eclipsing binary

|names1={{odlist | V=CM Dra | CCDM=J16343+5710A | GJ=630.1A | LHS=421 | LP=101-15 | NLTT=43148 | TIC=199574208 | WDS=J16345+5709A}}

|component2=White dwarf

|names2={{odlist | CCDM=J16343+5710B | EGGR=258 | GJ=630.1B | LHS=422 | LP=101-16 | NLTT=43149 | TIC=199574211 | WD=1633+57 | WDS=J16345+5709B}}

}}

{{Starbox reference

|Simbad=CM+Dra|sn=A

|Simbad2=EGGR+258|sn2=B

|ARICNS=01315|an=A

|ARICNS2=01316|an2=B

}}

CM Draconis (GJ 630.1A) is an eclipsing binary star system {{convert|48.5|ly|pc|lk=on|abbr=off}} 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). 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. These comparisons find that models underpredict the stellar radii by approximately 5%. This is attributed to consequences of the stars' strong magnetic activity.

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|bibcode=2008A&A...480..563D |title=Extrasolar planet detection by binary stellar eclipse timing: evidence for a third body around CM Draconis|author1=Deeg, H. J. |author2=Ocaña, B. |author3=Kozhevnikov, V. P. |author4=Charbonneau, D. |author5=O'Donovan, F. T. |author6=Doyle, L. R. |journal=Astronomy and Astrophysics|volume=480|issue=2|pages=563–571|year=2008|doi=10.1051/0004-6361:20079000|arxiv = 0801.2186 |s2cid=10252705}} Given the system's distance of 47 light years,{{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|author1=Gliese, W. |author2=Jahreiß, H.|year=1991|accessdate=2008-10-12}} this corresponds to a separation of at least 370 astronomical units between CM Draconis and GJ 630.1B.

History of observations

CM Draconis was discovered to be an eclipsing binary by Olin J. Eggen and Allan Sandage in 1967; at that time it was known by the designation LP 101-15. It was the second M-dwarf eclipsing binary discovered after YY Geminorum (Castor C), and they remained the only two known until CU Cancri (GJ 2069 A) was found to be an eclipsing binary in 1999.

Search for planets

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|bibcode=2000ApJ...535..338D|title=Observational Limits on Terrestrial-sized Inner Planets around the CM Draconis System Using the Photometric Transit Method with a Matched-Filter Algorithm|author1=Doyle, Laurance R. |author2=Deeg, Hans J. |author3=Kozhevnikov, Valerij P. |author4=Oetiker, Brian |author5=Martín, Eduardo L. |author6=Blue, J. Ellen |author7=Rottler, Lee |author8=Stone, Remington P. S. |author9=Ninkov, Zoran |author10=Jenkins, Jon M. |author11=Schneider, Jean |author12=Dunham, Edward W. |author13=Doyle, Moira F. |author14=Paleologou, Efthimious |journal=The Astrophysical Journal|volume=535|issue=1|pages=338–349|year=2000|doi=10.1086/308830|arxiv = astro-ph/0001177 |s2cid=18639250}}

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|bibcode=2000A&A...358L...5D|title=A search for Jovian-mass planets around CM Draconis using eclipse minima timing |author1=Deeg, Hans J. |author2=Doyle, Laurance R. |author3=Kozhevnikov, Valerij P. |author4=Blue, J. Ellen |author5=Martín, Eduardo L. |author6=Schneider, Jean |journal=Astronomy and Astrophysics |volume=358|pages=L5–L8|year=2000|arxiv = astro-ph/0003391 }} A later analysis of timing variations did not confirm this proposed planet and instead suggested that there was a Jovian planet in an 18.5-year orbit, or a more massive object further out. This analysis was itself not supported by a 2009 study that found the eclipse timings were indistinguishable from linear, though the binary stars do have a small eccentricity that may indicate that they are being perturbed by an orbiting body that prevents the orbit from being fully circularised by tidal effects. A massive planet or brown dwarf on an orbit of 50–200 days would fulfil the observational criteria: the requirement for dynamical stability, the constraints from the lack of observed timing variations and the requirement that the object can maintain the eccentricity of the binary stars.

{{As of|2024}}, no planet has been found orbiting CM Draconis.

References

{{reflist|refs=

{{cite journal |last1=Eggen |first1=Olin J. |last2=Sandage |first2=Allan |date=June 1967 |title=Examination of the Evidence for the Existence of Pygmy Stars |journal=Astrophysical Journal |volume=148 |issue= |page=911 |doi=10.1086/149215 |bibcode=1967ApJ...148..911E}}

{{cite journal |last1=Lacy |first1=C. H. |date=December 1977 |title=Absolute dimensions and masses of the remarkable spotted dM4e eclipsing binary flare star CM Draconis. |journal=Astrophysical Journal |volume=218 |issue= |pages=444-460 |doi=10.1086/155698 |bibcode=1977ApJ...218..444L}}

{{cite journal |last1=Delfosse |first1=X. |last2=Forveille |first2=T. |display-authors=etal |date=January 1999 |title=GJ 2069A, a new M dwarf eclipsing binary |journal=Astronomy and Astrophysics |volume=341 |issue= |pages=L63–L66 |bibcode=1999A&A...341L..63D}}

{{cite journal|title=Absolute Properties of the Low-Mass Eclipsing Binary CM Draconis|author1=Morales, Juan Carlos |author2=Ribas, Ignasi |author3=Jordi, Carme|author3-link=Carme Jordi |author4=Torres, Guillermo |author5=Gallardo, José |author6=Guinan, Edward F. |author7=Charbonneau, David |author8=Wolf, Marek |author9=Latham, David W. |author10=Anglada-Escudé, Guillem |author11=Bradstreet, David H. |author12=Everett, Mark E. |author13=O'Donovan, Francis T. |author14=Mandushev, Georgi |author15=Mathieu, Robert D. |year=2009|journal=The Astrophysical Journal|volume=691|issue=2|pages=1400–1411|doi=10.1088/0004-637X/691/2/1400|bibcode=2009ApJ...691.1400M|arxiv=0810.1541|s2cid=3752277 }}

{{cite journal |last1=Kozhevnikova |first1=A. V. |last2=Svechnikov |first2=M. A. |last3=Kozhevnikov |first3=V. P. |title=V.P. Starspot and flare activity of the dwarf system CM Dra |journal=Astrophysics |date=October 2009 |volume=52 |issue=4 |pages=512–522 |doi=10.1007/s10511-009-9090-4 |bibcode=2009Ap.....52..512K |s2cid=121618264 |url=https://ui.adsabs.harvard.edu/abs/2009Ap.....52..512K |access-date=3 January 2022}}

{{cite journal |last1=Terrien |first1=Ryan C. |last2=Fleming |first2=Scott W. |display-authors=etal |date=November 2012 |title=The Metallicity of the CM Draconis System |journal=The Astrophysical Journal Letters |volume=760 |issue=1 |pages=L9 |doi=10.1088/2041-8205/760/1/L9 |arxiv=1210.4736 |bibcode=2012ApJ...760L...9T}}

{{cite journal |last1=Martin |first1=David V. |last2=Sethi |first2=Ritika |display-authors=etal |date=February 2024 |title=The benchmark M dwarf eclipsing binary CM Draconis with TESS: spots, flares, and ultra-precise parameters |journal=Monthly Notices of the Royal Astronomical Society |volume=528 |issue=1 |pages=963–975 |doi=10.1093/mnras/stae015 |doi-access=free |arxiv=2301.10858 |bibcode=2024MNRAS.528..963M}}

}}

External links

{{cite web |url=http://www.solstation.com/stars2/cm-dra3.htm#cmdra-aa |title=CM Draconis 3 |accessdate=2008-06-11 |work=SolStation}}

Category:Draco (constellation)

Category:BY Draconis variables

Category:Flare stars

Category:Eclipsing binaries

Category:Triple star systems

Category:M-type main-sequence stars

Category:White dwarfs

0630.1

Draconis, CM