15 Cancri

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Template:Short description

15 Cancri
File:BMCncLightCurve.png
A light curve for BM Cancri, plotted from TESS data[1]
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Cancer
Right ascension Template:RA[2]
Declination Template:DEC[2]
Apparent magnitude (V) 5.53 - 5.65[3]
Characteristics
Spectral type A0:V:spSiSr[4]
B−V Template:Engvar Script error: No such module "val".[5]
Variable type α2 CVn[3]
Astrometry
Radial velocity (Rv)Script error: No such module "val".[6] km/s
Proper motion (μ) RA: −12.959[2] mas/yr
Dec.: −22.232[2] mas/yr
Parallax (π)3.3279±0.2458 mas[2]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−0.97[5]
Orbit[6]
Primary15 Cancri A
Companion15 Cancri B
Period (P)Script error: No such module "val". days[note 1]
Eccentricity (e)Script error: No such module "val".
Periastron epoch (T)Script error: No such module "val".
Argument of periastron (ω)
(primary)		Script error: No such module "val".°
Semi-amplitude (K1)
(primary)		Script error: No such module "val". km/s
Details
15 Cnc A
Luminosity327.24[5] Template:Solar luminosity
Surface gravity (log g)Script error: No such module "val".[7] cgs
TemperatureScript error: No such module "val".[7] K
Rotational velocity (v sin i)25[4] km/s
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[8]
Database references
SIMBADdata

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15 Cancri is an α2 CVn-type variable star in the zodiac constellation of Cancer, located around 980[2] light years away. It has the variable star designation BM Cancri (BM Cnc); 15 Cancri (15 Cnc) is the Flamsteed designation. This system is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of about 5.6. It is moving away from the Earth with a heliocentric radial velocity of 25 km/s.[6]

Radial velocity measurements taken at the Dominion Astrophysical Observatory in Victoria, British Columbia Canada in 1918 and 1919 led to the determination that 15 Cancri is a single-lined spectroscopic binary system.[9] The first orbit was calculated in 1973 by Helmut Abt and Michael Snowden with a period of 585 days[10] however later measurements showed that the orbital period was 635 days.[6][note 1]

15 Cancri A, the visible component, is an Ap star, a chemically peculiar star with an over-abundance of iron peak elements, particularly silicon, chromium, and strontium, in its spectrum.[11][4]

Like all Ap stars, 15 Cancri has a strong magnetic field. This magnetic field varies as it rotates and in 1968 the visual brightness of the star was shown to vary regularly over about four days.[12] 15 Cancri was given the variable star designation BM Cancri in 1972 as a member of the α2 CVn class of variable stars.[13] The period has since been measured more accurately at Script error: No such module "val"., believed to be the rotational period of the star.[14]

Notes

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  1. ↑ a b An alternate period of 475 days is possible but less likely.

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References

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  1. ↑ Script error: No such module "citation/CS1".
  2. ↑ a b c d e f Template:Cite Gaia DR2
  3. ↑ a b Script error: No such module "Citation/CS1".
  4. ↑ a b c Script error: No such module "Citation/CS1".
  5. ↑ a b c Script error: No such module "Citation/CS1".
  6. ↑ a b c d Script error: No such module "Citation/CS1".
  7. ↑ a b Script error: No such module "Citation/CS1".
  8. ↑ SIMBAD, 15 Cancri (accessed 2012 March 20)
  9. ↑ Script error: No such module "Citation/CS1".
  10. ↑ Script error: No such module "Citation/CS1".
  11. ↑ Script error: No such module "Citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".
  13. ↑ Script error: No such module "Citation/CS1".
  14. ↑ Script error: No such module "Citation/CS1".

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Template:Stars of Cancer

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