OGLE-LMC-CEP0227

OGLE-LMC-CEP0227

Artist’s impression of OGLE-LMC-CEP0227
Credit: ESO
Observation data
Epoch J2000      Equinox J2000
Constellation Mensa
Right ascension 04h 52m 15.678s[1]
Declination −70° 14′ 31.33″[1]
Apparent magnitude (V) 15.317[2]
Characteristics
Spectral type F7Ib + G4II[3][a]
Apparent magnitude (J) 13.727[1]
Apparent magnitude (H) 13.217[1]
Apparent magnitude (K) 13.262[1]
Variable type Eclipsing binary, δ Cep[4]
Astrometry
Distance163,000[5] ly
(50,000 pc)
Orbit[3]
Period (P)309.404±0.002 days
Semi-major axis (a)389.86±0.77
Eccentricity (e)0.1659±0.0006
Inclination (i)86.833±0.016°
Argument of periastron (ω)
(secondary)		342.0±0.6°
Details[3][a]
A (Cepheid)
Mass4.165±0.032 M☉
Radius34.92±0.34 R☉
Luminosity1,439 L☉
Surface gravity (log g)1.971±0.011 cgs
Temperature6,050±160 K
B
Mass4.134±0.037 M☉
Radius44.85±0.29 R☉
Surface gravity (log g)1.751±0.010 cgs
Temperature5,120±130 K
Rotational velocity (v sin i)11.1±1.2 km/s
Other designations
2MASS J04521567-7014313
Database references
SIMBADdata

OGLE-LMC-CEP0227 is an eclipsing binary and Cepheid variable star,[6] pulsating every 3.8 days.[4] The star, in the Large Magellanic Cloud, was the first Cepheid star system found to be orbiting exactly edge on.[4]

A near-infrared (I band) light curve for OGLE-LMC-CEP0227, adapted from Pietrzyński et al. (2010).[4] The main plot shows the eclipse light curve, with the Cepheid variation removed, and the inset plot shows the Cepheid variation.

The OGLE-LMC-CEP0227 system contains two stars which orbit each other almost exactly 'edge on' to the line of sight from the Earth. This unique configuration has allowed astronomers to refine their understanding of classical Cepheid variable stars. Studies of this system have allowed astronomers to measure the Cepheid mass with unprecedented accuracy. There is still disagreement over whether the pulsational properties accurately match the mass derived from the observed orbit.[4][6]

The two stars orbit each other every 309 days, and each has a mass close to 4.1 M☉. The primary component has an effective temperature of 6,050 K and the secondary a temperature of 5,120 K.[3]

  1. ^ a b c d e Cite error: The named reference 2MASS was invoked but never defined (see the help page).
  2. ^ Cite error: The named reference OGLE was invoked but never defined (see the help page).
  3. ^ a b c d Cite error: The named reference parameters was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference pietrzynski was invoked but never defined (see the help page).
  5. ^ Cite error: The named reference nature was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference neilson was invoked but never defined (see the help page).


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