Theta1 Orionis E

For other stars with this Bayer designation, see θ Orionis.
θ1 Orionis E

θ1 Orionis E and nearby stars in the Trapezium Cluster
Observation data
Epoch J2000      Equinox J2000
Constellation Orion
Right ascension 05h 35m 15.773s[1]
Declination −05° 23′ 10.02″[1]
Apparent magnitude (V) 11.40 - 11.81[2]
Characteristics
Evolutionary stage PMS[3]
Spectral type G2 IV[4]
Variable type Eclipsing[3]
Astrometry
Radial velocity (Rv)34.3[5] km/s
Proper motion (μ) RA: 1.45±0.03[6] mas/yr
Dec.: 1.02±0.08[6] mas/yr
Parallax (π)2.557 ± 0.051 mas[6]
Distance1,280 ± 30 ly
(391 ± 8 pc)
Absolute magnitude (MV)+1.43[7]
Orbit
Period (P)9.89520 ± 0.0007[4] days
Semi-major axis (a)34.430 ± 0.193[3] R☉
Eccentricity (e)< 0.001[4]
Inclination (i)73.7 ± 0.9[3]°
Semi-amplitude (K1)
(primary)		84.2 ± 1.2[4] km/s
Semi-amplitude (K2)
(secondary)		84.6 ± 1.3[4] km/s
Details
A
Mass2.807 ± 0.048[3] M☉
Radius7.1[7] R☉
Luminosity29[8] L☉
Temperature6,000[3] K
Rotational velocity (v sin i)37[8] km/s
B
Mass2.797 ± 0.048[3] M☉
Radius7.1[7] R☉
Luminosity29[8] L☉
Temperature6,000[3] K
Rotational velocity (v sin i)37[8] km/s
Age500[8] Myr
Other designations
41 Ori E, BD−05°1315E, COUP 732, 2MASS J05351577-0523100
Database references
SIMBADdata

θ1 Orionis E (Latinised as Theta1 Orionis E) is a double-lined spectroscopic binary located 4' north of θ1 Orionis A in the Trapezium Cluster. The two components are almost identical pre-main-sequence stars in a close circular orbit, and they show shallow eclipses that produce brightness variations of a few tenths of a magnitude.

A near-infrared (4.5 micron) light curve for Theta1 Orionis E, adapted from Morales-Calderón et al. (2012)[3]

Each component of the binary system is slightly under 3 M☉. Although they have a subgiant spectral classification, they are still contracting onto the main sequence and are estimated to be only about 500 million years old.[8] It is estimated that they will reach the main sequence as smaller hotter late-B stars.[7]

The variability was first reported in 1954[2] and confirmed as an eclipsing binary in 2012. It has not been assigned a variable star designation but is listed in the New Catalogue of Suspected Variable Stars.[2]

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  2. ^ a b c Cite error: The named reference nsv was invoked but never defined (see the help page).
  3. ^ a b c d e f g h i Cite error: The named reference m-c was invoked but never defined (see the help page).
  4. ^ a b c d e Cite error: The named reference costero was invoked but never defined (see the help page).
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  6. ^ a b c Cite error: The named reference Kounkel2017 was invoked but never defined (see the help page).
  7. ^ a b c d Cite error: The named reference herbig was invoked but never defined (see the help page).
  8. ^ a b c d e f Cite error: The named reference huenemoerder was invoked but never defined (see the help page).