θ1 Orionis E (Latinised asTheta1 Orionis E) is a double-linedspectroscopic binary located 4' north ofθ1 Orionis A in theTrapezium Cluster. The two components are almost identicalpre-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-Calderónet al. (2012)[3]
Each component of the binary system is slightly under 3 M☉. Although they have asubgiant spectral classification, they are still contracting onto themain sequence[8] and are estimated to be less than 100,000 years old.[5] It is estimated that they will reach the main sequence as smaller hotter late-B stars.[7]
^abCutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003)."VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)".CDS/ADC Collection of Electronic Catalogues.2246: II/246.Bibcode:2003yCat.2246....0C.
^abcKukarkin, B. V.; Kholopov, P. N.; Artiukhina, N. M.; Fedorovich, V. P.; Frolov, M. S.; Goranskij, V. P.; Gorynya, N. A.; Karitskaya, E. A.; Kireeva, N. N.; Kukarkina, N. P.; Kurochkin, N. E.; Medvedeva, G. I.; Perova, N. B.; Ponomareva, G. A.; Samus, N. N.; Shugarov, S. Y. (1981). "Catalogue of suspected variable stars. Moscow, Acad. Of Sciences USSR Shternberg,1951 (1981)".Nachrichtenblatt der Vereinigung der Sternfreunde E.V. (1981).Bibcode:1981NVS...C......0K.
^abcMorales-Calderón, M.; Stauffer, J. R.; Stassun, K. G.; Vrba, F. J.; Prato, L.; Hillenbrand, L. A.; Terebey, S.; Covey, K. R.; Rebull, L. M.; Terndrup, D. M.; Gutermuth, R.; Song, I.; Plavchan, P.; Carpenter, J. M.; Marchis, F.; García, E. V.; Margheim, S.; Luhman, K. L.; Angione, J.; Irwin, J. M. (2012). "YSOVAR: Six Pre-main-sequence Eclipsing Binaries in the Orion Nebula Cluster".The Astrophysical Journal.753 (2): 149.arXiv:1206.6350.Bibcode:2012ApJ...753..149M.doi:10.1088/0004-637X/753/2/149.S2CID44908832.
^Costero, R.; Allen, C.; Echevarría, J.; Georgiev, L.; Poveda, A.; Richer, M. G. (2008). "The Escaping Spectroscopic Binary θ^1 Ori E".IV Reunión Sobre Astronomía Dinámica en Latino América (Eds. C. Allen.34: 102.Bibcode:2008RMxAC..34..102C.
^abcdCostero, Rafael; Echevarría, Juan; Yilen Gómez Maqueo Chew; Ruelas-Mayorga, Alex; Sánchez, Leonardo J. (2025). "Medium-resolution spectroscopic study of the intermediate-mass pre-main sequence binary $θ^1$ Ori E".arXiv:2511.03067 [astro-ph.SR].
