Theta Cephei,Latinized from θ Cephei, is astellar class A7, fourth-magnitudestar in theconstellationCepheus. This displays at a metallic-lineAm star.[4] It is a white-hued, single-linedspectroscopic binary system, located about 127light-years fromEarth. The pair have anorbital period of 2.5 years;[8] theeccentricity was long thought to be low, at 0.03,[11] but recent calculations have put it at a much higher 0.377.[8] They are separated by4.16 AU.[12] The companion star is calculated to be about 400 times fainter than the primary. It is completely invisible in the spectrum, but is estimated to be a K7main sequence star.[9]
^abcJohnson, H. L.; et al. (1966), "UBVRIJKL photometry of the bright stars",Communications of the Lunar and Planetary Laboratory,4 (99): 99,Bibcode:1966CoLPL...4...99J.
^abAbt, Helmut A.; Morrell, Nidia I. (1995), "The Relation between Rotational Velocities and Spectral Peculiarities among A-Type Stars",The Astrophysical Journal Supplement Series,99: 135,Bibcode:1995ApJS...99..135A,doi:10.1086/192182.
^Skiff, B. A (2014), "VizieR Online Data Catalog: Catalogue of Stellar Spectral Classifications (Skiff, 2009-2016)",VizieR On-line Data Catalog: B/Mk. Originally Published in: Lowell Observatory (October 2014),1,Bibcode:2014yCat....1.2023S.
^Evans, D. S. (1967), "The Revision of the General Catalogue of Radial Velocities",Determination of Radial Velocities and Their Applications,30: 57,Bibcode:1967IAUS...30...57E.
