This is a yellow-white hued, F-type star with a stellar classification of F0 V (Sr II)[4] or F0 IV.[5] Thus it may either be an F-type main sequence star showing an abundance excess of strontium, or it could be a more evolvedsubgiant star. It is a Delta Scuti variable star that cycles between magnitudes 4.15 and 4.21 every 59.388 minutes.[3] The star displays an infrared excess, indicating the presence of a debris disk with a temperature of 65 K orbiting at a radius of 62 AU. This dust has a combined mass equal to 6.6% of the Earth's mass.[10]
Binary
There is a faint companion star at an angular separation of 330±50 mas along a position angle of 90°±10°. This corresponds to a projected physical separation of 8.6±1.4 AU. The probability of a random star being situated this close to Epsilon Cephei is about one in a million, so it is most likely physically associated. If so, then the debris disk is probably circumbinary. The fact that this companion was not detected during the Hipparcos mission may indicate its orbit has a high eccentricity. The companion star has a K-band magnitude of 7.8 and is probably of class K8–M2.[5]
^Bruntt, H.; Suárez, J. C.; Bedding, T. R.; Buzasi, D. L.; Moya, A.; Amado, P. J.; Martín-Ruiz, S.; Garrido, R.; López de Coca, P.; Rolland, A.; Costa, V.; Olivares, I.; García-Pelayo, J. M. (January 2007), "Asteroseismology with the WIRE satellite I. Combining ground- and space-based photometry of the δ Scuti star ɛ Cephei", Astronomy and Astrophysics, 461 (2): 619–630, arXiv:astro-ph/0610539, Bibcode:2007A&A...461..619B, doi:10.1051/0004-6361:20065766.
^ abGray, R. O.; et al. (2001), "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars", The Astronomical Journal, 121 (4): 2148–2158, Bibcode:2001AJ....121.2148G, doi:10.1086/319956.
^ abcdDavid, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID33401607.
^De Rosa, R. J.; Patience, J.; Wilson, P. A.; Schneider, A.; Wiktorowicz, S. J.; Vigan, A.; Marois, C.; Song, I.; MacIntosh, B.; Graham, J. R.; Doyon, R.; Bessell, M. S.; Thomas, S.; Lai, O. (2013), "The VAST Survey - III. The multiplicity of A-type stars within 75 pc", Monthly Notices of the Royal Astronomical Society, 437 (2): 1216, arXiv:1311.7141, Bibcode:2014MNRAS.437.1216D, doi:10.1093/mnras/stt1932.