Delta Cephei

Database links to δ Cephei

Star Delta Cephei
AladinLite
Observation dates equinox :  J2000.0 , epoch : J2000.0
Constellation	Cepheus
Right ascension	22 h 29 m 10.27 s
declination	+ 58 ° 24 ′ 54.7 ″
Apparent brightness	3.75 (3.49 to 4.36) mag
Typing
B − V color index	+0.60
U − B color index	+0.36
Spectral class	F5 Iab (F5Ib - G1Ib)
Variable star type	DCEP
Astrometry
Radial velocity	−24 km / s
parallax	Hip: 3.77 ± 0.16 mas HST: 3.66 ± 0.15  mas
distance	887 ± 26  ly 272 ± 8  pc
Visual absolute brightness M vis	−3.47 ± 0.10 mag
Proper movement
Rec. Share:	15.35  mas / a
Dec. portion:	3.52  mas / a
Physical Properties
Dimensions	4.5  M ☉
radius	44.5  R ☉
Luminosity	2000  L ☉
Effective temperature	5500-6800  K
Metallicity [Fe / H]	+0.08
Rotation time	40 d
Age	10 8  a
Other names and catalog entries
Bayer name δ Cephei Flamsteed name 27 Cephei Bonn survey BD +57 2548 Bright Star Catalog HR 8571 [1] Henry Draper Catalog HD 213306 [2] Hipparcos catalog HIP 110991 [3] SAO catalog SAO 34508 [4] Tycho catalog TYC 3995-1479-1 [5] 2MASS catalog 2MASS J22291029 + 5824549 [6] Other names FK5  847

Delta Cephei is a variable star in the constellation of Cepheus , the variability of which was discovered in 1784 by the English astronomer John Goodricke .

properties

The light curve of δ Cephei shows the magnitude as a function of time

Shock front around δ Cephei

Delta Cephei is a yellow supergiant , located at a distance of 272 parsecs (887 light years ) from the Sun is. Its apparent brightness fluctuates between 3.48 ^m and 4.37 ^m with a period of 5.36643 days , with its spectral type also changing between F5Ib and G2Ib. This is associated with a periodic change in the surface temperature of around 1000 ° C.

Delta Cephei is the prototype of a class of pulsation-variable stars , the so-called Delta Cephei stars , which - as their period duration only depends on the luminosity - plays a role in the measurement of the distance of galaxies .

Delta Cephei is also a double star that can be separated in prism binoculars . Its companion star is located at a position angle of 191 ° 41 " from Delta Cephei. It has an apparent magnitude of 6.3 ^m and belongs to spectral class B7.

Web links

• Delta Cephei . In: American Association of Variable Star Observers . September 2000. Archived from the original on June 8, 2008. Retrieved June 21, 2008.
• Delta Cephei . In: The Internet Encyclopedia of Science . Retrieved June 21, 2008.
• Delta Cephei, 27 Cephei . In: SEDS . Retrieved June 21, 2008.
• Jim Kaler: Delta Cephei . In: University of Illinois . STARS. Retrieved October 13, 2017.

Individual evidence

1. ^ ^{A b c} F. van Leeuwen: Validation of the new Hipparcos reduction . In: Astronomy and Astrophysics . 474, No. 2), November 2007, pp. 653-664. arxiv : 0708.1752 . bibcode : 2007A & A ... 474..653V . doi : 10.1051 / 0004-6361: 20078357 .
2. ↑ ^{a b c} del Cep. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed September 16, 2018 . 
3. ↑ ^{a b} del Cep. In: VSX. AAVSO, accessed September 16, 2018 . 
4. ^ G. Fritz Benedict, et al .: Astrometry with the Hubble Space Telescope: A Parallax of the Fundamental Distance Calibrator δ Cephei . In: Astronomical Journal . 2002. arxiv : astro-ph / 0206214 . bibcode : 2002AJ .... 124.1695B . doi : 10.1086 / 342014 .
5. Jump up ↑ D. Majaess, D. Turner, W. Gieren: New Evidence Supporting Cluster Membership for the Keystone Calibrator Delta Cephei . In: Astrophysical Journal . 747, No. 2, 2012, p. 145. arxiv : 1201.0993 . bibcode : 2012ApJ ... 747..145M . doi : 10.1088 / 0004-637X / 747/2/145 .
6. ↑ ^{a b c} L. D. Matthews, et al .: New Evidence for Mass Loss from δ Cephei from HI 21 cm Line Observations . In: The Astrophysical Journal . 744, No. 1, January 2012, p. 53. arxiv : 1112.0028 . bibcode : 2012ApJ ... 744 ... 53M . doi : 10.1088 / 0004-637X / 744/1/53 .
7. ^ MAT Groenewegen: Baade-Wesselink distances and the effect of metallicity in classical cepheids . In: Astronomy and Astrophysics . 488, No. 1, September 2008, pp. 25-35. arxiv : 0807.1269 . bibcode : 2008A & A ... 488 ... 25G . doi : 10.1051 / 0004-6361: 200809859 .
8. ^ Akira Uesugi, Ichiro Fukuda: Catalog of rotational velocities of the stars . In: Contributions from the Institute of Astrophysics and Kwasan Observatory (University of Kyoto) . 1970. bibcode : 1970crvs.book ..... U .