1 Persei

1 Persei (1 Per) is an eclipsing binary[3] star in the constellation Perseus. Its uneclipsed apparent magnitude is 5.49. The binary star consists of two B2 type main-sequence stars in a 25.9 day eccentric orbit.[5] The stars are surrounded by a faint cloud of gas visible in mid-infrared, although whether they are the origin of the gas or simply passing through it is unclear.

1 Persei
Location of 1 Persei (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Perseus
Right ascension 01h 51m 59.320s[1]
Declination +55° 08′ 50.58″[1]
Apparent magnitude (V) 5.49 - 5.74 - 5.85[2]
Characteristics
Spectral type B1.5V[2]
Variable type eclipsing binary[3]
Astrometry
Proper motion (μ) RA: 12.05 ± 0.25[1] mas/yr
Dec.: −9.18 ± 0.28[1] mas/yr
Parallax (π)2.52 ± 0.33[1] mas
Distanceapprox. 1,300 ly
(approx. 400 pc)
Absolute magnitude (MV)−1.37/−1.77[4]
Orbit[4]
Primary1 Persei A
Companion1 Persei B
Period (P)25.935951±0.000003 d
Eccentricity (e)0.3768±0.0014
Inclination (i)88.048±0.002°
Periastron epoch (T)2443563.466±0.005 HJD
Argument of periastron (ω)
(secondary)		109.83±0.10°
Semi-amplitude (K1)
(primary)		97.4±0.1 km/s
Semi-amplitude (K2)
(secondary)		91.2±0.1 km/s
Details[4]
Primary
Mass6.95 M☉
Radius3.29 R☉
Luminosity2,188 L☉
Surface gravity (log g)4.25 cgs
Temperature21,500 K
Rotation1.45 days
Rotational velocity (v sin i)115 km/s
Secondary
Mass7.42 M☉
Radius3.86 R☉
Luminosity3,311 L☉
Surface gravity (log g)4.14 cgs
Temperature22,000 K
Rotation1.40 days
Rotational velocity (v sin i)140 km/s
Other designations
V436 Persei, BD+54 396, HD 11241, HIP 8704, HR 533, SAO 22690
Database references
SIMBADdata

Observational history

The possible eclipsing binary nature of 1 Persei was first noticed by Donald Kurtz in 1977 when it was used as a comparison star to test for photometric variability of HD 11408.[6] In 1979 French amateur observers succeeded in determining an orbital period of 25.9 days.[7] During the primary eclipse, the brightness drops to magnitude 5.85. In the secondary eclipses, the brightness drops to magnitude 5.74. The eclipses each last for approximately 25 hours.[2]

References
  1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600.Vizier catalog entry
  2. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. North, P.; et al. (1981). "1 Per: a new eclipsing binary with a long period and an elliptical orbit". Information Bulletin on Variable Stars. 2036: 1. Bibcode:1981IBVS.2036....1N.
  4. Janík, J.; et al. (2003). "Search for forced oscillations in binaries. IV. The eclipsing binary V436 Per revisited". Astronomy and Astrophysics. 408 (2): 611–619. Bibcode:2003A&A...408..611J. doi:10.1051/0004-6361:20030960.
  5. Harmanec, P.; et al. (1997). "Search for forced oscillations in binaries. I. The eclipsing and spectroscopic binary V436 Persei = 1 Persei". Astronomy and Astrophysics. 319 (2): 867–880. Bibcode:1997A&A...319..867H.
  6. Kurtz, D. W. (1977). "The photometric variability of 1 Per". Publications of the Astronomical Society of the Pacific. 89: 939–940. Bibcode:1977PASP...89..939K. doi:10.1086/130251.
  7. Figer, Alain; Maurin, Luc (1979). "1 Persei, a low amplitude eclipsing binary, has a period of 25.939 days and an elliptical orbit". GEOS Circular on Eclipsing Binaries. 2 (EB 2). Bibcode:1979GEOCE...2.....F.
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