1 Persei

1 Persei

Location of 1 Persei (circled)
Observation data Epoch J2000.0       Equinox J2000.0
Constellation	Perseus
Right ascension	01h 51m 59.32008s [1]
Declination	+55° 08′ 50.5837″ [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: 12.716(74) [1] mas/yr Dec.: −8.410(79) [1] mas/yr
Parallax (π)	2.6944±0.0888  mas [1]
Distance	1,210 ± 40  ly (370 ± 10  pc)
Absolute magnitude  (MV)	−1.37/−1.77 [4]
Orbit [4]
Primary	1 Persei A
Companion	1 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
Mass	6.95  M☉
Radius	3.29  R☉
Luminosity	2,188  L☉
Surface gravity (log g)	4.25  cgs
Temperature	21,500  K
Rotation	1.45 days
Rotational velocity (v sin i)	115 km/s
Secondary
Mass	7.42  M☉
Radius	3.86  R☉
Luminosity	3,311  L☉
Surface gravity (log g)	4.14  cgs
Temperature	22,000  K
Rotation	1.40 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
SIMBAD	data

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.

Observational history

A visual band light curve for V436 Persei, adapted from Janik et al. (2003)

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. Brown, A. G. A.; et al. (Gaia collaboration) (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics . 649: A1. arXiv: 2012.01533 . Bibcode:2021A&A...649A...1G. doi: 10.1051/0004-6361/202039657 . S2CID   227254300. (Erratum:  doi:10.1051/0004-6361/202039657e). Gaia EDR3 record for this source at VizieR .
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" (PDF). 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.