HR 3562

HR 3562

Location of HR 3562 (circled)
Observation data Epoch J2000      Equinox ICRS
Constellation	Vela
HR 3562A
Right ascension	08h 55m 19.20215s
Declination	−45° 02′ 30.0241″
Apparent magnitude (V)	+6.26
HR 3562B
Right ascension	08h 55m 21.6s
Declination	−45° 02′ 52″
Apparent magnitude (V)	+12.639
Characteristics
HR 3562A
Evolutionary stage	main sequence
Spectral type	B3IV
U−B color index	−0.63
B−V color index	−0.16
J−H color index	−0.121
J−K color index	−0.132
Variable type	Slowly pulsating B-type star
Astrometry
HR 3562A
Radial velocity (Rv)	22.0±3.3 km/s
Proper motion (μ)	RA: -13.091 mas/yr Dec.: 7.601 mas/yr
Parallax (π)	2.6833±0.0455 mas
Distance	1,220 ± 20 ly (373 ± 6 pc)
Absolute magnitude (MV)	−2.55
HR 3562B
Absolute magnitude (MV)	5.22
Orbit
Primary	HR 3562A
Secondary	HR 3562B
Semi-major axis (a)	35.0" (10024 AU)
Details
HR 3562A
Mass	5.644±0.282 M☉
Radius	5.648±0.282 R☉
Luminosity	832 L☉
Surface gravity (log g)	3.67 or 4.01 cgs
Temperature	16,982 K
Rotational velocity (v sin i)	5 km/s
Age	36-38 Myr
HR 3562B
Mass	0.914 M☉
Radius	0.826 R☉
Luminosity	0.65 L☉
Temperature	5,613 K
Age	50-110 Myr
Other designations
WDS 08553-4503
HR 3562A: IY Velorum, CD−44°4951, CPD−44°3226, GC 12349, HD 76566, HIP 43807, HR 3562, SAO 220664, PPM 313785, TIC 30125083, TYC 8152-139-1, GSC 08152-00139, 2MASS J08551918-4502298, Gaia DR3 5331355759365786368
Database references
SIMBAD	A
	B

HR 3562 (HD 76566) is a visual binary consisting of a bluish-white hued variable star and a Sun-like secondary star in the southern constellation of Vela. It has the variable-star designation IY Velorum (abbreviated to IY Vel). With an apparent magnitude of 6.26, the brighter primary is near the limit for naked eye visibility. The fainter companion has an apparent magnitude of 12.639 and can be observed with a telescope with an aperture of 76 mm or wider. It is located approximately 373 parsecs (1,220 ly) distant according to Gaia DR3 parallax measurements, and is receding away from the Solar System at a heliocentric radial velocity of 22.0 km/s.

HR 3562A

This is a hot, luminous B-type subgiant (spectral type B3IV) with a mass of 5.644 M_☉ and a radius of 5.648 R_☉. It radiates 832 times the luminosity of the Sun from its photosphere at an effective temperature of 16,982 K (16,709 °C; 30,108 °F), almost three times hotter than the Sun (5,772 K). It is thought to be very young at around 36-38 million years old.

In 1982, Burki et al. reported that the star showed pulsations with multiple periods, namely 1.97 days, 1.73 days, and 1.66 days, all with amplitudes of several mmag that produce a combined peak-to-peak amplitude of about 0.04 mag. As such, they categorized the star as a multiperiodic slowly pulsating B-type star (SPB). In 1986, however, Balona & Laing were only able to confirm one major period of 2.22 days. Due to the small projected rotational velocity, they classified it as a rotating ellipsoidal variable instead, which would have been indicative of a close binary with an orbital period of 4.44 days. Further observations were conducted by Balona, who, in 1994, changed his position and concluded that the star was indeed a SPB, having discovered that the 2.22 day period he previously found was actually the mean of three distinct periods at 1.9566 days, 2.1072 days, and 2.4563 days. It shows similarities to HR 2680, another SPB.

HR 3562B

HR 3562 was first discovered to be a double star by John Herschel in 1836. In 2001, it was confirmed that this was a physical binary system rather than an optical double i.e., a pair of unrelated stars closely aligned by chance. The pair are spaced 10,024 AU (0.15850 ly) apart, based on the separation of 35.0 arcseconds. This secondary is a post-T Tauri star, currently in the main sequence, with a Sun-like mass (0.98-1.01 M_☉) and a slightly cooler temperature of 5,613 K (5,340 °C; 9,644 °F), emitting 64% the Sun's luminosity. The star is aged about 50-110 million years.

References