HR 3562
Visual binary in constellation Vela
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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[5] and can be observed with a telescope with an aperture of 76 mm or wider.[11] 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.
 | |
| Observation data Epoch J2000[1] Equinox J2000[1] | |
|---|---|
| Constellation | Vela |
| HR 3562A | |
| Right ascension | 08h 55m 19.20215s[2] |
| Declination | −45° 02′ 30.0241″[2] |
| Apparent magnitude (V) | +6.26[3] |
| HR 3562B | |
| Right ascension | 08h 55m 21.6s[4] |
| Declination | −45° 02′ 52″[4] |
| Apparent magnitude (V) | +12.639[5] |
| Characteristics | |
| HR 3562A | |
| Evolutionary stage | main sequence[2] |
| Spectral type | B3IV[6] |
| U−B color index | −0.63[3] |
| B−V color index | −0.16[3] |
| J−H color index | −0.121[7] |
| J−K color index | −0.132[7] |
| Variable type | Slowly pulsating B-type star |
| Astrometry | |
| HR 3562A | |
| Radial velocity (Rv) | 22.0±3.3[8] km/s |
| Proper motion (μ) | RA: -13.091[2] mas/yr Dec.: 7.601[2] mas/yr |
| Parallax (π) | 2.6833±0.0455 mas[2] |
| Distance | 1,220 ± 20 ly (373 ± 6 pc) |
| Absolute magnitude (MV) | −2.55[5] |
| HR 3562B | |
| Absolute magnitude (MV) | 5.22[5] |
| Orbit[5] | |
| Primary | HR 3562A |
| Name | HR 3562B |
| Semi-major axis (a) | 35.0" (10024 AU) |
| Details | |
| HR 3562A | |
| Mass | 5.644±0.282[6] M☉ |
| Radius | 5.648±0.282[6] R☉ |
| Luminosity | 832[5] L☉ |
| Surface gravity (log g) | 3.67 or 4.01[5] cgs |
| Temperature | 16,982[5] K |
| Rotational velocity (v sin i) | 5[9] km/s |
| Age | 36-38[5] Myr |
| HR 3562B | |
| Mass | 0.914[10] M☉ |
| Radius | 0.826[10] R☉ |
| Luminosity | 0.65[5] L☉ |
| Temperature | 5,613[5] K |
| Age | 50-110[5] 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[1] | |
| Database references | |
| SIMBAD | A |
| B | |
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☉.[6] 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.[5]
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).[13] 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.[9] 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.[14]
HR 3562B
HR 3562 was first discovered to be a double star by John Herschel in 1836.[15] 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.[5]