HR 3600

HR 3600
Location of HR 3600 (circled)
Observation data
Epoch J2000[1]      Equinox J2000[1]
Constellation Vela
Right ascension 09h 01m 20.86511s
Declination −41° 51′ 51.3343″
Apparent magnitude (V) +5.541[2]
Characteristics
HR 3562A
Spectral type B5V[3]
U−B color index −0.56[2][4]
B−V color index −0.133[2]
J−H color index −0.106[4]
J−K color index −0.106[4]
Variable type Slowly pulsating B-type star?[5]
Astrometry
Radial velocity (Rv)22.8±1.2[6] km/s
Proper motion (μ) RA: -22.727[7] mas/yr
Dec.: 12.139[7] mas/yr
Parallax (π)6.6050 ± 0.0711 mas[7]
Distance494 ± 5 ly
(151 ± 2 pc)
Absolute magnitude (MV)−0.71[8]
Absolute bolometric
magnitude (Mbol)		−2.08[8]
Details[8]
Mass3.999±0.200[9] M☉
Radius3.222±0.161[9] R☉
Luminosity535 L☉
Surface gravity (log g)4.30 cgs
Temperature14,966 K
Rotational velocity (v sin i)50[5] km/s
Other designations
IZ Velorum, CD−41° 4720, CPD−41° 3232, Gaia DR3 5428323854487771392, GC 12489, HD 77475, HIP 44299, HR 3600, SAO 220760, PPM 313879, WDS J08553-4503A, TIC 191446158, TYC 7685-2721-1, GSC 07685-02721, 2MASS J09012085-4151513[1]
Database references
SIMBADdata

HR 3600 (HD 77475) is a bluish-white hued variable star in the southern constellation of Vela. It has the variable-star designation IZ Velorum (abbreviated to IZ Vel). With an apparent magnitude of about 5.54, it is faintly visible by the naked eye under dark skies. It is located approximately 494 light-years (151 parsecs) distant according to Gaia EDR3 parallax measurements, and is receding from the Solar System at a heliocentric radial velocity of 22.8 km/s.

Physical properties

This is a hot, luminous B-type main-sequence star with a mass of 4.0 M☉ and a radius of 3.2 R☉.[9] With an effective temperature of 14,966 K (26,479 °F), it shines at an absolute bolometric magnitude of −2.08, meaning it radiates 535 L☉ from its photosphere; and an absolute visual magnitude of −0.71, that is 151 L☉ released in the visual (V) band of the UBV photometric system.[8]

This star was initially given the stellar classification B5III in 1978,[10] indicative of a blue giant, but was reclassified as a main-sequence star of the same spectral type by Burki et al. (1982) due to similarities to other stars such as 32 Orionis, Lambda Columbae, HW Velorum, and HD 186837, all of type B5V. They simultaneously reported that it was a slowly pulsating B-type star (SPB) with three tentative periods of 9.64 days, 14.4 days, and 10.7 days, all of them with amplitudes of several mmag that produce a combined peak-to-peak amplitude of roughly 0.03 mag.[3]

A light curve for IZ Velorum, plotted from TESS data.[11] The 0.905 day period derived by Balona is marked in red.

In 1986, Balona & Laing stated that HR 3600 in fact only had a single period of 1.10 days, an alias of the 9.64-day period presented by Burki et al. Citing the variable radial velocity of the star (20-30 km/s) and the low projected rotational velocity (50 km/s), they argued that it was more likely a rotating ellipsoidal variable, in which case the system would consist of a close binary orbiting each other every 2.20 days.[12] In 1994, Balona, who continued to observe the variable, revised the period to 0.905 days (or possibly 1.81 days), which was another alias of the 9.64-day period. The 14.4-day period could not be detected. The low rotational velocity contradicts with the hypotheses that the variability is caused by either binarity or rotational modulation, so the exact nature of this star has yet to be determined.[5]

References

  1. ^ a b "HD 77475". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 11 January 2025.
  2. ^ a b c Høg, E.; et al. (February 2000). "The Tycho-2 Catalogue of the 2.5 Million Brightest Stars". Astronomy and Astrophysics. 355 (1): L27 – L30. Bibcode:2000A&A...355L..27H.
  3. ^ a b Burki, G.; Burnet, M.; Magalhaes, A. S.; North, P.; Rufener, F.; Waelkens, C. (19 October 1982). "HR 3562 and HR 3600, Two New Multi-Periodic B-Type Stars". Information Bulletin on Variable Stars. 2211 (1). Konkoly Observatory, Budapest: International Astronomical Union. Bibcode:1982IBVS.2211....1B.
  4. ^ a b c Cutri, Roc M.; Skrutskie, Michael F.; Van Dyk, Schuyler D.; Beichman, Charles A.; Carpenter, John M.; Chester, Thomas; Cambresy, Laurent; Evans, Tracey E.; Fowler, John W.; Gizis, John E.; Howard, Elizabeth V.; Huchra, John P.; Jarrett, Thomas H.; Kopan, Eugene L.; Kirkpatrick, J. Davy; Light, Robert M.; Marsh, Kenneth A.; McCallon, Howard L.; Schneider, Stephen E.; Stiening, Rae; Sykes, Matthew J.; Weinberg, Martin D.; Wheaton, William A.; Wheelock, Sherry L.; Zacarias, N. (2003). "VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)". CDS/ADC Collection of Electronic Catalogues. 2246: II/246. Bibcode:2003yCat.2246....0C.
  5. ^ a b c Balona, L. A. (15 October 1994). "The 53 Per stars HR 3562 and HR 3600" (PDF). Monthly Notices of the Royal Astronomical Society. 270 (4): 914–920. doi:10.1093/mnras/270.4.914. ISSN 0035-8711. Retrieved 7 January 2025.
  6. ^ Gontcharov, G. A. (2006). "Pulkovo Compilation of Radial Velocities for 35 495 Hipparcos stars in a common system". Astronomy Letters. 32 (11): 759–771. doi:10.1134/S1063773706110065. ISSN 1063-7737. Retrieved 9 January 2025.
  7. ^ a b c 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.
  8. ^ a b c d North, P.; Paltani, S. (August 1994). "HD 37151: a new "slowly pulsating B star"". Astronomy & Astrophysics. 288: 155–164. Bibcode:1994A&A...288..155N.
  9. ^ a b c Kervella, Pierre; Arenou, Frédéric; Mignard, François; Thévenin, Frédéric (2019). "Stellar and substellar companions of nearby stars from Gaia DR2: Binarity from proper motion anomaly" (PDF). Astronomy & Astrophysics. 623: A72. doi:10.1051/0004-6361/201834371. ISSN 0004-6361. Retrieved 7 January 2025. Record for this source at VizieR.
  10. ^ Houk, Nancy (1978). Michigan catalogue of two-dimensional spectral types for the HD stars. Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan. Bibcode:1978mcts.book.....H.
  11. ^ "MAST: Barbara A. Mikulski Archive for Space Telescopes". Space Telescope Science Institute. Retrieved 10 January 2025.
  12. ^ Balona, L. A.; Laing, J. D. (1 December 1986). "HR 3562 and 3600: two short-period B-type variables". Monthly Notices of the Royal Astronomical Society. 223 (3): 621–627. doi:10.1093/mnras/223.3.621. ISSN 0035-8711.