BP Tauri

BP Tauri is a young T Tauri star in the constellation of Taurus about 416 light years away, belonging to the Taurus Molecular Cloud. It is still accreting mass at the low rate of 9 × 10−10 and 1.6×10−7 M☉/year,[6] as evidenced by X-rays produced by infalling matter,[7] and may be still in the process of spin-up.[8] Its chromospheric magnetic fields are rather strong at 2.5+0.15
−0.16 kilogauss,[5] and contains strong non-dipole components.[9] The star is producing 40% of its luminosity via the energy released by accretion.[4]

BP Tauri
Observation data
Epoch J2000      Equinox J2000
Constellation Taurus
Right ascension 04h 19m 15.8343s[1]
Declination +29° 06′ 26.9295″[1]
Apparent magnitude (V) 12.12
Characteristics
Evolutionary stage pre-main-sequence star
Spectral type K5
Apparent magnitude (G) 11.460[2]
Variable type T Tau
Astrometry
Radial velocity (Rv)15.76±0.13 km/s
Proper motion (μ) RA: 8.889[2] mas/yr
Dec.: -26.011[2] mas/yr
Parallax (π)7.8494 ± 0.0362[2] mas
Distance416 ± 2 ly
(127.4 ± 0.6 pc)
Details
Mass1.24+0.25
−0.32[3] M☉
Radius2.0[4] R☉
Luminosity0.93[4] L☉
Surface gravity (log g)4.32±0.14[5] cgs
Temperature3640+94
−92[5] K
Rotational velocity (v sin i)11.4+0.25
−0.55[5] km/s
Age6±4[3] Myr
Other designations
Gaia DR2 164832740220756608, HD 281934, HIP 20160, TYC 1827-554-1, GSC 01827-00554, 2MASS J04191583+2906269
Database references
SIMBADdata

Suspected stellar system

There were two suspected stellar companions to BP Tauri on projected separations 3.00 and 5.45 arcseconds.[10] These were proven to be a background stars not related to BP Tauri with Gaia data though.[11][12]

Protoplanetary system

The star is surrounded by a protoplanetary disk. The disk is strongly depleted in carbon and carbon monoxide.[13]

The planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
protoplanetary disk 0–120[14] AU 30[13]° —

Variability

BP Tauri varies in brightness, producing a strong flares due to unsteady accretion[4] held by stellar magnetic field. The lightcurve period is variable from 6.1 to 7.6 days, and quiescent periods without variability are also known.[15]

References
  1. "V* BP Tau". SIMBAD. Centre de données astronomiques de Strasbourg.
  2. 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. Gaia EDR3 record for this source at VizieR.
  3. Simon, M.; Dutrey, A.; Guilloteau, S. (2000), "Dynamical Masses of T Tauri Stars and Calibration of Pre–Main‐Sequence Evolution", The Astrophysical Journal, 545 (2): 1034–1043, arXiv:astro-ph/0008370, Bibcode:2000ApJ...545.1034S, doi:10.1086/317838, S2CID 18064837
  4. Errico, L.; Lamzin, S. A.; Vittone, A. A. (2001), "UV spectra of T Tauri stars from the HST and IUE satellites: BP Tau", Astronomy & Astrophysics, 377 (2): 557–565, Bibcode:2001A&A...377..557E, doi:10.1051/0004-6361:20011108
  5. Flores, C.; Connelley, M. S.; Reipurth, B.; Boogert, A. (2019), "Measuring the Magnetic Field of Young Stars Using iSHELL Observations: BP Tau and V347 Aur", The Astrophysical Journal, 882 (2): 75, arXiv:1908.08583, Bibcode:2019ApJ...882...75F, doi:10.3847/1538-4357/ab35d4, S2CID 201645503
  6. Long, M.; Romanova, M. M.; Kulkarni, A. K.; Donati, J.-F. (2010), "Global 3D simulations of disc accretion on to the classical T Tauri star BP Tauri", Monthly Notices of the Royal Astronomical Society, 413 (2): 1061–1071, arXiv:1009.3300, doi:10.1111/j.1365-2966.2010.18193.x, S2CID 55134816
  7. Schmitt, J. H. M. M.; Robrade, J.; Ness, J.-U.; Favata, F.; Stelzer, B. (2005), "X-rays from accretion shocks in T Tauri stars: The case of BP Tau", Astronomy & Astrophysics, 432 (2): L35–L38, arXiv:astro-ph/0503144, Bibcode:2005A&A...432L..35S, doi:10.1051/0004-6361:200500014, S2CID 2457531
  8. Ireland, Lewis G.; Zanni, Claudio; Matt, Sean P.; Pantolmos, George (2020), "Magnetic Braking of Accreting T Tauri Stars: Effects of Mass Accretion Rate, Rotation, and Dipolar Field Strength", The Astrophysical Journal, 906: 4, arXiv:2011.01087, doi:10.3847/1538-4357/abc828, S2CID 226236865
  9. Long, Min; Romanova, Marina M.; Lamb, Frederick K. (2009), "Accretion onto stars with octupole magnetic fields: Matter flow, hot spots and phase shifts", New Astronomy, 17 (2): 232–245, arXiv:0911.5455, doi:10.1016/j.newast.2011.08.001, S2CID 119113916
  10. Near-Infrared Spectroscopy of Faint Companions around Young Stellar Objects Associated with the Taurus Molecular Cloud
  11. 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. Gaia EDR3 record for this source at VizieR.
  12. 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. Gaia EDR3 record for this source at VizieR.
  13. Observations and modelling of CO and [C I in protoplanetary disks First detections of [C I] and constraints on the carbon abundance
  14. The BP Tau disk: A missing link between Class II and III objects
  15. THE ULTRAVIOLET AND VISIBLE LIGHT VARIABILITY OF BP TAURI: POSSIBLE CLUES FOR THE ORIGIN OF T TAURI STAR ACTIVITY
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