Astronomy:HK Tauri

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Short description: Young binary star system in the constellation of Taurus

Coordinates: Sky map 04h 31m 50.5723s, +24° 24′ 17.7755″

HK Tauri
HKTauLightCurve.png
A light curve for HK Tauri, adapted from Roggero et al. (2021)[1]
Observation data
{{#ifeq:J2000|J2000.0 (ICRS)|Epoch J2000.0      Equinox J2000.0 (ICRS)| Epoch J2000      [[Astronomy:Equinox (celestial coordinates)|Equinox J2000}}
Constellation Taurus
A
Right ascension  04h 31m 50.5716s[2]
Declination +24° 24′ 17.775″[2]
Apparent magnitude (V) 15.10
B
Right ascension  04h 31m 50.6002s[3]
Declination +24° 24′ 15.503″[3]
Apparent magnitude (V)
Characteristics
HK Tauri A
Evolutionary stage pre-main-sequence star
Spectral type M1.5[4]
Apparent magnitude (G) 14.106[2]
Variable type T Tau
HK Tauri B
Spectral type M2[4]
Apparent magnitude (G) 17.962[3]
Astrometry
HK Tauri A
Proper motion (μ) RA: 5.076[2] mas/yr
Dec.: −22.944[2] mas/yr
Parallax (π)7.6247 ± 0.0317[2] mas
Distance428 ± 2 ly
(131.2 ± 0.5 pc)
HK Tauri B
Proper motion (μ) RA: 2.668[3] mas/yr
Dec.: −20.457[3] mas/yr
Parallax (π)7.780 ± 0.6322[3] mas
Distance420 ± 30 ly
(130 ± 10 pc)
Position (relative to HK Tauri A)[4]
ComponentHK Tauri B
Angular distance2.32″
Position angle170.4°
Observed separation
(projected)		309 AU
Details
A
Mass0.44+0.14−0.11[4] M☉
Luminosity0.56[5] L☉
Temperature3680±150[6] K
B
Mass0.37±0.2[4] M☉
Luminosity0.42[5] L☉
Temperature3550±150[6] K
Other designations
HK Tauri A: Gaia EDR3 147847072275324416, Gaia DR2 147847072275324416
HK Tauri B: Gaia EDR3 147847072275766656, Gaia DR2 147847072274696704
Database references
SIMBADdata

HK Tauri is a young binary star system in the constellation of Taurus about 434 light-years away, belonging to the Taurus Molecular Cloud.

System

Artist's impressions of the two disks surrounding both stars

The two stars of the HK Tauri system are separated by 2.32″, equivalent to 309 astronomical unit|AU at the distance of HK Tauri. The primary is a pre-main sequence star with a mass of 0.44 M☉, while the secondary has a mass of 0.37 M☉.[4]

Properties

Both members of the binary are medium-mass objects still contracting towards the main sequence and accreting mass. Their ages are probably young (below 10 million years) but cannot be estimated with any accuracy because both stars are strongly obscured by the protoplanetary disks.[6]

Protoplanetary system

The companion star HK Tauri B is surrounded by a protoplanetary disk visible nearly edge-on. It contains water and carbon dioxide ices, along with gaseous carbon monoxide.[7] The disk is unusually flat, with an aspect ratio of 4.4, while most young stars host disks with aspect ratios of about 3.[8] The disk also contain relatively few large dust particles compared to fine dust, with a size distribution power-law slope of 4.2. The disk mass is relatively small, not larger than 0.0005M☉, and dust distribution is asymmetric.[9] The plane of the disk is not aligned with the orbit of the binary.[10]

Multiple planets embedded in the disk of HK Tauri B have been suspected since 1993,[11] although none were detected by 2020.[12]

The HK Tauri A planetary system[4]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
protoplanetary disk 0–28.7 AU 56.9±0.5° —
The HK Tauri B planetary system[4]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
protoplanetary disk 0–68.0 AU 83.2±0.2° —

References

  1. ↑ Roggero, Noemi; Bouvier, Jérôme; Rebull, Luisa M.; Cody, Ann Marie (July 2021). "The dipper population of Taurus seen with K2". Astronomy and Astrophysics 651: A44. doi:10.1051/0004-6361/202140646. Bibcode: 2021A&A...651A..44R. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Brown, A. G. A. (2021). "Gaia Early Data Release 3: Summary of the contents and survey properties". Astronomy & Astrophysics 649: A1. doi:10.1051/0004-6361/202039657. Bibcode: 2021A&A...649A...1G.  Gaia EDR3 record for this source at VizieR.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 Manara, C. F.; Tazzari, M.; Long, F.; Herczeg, G. J.; Lodato, G.; Rota, A. A.; Cazzoletti, P.; Van Der Plas, G. et al. (2019), "Observational constraints on dust disk sizes in tidally truncated protoplanetary disks in multiple systems in the Taurus region", Astronomy & Astrophysics 628: A95, doi:10.1051/0004-6361/201935964, Bibcode: 2019A&A...628A..95M 
  5. ↑ 5.0 5.1 Akeson, Rachel L.; Jensen, Eric L. N.; Carpenter, John; Ricci, Luca; Laos, Stefan; Nogueira, Natasha F.; Suen-Lewis, Emma M. (2019), "Resolved Young Binary Systems and Their Disks", The Astrophysical Journal 872 (2): 158, doi:10.3847/1538-4357/aaff6a, Bibcode: 2019ApJ...872..158A 
  6. ↑ 6.0 6.1 6.2 Simon, M.; Guilloteau, S.; Beck, Tracy L.; Chapillon, E.; Folco, E. Di; Dutrey, A.; Feiden, Gregory A.; Grosso, N. et al. (2019), "Masses and Implications for Ages of Low-mass Pre-main-sequence Stars in Taurus and Ophiuchus", The Astrophysical Journal 884 (1): 42, doi:10.3847/1538-4357/ab3e3b, Bibcode: 2019ApJ...884...42S 
  7. ↑ Aikawa, Y.; Kamuro, D.; Sakon, I.; Itoh, Y.; Noble, J. A.; Pontoppidan, K. M.; Fraser, H. J.; Terada, H. et al. (2011). "AKARI observations of ice absorption bands towards edge-on YSOs". The Molecular Universe 280: 78. Bibcode: 2011IAUS..280P..78A. 
  8. ↑ Wolff, S.; Duchêne, G.; Stapelfeldt, K.; Ménard, F.; Flores, C.; Padgett, D.; Pinte, C.; Villenave, M. et al. (2021), "The Anatomy of an Unusual Edge-on Protoplanetary Disk. I. Dust Settling in a Cold Disk", The Astronomical Journal 161 (5): 238, doi:10.3847/1538-3881/abeb1d, Bibcode: 2021AJ....161..238W 
  9. ↑ McCabe, C.; Duchêne, G.; Pinte, C.; Stapelfeldt, K. R.; Ghez, A. M.; Ménard, F. (2011). "Spatially Resolving the HK Tau B Edge-on Disk from 1.2 to 4.7 μm: A Unique Scattered Light Disk". The Astrophysical Journal 727 (2): 90. doi:10.1088/0004-637X/727/2/90. Bibcode: 2011ApJ...727...90M. 
  10. ↑ Fragner, M. M.; Nelson, R. P. (2009), "Evolution of warped and twisted accretion discs in close binary systems", Astronomy and Astrophysics 511: A77, doi:10.1051/0004-6361/200913088 
  11. ↑ Marsh, Kenneth A.; Mahoney, Michael J. (1993). "Do the Spectral Energy Distributions of GK Tauri and HK Tauri Indicate the Presence of Planetary Companions?". The Astrophysical Journal 405: L71. doi:10.1086/186768. Bibcode: 1993ApJ...405L..71M. 
  12. ↑ Wallace, A. L.; Kammerer, J.; Ireland, M. J.; Federrath, C.; Kraus, A. L.; Maddison, S. T.; Rizzuto, A.; Birchall, E. K. et al. (2020), "High-resolution survey for planetary companions to young stars in the Taurus molecular cloud", Monthly Notices of the Royal Astronomical Society 498: 1382–1396, doi:10.1093/mnras/staa2434 




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