HK Tauri

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HK Tauri
HKTauLightCurve.png
A light curve for HK Tauri, adapted from Roggero et al. (2021) [1]
Observation data
Epoch J2000       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]
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  mas [2]
Distance 428 ± 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  mas [3]
Distance 420 ± 30  ly
(130 ± 10  pc)
Position (relative to HK Tauri A) [4]
ComponentHK Tauri B
Angular distance 2.32
Position angle 170.4°
Projected separation 309 AU
Details
A
Mass 0.44+0.14
0.11
[4]   M
Luminosity 0.56 [5]   L
Temperature 3680±150 [6]   K
B
Mass 0.37±0.2 [4]   M
Luminosity0.42 [5]   L
Temperature 3550±150 [6]   K
Other designations
2MASS J04315056+2424180, WISE J043150.56+242417.6
HK Tauri A: Gaia EDR3 147847072275324416, Gaia DR2 147847072275324416
HK Tauri B: Gaia EDR3 147847072275766656, Gaia DR2 147847072274696704
Database references
SIMBAD data

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

Contents

System

Artist's impressions of the two disks surrounding both stars Artist's impression of the discs around the young stars HK Tauri A and B.jpg
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  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 028.7 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 068.0 AU 83.2±0.2°

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<span class="mw-page-title-main">CQ Tauri</span> Star in the constellation Taurus

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References

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