2020MNRAS.491.4902M


Query : 2020MNRAS.491.4902M

2020MNRAS.491.4902M - Mon. Not. R. Astron. Soc., 491, 4902-4924 (2020/February-1)

THOR 42: A touchstone 24 Myr-old eclipsing binary spanning the fully convective boundary.

MURPHY S.J., LAWSON W.A., ONKEN C.A., YONG D., DA COSTA G.S., ZHOU G., MAMAJEK E.E., BELL C.P.M., BESSELL M.S. and FEINSTEIN A.D.

Abstract (from CDS):

We present the characterization of CRTS J055255.7-004426 (=THOR 42), a young eclipsing binary comprising two pre-main sequence M dwarfs (combined spectral type M3.5). This nearby (103 pc), short-period (0.859 d) system was recently proposed as a member of the ∼24 Myr-old 32 Orionis Moving Group. Using ground- and space-based photometry in combination with medium- and high-resolution spectroscopy, we model the light and radial velocity curves to derive precise system parameters. The resulting component masses and radii are 0.497 ± 0.005 and 0.205 ± 0.002 {M}_{☉ }, and 0.659 ± 0.003 and 0.424 ± 0.002 {R}_{☉ }, respectively. With mass and radius uncertainties of ∼1 per cent and ∼0.5 per cent, respectively, THOR 42 is one of the most precisely characterized pre-main sequence eclipsing binaries known. Its systemic velocity, parallax, proper motion, colour-magnitude diagram placement, and enlarged radii are all consistent with membership in the 32 Ori Group. The system provides a unique opportunity to test pre-main sequence evolutionary models at an age and mass range not well constrained by observation. From the radius and mass measurements we derive ages of 22-26 Myr using standard (non-magnetic) models, in excellent agreement with the age of the group. However, none of the models can simultaneously reproduce the observed mass, radius, temperature, and luminosity of the coeval components. In particular, their H-R diagram ages are 2-4 times younger and we infer masses ∼50 per cent smaller than the dynamical values.

Abstract Copyright: © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society

Journal keyword(s): binaries: eclipsing - binaries: spectroscopic - stars: evolution - stars: fundamental parameters - stars: low mass - stars: pre-main-sequence

Nomenclature: THOR NNA (No. 42) added.

Simbad objects: 33

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Number of rows : 33
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 NAME THA As* 00 00 -62.0           ~ 424 0
2 NSVS 6507557 EB* 01 58 23.8767983544 +25 21 19.688871456   14.53 12.80     K9+M3 17 0
3 Cl Melotte 22 OpC 03 46 24 +24 06.8           ~ 3234 0
4 V* NP Per EB* 04 14 57.7571847888 +31 26 44.125700964   11.94 11.24     G6(N) 24 0
5 VSS XI-2 TT* 04 31 15.7844819592 +18 20 07.067360328     15.72     M4.25 47 0
6 NGC 1647 OpC 04 45 55 +19 04.7   6.82 6.4     ~ 153 0
7 2MASS J04463285+1901432 EB* 04 46 32.8622247312 +19 01 43.246330320   19.9 19.0     M 24 0
8 1RXS J052241.4-060623 * 05 22 40.6984000632 -06 06 23.956093728   15.77 14.23 13.93   M3 5 0
9 HD 35714 V* 05 26 59.9951056104 +07 10 13.023218856   7.16 7.03     A2V 17 0
10 NAME 32 Ori group OpC 05 27 11 +06 16.0           ~ 55 0
11 WISE J052857.68+090104.4 BD* 05 28 57.68808 +09 01 04.4040           L1 5 0
12 2MASS J05302546-0256255 * 05 30 25.4695126008 -02 56 25.502139096   17.26 15.65 15.40   M3 3 0
13 * 32 Ori ** 05 30 47.05091 +05 56 53.2925 3.51 4.07 4.20 4.26 4.40 B5IV+B7V 184 0
14 PM J05319-0303W Y*? 05 31 57.8626869096 -03 03 36.799294032   15.435 13.855 14.119   M5 11 0
15 ESO-HA 737 Em* 05 32 05.9590455456 -03 01 15.981118428   17.36 15.61 15.22   M5 7 0
16 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2175 1
17 NAME Ori I As* 05 38 -02.8           ~ 588 0
18 1RXS J054304.3+060646 * 05 43 03.5399471472 +06 06 34.097081904   16.53 14.98 14.52   M2.5 4 0
19 1RXS J054424.7+050153 Y*? 05 44 24.4759540416 +05 02 11.603688720   16.59 15.09 15.089 12.45 M3 5 0
20 1RXS J054926.3+040541 TT* 05 49 26.3247124416 +04 05 37.872922632   16.55 14.96 14.56   M3 6 0
21 CVSO 1975 TT* 05 52 55.7204335992 -00 44 26.713737672     13.45     M3.5e 9 0
22 2RXS J055257.6-004422 X 05 52 57.200016 -00 44 37.00032           ~ 1 0
23 NGC 2264 OpC 06 40 52 +09 52.6           ~ 1703 0
24 BD+05 1668 PM* 07 27 24.4989685603 +05 13 32.841491057 12.558 11.443 9.872 8.699 7.161 M3.5V 378 0
25 LAWD 25 WD* 07 40 20.7886676070 -17 24 49.156867583   13.36 13.061 12.886 12.70 DZQA6 193 0
26 NGC 2632 OpC 08 40 13 +19 37.3           ~ 1421 0
27 2MASS J08504984+1948364 EB* 08 50 49.8423820800 +19 48 36.547637508           M5V 32 0
28 NAME beta Pic Moving Group MGr 14 30 -42.0           ~ 691 0
29 CD-35 9931 TT* 14 58 37.6872422736 -35 40 30.394769052   11.92 10.75   9.85 K2.5IV 31 0
30 NAME Upper Centaurus Lupus As* 15 24 -41.9           ~ 422 1
31 UGCS J160339.22-185129.4 EB* 16 03 39.2319975144 -18 51 29.400368220           M2.5e 23 0
32 NAME Upper Sco Association As* 16 12 -23.4           ~ 1222 1
33 NAME Upper Sco-Cen As* 16 15 -24.2           ~ 1247 1

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2022.10.05-19:29:30

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