2013MNRAS.435.1325M


Query : 2013MNRAS.435.1325M

2013MNRAS.435.1325M - Mon. Not. R. Astron. Soc., 435, 1325-1349 (2013/October-3)

Re-examining the membership and origin of the ε Cha association.

MURPHY S.J., LAWSON W.A. and BESSELL M.S.

Abstract (from CDS):

We present a comprehensive investigation of the ε Chamaeleontis association (ε Cha), one of several young moving groups spread across the southern sky. We re-assess the putative membership of ε Cha using the best available proper motion and spectroscopic measurements, including new ANU 2.3-m/Wide Field Spectrograph observations. After applying a kinematic analysis, our final membership comprises 35-41 stars from B9 to mid-M spectral types, with a mean distance of 110±7pc and a mean space motion of (U, V, W) = (-10.9±0.8, -20.4±1.3, -9.9±1.4)km/s. Theoretical evolutionary models suggest ε Cha is 3-5Myr old, distinguishing it as the youngest moving group in the solar neighbourhood. 15 members show 3-22µm spectral energy distributions attributable to circumstellar discs, including 11 stars which appear to be actively accreting. ε Cha's disc and accretion fractions (29^+8_-6 and 32^+9_-7 percent, respectively) are both consistent with a typical 3-5Myr old population. Multi-epoch spectroscopy reveals three M-type members with broad and highly variable Hα emission as well as several new spectroscopic binaries. We reject 11 stars proposed as members in the literature and suggest they may belong to the background Cha I and II clouds or other nearby young groups. Our analysis underscores the importance of a holistic and conservative approach to assigning young stars to kinematic groups, many of which have only subtly different properties and ill-defined memberships. We conclude with a brief discussion of ε Cha's connection to the young open cluster η Cha and the Scorpius-Centaurus OB association (Sco-Cen). Contrary to earlier studies which assumed η and ε Cha are coeval and were born in the same location, we find the groups were separated by ∼ 30pc when η Cha formed 4-8Myr ago in the outskirts of Sco-Cen, 1-3Myr before the majority of ε Cha members.

Abstract Copyright: © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society (2013)

Journal keyword(s): stars: formation - stars: kinematics and dynamics - stars: low-mass - stars: pre-main sequence - open clusters and associations: individual (ε Chamaeleontis, η Chamaeleontis)

VizieR on-line data: <Available at CDS (J/MNRAS/435/1325): table7.dat table8.dat tableb1.dat tableb2.dat refs.dat>

Nomenclature: Table 7: [FLG2003] eps Cha NN (Nos 22-40) added.

Simbad objects: 100

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Number of rows : 100
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           ~ 391 0
2 PM J01071-1935 ** 01 07 11.9505 -19 35 36.090   13.80 11.457 11.087   M1 30 0
3 Ross 15 Er* 01 59 23.5138062650 +58 31 16.105242872   12.90 12.155 11.871   M4Ve 85 0
4 MBM 12 MoC 02 56 50 +19 32.0           ~ 214 1
5 Cl Melotte 22 OpC 03 46 24 +24 06.8           ~ 3132 0
6 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 3808 0
7 V* AF Lep RS* 05 27 04.7631691589 -11 54 03.466187467   6.832 6.295     F8V(n)k: 217 0
8 * bet Pic PM* 05 47 17.0876901 -51 03 59.441135 4.13 4.03 3.86 3.74 3.58 A6V 1753 1
9 NAME AB Dor Moving Group MGr 06 38 53.4 -42 50 04           ~ 408 0
10 2MASS J08014860-8058052 Y*? 08 01 48.6212229586 -80 58 05.401231296           M4.4 7 0
11 2MASS J08202975-8003259 Y*? 08 20 29.7768932435 -80 03 26.045255910           m4.3 8 0
12 V* EG Cha Or* 08 36 56.2143612523 -78 56 45.644993177   11.82 10.457   9.010 K4Ve 84 0
13 * eta Cha * 08 41 19.5144242735 -78 57 48.102318990 5.02 5.351 5.453     B8V 217 0
14 V* EH Cha LM* 08 41 37.0153250643 -79 03 30.542210498     14.4     M3 50 0
15 HD 75505 * 08 41 44.7054612559 -79 02 53.257480165   7.55 7.38     A1V 47 0
16 V* EI Cha Or* 08 42 23.7597511980 -79 04 02.974504684     12.7     K7 55 0
17 V* EK Cha LM* 08 42 27.0970495336 -78 57 47.916541725     15.2     M5 67 0
18 NAME eta Cha Association OpC 08 42 33 -78 57.8           ~ 330 0
19 V* EL Cha LM* 08 42 38.7835569558 -78 54 42.736779291     14.1     M2 49 0
20 * 9 Cha EB* 08 43 12.1978606956 -79 04 12.366179858   6.28 6.07     A7V 216 0
21 V* EN Cha LM* 08 44 16.2413047260 -78 59 07.640832807     15.0     M4 55 0
22 V* EO Cha Or* 08 44 31.8938598641 -78 46 31.142380687     12.531   10.646 M0 66 0
23 V* EP Cha Or* 08 47 01.6438574841 -78 59 34.378576588     11.1     K5 78 0
24 V* EQ Cha LM* 08 47 56.7571398344 -78 54 53.189801719     13.275   10.795 M3 73 0
25 * 5 LMi PM* 08 50 32.2225492041 +33 17 06.200101841   6.738 6.210     F7Vs 151 0
26 HD 82859 * 09 28 15.0119036791 -78 15 22.363747493   9.03 8.64     F3/5V 10 0
27 HD 82879 TT* 09 28 21.1229093124 -78 15 35.361916796   9.43 8.99     F6/7IV/V 23 0
28 2MASS J09424962-7726407 TT* 09 42 49.6248175256 -77 26 40.826595530     13.48     M1 13 0
29 MCC 124 BY* 10 14 19.1632274905 +21 04 29.817290641 12.667 11.451 10.083 9.155 8.250 M0.7V 112 1
30 CPD-68 1388 Y*O 10 57 49.3756466179 -69 13 59.946988654   11.34 10.310   9.163 K1V(e) 28 0
31 V* TW Hya TT* 11 01 51.9054298616 -34 42 17.031550898   11.94 10.50 10.626 9.18 K6Ve 1672 1
32 NAME TW Hya Association As* 11 01.9 -34 42           ~ 867 0
33 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1040 1
34 V* VW Cha Or* 11 08 01.3974165580 -77 42 28.579297348 13.91 14.04 12.80   10.69 K7+M0 170 0
35 TYC 9414-191-1 * 11 16 29.0060587316 -78 25 20.836128352   12.38 10.95     K5 5 0
36 IRAS F11171-7919 Y*O 11 18 35.821080 -79 35 54.93624   16.49 15.06 14.99 12.22 M4.75 19 0
37 RX J1123.2-7924 TT* 11 22 55.6424838079 -79 24 44.004919373     13.72     M1.5 16 0
38 HD 99827 TT* 11 25 17.74052 -84 57 16.3442           F5V 41 1
39 [FLG2003] eps Cha 15 Y*O 11 33 49.2936458918 -76 18 40.058321656         14.08 M4.5 6 0
40 1RXS J113726.7-764804 PM* 11 37 31.3358723906 -76 47 58.850062926           M2.2 4 0
41 [FLG2003] eps Cha 16 Y*O 11 40 49.6758936384 -74 59 39.247725825         15.02 M5.75 9 0
42 TYC 9238-612-1 * 11 41 27.6290816729 -73 47 02.992253379   11.41 10.70     G5 10 0
43 [FLG2003] eps Cha 17 Y*O 11 43 26.6929738153 -78 04 45.469950865         13.33 M5 18 0
44 2MASS J11474812-7841524 Y*? 11 47 48.1124737319 -78 41 52.562774627   15.095 13.552     M3.5 9 0
45 V* DZ Cha LM* 11 49 31.8520891363 -78 51 01.058647109     12.832   10.732 M0Ve 67 0
46 RX J1150.4-7704 TT* 11 50 28.3020693049 -77 04 38.244495921     12.0   10.54 K4 23 0
47 RX J1150.9-7411 TT* 11 50 44.9907703423 -74 11 13.484019426   16.10 14.63 14.28 11.84 M3.7 17 0
48 [DB2002b] G300.23-16.89 DNe 11 54 31 -79 27.8           ~ 43 1
49 NAME Chamaeleon Region SFR 11 55 -78.0           ~ 724 0
50 NAME T Cha B TT* 11 55 04.8288074224 -79 19 11.053509386       16.59 13.26 M3 14 0
51 V* T Cha Or* 11 57 13.5268556629 -79 21 31.521755129   10.00 11.86     K0e 249 1
52 [FLG2003] eps Cha 20 TT* 11 58 26.8118541887 -77 54 45.268534759   15.85 14.29     M3Ve 18 0
53 V* DW Cha Ro* 11 58 28.1599177302 -77 54 29.528939536   11.63 10.502   9.011 K4Ve 44 1
54 V* EE Cha dS* 11 58 35.2396720621 -77 49 31.497404558   6.918 6.738     A7V 52 0
55 2MASS J11590798-7812322 Y*? 11 59 07.9818375611 -78 12 32.037192393           M4.75 10 0
56 * eps Cha ** 11 59 37.57634 -78 13 18.6179           B9V(n) 96 0
57 RX J1159.7-7601 TT* 11 59 42.2712277320 -76 01 26.175720428   12.46 11.11   9.858 K4Ve 57 0
58 NAME eps Cha Association OpC 11 59 51 -78 12.4           ~ 135 1
59 NAME Cha-near Moving Group As* 12 00 -79.0           ~ 11 0
60 [FLG2003] eps Cha 3 ** 12 00 03.70 -78 11 31.0           ~ 14 0
61 [FLG2003] eps Cha 4 * 12 00 04.008 -78 11 36.96           K3V 14 0
62 V* DX Cha Ae* 12 00 05.0870448690 -78 11 34.559255151   6.81 6.60     A0_sh 316 0
63 [FLG2003] eps Cha 5 * 12 00 05.100 -78 11 34.60           A4V 5 0
64 [FLG2003] eps Cha 6 Y*? 12 00 08.2616073327 -78 11 39.365796807           M3.5 15 0
65 [FLG2003] eps Cha 7 * 12 00 09.3133094261 -78 11 42.317079478           K3IV 19 0
66 [FLG2003] eps Cha 10 Y*? 12 00 55.1832424754 -78 20 29.423870968           M5.75 11 0
67 HD 104467 TT* 12 01 39.1114993208 -78 59 16.909916962   9.26 8.466   7.678 G3V(e) 55 0
68 [FLG2003] eps Cha 11 * 12 01 43.4652324026 -78 35 47.164511556           M2.25 8 0
69 [FLG2003] eps Cha 8 Y*? 12 01 44.4323042336 -78 19 26.564723560           M5 10 0
70 [FLG2003] eps Cha 9 Y*? 12 01 52.5589876146 -78 18 41.206429934           M4.75 8 0
71 GSC 09420-00948 TT* 12 02 03.7197660683 -78 53 01.328413446     12.450   10.49 M0e 27 0
72 2MASS J12025461-7718382 TT* 12 02 54.6334148957 -77 18 38.077073878     14.483   12.081 M3.5 21 0
73 2MASS J12043615-7731345 TT* 12 04 36.1401210475 -77 31 34.728906529     13.873   11.297 M3 30 0
74 CD-78 487 * 12 04 57.4303322736 -79 32 04.719402824   10.95 10.32     F0 5 0
75 V* EF Cha dS* 12 07 05.5213509446 -78 44 28.013631162   7.74 7.46     A9III/IV 45 0
76 [FLG2003] eps Cha 12 PM* 12 07 45.9736635463 -78 16 06.460141875           M3.75 9 0
77 2MASS J12074825-7952424 TT* 12 07 48.2793137368 -79 52 42.375712804     14.455   11.943 M2/3 16 0
78 HD 105515 Pu* 12 09 07.6934764109 -78 46 52.725875139   7.08 6.85     A6III/IV 24 0
79 HD 105923 Y*O 12 11 38.1468993379 -71 10 36.026022010   9.86 9.140   8.286 G8V 28 0
80 2MASS J12164593-7753333 TT* 12 16 45.9346907497 -77 53 33.462520510     13.851   11.568 M3 23 0
81 NAME Lower Centaurus Crux As* 12 19 -57.1           ~ 394 1
82 GSC 09239-01495 LM* 12 19 43.7029970237 -74 03 57.252406710     13.1   10.95 M1 31 0
83 RX J1220.4-7407 LM* 12 20 21.7903218923 -74 07 39.564137123     12.780   10.52 M1V 36 0
84 ASAS J122105-7116.9 LM* 12 21 04.9982181061 -71 16 49.277088299   13.05 11.73 11.32 10.08 K7V 23 0
85 IRAS 12340-7958 LP? 12 37 39.7466355997 -80 15 13.713429632   16.11 14.39 13.63 9.81 ~ 105 0
86 NAME Cha III MoC 12 37.8 -80 15           ~ 134 2
87 CD-74 712 TT* 12 39 21.2758227460 -75 02 39.184171990   11.15 10.303   9.197 K3Ve 43 0
88 RX J1243.1-7458 TT* 12 42 53.337 -74 58 47.98   16.37 14.81 14.51 12.36 M3e 12 1
89 NAME Cha II MoC 12 54 -77.2           ~ 311 0
90 CD-69 1055 Y*O 12 58 25.5836293658 -70 28 49.148845210   10.77 9.992   8.941 K0Ve 39 0
91 V* CM Cha TT* 13 02 13.5239808158 -76 37 57.814400439   14.70 13.40     K7IVe 37 0
92 CPD-68 1894 TT* 13 22 07.5420267499 -69 38 12.216304202   11.38 10.393   9.117 K1Ve 140 0
93 NAME beta Pic Moving Group MGr 14 30 -42.0           ~ 632 0
94 NAME ASSOC II SCO As* 16 15 -24.2           ~ 1199 1
95 NAME Galactic Center gam 17 45 39.60213 -29 00 22.0000           ~ 12532 0
96 LAWD 74 WD* 19 20 34.9229875534 -07 40 00.066805378 11.553 12.345 12.290 12.229 12.164 DBQA5 206 0
97 HD 181321 SB* 19 21 29.7277723051 -34 59 00.356331012 7.22 7.11 6.48     G2V 128 0
98 BD+19 5116 ** 23 31 52.17898 +19 56 14.1505 12.737 11.749 10.165 8.982 7.446 M4+M5 430 0
99 NAME R CrA Association As* ~ ~           ~ 20 0
100 NAME Octans Association As* ~ ~           ~ 77 0

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2021.11.28-21:17:09

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