2022A&A...661A..34R


Query : 2022A&A...661A..34R

2022A&A...661A..34R - Astronomy and Astrophysics, volume 661A, 34-34 (2022/5-1)

eROSITA X-ray scan of the η Chamaeleontis cluster. Member study and search for dispersed low-mass stars.

ROBRADE J., CZESLA S., FREUND S., SCHMITT J.H.M.M. and SCHNEIDER P.C.

Abstract (from CDS):


Context. The nearby young open cluster η Chamaeleontis has been observed by eROSITA/SRG during its CalPV phase for 150 ks. The extended ROentgen Survey with an Imaging Telescope Array (eROSITA) data were taken in the field-scan mode, an observing mode of Spectrum-Roentgen-Gamma (SRG) that follows a rectangular grid-like pattern, here covering a 5 x 5 deg field with an exposure depth of about 5 ks.
Aims. The η Cha cluster with an age of about 8 Myr is a key target for investigating the evolution of young stars, and we aim to study the known members in X-rays. Additionally, we search for potential new members of the anticipated dispersed low-mass cluster population in a sensitive wide-field X-ray observation.
Methods. Using eROSITA X-ray data, we studied the η Cha region. Detected sources were identified by cross-matching X-ray sources with Gala and 2MASS, and young stars were identified by their X-ray activity, the position in the color-magnitude diagram, and by their astrometric and kinematic properties. X-ray-luminosities, light curves, and spectra of cluster members were obtained and compared with previous X-ray data. Literature results of other member searches were used to verify our new member candidates in the observed field.
Results. We determine X-ray properties of virtually all known η Cha members and identify five additional stellar systems that show basically identical characteristics, but they are more dispersed. Four of them were previously proposed as potential members; this status is supported by our X-ray study. Based on their spatial distribution, further members are expected beyond the sky region we surveyed. The identified stellar systems very likely belong to the ejected halo population, which brings the total number of η Cha cluster members to at least 23.
Conclusions. Sensitive X-ray surveys are best suited to identifying active stars, and the combination of the ongoing eROSITA all-sky survey with Gala measurements provides an unprecedented opportunity to study the nearby, young stellar population.

Abstract Copyright: © ESO 2022

Journal keyword(s): stars: activity - stars: coronae - stars: pre-main sequence - X-rays: stars

VizieR on-line data: <Available at CDS (J/A+A/661/A34): etacha_m.dat etacha_h.dat>

Status at CDS : Tables of objects will be appraised for possible ingestion in SIMBAD.

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 2MASS J08014860-8058052 Y*? 08 01 48.6226444584 -80 58 05.399660676           M4.4 8 0
2 V* Z Cha CV* 08 07 27.7517751528 -76 32 00.665029356           M5.5 601 1
3 2MASS J08202975-8003259 Y*? 08 20 29.7781345968 -80 03 26.041747716           m4.3 10 0
4 ECHA J0836.2-7908 LM* 08 36 10.7009266536 -79 08 18.356133120     17.5     M5.5 32 0
5 V* EG Cha Or* 08 36 56.2143359952 -78 56 45.633633000   11.82 10.457   9.010 K4Ve 88 0
6 ECHA J0838.9-7916 LM* 08 38 51.4849263144 -79 16 13.752884532   16.82 16.4     M5 32 0
7 * eta Cha * 08 41 19.5125857944 -78 57 48.105898056 5.02 5.351 5.453     B8V 221 0
8 V* ES Cha LM* 08 41 30.3105474648 -78 53 06.477949932     17.07     M4 40 0
9 V* EH Cha LM* 08 41 37.0144539384 -79 03 30.535583220     14.4     M3 53 0
10 HD 75505 * 08 41 44.7049093968 -79 02 53.258689068   7.55 7.38     A1V 49 0
11 V* EI Cha Or* 08 42 23.7595500240 -79 04 02.976309552     12.7     K7 58 0
12 V* EK Cha LM* 08 42 27.0967343784 -78 57 47.910415932     15.2     M5 70 0
13 NAME eta Cha Association OpC 08 42 33 -78 57.8           ~ 339 0
14 V* EL Cha LM* 08 42 38.7832034688 -78 54 42.736732812     14.1     M2 52 0
15 V* EM Cha Or* 08 43 07.2443828304 -79 04 52.483961064     10.8     K3 55 0
16 * 9 Cha EB* 08 43 12.1984130688 -79 04 12.368512452   6.28 6.07     A7V 220 0
17 V* ET Cha Or* 08 43 18.5853516024 -79 05 18.232481832     13.97     M2 75 0
18 2MASS J08440915-7833457 LM* 08 44 09.1596371520 -78 33 45.774374724     18.4     M5.5 34 0
19 V* EN Cha LM* 08 44 16.2375168408 -78 59 07.625338152     15.0     M4 57 0
20 V* EO Cha Or* 08 44 31.8938144088 -78 46 31.143275076     12.531   10.646 M0 69 0
21 V* EP Cha Or* 08 47 01.6439909496 -78 59 34.380161016     11.1     K5 83 0
22 V* EQ Cha LM* 08 47 56.7585043512 -78 54 53.185560516     13.275   10.795 M3 76 0
23 UCAC4 062-007756 Y*? 08 57 51.7851251520 -77 38 13.054202448   16.261 14.596 14.185   ~ 2 0
24 UCAC3 25-17479 TT* 09 02 51.2713949520 -77 59 34.668343068     13.99     M3 19 0
25 2MASS J09053087-8134572 Y*? 09 05 30.8959165176 -81 34 57.256163688           M4.9 5 0
26 2MASS J09353193-8018317 IR 09 35 31.93200 -80 18 31.7628           ~ 1 0
27 2MASS J09424962-7726407 TT* 09 42 49.6245150312 -77 26 40.827783840     13.48     M1 14 0
28 NAME Cha 1 MoC 11 06 48 -77 18.0           ~ 1070 1
29 NAME Chamaeleon Region SFR 11 55 -78.0           ~ 747 0
30 NAME Lower Centaurus Crux As* 12 19 -57.1           ~ 413 1
31 NAME Cha II MoC 12 54 -77.2           ~ 316 0
32 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 13083 0
33 NAME Osca As* ~ ~           ~ 9 0

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2022.08.09-15:23:40

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