J/A+A/661/A34 eta Cha cluster eROSITA X-ray scan (Robrade+, 2022)
eROSITA X-ray scan of the eta Chamaeleontis cluster.
Member study and search for dispersed low-mass stars.
Robrade J., Czesla S., Freund S., Schmitt J.H.M.M., Schneider P.C.
<Astron. Astrophys. 661, A34 (2022)>
=2022A&A...661A..34R 2022A&A...661A..34R (SIMBAD/NED BibCode)
ADC_Keywords: X-ray sources ; Clusters, open
Keywords: stars: activity - stars: coronae - stars: pre-main sequence -
X-rays: stars
Abstract:
The nearby young open cluster η Chamaeleontis has been observed by
eROSITA/SRG during its CalPV phase for 150ks. 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
5x5deg field with an exposure depth of about 5ks.
The η Cha cluster with an age of about 8Myr 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.
Using eROSITA X-ray data, we studied the η Cha region. Detected
sources were identified by cross-matching X-ray sources with Gaia 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.
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.
Sensitive X-ray surveys are best suited to identifying active stars,
and the combination of the ongoing eROSITA all-sky survey with Gaia
measurements provides an unprecedented opportunity to study the
nearby, young stellar population.
Description:
The nearby young open cluster eta Chamaeleontis has been observed by
eROSITA/SRG during its CalPV phase for 150ks. 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
5x5deg field with an exposure depth of about 5ks. We present the
X-ray source catalog of the eROSITA eta Cha field scan in the main
(0.2-2.3keV) and hard (2.3-5.0keV) energy band.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
etacha_m.dat 220 7933 X-ray source catalog of the eROSITA η Cha
field scan in the main (0.2-2.3keV) energy band
etacha_h.dat 189 96 X-ray source catalog of the eROSITA η Cha
field scan in the hard (2.3-5.0keV) energy band
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See also:
J/A+A/661/A1 : The eFEDS X-ray catalogs (V7.4) (Brunner+, 2022)
J/A+A/661/A2 : Galaxy clusters and groups in eFEDS (Liu+, 2022)
J/A+A/661/A3 : eFEDS counterparts to point-like sources (Salvato+, 2022)
J/A+A/661/A4 : eFEDS optical cluster and group catalog (Klein+, 2022)
J/A+A/661/A5 : The eFEDS AGN catalog (Liu+, 2022)
J/A+A/661/A7 : X-ray properties of eFEDS clusters and groups (Bahar+, 2022)
J/A+A/661/A8 : eFEDS catalogue of variable X-ray sources (Boller+, 2022)
J/A+A/661/A10 : eFEDS galaxy clusters and groups in disguise (Bulbul+, 2022)
J/A+A/661/A23 : Exoplanet X-ray irradiation & evaporation rates (Foster+, 2022)
J/A+A/661/A24 : Corona-chromosphere connection (Fuhrmeister+, 2022)
J/A+A/661/A29 : First eROSITA study of nearby M dwarfs (Magaudda+, 2022)
J/A+A/661/A35 : eROSITA study of 47 Tuc globular cluster (Saeedi+, 2022)
J/A+A/661/A38 : SRG/ART-XC 1st year all-sky X-ray survey (Pavlinsky+, 2022)
J/A+A/661/A40 : eRASS1 X-ray sources Sco-Cen members (Schmitt+, 2022)
J/A+A/661/A44 : A first eROSITA view of ultracool dwarfs (Stelzer+, 2022)
https://erosita.mpe.mpg.de : eROSITA EDR page at MPE
Byte-by-byte Description of file: etacha_m.dat
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Bytes Format Units Label Explanations
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1- 21 A21 --- ERO eROSITA/SRG source name,
SRGE JHHMMSS.s+DDMMSS (ERO_NAME)
23- 26 I4 --- ID-SRC Source ID within the table (ID_SRC)
28- 45 F18.14 deg RAdeg Right ascension (J2000) (RA)
47- 64 F18.14 deg DEdeg Declination (J2000) (DEC)
66- 77 F12.9 arcsec ePos Combined error in RA/DEC (RADEC_ERR)
79- 88 F10.6 arcsec Ext Source extent (EXT)
90- 99 F10.7 arcsec e_Ext Error of extent (EXT_ERR)
101-111 F11.7 --- ExtLike Extent likelihood (EXT_LIKE)
113-125 F13.7 ct MLcts Source counts from PSF fitting (ML_CTS)
127-138 F12.7 ct e_MLcts Error on source counts (MLCTSERR)
140-151 F12.10 ct/s MLRate Source rate (ML_RATE)
153-164 F12.10 ct/s e_MLRate Error on source rate (MLRATEERR)
166-179 E14.9 mW/m2 MLFlux Source flux (ML_FLUX)
181-194 E14.9 mW/m2 e_MLFlux Error on source flux (MLFLUXERR)
196-208 F13.7 --- DetLike Detection likelihood (DET_LIKE)
210-220 F11.8 ct/arcmin MLBkg Background at source position (ML_BKG)
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Byte-by-byte Description of file: etacha_h.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 21 A21 --- ERO eROSITA/SRG source name,
SRGE JHHMMSS.s+DDMMSS (ERO_NAME)
23- 25 I3 --- ID-SRC Source ID within the table (ID_SRC)
27- 30 I4 --- ID-MAIN ?=0 Corresponding ID (ID_SRC) in main
catalog (etacha_m.dat) (ID_MAIN)
32- 49 F18.14 deg RAdeg Right ascension (J2000) (RA)
51- 68 F18.14 deg DEdeg Declination (J2000) (DEC)
70- 78 F9.7 arcsec ePos Combined error in RA/DEC (RADEC_ERR)
80- 82 F3.1 arcsec Ext Source extent (EXT)
84- 86 F3.1 arcsec e_Ext Error of extent (EXT_ERR)
88- 90 F3.1 --- ExtLike Extent likelihood (EXT_LIKE)
92-101 F10.6 ct MLcts Source counts from PSF fitting (ML_CTS)
103-112 F10.7 ct e_MLcts Error on source counts (MLCTSERR)
114-125 F12.10 ct/s MLRate Source rate (ML_RATE)
127-138 F12.10 ct/s e_MLRate Error on source rate (MLRATEERR)
140-153 E14.9 mW/m2 MLFlux Source flux (ML_FLUX)
155-167 E13.8 mW/m2 e_MLFlux Error on source flux (MLFLUXERR)
169-179 F11.7 --- DetLike Detection likelihood (DET_LIKE)
181-189 F9.7 ct/arcmin2 MLBkg Background at source position (ML_BKG)
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Acknowledgements:
Jan Robrade, jrobrade(at)hs.uni-hamburg.de
References:
The Early Data Release of eROSITA and Mikhail Pavlinsky ART-XC on the
SRG mission, 2022, A&A, 661, A1-A46
(End) Patricia Vannier [CDS] 15-Feb-2022