J/other/AstL/51.536 SRG/eROSITA sources in Blanco 1 (Khamitov+, 2025)
Coronal Activity of Stars in the Blanco 1 Open Cluster from SRG/eROSITA
All-Sky Survey Data.
Khamitov I.M., Bikmaev I.F., Gilfanov M.R., Sunyaev R.A., Gorbachev M.A.,
Panarin S.S., Medvedev P.S.
<Astronomy Letters, 51, 536-550 (2025)>
=2025AstL...51..536K 2025AstL...51..536K (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; X-ray sources
Keywords: X-ray sources - stars - open clusters: Blanco 1 -
instruments: SRG/eROSITA
Abstract:
Using data from the all-sky X-ray survey with the eROSITA telescope
onboard the SRG orbital observatory and the optical catalog of Blanco
1 cluster members constructed from Gaia data, we have investigated the
X-ray emission from cluster stars. Of the 723 cluster members located
in the eastern Galactic part of the sky, eROSITA detects X-ray
emission from 110 stars, thereby increasing the number of known
sources by more than a factor of 2. At the Blanco 1 distance (∼234pc)
the median eROSITA sensitivity in this sky region corresponds to a
0.3-2.3keV luminosity LX∼1.1*1029erg/s, allowing more than 60% of
the solar-type stars to be detected within the Blanco 1 tidal radius.
For one source a strong (more than a factor of 10) X-ray variability
on a time scale of six months has been recorded. This is a late-M
star. The RX=log(LX/Lbol) distribution of Blanco 1 stars is bimodal.
The left peak at RX_-4.2 is formed by FGK stars, while the right peak
at RX~-3.1 consists predominantly of K and M stars. A comparison of
the properties of X-ray sources in the similarly aged Blanco 1 and
Pleiades clusters has shown a high level of consistency, pointing to a
common evolutionary scenario for the X-ray activity of stars in these
clusters.
Description:
The catalogue of SRG/eROSITA sources associated with Blanco 1 within
three tidal radii at the Eastern Galactic hemisphere with X-ray
characteristics is presented in table1.dat.
Objects:
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RA (2000) DE Designation(s)
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00 03 04.10 -29 48 55.0 Blanco 1 = C 0001-302
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 134 117 Catalogue of SRG/eROSITA sources associated
with Blanco 1
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
J/A+A/678/A75 : Young nearby open clusters members photometry (Zerjal+, 2023)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 20 A20 --- SRGe Designaton of SRGe+
22- 40 I19 --- GaiaDR3 Designaton of GAIA DR3+ (1)
42- 52 F11.7 deg RAdeg Gaia DR3 right ascension (ICRS)
at Ep=2016.0 (ra) (1)
54- 64 F11.7 deg DEdeg Gaia DR3 declination (ICRS)
at Ep=2016.0 (dec) (1)
66- 75 F10.7 mag Gmag GAIA DR3 G-band mean magnitude (1)
77- 81 F5.2 arcsec r98 eROSITA source position error
83- 87 F5.2 arcsec sep Separation between X-ray (eROSITA) and
optical (GAIA DR3) positions of source
89 I1 --- Ngaia [1/3] Number of GAIA DR3 sources within r98
91- 96 F6.3 10+22W LX X-ray luminosity in 0.3-2.3keV band according
to 4 eROSITA surveys (in 10+29erg/s unit)
98-102 F5.3 10+22W e_LX 1-sigma error of X-ray luminosity in
0.3-2.3keV band according to 4 eROSITA
surveys (in 10+29erg/s unit)
104-111 F8.5 --- logRX Log of ratio X-ray in 0.3-2.3keV
to bolometric luminosities (4)
113 A1 --- f_Xvar [012] Flag on Xvar (2)
115-124 F10.7 --- Xvar ? Factor of X-ray variability (3)
126-130 A5 --- SpType Spectral type (4)
132 I1 --- N6d [1/2] The number of Blanco 1 stars within r98
134 I1 --- bflag [0/1] Binarity parameter,
1 indicates the system with binarity
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Note (1): From Zerjal et al. (2023A&A...678A..75Z 2023A&A...678A..75Z; Cat. J/A+A/678/A75).
Note (2): Flag on Xvar as follows:
0 = Xvar measured value
1 = lower limit on Xvar determination
2 = Xvar not determined
Note (3): Xvar is the X-ray variability factor defined as the ratio of the
maximum and minimum fluxes recorded in five eROSITA surveys including the
flux measurement error.
Note (4): The bolometric luminosities (used in RX determination) and the
spectral types were estimated by interpolating the dependence of these
parameters on the absolute magnitude (MG) in the G band (Gaia DR3) for
main-sequence stars. For this purpose we used the version of Mamajek's tables
(the version of April 16, 2022) originally published in Pecaut and Mamajek,
(2013ApJS..208....9P 2013ApJS..208....9P, Cat. J/ApJS/208/9).
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Acknowledgements:
Irek Khamitov, irek_khamitov(at)hotmail.com
License: CC-BY-4.0 [see https://spdx.org/licenses/]
(End) Patricia Vannier [CDS] 18-Apr-2026