Bringing the Norma Dark Cloud to Light in X-Rays

Stephen L. Skinner; Manuel Güdel; Luisa M. Rebull

doi:10.3847/1538-3881/ade8f4

Bringing the Norma Dark Cloud to Light in X-Rays

Stephen L. Skinner
, Manuel Güdel
, Luisa M. Rebull

Department of Astrophysics

Publications: Contribution to journal › Article › Peer Reviewed

Abstract

The filamentary dark cloud complex in Norma reveals signs of active low-mass star formation including protostars, Hα emission line stars, Herbig-Haro objects, and the eruptive FU Orionis-like star V346 Nor. We present results of the first pointed X-ray observations of the Norma dark cloud, focusing on the westernmost Sandqvist 187 region. Chandra detected 75 X-ray sources, and a complementary XMM-Newton observation detected 92 sources within the Chandra field of view, of which 46 are cross-matched to Chandra, yielding 121 unique X-ray sources. We present a catalog of X-ray sources along with basic X-ray properties and candidate IR and optical counterparts. Existing near-IR photometry reveals several X-ray sources with color excesses typical of young stars with disks. Gaia parallaxes single out foreground stars and X-ray sources at distances of 500-1000 pc that are probable cloud members. The known emission line stars Sz 136 and Sz 137 were detected but V346 Nor was not. Interestingly, the optical and IR counterparts of the brightest Chandra source are not known with certainty but the prime suspects are very faint. Thus, the nature of the object responsible for the bright X-ray emission remains speculative. The X-ray observations presented here will serve as a pathfinder for identifying and characterizing the young stellar population in the Norma dark cloud.

Original language	English
Article number	114
Number of pages	18
Journal	Astronomical Journal
Volume	170
Issue number	2
DOIs	https://doi.org/10.3847/1538-3881/ade8f4
Publication status	Published - 31 Jul 2025

Funding

Support for this work was provided by Chandra award number GO1-22008X issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory (SAO) for and on behalf of NASA. Support was also provided by NASA/GSFC award 80NSSC22K0689. Observations were obtained with XMM-Newton, an ESA science mission directly funded by ESA member states and the USA (NASA). This research has made use of the NASA/IPAC Infrared Science Archive (IRSA), which is funded by NASA and operated by the California Institute of Technology. This work has made use of data products from the Two Micron All Sky Survey (2MASS; M. F. Skrutskie et al. 2003, 2006), which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC)/California Institute of Technology, funded by NASA and the NSF, and data products from the Wide-field Infrared Survey Explorer (WISE; E. L. Wright et al. 2010, 2019), which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by NASA. This work has made use of data from the unWISE Catalog (E. F. Schlafly et al. 2019; UnWISE Team 2021). This work has made use of data from the European Space Agency (ESA) Gaia mission (https://www.cosmos.esa.int/gaia; IRSA 2022), processed by the Gaia Data Processing and Analysis Consortium. Support for this work was provided by Chandra award number GO1-22008X issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory (SAO) for and on behalf of NASA. Support was also provided by NASA/GSFC award 80NSSC22K0689. Observations were obtained with XMM-Newton, an ESA science mission directly funded by ESA member states and the USA (NASA). This research has made use of the NASA/IPAC Infrared Science Archive (IRSA), which is funded by NASA and operated by the California Institute of Technology. This work has made use of data products from the Two Micron All Sky Survey (2MASS; M. F. Skrutskie et al. , ), which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC)/California Institute of Technology, funded by NASA and the NSF, and data products from the Wide-field Infrared Survey Explorer (WISE; E. L. Wright et al. , ), which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by NASA. This work has made use of data from the unWISE Catalog (E. F. Schlafly et al. ; UnWISE Team ). This work has made use of data from the European Space Agency (ESA) Gaia mission ( https://www.cosmos.esa.int/gaia ; IRSA ), processed by the Gaia Data Processing and Analysis Consortium.

Austrian Fields of Science 2012

103003 Astronomy
103004 Astrophysics

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10.3847/1538-3881/ade8f4Licence: CC BY 4.0

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title = "Bringing the Norma Dark Cloud to Light in X-Rays",

abstract = "The filamentary dark cloud complex in Norma reveals signs of active low-mass star formation including protostars, Hα emission line stars, Herbig-Haro objects, and the eruptive FU Orionis-like star V346 Nor. We present results of the first pointed X-ray observations of the Norma dark cloud, focusing on the westernmost Sandqvist 187 region. Chandra detected 75 X-ray sources, and a complementary XMM-Newton observation detected 92 sources within the Chandra field of view, of which 46 are cross-matched to Chandra, yielding 121 unique X-ray sources. We present a catalog of X-ray sources along with basic X-ray properties and candidate IR and optical counterparts. Existing near-IR photometry reveals several X-ray sources with color excesses typical of young stars with disks. Gaia parallaxes single out foreground stars and X-ray sources at distances of 500-1000 pc that are probable cloud members. The known emission line stars Sz 136 and Sz 137 were detected but V346 Nor was not. Interestingly, the optical and IR counterparts of the brightest Chandra source are not known with certainty but the prime suspects are very faint. Thus, the nature of the object responsible for the bright X-ray emission remains speculative. The X-ray observations presented here will serve as a pathfinder for identifying and characterizing the young stellar population in the Norma dark cloud.",

author = "Skinner, \{Stephen L.\} and Manuel G{\"u}del and Rebull, \{Luisa M.\}",

note = "Publisher Copyright: {\textcopyright} 2025. The Author(s). Published by the American Astronomical Society.",

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N2 - The filamentary dark cloud complex in Norma reveals signs of active low-mass star formation including protostars, Hα emission line stars, Herbig-Haro objects, and the eruptive FU Orionis-like star V346 Nor. We present results of the first pointed X-ray observations of the Norma dark cloud, focusing on the westernmost Sandqvist 187 region. Chandra detected 75 X-ray sources, and a complementary XMM-Newton observation detected 92 sources within the Chandra field of view, of which 46 are cross-matched to Chandra, yielding 121 unique X-ray sources. We present a catalog of X-ray sources along with basic X-ray properties and candidate IR and optical counterparts. Existing near-IR photometry reveals several X-ray sources with color excesses typical of young stars with disks. Gaia parallaxes single out foreground stars and X-ray sources at distances of 500-1000 pc that are probable cloud members. The known emission line stars Sz 136 and Sz 137 were detected but V346 Nor was not. Interestingly, the optical and IR counterparts of the brightest Chandra source are not known with certainty but the prime suspects are very faint. Thus, the nature of the object responsible for the bright X-ray emission remains speculative. The X-ray observations presented here will serve as a pathfinder for identifying and characterizing the young stellar population in the Norma dark cloud.

AB - The filamentary dark cloud complex in Norma reveals signs of active low-mass star formation including protostars, Hα emission line stars, Herbig-Haro objects, and the eruptive FU Orionis-like star V346 Nor. We present results of the first pointed X-ray observations of the Norma dark cloud, focusing on the westernmost Sandqvist 187 region. Chandra detected 75 X-ray sources, and a complementary XMM-Newton observation detected 92 sources within the Chandra field of view, of which 46 are cross-matched to Chandra, yielding 121 unique X-ray sources. We present a catalog of X-ray sources along with basic X-ray properties and candidate IR and optical counterparts. Existing near-IR photometry reveals several X-ray sources with color excesses typical of young stars with disks. Gaia parallaxes single out foreground stars and X-ray sources at distances of 500-1000 pc that are probable cloud members. The known emission line stars Sz 136 and Sz 137 were detected but V346 Nor was not. Interestingly, the optical and IR counterparts of the brightest Chandra source are not known with certainty but the prime suspects are very faint. Thus, the nature of the object responsible for the bright X-ray emission remains speculative. The X-ray observations presented here will serve as a pathfinder for identifying and characterizing the young stellar population in the Norma dark cloud.

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UR - https://ui.adsabs.harvard.edu/abs/2025AJ....170..114S/abstract

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ER -

Bringing the Norma Dark Cloud to Light in X-Rays

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Austrian Fields of Science 2012

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