2025AJ....170..114S


Query : 2025AJ....170..114S

2025AJ....170..114S - Astron. J., 170, 114 (2025/August-0)

Bringing the Norma Dark Cloud to Light in X-Rays.

SKINNER S.L., GUDEL M. and REBULL L.M.

Abstract (from CDS):

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.

Abstract Copyright: © 2025. The Author(s). Published by the American Astronomical Society.

Journal keyword(s): Dark interstellar clouds - Star forming regions - Pre-main sequence stars

Nomenclature: Table 1, col(1): [SGR2025] CXO NN (Nos 1-75). Table 2, col(1): [SGR2025] XMM NN (Nos 1-92).

Status at CDS : All or part of tables of objects could be ingested in SIMBAD with priority 2.

Simbad objects: 23

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Number of rows : 23
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026
#notes
1 V* AB Aur Ae* 04 55 45.8458932216 +30 33 04.292077032 7.20 7.16 7.05 6.96 6.70 A0Ve 1176 2
2 NAME Orion Nebula Cluster OpC 05 35.0 -05 29           ~ 2514 0
3 V* FU Ori Or* 05 45 22.3647842544 +09 04 12.291320064   10.72 9.60     F0Iab 888 1
4 HD 100546 Be* 11 33 25.4408872296 -70 11 41.241297948   6.71 6.30   6.64 A0VaekB8_lB 894 1
5 V* V380 Nor LP* 16 31 59.4481559856 -44 53 12.430397580   9.37 7.58     M1III 18 0
6 Sandqvist 187 Cld 16 32 17.2 -44 53 40           ~ 21 1
7 HBC 645 Em* 16 32 27.22 -44 55 36.0           ~ 26 0
8 2MASS J16322723-4455303 mm 16 32 27.23 -44 55 30.3           ~ 3 0
9 HH 56 HH 16 32 29.32 -44 54 57.5           ~ 42 0
10 HH 57 HH 16 32 31.96 -44 55 37.2           ~ 69 1
11 IRAS 16289-4449 Or* 16 32 32.19264 -44 55 30.6552       15.95   ~ 149 1
12 HD 328329 * 16 32 32.6751466392 -44 56 38.928594084   11.94 11.54     A2 5 0
13 TYC 7866-2460-1 * 16 32 37.7395166952 -44 52 54.424210116   12.38 11.90     ~ 1 0
14 Sz 136 Or* 16 33 04.4954049264 -44 57 18.256493448   13.9       ~ 5 0
15 [NC2005] MMS 5 mm 16 33 07.2 -44 59 24           ~ 2 0
16 IRAS 16295-4452 Y*? 16 33 07.73 -44 58 24.7           ~ 11 0
17 TYC 7866-2378-1 * 16 33 10.0190752728 -44 54 12.291370776   12.62 11.61     ~ 1 0
18 Sz 137 Or* 16 33 12.0637081560 -44 56 14.213421204   15.6       ~ 4 0
19 NAME Norma Cloud Cld 16 34 -45.0           ~ 32 1
20 Sandqvist 188 Cld 16 34.6 -45 03           ~ 4 1
21 [NC2005] MMS 6 mm 16 35 36.8 -45 02 48           ~ 2 0
22 HD 163296 Ae* 17 56 21.2881851168 -21 57 21.871819008 7.00 6.93 6.85 6.86 6.67 A3VaekA1mA1 1301 0
23 V* V733 Cep Or* 22 53 33.2578965000 +62 32 23.629387452     18.57   14.63 ~ 48 0

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