- ID:
- ivo://CDS.VizieR/J/A+A/418/509
- Title:
- Chandra observation of M67
- Short Name:
- J/A+A/418/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a 47-ks Chandra/ACIS observation of the old open cluster M67. We detected 25 proper-motion cluster members (including ten new sources) and 12 sources (all new) that we suspect to be members from their locations close to the main sequence (1<B-V<1.7). Of the detected members, 23 are binaries.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/137/3210
- Title:
- Chandra observations of h Persei
- Short Name:
- J/AJ/137/3210
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe Chandra/ACIS-I observations of the massive ~13-14Myr-old cluster, h Persei, part of the famous Double Cluster (h and {chi} Per) in Perseus. Combining the list of Chandra-detected sources with new optical/IR photometry and optical spectroscopy reveals ~165 X-ray bright stars with V<~23. Roughly 142 have optical magnitudes and colors consistent with cluster membership.
- ID:
- ivo://CDS.VizieR/J/ApJ/675/464
- Title:
- Chandra observations of NGC 2244
- Short Name:
- J/ApJ/675/464
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first high spatial resolution X-ray study of NGC 2244, the 2Myr old stellar cluster in the Rosette Nebula, using Chandra. Over 900 X-ray sources are detected; 77% have optical or FLAMINGOS NIR stellar counterparts and are mostly previously uncataloged young cluster members.
- ID:
- ivo://CDS.VizieR/J/AJ/127/2659
- Title:
- CHANDRA observations of NGC 2264
- Short Name:
- J/AJ/127/2659
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of a Chandra observation of a field in NGC 2264. The observations were taken with the ACIS-I camera with an exposure time of 48.1ks. We present a catalog of 263 sources, which includes X-ray luminosity, optical and infrared photometry, and X-ray variability information. We found 41 variable sources, 14 of which have a flarelike light curve, and two of which have a pattern of a steady increase or decrease over a 10-hr period. The optical and infrared photometry for the stars identified as X-ray sources are consistent with most of these objects being premain-sequence stars with ages younger than 3Myr.
- ID:
- ivo://CDS.VizieR/J/ApJ/549/441
- Title:
- Chandra observations of Orion Trapezium
- Short Name:
- J/ApJ/549/441
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the High-Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory to perform two observations, separated by 3 weeks, of the Orion Trapezium region. The zeroth-order images on the Advanced CCD Imaging Spectrometer provide spatial resolution of 0.5" and moderate energy resolution. Within a 160"x140" region around the Orion Trapezium, we resolve 111 X-ray sources with luminosities between 7x10^28^ and 2x10^32^ergs/s. We do not detect any diffuse emission. All but six sources are identified.
- ID:
- ivo://CDS.VizieR/J/ApJ/589/509
- Title:
- Chandra observations of Trumpler 14 and 16
- Short Name:
- J/ApJ/589/509
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The region around the {eta} Carinae Nebula has three OB associations, which contain a Wolf-Rayet star and several massive O3 stars. An early Chandra ACIS-I image was centered on {eta} Car and includes Trumpler 16 and part of Trumpler 14. The Chandra image confirms the well-known result that O and very early B stars are X-ray sources with LX~=10^-7^Lbol over an X-ray luminosity range of about 100. Two new, anomalously strong X-ray sources have been found among the hot star population: Tr 16-244, a heavily reddened O3 I star, and Tr 16-22, a heavily reddened O8.5 V star. Two stars have an unusually large LX/Lbol: HD 93162, a Wolf-Rayet star (and possible binary), and Tr 16-22, a possible colliding-wind binary. In addition, a population of sources associated with cool stars is detected. In the color-magnitude diagram, these X-ray sources sit above the sequence of field stars in the Carina arm. The OB stars are on average more X-ray luminous than the cool star X-ray sources. X-ray sources among A stars have X-ray luminosities similar to those of cooler stars and may be due to cooler companions. Upper limits are presented for B stars that are not detected in X-rays. These upper limits are also the upper limits for any cool companions that the hot stars may have. Hardness ratios are presented for the most luminous sources in bands 0.5-0.9, 0.9-1.5, and 1.5-2.04keV. The available information on the binary nature of the hot stars is discussed, but binarity does not correlate with X-ray strength in a simple way.
- ID:
- ivo://CDS.VizieR/J/ApJ/614/267
- Title:
- Chandra sources in Cha I North
- Short Name:
- J/ApJ/614/267
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sensitive X-ray imaging surveys provide a new and effective tool to establish the census of pre-main-sequence (PMS) stars in nearby young stellar clusters. We report here a deep Chandra X-Ray Observatory observation of PMS stars in the Chamaeleon I North cloud, achieving a limiting luminosity of log L_t_~27ergs/s (0.5-8keV band) in a 0.8x0.8pc^2^ region. Of the 107 X-ray sources, 37 are associated with Galactic stars of which 27 are previously recognized cloud members.
- ID:
- ivo://CDS.VizieR/J/ApJS/169/353
- Title:
- Chandra sources in M17
- Short Name:
- J/ApJS/169/353
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report here results from a Chandra ACIS observation of the stellar populations in and around the M17 HII region. The field reveals 886 sources with observed X-ray luminosities (uncorrected for absorption) between ~29.3ergs/s<logL_X_<32.8ergs/s, 771 of which have stellar counterparts in infrared images.
- ID:
- ivo://CDS.VizieR/J/ApJ/770/98
- Title:
- Chandra study of NGC 6791
- Short Name:
- J/ApJ/770/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first X-ray study of NGC 6791, one of the oldest open clusters known (8Gyr). Our Chandra observation is aimed at uncovering the population of close interacting binaries down to L_X_~1x10^30^erg/s (0.3-7keV). We detect 86 sources within 8' of the cluster center, including 59 inside the half-mass radius. We identify 20 sources with proper-motion cluster members, which are a mix of cataclysmic variables (CVs), active binaries (ABs), and binaries containing sub-subgiants. With follow-up optical spectroscopy, we confirm the nature of one CV. We discover one new, X-ray variable candidate CV with Balmer and He II emission lines in its optical spectrum; this is the first X-ray-selected CV in an open cluster. The number of CVs per unit mass is consistent with the field, suggesting that the 3-4 CVs observed in NGC 6791 are primordial. We compare the X-ray properties of NGC 6791 with those of a few old open (NGC 6819, M67) and globular clusters (47 Tuc, NGC 6397). It is puzzling that the number of ABs brighter than 1x10^30^erg/s normalized by cluster mass is lower in NGC 6791 than in M 67 by a factor ~3-7. CVs, ABs, and sub-subgiants brighter than 1x10^30^erg/s are under-represented per unit mass in the globular clusters compared to the oldest open clusters, and this accounts for the lower total X-ray luminosity per unit mass of the former. This indicates that the net effect of dynamical encounters may be the destruction of even some of the hardest (i.e., X-ray-emitting) binaries.
- ID:
- ivo://CDS.VizieR/J/A+A/490/1055
- Title:
- Chandra survey of Tr 16 low-mass stars
- Short Name:
- J/A+A/490/1055
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify and characterize low-mass stars in the ~3Myr old Trumpler 16 region by means of a deep Chandra X-ray observation, and study their optical and near-IR properties. We compare the X-ray activity of Trumpler 16 stars with the known characteristics of Orion and Cygnus OB2 stars. We analyzed a 88.4ks Chandra ACIS-I observation pointed at the center of Trumpler 16. Because of diffuse X-ray emission, source detection was performed using the PWDetect code for two different energy ranges: 0.5-8.0keV and 0.9-8.0keV. Results were merged into a single final list. We positionally correlated X-ray sources with optical and 2MASS catalogs. Source events were extracted with the IDL-based routine ACIS-Extract. X-ray variability was characterized using the Kolmogorov-Smirnov test and spectra were fitted by using XSPEC. The X-ray spectra of early-type, massive stars were analyzed individually. Our list of X-ray sources consists of 1035 entries, 660 of which have near-IR counterparts and are probably associated with Trumpler 16 members.