- ID:
- ivo://CDS.VizieR/J/AJ/154/87
- Title:
- Stellar population of the young star cluster NGC 6231
- Short Name:
- J/AJ/154/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NGC 6231 is a young cluster (age ~2-7 Myr) dominating the Sco OB1 association (distance ~1.59 kpc) with ~100 O and B stars and a large pre-main-sequence stellar population. We combine a reanalysis of archival Chandra X-ray data with multiepoch near-infrared (NIR) photometry from the VISTA Variables in the Via Lactea (VVV) survey and published optical catalogs to obtain a catalog of 2148 probable cluster members. This catalog is 70% larger than previous censuses of probable cluster members in NGC 6231. It includes many low-mass stars detected in the NIR but not in the optical and some B stars without previously noted X-ray counterparts. In addition, we identify 295 NIR variables, about half of which are expected to be pre-main-sequence stars. With the more complete sample, we estimate a total population in the Chandra field of 5700-7500 cluster members down to 0.08 M_{sun}_ (assuming a universal initial mass function) with a completeness limit at 0.5 M_{sun}_. A decrease in stellar X-ray luminosities is noted relative to other younger clusters. However, within the cluster, there is little variation in the distribution of X-ray luminosities for ages less than 5 Myr. The X-ray spectral hardness for B stars may be useful for distinguishing between early-B stars with X-rays generated in stellar winds and B-star systems with X-rays from a pre-main-sequence companion (>35% of B stars). A small fraction of catalog members have unusually high X-ray median energies or reddened NIR colors, which might be explained by absorption from thick or edge-on disks or being background field stars.
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- ID:
- ivo://CDS.VizieR/J/A+A/581/A28
- Title:
- Stellar X-ray flares from the 2XMM catalog
- Short Name:
- J/A+A/581/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a uniform, large-scale survey of X-ray flare emission, based on the XMM-Newton Serendipitous Source Catalogue and its associated data products. Our survey comprises both XMM-targeted active stars and those observed serendipitously in the field-of-view of each observation. The 2XMM Catalogue and the associated time-series ('light-curve') data products have been used as the basis for the survey of X-ray flares from cool stars in the Hipparcos Tycho-2 catalogue. Our sample contains ~130 flares with well-observed profiles; they originate from ~70 stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/480
- Title:
- Stellar X-ray sources in the COSMOS survey
- Short Name:
- J/ApJ/725/480
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the X-ray properties of a sample of solar- and late-type field stars identified in the Chandra Cosmic Evolution Survey (COSMOS), a deep (160ks) and wide (~0.9deg^2^) extragalactic survey. The sample of 60 sources was identified using both morphological and photometric star/galaxy separation methods. We determine X-ray count rates, extract spectra and light curves, and perform spectral fits to determine fluxes and plasma temperatures. Complementary optical and near-IR photometry is also presented and combined with spectroscopy for 48 of the sources to determine spectral types and distances for the sample. We find distances ranging from 30pc to ~12kpc, including a number of the most distant and highly active stellar X-ray sources ever detected. Overall the sample is typically more luminous than the active Sun, representing the high-luminosity end of the disk and halo X-ray luminosity functions. The halo population appears to include both low-activity spectrally hard sources that may be emitting through thermal bremsstrahlung, as well as a number of highly active sources in close binaries.
- ID:
- ivo://CDS.VizieR/J/ApJ/850/66
- Title:
- Stripe 82X survey multiwavelength catalog
- Short Name:
- J/ApJ/850/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multiwavelength surveys covering large sky volumes are necessary to obtain an accurate census of rare objects such as high-luminosity and/or high-redshift active galactic nuclei (AGNs). Stripe 82X is a 31.3 X-ray survey with Chandra and XMM-Newton observations overlapping the legacy Sloan Digital Sky Survey Stripe 82 field, which has a rich investment of multiwavelength coverage from the ultraviolet to the radio. The wide-area nature of this survey presents new challenges for photometric redshifts for AGNs compared to previous work on narrow-deep fields because it probes different populations of objects that need to be identified and represented in the library of templates. Here we present an updated X-ray plus multiwavelength matched catalog, including Spitzer counterparts, and estimated photometric redshifts for 5961 (96% of a total of 6181) X-ray sources that have a normalized median absolute deviation, {sigma}_nmad_=0.06, and an outlier fraction, {eta}=13.7%. The populations found in this survey and the template libraries used for photometric redshifts provide important guiding principles for upcoming large-area surveys such as eROSITA and 3XMM (in X-ray) and the Large Synoptic Survey Telescope (optical).
- ID:
- ivo://CDS.VizieR/J/ApJS/179/124
- Title:
- Subaru/XMM-Newton deep survey (SXDS) III.
- Short Name:
- J/ApJS/179/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the X-ray source catalog in the Subaru/XMM-Newton deep survey. A continuous area of 1.14deg^2^ centered at RA=02h18m and DE=-05{deg} is mapped by seven pointings with XMM-Newton covering the 0.2-10keV band. From the combined images of the EPIC pn and MOS cameras, we detect 866, 1114, 645, and 136 sources with sensitivity limits of 6x10^-16^, 8x10^-16^, 3x10^-15^, and 5x10^-15^ergs/cm^2^/s in the 0.5-2, 0.5-4.5, 2-10, and 4.5-10keV bands, respectively, with detection likelihood >=7 (corresponding to a confidence level of 99.91%). The catalog consists of 1245 sources in total including 32 extended-source candidates. The averaged logN-logS relations are in good agreement with previous results, bridging the flux range between Chandra deep surveys and brighter surveys.
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/505
- Title:
- Sub-mm observations in Extended Chandra DFS
- Short Name:
- J/MNRAS/411/505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a joint analysis of the overlapping Balloon-borne Large Aperture Submillimetre Telescope (BLAST) 250, 350, 500um, and LABOCA 870um observations [from the LABOCA ECDFS Submm Survey (LESS) survey] of the Extended Chandra Deep Field-South. Out to z~3, the BLAST filters sample near the peak wavelength of thermal far-infrared (FIR) emission from galaxies (rest-frame wavelengths ~60-200um), primarily produced by dust heated through absorption in star-forming clouds. However, identifying counterparts to individual BLAST peaks is very challenging, given the large beams [full-width at half-maximum (FWHM) 36-60 arcsec]. In contrast, the ground-based 870um observations have a significantly smaller 19 arcsec FWHM beam, and are sensitive to higher redshifts (z~1-5, and potentially beyond) due to the more favourable negative K-correction. We use the LESS data, as well as deep Spitzer and VLA imaging, to identify 118 individual sources that produce significant emission in the BLAST bands.
- ID:
- ivo://CDS.VizieR/J/ApJ/871/16
- Title:
- Sun active regions from 1976-2017
- Short Name:
- J/ApJ/871/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The purpose of this paper is to show that large active regions (ARs) with different magnetic configurations have different contributions to short-term and long-term variations of the Sun. As a case study, the complex {delta}-type AR12673 and the simple {beta}-type AR12674 are investigated in detail. Since the axial dipole moment at cycle minimum determines the amplitude of the subsequent cycle and space climate, we have assimilated the individual observed magnetic configurations of these two ARs into a surface flux transport model to compare their contributions to the axial dipole moment D. We find that AR12673 has a significant effect on D at the end of the cycle, making it weaker because of abnormal and complicated magnetic polarities. An initial strongly positive D ends up with a strongly negative value. The flare- poor AR12674 has a greater contribution to the long-term axial dipole moment than the flare-rich AR12673. We then carry out a statistical analysis of ARs larger than 800{mu}Hem (solar hemisphere) from 1976 to 2017. We use the flare index (FI) and define an axial dipole moment index (DI) to quantify the effects of each AR on space weather and space climate, respectively. Whereas the FI has a strong dependence on the magnetic configuration, the DI shows no such dependence. The DI is mainly determined by the latitudinal location and the latitudinal separation of the positive and negative magnetic fluxes of the ARs. Simple ARs have the same possibility as complex ARs to produce big DI values affecting space climate.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/23
- Title:
- SUPER GOODS. IV. 850um data of CDFS X-ray sources
- Short Name:
- J/ApJ/887/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Chandra Deep Field (CDF)-S is the deepest X-ray image available and will remain so for the near future. We provide a spectroscopic (64.5%; 64% with spectral classifications) and photometric redshift catalog for the full 7Ms sample, but much of our analysis focuses on the central (off-axis angles <5.7') region, which contains a large, faint ALMA sample of 75 >4.5{sigma} 850{mu}m sources. We measure the 850{mu}m fluxes at the X-ray positions using the ALMA images, where available, or an ultradeep SCUBA-2 map. We find that the full X-ray sample produces ~10% of the 850{mu}m extragalactic background light. We separate the submillimeter-detected X-ray sources into star-forming galaxies and active galactic nuclei (AGNs) using a star formation rate (SFR) versus X-ray luminosity calibration for high-SFR galaxies. We confirm this separation using the X-ray photon indices. We measure the X-ray fluxes at the accurate positions of the 75 ALMA sources and detect 70% at >3{sigma} in either the 0.5-2 or 2-7keV bands. However, many of these may produce both their X-ray and submillimeter emission by star formation. Indeed, we find that only 20% of the ALMA sources have intermediate X-ray luminosities (rest-frame 8-28 keV luminosities of 10^42.5^-10^44^erg/s), and none has a high X-ray luminosity (>10^44^erg/s). Conversely, after combining the CDF-S with the CDF-N, we find extreme star formation (SFR>300M_{sun}_/yr) in some intermediate X-ray luminosity sources but not in any high X-ray luminosity sources. We argue that the quenching of star formation in the most luminous AGNs may be a consequence of the clearing of gas in these sources.
- ID:
- ivo://CDS.VizieR/J/MNRAS/472/308
- Title:
- Supernova remnants in M33: X-ray properties
- Short Name:
- J/MNRAS/472/308
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a study of the X-ray properties of the supernova remnant (SNR) population in M33 with XMM-Newton, comprising deep observations of eight fields in M33 covering all of the area within the D_25_ contours, and with a typical luminosity of 7.1x10^34^erg/s (0.2-2.0keV). Here, we report our work to characterize the X-ray properties of the previously identified SNRs in M33, as well as our search for new X-ray detected SNRs. With our deep observations and large field of view we have detected 105 SNRs at the 3{sigma} level, of which 54 SNRs are newly detected in X-rays, and three are newly discovered SNRs. Combining XMM-Newton data with deep Chandra survey data allows detailed spectral fitting of 15 SNRs, for which we have measured temperatures, ionization time-scales and individual abundances. This large sample of SNRs allows us to construct an X-ray luminosity function, and compare its shape to luminosity functions from host galaxies of differing metallicities and star formation rates to look for environmental effects on SNR properties. We conclude that while metallicity may play a role in SNR population characteristics, differing star formation histories on short time-scales, and small-scale environmental effects appear to cause more significant differences between X-ray luminosity distributions. In addition, we analyse the X-ray detectability of SNRs, and find that in M33 SNRs with higher [SII]/H{alpha} ratios, as well as those with smaller galactocentric distances, are more detectable in X-rays.
- ID:
- ivo://CDS.VizieR/J/other/NewA/5.137
- Title:
- Supersoft X-ray sources catalog
- Short Name:
- J/other/NewA/5.1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog comprises an up-to-date (December 1999) list of luminous (>10^36^erg/s), binary supersoft X-ray sources.