- ID:
- ivo://nasa.heasarc/elaiss1xmm
- Title:
- ELAIS S1 Field XMM-Newton X-Ray Source Catalog
- Short Name:
- ELAISS1XMM
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The formation and evolution of cosmic structures can be probed by studying the evolution of the luminosity function of the Active Galactic Nuclei (AGNs), galaxies and clusters of galaxies and of the clustering of the X-ray active Universe, compared to the IR-UV active Universe. To this purpose, the authors have surveyed with XMM-Newton the central ~0.6 deg<sup>2</sup> region of the ELAIS-S1 field down to flux limits of ~5.5 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> (0.5-2 keV, soft band, S), ~2 x 10<sup>-15</sup> erg cm<sup>-2</sup> s<sup>-1</sup> (2-10 keV, hard band, H), and ~4 x 10<sup>-15</sup> erg cm<sup>-2</sup> s<sup>-1</sup> (5-10 keV, ultra-hard band, HH). They present here the analysis of the XMM-Newton observations, the number counts in different energy bands and the clustering properties of the X-ray sources. They have detected a total of 478 sources, 395 and 205 of which detected in the S and H bands respectively. They identified 7 clearly extended sources and estimated their redshift through X-ray spectral fits with thermal models. In four cases the redshift is consistent with z = 0.4, so they may have detected a large scale structure formed by groups and clusters of galaxies through their hot intra-cluster gas emission. The relative density of the S band sources is higher near the clusters and groups at z ~ 0.4 and extends toward East and the South/West. This suggests that the structure is complex, with a size comparable to the full XMM-Newton field. Conversely, the highest relative source densities of the H band sources are located in the central-west region of the field. The mosaic of four partially overlapping deep XMM-Newton pointings covers a large (~0.6 deg<sup>2</sup>) and contiguous area of the ELAIS-S1 region. The pointings are named <pre> ELAIS-S1-A (RA=8.91912, DE=-43.31344, J2000), ELAIS-S1-B (RA=8.92154, DE=-43.65575, J2000), ELAIS-S1-C (RA=8.42195, DE=-43.30488, J2000) and ELAIS-S1-D (RA=8.42375, DE=-43.65327, J2000). </pre> The X-ray observations were performed on May 2003 through July 2003 with XMM-Newton's European Photon Imaging Camera (EPIC) and two MOS-CCD cameras. This table was created by the HEASARC in June 2008 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/457/501">CDS Catalog J/A+A/457/501</a> files elaisxmm.dat and catalog.dat. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/elaiss1oid
- Title:
- ELAIS S1 Field X-Ray Source Optical/IR Identifications Catalog
- Short Name:
- ELAISS1OID
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the optical identifications and a multi-band catalog of a sample of 478 X-ray sources detected in the XMM-Newton and Chandra surveys of the central 0.6 deg<sup>2</sup> of the ELAIS-S1 field. The most likely optical/infrared counterpart of each X-ray source was identified using the chance coincidence probability in the R and IRAC 3.6 micron bands.This method was complemented by the precise positions obtained through Chandra observations. The authors were able to associate a counterpart to each X-ray source in the catalogue. Approximately 94% of them are detected in the R band, while the remaining are blank fields in the optical down to R ~ 24.5, but have a near-infrared counterpart detected by IRAC within 6 arcsec of the XMM-Newton centroid. The multi-band catalog, produced using the positions of the identified optical counterparts, contains photometry in ten photometric bands, from B to the MIPS 24 micron band. The spectroscopic follow-up allowed us to determine the redshift and classification for 237 sources (~ 50% of the sample) brighter than R = 24. The spectroscopic redshifts were complemented by reliable photometric redshifts for 68 sources. The authors classified 47% of the sources with spectroscopic redshift as broad-line active galactic nuclei (BL AGNs) with z = 0.1-3.5, while sources without broad-lines (NOT BL AGNs) are about 46% of the spectroscopic sample and are found up to z = 2.6. The remaining fraction is represented by extended X-ray sources and stars. The authors spectroscopically identified 11 type 2 QSOs among the sources with F(2-10 keV)/F(R) > 8, with redshift between 0.9 and 2.6, high 2-10 keV luminosity (log L(2-10 keV) >= 43.8 erg/s) and hard X-ray colors suggesting large absorbing columns at the rest frame (log N<sub>H</sub> up to 23.6 cm<sup>-2</sup>). BL AGNs show on average blue optical-to-near-infrared colors, softer X-ray colors and X-ray-to-optical colors typical of optically selected AGNs. Conversely, narrow-line sources show redder optical colors, harder X-ray flux ratio and span a wider range of X-ray-to-optical colors. On average the Spectral Energy Distributions (SEDs) of high-luminosity BL AGNs resemble the power-law typical of unobscured AGNs. The SEDs of NOT BLAGNs are dominated by the galaxy emission in the optical/near-infrared, and show a rise in the mid-infrared which suggests the presence of an obscured active nucleus. The authors have used the infrared-to-optical colors and near-infrared SEDs to infer the properties of the AGN host galaxies. Identifications and photometric parameters for 478 sources detected by XMM-Newton in the ELAIS-S1 field are given. For each source, the X-ray positions and fluxes, optical position and photometry, Spitzer IRAC and MIPS 24 micron positions and fluxes, spectroscopic redshift where available, photometric redshift and SED shape classification are given. This table was created by the HEASARC in December 2008 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/488/417">CDS Catalog J/A+A/488/417</a> file catalog.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/xmmvaragn
- Title:
- Ensemble X-Ray Variability of AGN in 2XMMi-DR3
- Short Name:
- XMMVARAGN
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The X-ray variability of active galactic nuclei (AGN) has been most often investigated with studies of individual, nearby sources, and only a few ensemble analyses have been applied to large samples in wide ranges of luminosity and redshift. In their study, the authors aimed to determine the ensemble variability properties of two serendipitously selected AGN samples extracted from the catalogs of XMM-Newton and Swift (the latter is not included in this table, notice), with redshift between ~ 0.2 and ~ 4.5, and X-ray luminosities, in the 0.5 - 4.5 keV band, between ~ 10<sup>43</sup> erg/s and ~ 10<sup>46</sup> erg/s. They used the structure function (SF), which operates in the time domain, and allows for an ensemble analysis even when only a few observations are available for individual sources and the power spectral density (PSD) cannot be derived. The SF is also more appropriate than fractional variability and excess variance, because these parameters are biased by the duration of the monitoring time interval in the rest-frame, and therefore by cosmological time dilation. The authors find statistically consistent results for the two samples, with the SF described by a power law of the time lag tau, approximately as SF ~ tau<sup>0.1</sup>. They do not find evidence of the break in the SF, at variance with the case of lower luminosity AGNs. They confirm a strong anti-correlation of the variability with X-ray luminosity, accompanied by a change of the slope of the SF. They also find evidence in support of a weak, intrinsic, average increase of X-ray variability with redshift. For XMM, the authors used the version of the Serendipitous Source Catalog then available, namely 2XMMi-DR3, the latest incremental update of the second version of the catalogue, with observations made between 2000 February 3 and 2008 October 08; all datasets were publicly available by 2009 October 31, but not all public observations are included in this catalog. The total area of the catalog fields is ~ 814 deg<sup>2</sup>, but taking account of the substantial overlaps between observations, the net sky area covered independently is ~ 504 deg<sup>2</sup>. The 2XMMi-DR3 catalogue contains 353,191 detections (above the processing likelihood threshold of 6), related to 262,902 unique X-ray sources, therefore a significant number of sources (41,979) have more than one record within the catalog. The selected sources were cross-correlated with the DR7 edition of the SDSS Quasar Catalog (Schneider et al. 2010, AJ, 139, 2360) to obtain redshifts and spectral classifications for the sources. The authors used a maximum distance of 1.5 arcseconds, corresponding to the uncertainty in the X-ray positions, resulting in 412 quasars that were observed by XMM-Newton from 2 to 25 epochs each for a total of 1376 observations. The authors refer to these sources as the XMM-Newton sample. This table was created by the HEASARC in April 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/536/A84">CDS Catalog J/A+A/536/A84</a> file table1.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/erosxmm
- Title:
- Extremely Red Objects XMM-Newton Survey Catalog
- Short Name:
- EROSXMM
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the results of a deep (about 80 ks) XMM-Newton survey of the largest sample of near-infrared-selected Extremely Red Objects (R-K > 5) available to date to K<sub>s</sub> < ~19.2. At the relatively bright X-ray fluxes ((F(2-10 keV) >~ 4 x 10<sup>-15</sup> erg cm<sup>-2</sup> s<sup>-1</sup>) and near-infrared magnitude probed by the present observations, the fraction of AGN (i.e. X-ray detected) among the ERO population is small (~3.5%); conversely, the fraction of EROs among hard X-ray selected sources is much higher (~20%). The X-ray properties of the 9 EROs detected in this XMM-Newton observation indicate absorption in excess of 10<sup>22</sup> cm<sup>-2</sup> in a large fraction of them. The X-ray, optical and near-infrared properties of those X-ray selected EROs with a spectroscopic or photometric redshift nicely match those expected for type 2 quasars, the high-luminosity, high-redshift obscured AGNs predicted in baseline XRB synthesis models. A close correlation is detected between X-ray and K-band fluxes. This table contains the X-ray and optical information for the sources detected in the sum of 3 separate XMM-Newton observations of a field centered on 14 49 25, +09 00 13 (J2000.0 RA and Dec) known as the "Daddi" field (Daddi et al. 2000, A&A, 361, 535) in which 257 EROs are known to be present. The data from all 3 EPIC instruments (PN, MOS1 and MOS2) obtained in the 3 observations was combined, yielding a total exposure time for the PN of ~82 ks, and for the MOS instruments of ~78 ks. The X-ray hardness ratio (HR) and the optical to near-infrared color (R and K magnitudes) are reported for all the detected X-ray sources and their counterparts, along with the reliability of the X-ray to optical or near-infrared associations as measured by the likelihood ratios, LR(R) and LR(K). This table lists data for the 111 proposed optical/infrared counterparts for the 97 detected X-ray sources, i.e., X-ray sources with more than one possible optical/IR counterpart will have multiple entries in this table, one for each counterpart, as follows: 73 X-ray sources have secure optical/near-IR counterparts (counterpart_status=1), 7 X-ray sources have 2 possible 'likely' counterparts, and 1 X-ray source has 3 such counterparts (counterpart_status=2), 6 X-ray sources have only low-likelihood counterparts all of which lie outside the 3" matching radii (counterpart_status=3), and the remaining 9 X-ray sources lack optical and infrared photometry (counterpart_status=4). This table was created by the HEASARC in February 2007 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/432/69">CDS Catalog J/A+A/432/69</a> files table1.dat and table2.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/fornaxxmm
- Title:
- Fornax Dwarf Galaxy XMM-Newton X-Ray Point Source Catalog
- Short Name:
- FORNAXXMM
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results of a deep archive XMM-Newton observation of the Fornax spheroidal galaxy that the authors analyzed with the aim of fully characterizing the X-ray source population (in most of the cases likely to be background active galactic nuclei) detected towards the target. A cross-correlation with the available databases allowed them to find a source that may be associated with a variable star belonging to the galaxy. The authors also searched for X-ray sources in the vicinity of the Fornax globular clusters GC 3 and GC 4 and found two sources probably associated with the respective clusters. The deep X-ray observation was also suitable for the search for the intermediate-mass black hole (of mass ~ 10<sup>4</sup> solar masses) expected to be hosted in the center of the galaxy. In the case of Fornax, this search is extremely difficult since the galaxy centroid of gravity is poorly constrained because of the large asymmetry observed in the optical surface brightness. Since the authors cannot firmly establish the existence of an X-ray counterpart of the putative black hole, they put constraints only on the accretion parameters. In particular, they found that the corresponding upper limit on the accretion efficiency, with respect to the Eddington luminosity, is as low as a few 10<sup>-5</sup>. This table was created by the HEASARC in February 2013 based on an electronic version of Table 1 from the reference paper which was obtained from the A&A web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ic10xmmcxo
- Title:
- IC 10 XMM-Newton and Chandra X-Ray Point Source Catalog
- Short Name:
- IC10XMMCXO
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains some of the results from an X-ray study of our nearest starburst galaxy IC 10, based on XMM-Newton and Chandra observations. It contains a list of 73 XMM-Newton and 28 Chandra detections of point-like X-ray sources in the field of this galaxy; a substantial fraction of them are likely to be stellar objects in the Milky Way due to the low Galactic latitude location of IC 10. The brightest source in the IC 10 field, X-1, has a mean 0.3-8.0 keV luminosity of ~1.2E38 erg s<sup>-1</sup> and shows a large variation by a factor of up to ~6 on timescales of ~10<sup>4</sup> s during the XMM-Newton observation. The XMM-Newton observations were taken on 2003 July 3 with a total exposure time of ~45 ks for the EPIC-MOS cameras and ~42 ks for the European Photon Imaging Camera (EPIC) PN camera. The authors use only the data from the PN camera (with a thin optical blocking filter) because of its high sensitivity to soft X-rays in the study of diffuse emission and include the data from the MOS cameras in the analysis of X-1. The Chandra observation, taken on 2003 March 12 with an exposure of 29 ks and already described by Bauer and Brandt (2004, ApJ, 601, 67), was reprocessed by the authors using the then-latest CIAO software (version 3.2.1) and calibration database (version 3.0.0). The authors used the Two-Micron All Sky Survey (2MASS) All-Sky Catalog of Point Sources (Cutri et al. 2003 <a href="https://cdsarc.cds.unistra.fr/ftp/cats/II/246">CDS Catalog II/246</a>) to search for potential counterparts. They cross-correlated the spatial positions of the objects in this catalog with their X-ray source positions, using a matching radius of 4 arcsec for XMM-Newton PN sources and 2 arcsec for Chandra ACIS sources. The radius was chosen to be greater than the 1-sigma statistical position uncertainty of almost all the sources.In no case is there a match with multiple 2MASS objects. The 3-sigma limiting sensitivities of the 2MASS Catalog are 17.1, 16.4 and 15.3 mag in the three bands, J, H, and K<sub>S</sub>, respectively. This table was created by the HEASARC in October 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/362/1065">CDS Catalog J/MNRAS/362/1065</a> files table1.dat, table2.dat and table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ic1805xmm
- Title:
- IC 1805 XMM-Newton X-Ray Source Catalog
- Short Name:
- IC1805XMM
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Very young open clusters are ideal places to study the X-ray properties of a homogeneous population of early-type stars. In this respect, the IC 1805 open cluster is very interesting as it hosts the O4 If+ star HD 15570 that is thought to be in an evolutionary stage intermediate between a normal O-star and a Wolf-Rayet star. Such a star could provide a test for theoretical models aiming at explaining the empirical scaling relation between the X-ray and bolometric luminosities of O-type stars. The authors have observed IC 1805 with XMM-Newton and further collected optical spectroscopy of some of the O-star members of the cluster. The optical spectra allowed them to revisit the orbital solutions of BD +60 497 and HD 15558, and provided the first evidence of binarity for BD +60 498. X-ray emission from colliding winds does not appear to play an important role among the O-stars of IC 1805. Notably, the X-ray fluxes do not vary significantly between archival X-ray observations and the present XMM-Newton pointing. The very fast rotator BD +60 513, and to a lesser extent the O4 If+ star HD 15570, appear somewhat underluminous. While the underluminosity of HD 15570 is only marginally significant, its amplitude is found to be compatible with theoretical expectations based on its stellar and wind properties. A number of other X-ray sources are detected in the field, and the brightest objects, many of which are likely low-mass pre-main sequence stars, are analyzed in detail. This table provides the full catalog of the 191 X-ray sources detected with the EPIC detectors onboard XMM-Newton in the direction of the IC 1805 cluster. The coordinates of the sources were cross-correlated with the optical and IR catalogs of Straizys et al. (2013, A&A, 554, A3), Wolff et al. (2011, ApJ, 726, 19), and the SIMBAD database. The authors adopted in each case a correlation radius of 4 arcseconds. This table was created by the HEASARC in October 2016 based on the electronic version of Table A1 from the reference paper which was obtained from the CDS (their catalog J/A+A/594/A82 file tablea1.dat). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/ic2944xmm
- Title:
- IC 2944/2948 XMM-Newton X-Ray Source Catalog
- Short Name:
- IC2944XMM
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- Using XMM-Newton data, the authors have studied for the first time the X-ray emission of the young star clusters HM1 and IC 2944/2948. Low-mass, pre-main sequence objects with an age of a few Myr are detected, as well as a few background or foreground objects. Most massive stars in both clusters display the usual high-energy properties of that kind of objects, though with log(L<sub>x</sub>/L<sub>bol</sub>) apparently lower in HM1 than in IC 2944/2948. Comparing with studies of other clusters, it seems that low S/N at soft energies, due to the high extinction, may the main cause of this difference. In HM1, the two Wolf-Rayet stars show contrasting behaviors: WR89 is extremely bright, but much softer than WR87. It remains to be seen whether wind-wind collisions or magnetically confined winds can explain such emissions. In IC 2944/2948, the X-ray sources concentrate around HD 101205; a group of massive stars to the north of this object appears rather isolated, suggesting that there exist two sub-clusters in the field of view. This tables provides the list of 368 detected X-ray sources in/toward the Cen OB2 association cluster(s) IC 2944/2948 only, i.e., the 58 X-ray sources detected in/toward the HM1 cluster are not contained herein. This tables lists the basic X-ray source properties (position, count rates, hardness ratios) and their probable optical/infrared counterparts (offset angular distance, name). XMM-Newton has observed IC 2944/2948 for 40 ks on XMM-Newton Rev. 2209 (with the THICK filter). No background flare affected the observation, and no source is bright enough to suffer from pile-up. This table was created by the HEASARC in September 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/555/A83">CDS Catalog J/A+A/555/A83</a> files table3.dat and table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/kaporixmm
- Title:
- Kappa Orionis XMM-Newton X-Ray Point Source Catalog
- Short Name:
- KAPORIXMM
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- X-rays are a powerful probe of activity in the early stages of star formation. They allow us to identify young stars even after they have lost the IR signatures of circumstellar disks and provide constraints on their distance. Here, the authors report on XMM-Newton observations that detected 121 young stellar objects (YSOs) in two fields between the filamentary dark cloud complex Lynds 1641S and the star Kappa Ori. These observations extend the Survey of Orion A with XMM and Spitzer (SOXS). The YSOs are contained in a ring of gas and dust apparent at millimeter wavelengths, and in far-IR and near-IR surveys. The X-ray luminosity function of the YSOs detected in the two fields indicates a distance of 250-280 pc, much closer than the Orion A cloud and similar to the distance estimates for Kappa Ori. The authors propose that the ring is a 5-8 pc diameter shell that has been swept up by Kappa Ori. This ring contains several groups of stars detected by Spitzer and WISE including one surrounding the Herbig Ae/Be star V1818 Ori. In this interpretation, the Kappa Ori ring is one of several shells swept up by massive stars within the Orion Eridanus Superbubble and is unrelated to the southern portion of Orion A/L 1641S. The XMM-Newton observations consist of two fields, north (Field N = KN) and south (Field S = KS), and were obtained in 2015 March 10 and 15 using EPIC as the primary instrument. Table 1 in the reference paper shows the details of the exposures, each one with a duration of about 50 ks and taken with the Medium filter. The authors used SAS version 14.0 to reduce the observation data files (ODFs) and to obtain calibrated lists of events for the MOS and pn instruments. They filtered the events in the 0.3-0.8 keV energy band and used only events with FLAG = 0 and PATTERN < 12 as prescribed by the SAS manual. With SAS, the authors obtained exposure maps in the 0.3-8.0 keV band and performed source detection with a code based on wavelet convolution that operated simultaneously on MOS and pn data. They used a threshold of significance of 4.5 sigma of the local background to discriminate real sources from spurious background fluctuations. However, they added few sources to the final list with significance S in 4.0 < S < 4.5 for the cases of positional match with objects in SIMBAD or PPMX catalogs. The final list was also checked for spurious sources that could appear at the border of the CCDs. In sum, the authors detected 238 X-ray sources with significance > 4 sigma of the local background; 104 sources are in KN and 134 in KS. The authors cross-correlated the positions of the X-ray sources with the coordinates of the IR catalog of Megeath et al. (2012, AJ, 144, 192). This IR catalog is the result of a survey of Orion with Spitzer that produced a classification of protostars and stars with disks. Of the 238 X-ray sources, 191 are identified within 8 arcseconds of one of 206 IR objects, 99 sources in KS, 92 sources in KN. Some X-ray sources were multiple matches within 8 arcsec of IR objects. For these cases, the authors assigned the most likely counterparts based on IR photometry and visual inspection of X-rays and IR images. However, nine X-ray sources were left associated with two or three IR objects. Among the IR matches, the authors found 15 stars with disks in KN and 35 in KS with X-ray detection. One protostar in KN and three in KS were detected in X-rays. The authors used X-ray detection of sources without IR excess as criteria to identify disk-less stars (hereafter Class III stars). They classified as Class III stars those IR objects with X-ray detections, with [4.5um]-[8.0um] colors < 0.3 mag and brighter than [4.5um] magnitude < 14. At the distance of the ONC (400 pc), the [4.5um] magnitude ~ 14 threshold at an age of 4-5 Myrs roughly identifies M3-M4 spectral types and masses around 0.3 solar masses. With this selection scheme, the authors identified 48 objects in KN and 19 in KS as Class III candidates. This table was created by the HEASARC in August 2016 based on the electronic version of Table 2 from the reference paper which was obtained from the CDS (their catalog J/ApJ/820/L28 file table2.dat). This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/lamorixmm
- Title:
- Lambda Orionis Cluster XMM-Newton X-Ray Point Source Catalog
- Short Name:
- LAMORIXMM
- Date:
- 18 Apr 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The authors studied the X-ray properties of the young (~1-8M yr) open cluster around the hot (O8 III) star Lambda Ori and compared them with those of the similarly-aged Sigma Ori cluster in order to investigate the possible effects of the different ambient environments. They analyzed an XMM-Newton observation of the cluster using EPIC imaging and low-resolution spectral data. They studied the variability of the detected sources, and performed a spectral analysis of the brightest sources in the field using multi-temperature models. The authors detected 167 X-ray sources above a 5-sigma detection threshold the properties of which are listed in this table, of which 58 are identified with known cluster members and candidates, from massive stars down to low-mass stars with spectral types of ~ M5.5. Another 23 sources were identified with new possible photometric candidates. Late-type stars have a median log L<sub>X</sub>/L<sub>bol</sub> ~ -3.3, close to the saturation limit. Variability was observed in ~ 35% of late-type members or candidates, including six flaring sources. The emission from the central hot star Lambda Ori is dominated by plasma at 0.2 - 0.3 keV, with a weaker component at 0.7 keV, consistent with a wind origin. The coronae of late-type stars can be described by two plasma components with temperatures T<sub>1</sub> ~ 0.3-0.8 keV and T<sub>2</sub> ~ 0.8-3 keV, and subsolar abundances Z ~ 0.1-0.3 Z<sub>sun</sub>, similar to what is found in other star-forming regions and associations. No significant difference was observed between stars with and without circumstellar discs, although the smallness of the sample of stars with discs and accretion does not definitive conclusions to be drawn. The authors concluded that the X-ray properties of Lambda Ori late-type stars are comparable to those of the coeval Sigma Ori cluster, suggesting that stellar activity in Lambda Ori has not been significantly affected by the different ambient environment. The lambda Ori cluster was observed by XMM-Newton from 20:46 UT on September 28, 2006 to 12:23 UT on September 29, 2006 (Obs. ID 0402050101), for a total duration of 56ks, using both the EPIC MOS and PN cameras and the RGS instruments. The EPIC cameras were operated in full frame mode with the thick filter. This table was created by the HEASARC in November 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/530/A150">CDS Catalog J/A+A/530/A150</a> files tablea1.dat ('X-ray sources detected in the Lambda Ori Cluster'), table1,dat ('X-ray and optical properties of sources identified with known cluster members and candidates') and table2.dat ('X-ray sources identified with possible new cluster candidates'). It does not include the objects listed in tablea2.dat ('3-sigma upper limits and optical properties of undetected cluster members and candidates'). This is a service provided by NASA HEASARC .
