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23941. Westerlund 1 Chandra X-Ray Point Source Catalog
ID:
ivo://nasa.heasarc/wd1cxo
Title:
Westerlund 1 Chandra X-Ray Point Source Catalog
Short Name:
WD1CXO
Date:
14 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
The nature of the X-ray point source population within the young massive cluster Westerlund 1 (Wd 1) is investigated. Chandra X-ray Observatory (CXO) observations were used to determine the X-ray properties of emitters within Wd 1, while a comprehensive multi-wavelength dataset was employed to constrain their nature. Wd 1 (l=339.5, b=-0.4) was observed with the CXO Advanced CCD Spectrometer Spectroscopic array on 2005 May 22 for 18 ks (sequence 6283) and 2005 June 20 for 42 ks (sequence 5411). 241 sources were found above a sensitivity threshold that corresponded to a 10<sup>-6</sup> chance per PSF element of detecting a spurious source. X-ray emission from a multitude of different stellar sources within Wd 1, including both evolved high mass and low-mass pre-MS stars, is found. This table was created by the HEASARC in May 2008 based on CDS table J/A+A/477/147 files table1.dat and table3.dat. This is a service provided by NASA HEASARC .
23942. Westerlund 2 JHKs photometry
ID:
ivo://CDS.VizieR/J/A+A/466/137
Title:
Westerlund 2 JHKs photometry
Short Name:
J/A+A/466/137
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photometry for the stars detected with SOFI, NTT in J, H and Ks in the field containing the massive cluster Westerlund 2 (also know as RCW 49) associated with the HII region Gum29. For each star detected in all three bands the table contains the ID, equatorial coordinates, J, H and Ks magnitude and photometric errors. For the stars detected only in Ks or in H and Ks the magnitude and photometric error fields in the absent bands are filled with the values 99.99 and 9.999 respectively.
23943. Westerlund 1 reduced images of radio emission
ID:
ivo://CDS.VizieR/J/A+A/632/A38
Title:
Westerlund 1 reduced images of radio emission
Short Name:
J/A+A/632/A38
Date:
21 Oct 2021
Publisher:
CDS
Description:
Massive stars and their stellar winds are important for a number of feedback processes. The mass lost in the stellar wind can help determine the end-point of the star as a neutron star (NS) or a black hole (BH). However, the impact of mass loss on the post-main sequence evolutionary stage of massive stars is not well understood. Westerlund 1 is an ideal astrophysical laboratory in which to study massive stars and their winds in great detail over a large range of different evolutionary phases. We aim to study the radio emission from Westerlund 1, in order to measure radio fluxes from the population of massive stars, and determine the mass-loss rates and spectral indices where possible. Observations were carried out in 2015 and 2016 with the Australia Telescope Compact Array (ATCA) at 5.5 and 9GHz using multiple configurations, with maximum baselines ranging from 750m to 6km. Thirty stars are detected in the radio from the fully concatenated dataset, ten of which are Wolf Rayet stars (WRs) (predominantly late type WN stars), five yellow hypergiants (YHGs), four red supergiants (RSGs), one luminous blue variable (LBV), the sgB[e] star W9, and several OB supergiants. New source detections in the radio are found for the WR stars, and five OB supergiants. These detections lead to evidence for three new OB supergiant binary candidates, which is inferred from derived spectral index limits. Spectral indices and index limits were determined for massive stars in Westerlund 1. For cluster members found to have partially optically thick emission, mass-loss rates were calculated. Under the approximation of a thermally emitting stellar wind and a steady mass-loss rate, clumping ratios were then estimated for eight WRs. Diffuse radio emission was detected throughout the cluster. Detections of knots of radio emission with no known counterparts indicate the highly clumped structure of this intra-cluster medium, likely shaped by a dense cluster wind.
23944. Westerlund 2 UBVIc photometry
ID:
ivo://CDS.VizieR/J/MNRAS/446/3797
Title:
Westerlund 2 UBVIc photometry
Short Name:
J/MNRAS/446/3797
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep UBVI_c_ photometric data of the young open cluster Westerlund 2. An abnormal reddening law of R_V,cl_=4.14+/-0.08 was found for the highly reddened early-type members (E(B-V)>=1.45), whereas a fairly normal reddening law of R_V,fg_=3.33+/-0.03 was confirmed for the foreground early-type stars (E(B-V)_fg_<1.05). The distance modulus was determined from zero-age main-sequence fitting to the reddening-corrected colour-magnitude diagram of the early-type members to be V_0_-M_V_=13.9+/-0.14 (random error) _-0.1_^+0.4^ (the upper limit of systematic error) mag (d=6.0+/-0.4_-0.3_^+1.2^kpc). To obtain te initial mass function, pre-main-sequence (PMS) stars were selected by identifying the optical counterparts of Chandra X-ray sources and mid-infrared emission stars from the Spitzer GLIMPSE (Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) source catalogue. The initial mass function shows a shallow slope of {Gamma}=-1.1+/-0.1 down to log(m)=0.7. The total mass of Westerlund 2 is estimated to be at least 7400M_{sun}_. The age of Westerlund 2 from the main-sequence turn-on and PMS stars is estimated to be <~1.5Myr. We confirmed the existence of a clump of PMS stars located ~1-arcmin north of the core of Westerlund 2, but we could not find any clear evidence for an age difference between the core and the northern clump.
23945. Western Magellanic Bridge HI observations
ID:
ivo://CDS.VizieR/J/MNRAS/339/105
Title:
Western Magellanic Bridge HI observations
Short Name:
J/MNRAS/339/105
Date:
21 Oct 2021
Publisher:
CDS
Description:
The 21-cm line emission from a 7x6deg^2^ region east of and adjoining the Small Magellanic Cloud (SMC) has been observed with the Australia Telescope Compact Array and the Parkes telescopes. This region represents the westernmost part of the Magellanic Bridge, a gas-rich tail extending ~14{deg} to the Large Magellanic Cloud. A rich and complex neutral hydrogen (HI) structure containing shells, bubbles and filaments is revealed. On the larger scale, the HI of the Bridge is organized into two velocity components. This bimodality, which appears to originate in the SMC, converges to a single velocity component within the observed region. A census of shell-like structures suggests a shell population with characteristics similar to that of the SMC.
23946. WFAU CEA Commandline
ID:
ivo://wfau.roe.ac.uk/cea-server
Title:
WFAU CEA Commandline
Date:
19 Mar 2008 13:49:03
Publisher:
WFAU
Description:
Applications deployed by WFAU.
23947. WFAU Community
ID:
ivo://wfau.roe.ac.uk/community
Title:
WFAU Community
Date:
24 Apr 2008 13:31:24
Publisher:
WFAU
Description:
This AstroGrid community is for users from the Univeristy of Edinburgh, as well as users from continental Europe who have requested AstroGrid access to UKIDSS data. It is also for those users who will be using UKIDSS heavily and would like to have their online data storage close to the actual database server.
23948. WFAU Publishing Registry
ID:
ivo://wfau.roe.ac.uk/org.astrogrid.registry.RegistryService
Title:
WFAU Publishing Registry
Date:
04 Nov 2024 11:01:54
Publisher:
Wide Field Astronomy Unit (WFAU)
Description:
WFAU Publishing registry
23949. WFCAM Variable Star Catalog
ID:
ivo://CDS.VizieR/J/A+A/573/A100
Title:
WFCAM Variable Star Catalog
Short Name:
J/A+A/573/A100
Date:
21 Oct 2021
Publisher:
CDS
Description:
Stellar variability in the near-infrared (NIR) remains largely unexplored. The exploitation of public science archives with data-mining methods offers a perspective for a time-domain exploration of the NIR sky. We perform a comprehensive search for stellar variability using the optical-NIR multiband photometric data in the public Calibration Database of the WFCAM Science Archive (WSA), with the aim of contributing to the general census of variable stars and of extending the current scarce inventory of accurate NIR light curves for a number of variable star classes.
23950. WFC3/UVIS quasar-stacked spectrum at z=~2.4
ID:
ivo://CDS.VizieR/J/MNRAS/449/4204
Title:
WFC3/UVIS quasar-stacked spectrum at z=~2.4
Short Name:
J/MNRAS/449/4204
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ionizing continuum from active galactic nuclei is fundamental for interpreting their broad emission lines and understanding their impact on the surrounding gas. Furthermore, it provides hints on how matter accretes on to supermassive black holes. Using Hubble Space Telescope's Wide Field Camera 3, we have constructed the first stacked ultraviolet (rest-frame wavelengths 600-2500{AA}) spectrum of 53 luminous quasars at z=~2.4, with a state-of-the-art correction for the intervening Lyman forest and Lyman continuum absorption. The continuum slope (f_{nu}_{prop.to}{nu}^{alpha}{nu}^) of the full sample shows a break at ~912{AA} with spectral index {alpha}_{nu}_=-0.61+/-0.01 at {lambda}>912{AA} and a softening at shorter wavelengths ({alpha}_{nu}_=-1.70+/-0.61 at {lambda}<=912{AA}). Our analysis proves that a proper intergalactic medium absorption correction is required to establish the intrinsic continuum emission of quasars. We interpret our average ultraviolet spectrum in the context of photoionization, accretion disc models, and quasar contribution to the ultraviolet background. We find that observed broad line ratios are consistent with those predicted assuming an ionizing slope of {alpha}_ion_=-2.0, similar to the observed ionizing spectrum in the same wavelength range. The continuum break and softening are consistent with accretion disc plus X-ray corona models when black hole spin is taken into account. Our spectral energy distribution yields a 30 per cent increase to previous estimates of the specific quasar emissivity, such that quasars may contribute significantly to the total specific Lyman limit emissivity estimated from the Ly{alpha} forest at z<3.2.

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