- ID:
- ivo://CDS.VizieR/J/A+A/35/393
- Title:
- Westerbork Second Deep Survey
- Short Name:
- J/A+A/35/393
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A radio survey has been made of an area centered at 01h 03min +29{deg}, using the Westerbork telescope at 1415MHz. The completeness limit of the survey is 7mJy. Additional observations have been made at 610MHz. The Lick 120" telescope has been used to obtain deep (O98-O2 emulsion) plates to serve as an optical counterpart. A catalogue is presented of 58 sources found in the survey. 53 of these comprise a complete sample. 31 sources of the complete sample lie in areas of which Lick plates were taken. Of the sources in Lick plates areas, 11 could be identified with galaxies and 3 with possible QSO's, yielding an identification percentage of 46. For the other 22 sources an identification programme was carried out using Palomar Sky Survey prints and other large 48" Schmidt plates: three of these sources could be identified with galaxies and two with possible QSO's. The survey was also used to derive source counts and a spectral index distribution. The source counts agree well with those derived for an earlier survey. The spectral index distribution has a mean of 0.52 and a width of 0.39. the explanation for the flatter spectra is not clear but might possibly lie in another source population that begins to dominate the results at low flux densities.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/VIII/64
- Title:
- Westerhout's Catalogue of 82 Discrete Sources
- Short Name:
- VIII/64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue was created based on the original published catalogue in the article by Westerhout G., 1958, Bull. Astron. Inst. Netherlands, vol.14, p.215, "A Survey of the Continuous Radiation from the Galactic System at a Frequency of 1390 Mc/s." His article describes the results of a survey of the radiation along the galactic ridge and a search for discrete sources. The observations were made with the 25-m radio telescope at Dwingeloo, which has a beamwidth of 0.57 degree at a frequency of 1390 Mc/s. The catalogue contains positions of 82 discrete sources. The epoch for positions in the original published catalogue was 1957.0. Positions referred to 2000.0 are shown in this machine-readable catalogue.
- 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 .
23374. 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.
- 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.
- 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.
- 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.
23378. 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.
- 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.
- ID:
- ivo://CDS.VizieR/J/A+A/470/281
- Title:
- WFI optical photometry in Cha II dark cloud
- Short Name:
- J/A+A/470/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an optical multi-band survey for low-mass pre-main sequence (PMS) stars and young brown dwarfs (BDs) in the Chamaeleon II (Cha II) dark cloud. This survey constitutes the complementary optical data to the c2d Spitzer Legacy survey in Cha II.
