- ID:
- ivo://CDS.VizieR/J/A+AS/136/81
- Title:
- A ROSAT PSPC X-Ray Survey of the SMC
- Short Name:
- J/A+AS/136/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a systematic search for point-like and moderately extended soft (0.1-2.4keV) X-ray sources in a raster of nine pointings covering a field of 8.95deg^2^ and performed with the ROSAT PSPC between October 1991 and October 1993 in the direction of the Small Magellanic Cloud (SMC). We detect 248 objects which we include in the first version of our SMC catalogue of soft X-ray sources. We set up seven source classes defined by selections in the count rate, hardness ratio and source extent. We find five high luminosity super-soft sources (1E 0035.4-7230, 1E 0056.8-7146, RX J0048.4-7332, RX J0058.6-7146 and RX J0103-7254), one low-luminosity super-soft source RX J0059.6-7138 correlating with the planetary nebula L357, 51 candidate hard X-ray binaries including eight bright hard X-ray binary candidates, 19 supernova remnants (SNRs), 19 candidate foreground stars and 53 candidate background active galactic nuclei (and quasars). We give a likely classification for ~60% of the catalogued sources. The total count rate of the detected point-like and moderately extended sources in our catalogue is 6.9+/-0.3s^-1, comparable to the background subtracted total rate from the integrated field of ~6.1+/-0.1s^-1.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/131/633
- Title:
- A ROSAT survey of contact binary stars
- Short Name:
- J/AJ/131/633
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Contact binary stars are common variable stars that are all believed to emit relatively large fluxes of X-rays. In this work we combine a large new sample of contact binary stars derived from the ROTSE-I telescope (Cat. <J/AJ/131/621>) with X-ray data from the ROSAT All Sky Survey (RASS, Cat. <IX/10>) to estimate the X-ray volume emissivity of contact binary stars in the Galaxy. We obtained X-ray fluxes for 140 contact binaries from the RASS, as well as two additional stars observed by the XMM-Newton observatory.
1093. Arp 2
- ID:
- ivo://CDS.VizieR/J/AJ/109/650
- Title:
- Arp 2
- Short Name:
- J/AJ/109/650
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained the first B,V CCD color-magnitude diagram (CMD) of the galactic globular cluster Arp 2. About 1600 stars have been measured between the tip of the red giant branch at V ~ 15.5 and V ~ 23.5, about two magnitudes below the main sequence turnoff. A centrally concentrated population of blue stragglers has been detected. The slope of the red giant branch and the overall CMD morphology are consistent with that of a metal-poor cluster, with [Fe/H] = 18.4+/-0.25. A preliminary spectroscopic measurement based on the Ca II triplet yields [Fe/H] = -1.73+/-0.05. The comparison of the CMD of Arp 2 with that of other clusters favors a value more metal-poor than that indicated by the Ca II triplet. In this respect, Arp 2 is similar to Ruprecht 106 [Buonanno et al. =1990AJ....100.1811B and =1993AJ....105..184B]. Differential ages between Arp 2 and a number of reference clusters are obtained from the vertical age parameter Delta V^TO_HB, and the horizontal age parameter, {Delta}(B-V)^TO_RGB. By requiring both age estimators to give consistent results, we find that Arp 2 is ~ 3 Gyr younger than the group of the metal-poor clusters and slightly older than Ruprecht 106. The detection of young metal-poor clusters ([Fe/H] <= -1.8) implies a complex scenario for the origin of the galactic halo, possibly involving interactions with satellite galaxies and their cluster systems.
- ID:
- ivo://CDS.VizieR/J/ApJ/799/10
- Title:
- Arp 220 6 and 33GHz images
- Short Name:
- J/ApJ/799/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new Karl G. Jansky Very Large Array radio continuum images of the nuclei of Arp 220, the nearest ultra-luminous infrared galaxy. These new images have both the angular resolution to study the detailed morphologies of the two nuclei that power the galaxy merger and sensitivity to a wide range of spatial scales. At 33GHz, we achieve a resolution of 0.081"x0.063" (29.9x23.3pc) and resolve the radio emission surrounding both nuclei. We conclude from the decomposition of the radio spectral energy distribution that a majority of the 33GHz emission is synchrotron radiation. The spatial distributions of radio emission in both nuclei are well described by exponential profiles. These have deconvolved half-light radii (R_50d_) of 51 and 35pc for the eastern and western nuclei, respectively, and they match the number density profile of radio supernovae observed with very long baseline interferometry. This similarity might be due to the fast cooling of cosmic rays electrons caused by the presence of a strong (~mG) magnetic field in this system. We estimate extremely high molecular gas surface densities of 2.2_-1.0_^+2.1^x10^5^M_{sun}_/pc^2^ (east) and 4.5_-1.9_^+4.5^x10^5^M_{sun}_/pc^2^ (west), corresponding to total hydrogen column densities of N_H_=2.7_-1.2_^+2.7^x10^25^cm^-2^ (east) and 5.6_-2.4_^+5.5^x10^25^cm^-2^ (west). The implied gas volume densities are similarly high, n_H2_~3.8_-1.6_^+3.8^x10^4^cm^-3^ (east) and ~11_-4.5_^+12^x10^4^cm^-3^ (west). We also estimate very high luminosity surface densities of {Sigma}_IR_~4.2_-0.7_^+1.6^x10^13^L_{sun}_/kpc^2^ (east) and {Sigma}_IR_ ~ 9.7_-2.4_^+3.7^x10^13^_L_{sun}/kpc^2^ (west), and star formation rate surface densities of {Sigma}_SFR_~10^3.7+/-0.1^M_{sun}_/yr/kpc^2^ (east) and {Sigma}_SFR_~10^4.1+/-0.1^M_{sun}_/yr/kpc^2^ (west). These values, especially for the western nucleus are, to our knowledge, the highest luminosity surface densities and star formation rate surface densities measured for any star-forming system. Despite these high values, the nuclei appear to lie below the dusty Eddington limit in which radiation pressure is balanced only by self-gravity. The small measured sizes also imply that at wavelengths shorter than {lambda}=1mm, dust absorption effects must play an important role in the observed light distribution while below 5GHz free-free absorption contributes substantial opacity. According to these calculations, the nuclei of Arp 220 are only transparent in the frequency range ~5-350GHz. Our results offer no clear evidence that an active galactic nucleus dominates the emission from either nucleus at 33GHz.
- ID:
- ivo://CDS.VizieR/J/AJ/136/614
- Title:
- Arp 2 and Ter 8 red giants equivalent widths
- Short Name:
- J/AJ/136/614
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To compare the globular clusters (GCs) associated with the Sagittarius Galaxy (Sgr) we report the results obtained from new high-resolution spectra of red giant stars in Terzan 8 and Arp 2, collected with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph at Las Campanas Observatory.
- ID:
- ivo://CDS.VizieR/J/A+A/559/A10
- Title:
- Arp 102B spectral optical monitoring
- Short Name:
- J/A+A/559/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of long-term (1987-2010) optical spectral monitoring of the broad-line radio galaxy Arp 102B, a prototype of an active galactic nucleus with double-peaked broad emission lines that are commonly assumed to be emitted from an accretion disk. To explore the structure of the broad-line region (BLR), we analyze the light-curves of the broad H{alpha} and H{beta} lines and the continuum flux. We aim to estimate the dimensions of the broad-line emitting regions and the mass of the central black hole. We used the cross correlation function to find lags between the lines and continuum variations. We investigated the correlation between line and continuum fluxes in more detail, and explored periodical variations of the red-to-blue line flux ratio using Lomb-Scargle periodograms.
- ID:
- ivo://CDS.VizieR/J/A+A/621/A25
- Title:
- Arp 240 Fabry-Perot interferometry
- Short Name:
- J/A+A/621/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Encounters between galaxies modify their morphology, kinematics, and star formation history. The relation between these changes and external perturbations is not straightforward. The great number of parameters involved requires both the study of large samples and individual encounters where particular features, motions, and perturbations can be traced and analysed in detail. We analysed the morphology, kinematics, and dynamics of two luminous infrared spiral galaxies of almost equal mass, NGC 5257 and NGC 5258, in which star formation is mostly confined to the spiral arms, in order to understand interactions between galaxies of equivalent masses and star-forming processes during the encounter. Using scanning Fabry-Perot interferometry, we studied the contribution of circular and non-circular motions and the response of the ionized gas to external perturbations. We compared the kinematics with direct images of the pair and traced the star-forming processes and gravitational effects due to the presence of the other galaxy. The spectral energy distribution of each member of the pair was fitted. A mass model was fitted to the rotation curve of each galaxy. Large, non-circular motions detected in both galaxies are associated with a bar, spiral arms, and HII regions for the inner parts of the galaxies, and with the tidal interaction for the outer parts of the discs. Bifurcations in the rotation curves indicate that the galaxies have recently undergone their pericentric passage. The pattern speed of a perturbation of one of the galaxies is computed. Location of a possible corotation seems to indicate that the gravitational response of the ionized gas in the outer parts of the disc is related to the regions where ongoing star formation is confined. The spectral energy distribution (SED) fit indicates a slightly different star formation history for each member of the pair. For both galaxies, a pseudo-isothermal halo better fits the global mass distribution.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A25
- Title:
- Arp 220 HCN and HCO^+^ data cubes
- Short Name:
- J/A+A/590/A25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The origin of the enormous luminosities of the two opaque nuclei of Arp 220, the prototypical ultra-luminous infrared galaxy, remains a mystery because we lack observational tools to explore the innermost regions around the nuclei. We explore the potential of imaging vibrationally excited molecular emission at high angular resolution to better understand the morphology and physical structure of the dense gas in Arp 220 and to gain insight into the nature of the nuclear powering sources. The Atacama Large Millimeter/submillimeter Array (ALMA) provided simultaneous observations of HCN, HCO^+^, and vibrationally excited HCN v_2_=1f emission. Their J=4-3 and 3-2 transitions were observed at a matching resolution of ~0.5", which allows us to isolate the emission from the two nuclei.
- ID:
- ivo://CDS.VizieR/J/A+A/593/A86
- Title:
- Arp 220 LOFAR radio images at 150MHz
- Short Name:
- J/A+A/593/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse new observations with the International Low Frequency Array (LOFAR) telescope, and archival data from the Multi-Element Radio Linked Interferometer Network (MERLIN) and the Karl G. Jansky Very Large Array (VLA). We model the spatially resolved radio spectrum of Arp 220 from 150MHz to 33GHz. We present an image of Arp 220 at 150MHz with resolution 0.65"x0.35", sensitivity 0.15mJy/beam, and integrated flux density 394+/-59mJy. More than 80% of the detected flux comes from extended (6"~2.2kpc) steep spectrum (alpha=-0.7) emission, likely from star formation in the molecular disk surrounding the two nuclei. We find elongated features extending 0.3" (110pc) and 0.9" (330pc) from the eastern and western nucleus respectively, which we interpret as evidence for outflows. The extent of radio emission requires acceleration of cosmic rays far outside the nuclei. We find that a simple three component model can explain most of the observed radio spectrum of the galaxy. When accounting for absorption at 1.4GHz, Arp 220 follows the FIR/radio correlation with q=2.36, and we estimate a star formation rate of 220M_{sun}_/yr. We derive thermal fractions at 1GHz of less than 1% for the nuclei, which indicates that a major part of the UV-photons are absorbed by dust. International LOFAR observations shows great promise to detect steep spectrum outflows and probe regions of thermal absorption. However, in LIRGs the emission detected at 150MHz does not necessarily come from the main regions of star formation. This implies that high spatial resolution is crucial for accurate estimates of star formation rates for such galaxies at 150MHz.
1100. Arp's Peculiar Galaxies
- ID:
- ivo://CDS.VizieR/VII/192
- Title:
- Arp's Peculiar Galaxies
- Short Name:
- VII/192
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Halton C. Arp photographed 338 views of notable peculiar galaxies and published them as his 1966 "Atlas of Peculiar Galaxies." Since then, galaxy catalogs have named 585 of the involved galaxies. This contemporary index collects names and characteristics of the involved objects for use by contemporary observers of the historical views.
