Number of results to display per page
Search Results
22202. THOR DR2 source list
- ID:
- ivo://CDS.VizieR/J/A+A/634/A83
- Title:
- THOR DR2 source list
- Short Name:
- J/A+A/634/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic plane has been observed extensively by a large number of Galactic plane surveys from infrared to radio wavelengths at an angular resolution below 40". However, a 21cm line and continuum survey with comparable spatial resolution is lacking. The first half of THOR data (l=14.0{deg}-37.9{deg}, and l=47.1{deg}-51.2{deg}, |b|<=1.25{deg}) has been published in our data release 1 paper. With this data release 2 paper, we publish all the remaining spectral line data and Stokes I continuum data with high angular resolution (10"-40"), including a new HI dataset for the whole THOR survey region (l=14.0{deg}-67.4{deg} and |b|<=1.25{deg}). As we published the results of OH lines and continuum emission elsewhere, we concentrate on the HI analysis in this paper With the Karl G. Jansky Very Large Array (VLA) in C-configuration, we observed a large portion of the first Galactic quadrant, achieving an angular resolution of 40". At L Band, the WIDAR correlator at the VLA was set to cover the 21cm HI line, four OH transitions, a series of Hn{alpha} radio recombination lines (RRLs; n=151 to 186), and eight 128MHz-wide continuum spectral windows (SPWs), simultaneously. We publish all OH and RRL data from the C-configuration observations, and a new HI dataset combining VLA C+D+GBT (VLA D-configuration and GBT data are from the VLA Galactic Plane Survey) for the whole survey. The HI emission shows clear filamentary substructures at negative velocities with low velocity crowding. The emission at positive velocities is more smeared-out, likely due to higher spatial and velocity crowding of structures at the positive velocities. Compared to the spiral arm model of the Milky Way, the atomic gas follows the Sagittarius and Perseus Arm well, but with significant material in the inter-arm regions. With the C-configuration-only HI+continuum data, we produced a HI optical depth map of the THOR areal coverage from 228 absorption spectra with the nearest-neighbor method. With this map, we corrected the HI emission for optical depth, and the derived column density is 38% higher than the column density with optically thin assumption. The total HI mass with optical depth correction in the survey region is 4.7x10^8^M_{sun}_, 31% more than the mass derived assuming the emission is optically thin. If we applied this 31% correction to the whole Milky Way, the total atomic gas mass would be 9.4-10.5x10^9^M_{sun}_. Comparing the HI with existing CO data, we find a significant increase in the atomic-to-molecular gas ratio from the spiral arms to the inter-arm regions. The high-sensitivity and resolution THOR HI dataset provides an important new window on the physical and kinematic properties of gas in the inner Galaxy. Although the optical depth we derive is a lower limit, our study shows that the optical depth correction is significant for Hi column density and mass estimation. Together with the OH, RRL and continuum emission from the THOR survey, these new HI data provide the basis for high-angular-resolution studies of the interstellar medium (ISM) in different phases.
- ID:
- ivo://CDS.VizieR/J/A+A/468/1115
- Title:
- Thorium and argon lines in the visible
- Short Name:
- J/A+A/468/1115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new list of thorium and argon emission lines in the visible obtained by analyzing high-resolution (R=110000) spectra of a ThAr hollow cathode lamp. The aim of this new line list is to allow significant improvements in the quality of wavelength calibration for medium- to high-resolution astronomical spectrographs. We use a series of ThAr lamp exposures obtained with the HARPS instrument (High Accuracy Radial-velocity Planet Searcher) to detect previously unknown lines, perform a systematic search for blended lines and correct individual wavelengths by determining the systematic offset of each line relative to the average wavelength solution.
22204. Thorium line list
- ID:
- ivo://CDS.VizieR/J/A+A/648/A103
- Title:
- Thorium line list
- Short Name:
- J/A+A/648/A103
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The solar telescope connected to HARPS-N has observed the Sun since the summer of 2015. Such high-cadence, longbaseline data set is crucial for understanding spurious radial-velocity signals induced by our Sun and by the instrument. Aims. This manuscript describes the data reduction performed to obtain unprecedented radial-velocity precision for the three years of solar data released along with this paper. The nearly continuous observation of our Sun has allowed us to detect sub-m/s systematics in the HARPS-N solar data reduced by the current data reduction software. To improve the radial-velocity precision of the solar data, we reduced them using the new ESPRESSO data reduction software and developed new recipes to mitigate the detected systematics. The most significant improvement brought by the new data reduction is a strong decrease in the day-to-day radial-velocity scatter, from 1.28 to 1.09m/s; this is thanks to a more stable method to derive wavelength solutions, but also to the use of calibrations closer in time. We also demonstrate that the current HARPS-N data reduction software induces a long-term drift of 1.2m/s, due to the use of non-stable thorium lines. As a result, the old solar RVs are weakly correlated to the solar magnetic cycle, which is not expected. On the contrary, the newly derived radial velocities are much more correlated, with a Pearson correlation coefficient of 0.93. We also discuss a special correction for ghost contamination, to extract a calcium activity index free from instrumental systematics. Our work leads toward a better understanding of the instrumental and data reduction systematics affecting the HARPSN spectrograph. The new solar data released, representing an unprecedented time-series of 34550 high-resolution spectra and precise radial velocities will be crucial to understanding stellar activity signals of solar-type stars, with the goal of enabling the detection of other Earths.
- ID:
- ivo://CDS.VizieR/J/ApJS/211/4
- Title:
- Thorium spectrum from 250nm to 5500nm
- Short Name:
- J/ApJS/211/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have made precise observations of a thorium-argon hollow cathode lamp emission spectrum in the region between 350nm and 1175nm using a high-resolution Fourier transform spectrometer. Our measurements are combined with results from seven previously published thorium line lists to re-optimize the energy levels of neutral, singly, and doubly ionized thorium (Th I, Th II, and Th III). Using the optimized level values, we calculate accurate Ritz wavelengths for 19874 thorium lines between 250nm and 5500nm (40000/cm to 1800/cm). We have also found 102 new thorium energy levels. A systematic analysis of previous measurements in light of our new results allows us to identify and propose corrections for systematic errors in Palmer & Engleman (1983ats..book.....P) and typographical errors and incorrect classifications in Kerber et al. (2008ApJS..178..374K). We also found a large scatter with respect to the thorium line list of Lovis & Pepe (Cat. J/A+A/468/1115). We anticipate that our Ritz wavelengths will lead to improved measurement accuracy for current and future spectrographs that make use of thorium-argon or thorium-neon lamps as calibration standards.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A124
- Title:
- THOR survey in northern Galactic plane
- Short Name:
- J/A+A/619/A124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Radio continuum surveys of the Galactic plane can find and characterize HII regions, supernova remnants (SNRs), planetary nebulae (PNe), and extragalactic sources. A number of surveys at high angular resolution (<~25") at different wavelengths exist to study the interstellar medium (ISM), but no comparable high-resolution and high-sensitivity survey exists at long radio wavelengths around 21cm. Our goal is to investigate the 21cm radio continuum emission in the northern Galactic plane at <25" resolution. We observed a large fraction of the Galactic plane in the first quadrant of the Milky Way (l=14.0{deg}-67.4{deg} and |b|<=1.25{deg}) with the Karl G. Jansky Very Large Array (VLA) in the C-configuration covering six continuum spectral windows. These data provide a detailed view on the compact as well as extended radio emission of our Galaxy and thousands of extragalactic background sources. We used the BLOBCAT software and extracted 10916 sources. After removing spurious source detections caused by the sidelobes of the synthesised beam, we classified 10387 sources as reliable detections.We smoothed the images to a common resolution of 25" and extracted the peak flux density of each source in each spectral window (SPW) to determine the spectral indices {alpha} (assuming I(nu){prop.to}nu^alpha^). By cross-matching with catalogs of HII regions, SNRs, PNe, and pulsars, we found radio counterparts for 840 HII regions, 52 SNRs, 164 PNe, and 38 pulsars. We found 79 continuum sources that are associated with X-ray sources. We identified 699 ultrasteep spectral sources (alpha<-1.3) that could be high-redshift galaxies. Around 9000 of the sources we extracted are not classified specifically, but based on their spatial and spectral distribution, a large fraction of them is likely to be extragalactic background sources. More than 7750 sources do not have counterparts in the SIMBAD database, and more than 3760 sources do not have counterparts in the NED database. Studying the long wavelengths cm continuum emission and the associated spectral indices allows us to characterize a large fraction of Galactic and extragalactic radio sources in the area of the northern inner Milky Way. This database will be extremely useful for future studies of a diverse set of astrophysical objects.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A112
- Title:
- THOR. The HI, OH, Recombination Line Survey
- Short Name:
- J/A+A/580/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To study the atomic, molecular and ionized emission of Giant Molecular Clouds (GMCs), we have initiated a Large Program with the VLA: 'THOR - The HI, OH, Recombination Line survey of the Milky Way'. We map the 21cm HI line, 4 OH lines, 19 H{alpha} recombination lines and the continuum from 1 to 2GHz of a significant fraction of the Milky Way (l=15-67{deg}, |b|<1{deg}) at ~20" resolution. In this paper, we focus on the HI emission from the W43 star-formation complex. Classically, the HI 21cm line is treated as optically thin with column densities calculated under this assumption. This might give reasonable results for regions of low-mass star-formation, however, it is not sufficient to describe GMCs. We analyzed strong continuum sources to measure the optical depth, and thus correct the HI 21cm emission for optical depth effects and weak diffuse continuum emission. Hence, we are able to measure the HI mass of W43 more accurately and our analysis reveals a lower limit of M=6.6x10^6^M_{sun}_, which is a factor of 2.4 larger than the mass estimated with the assumption of optically thin emission. The HI column densities are as high as N(HI)~150M_{sun}_/pc^2^~1.9x10^22cm^-2^, which is an order of magnitude higher than for low mass star formation regions. This result challenges theoretical models that predict a threshold for the HI column density of ~10M_{sun}_/pc^2^, at which the formation of molecular hydrogen should set in. By assuming an elliptical layered structure for W43, we estimate the particle density profiles. While at the cloud edge atomic and molecular hydrogen are well mixed, the center of the cloud is strongly dominated by molecular hydrogen. We do not identify a sharp transition between hydrogen in atomic and molecular form. Our results are an important characterization of the atomic to molecular hydrogen transition in an extreme environment and challenges current theoretical models.
- ID:
- ivo://CDS.VizieR/J/AJ/158/185
- Title:
- Three binary systems in the Large Magellanic Cloud
- Short Name:
- J/AJ/158/185
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the physical properties and apsidal motion elements of three eccentric eclipsing binaries in the Large Magellanic Cloud. The time-series photometric observations were carried out for a total of 41 nights between 2018 November and 2019 February using the KMTNet 1.6 m telescopes installed in South Africa and Australia. The radial velocities of binary components were measured using about 15 spectra per system collected from the ESO Science Archive Facility, which were observed with the Very Large Telescope 8.2 m telescope. The effective temperatures of the more massive binary components were determined to be 19000+/-500 K for OGLE-LMC-ECL-05797, 17000+/-500 K for OGLE-LMC-ECL-05861, and 19000+/-500 K for OGLE-LMC-ECL-06510 by comparing the observed spectra and the stellar atmosphere models obtained from the BOSZ spectral library. The absolute dimensions of each system were derived by analyzing the radial velocity curves together with the light curves obtained from the KMTNet, OGLE, and MACHO observations during about three decades. For the apsidal motion study, new eclipse timings were derived from the KMTNet and survey photometry. The apsidal motion elements of the three binaries were determined from both light curve and eclipse timing analysis. The periods of apsidal motion were 67+/-2 yr for OGLE-LMC-ECL-05797, 124+/-6 yr for OGLE-LMC-ECL-05861, and 39+/-1 yr for OGLE-LMC-ECL-06510 and their internal structure constants (ISCs) were log k_2,obs_=-2.3+/-0.1, -2.4+/-0.1, and -2.1+/-0.1 in the same order. The observed ISCs of OGLE-LMC-ECL-05797 and OGLE-LMC-ECL-05861 showed a good match to the theoretical ISC values, while the value of OGLE- LMC-ECL-06510 was somewhat larger than the theoretical one.
- ID:
- ivo://CDS.VizieR/J/A+A/541/A121
- Title:
- Three conformers of n-butyl cyanide
- Short Name:
- J/A+A/541/A121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The saturated n-propyl cyanide has recently been detected in Sagittarius B2(N). The next larger unbranched alkyl cyanide is n-butyl cyanide. We want to provide accurate rest frequency predictions beyond the millimeter wave range to search for this molecule in the Galactic center source Sagittarius B2(N) and facilitate its detection in space. The laboratory rotational spectrum of n-butyl cyanide has been investigated between 75 and 348GHz. We have searched for emission lines caused by the molecule in our sensitive IRAM 30m molecular line survey of Sagittarius B2(N). More than one thousand rotational transitions have been identified in the laboratory for each of the three conformers for which limited data had been obtained previously in a molecular beam microwave study. The quantum number range has been greatly extended to J~120 or more and Ka>35, resulting in accurate spectroscopic parameters and accurate rest frequency calculations up to about 500GHz for strong to moderately weak transitions of the two lower energy conformers. Upper limits of the column densities of N<=3x10^15^cm^-2^ and 8x10^15^cm^-2^ were derived towards Sagittarius B2(N) for the two lower energy conformers, anti-anti and gauche-anti, respectively. The present data will be helpful to identify n-butyl cyanide at millimeter or longer wavelengths with radio telescope arrays such as ALMA, NOEMA, or EVLA. In particular, its detection in Sagittarius B2(N) with ALMA seems feasible.
- ID:
- ivo://CDS.VizieR/J/MNRAS/483/5508
- Title:
- Three new Galactic star clusters
- Short Name:
- J/MNRAS/483/5508
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the serendipitous discovery of three new open clusters, named UFMG 1, UFMG 2 and UFMG 3 in the field of the intermediate-age cluster NGC 5999, by using Gaia DR2 data. A colour-magnitude filter tailored for a proper selection of main-sequence stars and red clump giants turned evident the presence of NGC 5999 and these three new stellar groups in proper motion space. Their structural parameters were derived from King-profile fittings over their projected stellar distributions and isochrone fits were performed on the clusters cleaned colour-magnitude diagrams built with Gaia bands to derive their astrophysical parameters. The clusters projected sky motion were calculated for each target using our members selection. Distances to the clusters were inferred from stellar parallaxes through a bayesian model, showing that they are marginally consistent with their isochronal distances , considering the random and systematic uncertainties involved. The new clusters are located in the nearby Sagittarius arm (d~1.5kpc) with NGC 5999 at the background (d~1.8kpc). They contain at least a few hundred stars of nearly solar metallicity and have ages between 100 and 1400Myr.
![To the extent possible under law, the publisher has waived all copyright and related or neighboring rights to GAVO's ADQL course. For details, see the `Creative Commons CC0 1.0 Public Domain dedication <http://creativecommons.org/publicdomain/zero/1.0/>`_. Of course, you should still give proper credit when using this data as required by good scientific practice. .. image:: /static/img/cc0.png :alt: [CC0]](/registry-search/?f%5Brights_facet%5D%5B%5D=To+the+extent+possible+under+law%2C+the+publisher+has+waived+all+copyright+and+related+or+neighboring+rights+to+GAVO%27s+ADQL+course.++For+details%2C+see+the+%60Creative+Commons+CC0+1.0+Public+Domain+dedication+%3Chttp%3A%2F%2Fcreativecommons.org%2Fpublicdomain%2Fzero%2F1.0%2F%3E%60_.++Of+course%2C+you+should+still+give+proper+credit+when+using+this+data+as+required+by+good+scientific+practice.%0A%0A..+image%3A%3A+%2Fstatic%2Fimg%2Fcc0.png%0A+++%3Aalt%3A+%5BCC0%5D%0A%0A&f%5BvalidationLevel_facet%5D%5B%5D=2){kind=link}