- ID:
- ivo://CDS.VizieR/J/ApJ/883/158
- Title:
- Dark molecular gas in the Galaxy II. Perseus arm
- Short Name:
- J/ApJ/883/158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results from a new, highly sensitive ({Delta}T_mb_~3mK) survey for thermal OH emission at 1665 and 1667MHz over a dense, 9x9pix grid covering a 1{deg}x1{deg} patch of sky in the direction of l=105.00{deg}, b=+2.50{deg} toward the Perseus spiral arm of our Galaxy. We compare our Green Bank Telescope 1667MHz OH results with archival ^12^CO(1-0) observations from the Five College Radio Astronomy Observatory Outer Galaxy Survey within the velocity range of the Perseus Arm at these galactic coordinates. Out of the 81 statistically independent pointings in our survey area, 86% show detectable OH emission at 1667MHz, and 19% of them show detectable CO emission. We explore the possible physical conditions of the observed features using a set of diffuse molecular cloud models. In the context of these models, both OH and CO disappear at current sensitivity limits below an A_v_ of 0.2, but the CO emission does not appear until the volume density exceeds 100-200cm^-3^. These results demonstrate that a combination of low column density A_v_ and low volume density n_H_ can explain the lack of CO emission along sight lines exhibiting OH emission. The 18cm OH main lines, with their low critical density of n*~1cm^-3^, are collisionally excited over a large fraction of the quiescent galactic environment and, for observations of sufficient sensitivity, provide an optically thin radio tracer for diffuse H_2_.
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Search Results
- ID:
- ivo://CDS.VizieR/VII/68A
- Title:
- Dark Nebulae and Globules for l=240-360deg
- Short Name:
- VII/68A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (adapted from Anne C. Raugh, NASA STI-T-1-5810-508-86) The catalog is a compilation of data gleened from a study of the European Southern Observatory Quick Blue Survey (ESO(b)) and SRC-J Sky Atlas on 489 dark clouds and 331 globules. The data compiled include position, size, opacity and morphological classification (in the system of van den Bergh, 1972). Also included is a FITS file containing a 500x1400 pixel map of the survey area.
- ID:
- ivo://CDS.VizieR/J/AJ/157/152
- Title:
- Dark spots on Neptune from 25 years of HST images
- Short Name:
- J/AJ/157/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We scoured the full set of blue-wavelength Hubble Space Telescope images of Neptune, finding one additional dark spot in new Hubble data beyond those discovered in 1989, 1994, 1996, and 2015. We report the complete disappearance of the SDS-2015 dark spot, using new Hubble data taken on 2018 September 9-10, as part of the Outer Planet Atmospheres Legacy (OPAL) program. Overall, dark spots in the full Hubble data set have lifetimes of at least one to two years, and no more than six years. We modeled a set of dark spots randomly distributed in time over the latitude range on Neptune that is visible from Earth, finding that the cadence of archival Hubble images would have detected about 70% of these spots if their lifetimes are only one year, or about 85%-95% of simulated spots with lifetimes of two or more years. Based on the Hubble data set, we conclude that dark spots have average occurrence rates of one dark spot every four to six years. Many numerical models to date have simulated much shorter vortex lifetimes, so our findings provide constraints that may lead to improved understanding of Neptune's wind field, stratification, and humidity.
- ID:
- ivo://CDS.VizieR/J/ApJ/915/19
- Title:
- Data and parameters for subgiant sample
- Short Name:
- J/ApJ/915/19
- Date:
- 02 Feb 2022 06:48:11
- Publisher:
- CDS
- Description:
- Given their location on the Hertzsprung-Russell (H-R) diagram, thoroughly characterized subgiant stars can place stringent constraints on a wide range of astrophysical problems. Accordingly, they are prime asteroseismic targets for the Transiting Exoplanet Survey Satellite (TESS) mission. In this work, we infer stellar properties for a sample of 347 subgiants located in the TESS Continuous Viewing Zones, which we select based on their likelihood of showing asteroseismic oscillations. We investigate how well they can be characterized using classical constraints (photometry, astrometry) and validate our results using spectroscopic values. We derive luminosities, effective temperatures, and radii with mean 1{sigma} random (systematic) uncertainties of 4.5% (2%), 33K (60K), and 2.2% (2%), as well as more model-dependent quantities such as surface gravities, masses, and ages. We use our sample to demonstrate that subgiants are ideal targets for mass and age determination based on H-R diagram location alone, discuss the advantages of stellar parameters derived from a detailed characterization over widely available catalogs, show that the generally used 3D extinction maps tend to overestimate the extinction for nearby stars (distance <=500pc), and find a correlation that supports the rotation-activity connection in post-main-sequence stars. The complementary roles played by classical and asteroseismic data sets will open a window to unprecedented astrophysical studies using subgiant stars.
- ID:
- ivo://CDS.VizieR/J/A+A/582/A68
- Title:
- Database of circumstellar OH masers
- Short Name:
- J/A+A/582/A68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new database of circumstellar OH masers at 1612, 1665, and 1667MHz in the Milky Way galaxy. The database (version 2.4) contains 13655 observations and 2341 different stars detected in at least one transition. Detections at 1612MHz are considered to be complete until the end of 2014 as long as they were published in refereed papers. Detections of the main lines (1665 and 1667MHz) and non-detections in all transitions are included only if published after 1983. The database contains flux densities and velocities of the two strongest maser peaks, the expansion velocity of the shell, and the radial velocity of the star. Links are provided for about 100 stars (<5% of all stars with OH masers) to interferometric observations and monitoring programs of the maser emission published since their beginnings in the 1970s. Access to the database is possible over the Web (www.hs.uni-hamburg.de/maserdb), allowing cone searches for individual sources and lists of sources. A general search is possible in selected regions of the sky and by defining ranges of flux densities and/or velocities. Alternative ways to access the data are via the German Virtual Observatory and the CDS.
- ID:
- ivo://CDS.VizieR/B/comets
- Title:
- Database of the orbital elements of comets
- Short Name:
- B/comets
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- comets.dat is an ASCII file of cometary orbital elements prepared at the "Institut de Mecanique Celeste et de Calcul des Ephemerides" (related to the Bureau des Longitudes, Paris). The research and computing needed to generate comets.dat are funded by the French Ministry of Education. The data can be freely used, provided that their origin (Bureau des longitudes) and the author (P. Rocher) are properly cited. User feed-back is encouraged. Unless otherwise specified, send comments and bug reports to: E-mail : stc@imcce.fr Fax : (33) 1 46 33 28 34 Postal mail : IMCCE - Observatoire de Paris 77 avenue Denfert Rochereau F-75014 PARIS
- ID:
- ivo://CDS.VizieR/J/A+A/550/A88
- Title:
- Data cubes of NGC 5253 (476-682nm)
- Short Name:
- J/A+A/550/A88
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Gemini-S/GMOS-IFU optical spectroscopy of four regions near the centre of the nearby (3.8Mpc) dwarf starburst galaxy NGC 5253.
- ID:
- ivo://CDS.VizieR/J/A+A/615/A158
- Title:
- Data cubes of observed species toward Messier 8
- Short Name:
- J/A+A/615/A158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Messier 8 (M8) is one of the brightest HII regions in the sky. We collected an extensive dataset comprising multiple submillimeter spectral lines from neutral and ionized carbon and from CO. Based on this dataset, we aim to understand the morphology of M8 and that of its associated photodissociation region (PDR) and to carry out a quantitative analysis of the physical conditions of these regions such as kinetic temperatures and volume densities. We used the Stratospheric Observatory For Infrared Astronomy (SOFIA), the Atacama Pathfinder Experiment (APEX) 12m, and the Institut de Radioastronomie Millimetrique (IRAM) 30m telescopes to perform a comprehensive imaging survey of the emission from the fine structure lines of CII and CI and multiple rotational transitions of carbon monoxide (CO) isotopologs within 1.3x1.3pc around the dominant Herschel 36 (Her 36) system, which is composed of at least three massive stars. To further explore the morphology of the region, we compared archival infrared, optical, and radio images of the nebula with our newly obtained fine structure line and CO data, and in particular with the velocity information these data provide. We performed a quantitative analysis, using both LTE and non-LTE methods to determine the abundances of some of the observed species, kinetic temperatures, and volume densities. Bright CO, CII and CI emission have been found toward the HII region and the PDR in M8. Our analysis places the bulk of the molecular material in the background of the nebulosity illuminated by the bright stellar systems Her 36 and 9 Sagitarii. Since the emission from all observed atomic and molecular tracers peaks at or close to the position of Her 36, we conclude that the star is still physically close to its natal dense cloud core and heats it. A veil of warm gas moves away from Her 36 toward the Sun and its associated dust contributes to the foreground extinction in the region. One of the most prominent star forming regions in M8, the Hourglass Nebula, is particularly bright due to cracks in this veil close to Her 36. We obtain H_2_ densities ranging from ~10^4^-10^6^cm^-3^ and kinetic temperatures of 100-150K in the bright PDR caused by Her 36 using radiative transfer modeling of various transitions of CO isotopologs.
- ID:
- ivo://CDS.VizieR/J/AJ/159/41
- Title:
- Data for ~550 exoplanets using a neural network
- Short Name:
- J/AJ/159/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While thousands of exoplanets have been confirmed, the known properties about individual discoveries remain sparse and depend on detection technique. To utilize more than a small section of the exoplanet data set, tools need to be developed to estimate missing values based on the known measurements. Here, we demonstrate the use of a neural network that models the density of planets in a space of six properties that is then used to impute a probability distribution for missing values. Our results focus on planetary mass, which neither the radial velocity nor transit techniques for planet identification can provide alone. The neural network can impute mass across the four orders of magnitude in the exoplanet archive, and return a distribution of masses for each planet that can inform us about trends in the underlying data set. The average error on this mass estimate from a radial velocity detection is a factor of 1.5 of the observed value, and 2.7 for a transit observation. The mass of Proxima Centauri b found by this method is 1.6_-0.36_^+0.46^M{Earth}, where the upper and lower bounds are derived from the root mean square deviation from the log mass probability distribution. The network can similarly impute the other potentially missing properties, and we use this to predict planet radius for radial velocity measurements, with an average error of a factor 1.4 of the observed value. The ability of neural networks to search for patterns in multidimensional data means that such techniques have the potential to greatly expand the use of the exoplanet catalog.
- ID:
- ivo://CDS.VizieR/V/51
- Title:
- Data Inventory of Space-Based Obs, Ver 1.1
- Short Name:
- V/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The "Data Inventory of Space-Based Celestial Observations Version 1.0" (DISCO) is a directory to data contained in sixteen catalogs dealing with observations from space. (Sounding rocket, solar, and planetary observations have been excluded.) The information extracted from the catalogs includes names of objects observed, 1950 equatorial coordinates, and the name of the catalog or instrument. A second file contains full references to the source catalogs and other pertinent information. The purpose of creating DISCO is (1) to unify astronomical observations from space, which are at present scattered and hard to locate, and then (2) to provide a machine-readable index to these observations, thus enabling easy access by computer. Such a directory will permit an astronomer to find out what objects have been observed from space, which spacecraft and instruments made the observations, and where to go to find the data themselves.