- ID:
- ivo://CDS.VizieR/J/ApJ/699/453
- Title:
- Determination of black hole masses
- Short Name:
- J/ApJ/699/453
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of correlations between X-ray spectral and timing properties observed from a number of Galactic black hole (BH) binaries during hard-soft state spectral evolution. We analyze 17 transition episodes from eight BH sources observed with Rossi X-Ray Timing Explorer. Our scaling technique for BH mass determination uses a correlation between the spectral index and quasi-periodic oscillation (QPO) frequency. In addition, we use a correlation between the index and the normalization of the disk "seed" component to cross-check the BH mass determination and estimate the distance to the source. We use GRO J1655-40 as a primary reference source for which the BH mass, distance, and inclination angle are evaluated by dynamical measurements with unprecedented precision among other Galactic BH sources. We apply our scaling technique to determine BH masses and distances for Cygnus X-1, GX 339-4, 4U 1543-47, XTE J1550-564, XTE J1650-500, H 1743-322, and XTE J1859-226. A good agreement of our results for sources with known values of BH masses and distance provides independent verification for our scaling technique.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/645/A7
- Title:
- Determining true mass of RV exoplanets with Gaia
- Short Name:
- J/A+A/645/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mass is one of the most important parameters for determining the true nature of an astronomical object. Yet, many published exoplan- ets lack a measurement of their true mass, in particular those detected as a result of radial-velocity (RV) variations of their host star. For those examples, only the minimum mass, or msini, is known, owing to the insensitivity of RVs to the inclination of the detected orbit compared to the plane of the sky. The mass that is given in databases is generally that of an assumed edge-on system (~90{deg}), but many other inclinations are possible, even extreme values closer to 0{deg} (face-on). In such a case, the mass of the published object could be strongly underestimated by up to two orders of magnitude. In the present study, we use GASTON, a recently developed tool taking advantage of the voluminous Gaia astrometric database to constrain the inclination and true mass of several hundreds of published exoplanet candidates. We find 9 exoplanet candidates in the stellar or brown dwarf (BD) domain, among which 6 were never characterized. We show that 30 Ari B b, HD 141937 b, HD 148427 b, HD 6718 b, HIP 65891 b, and HD 16760 b have masses larger than 13.5 M_J_ at 3{sigma}. We also confirm the planetary nature of 27 exoplanets, including HD 10180 c, d and g. Studying the orbital periods, eccentricities, and host-star metallicities in the BD domain, we found distributions with respect to true masses consistent with other publications. The distribution of orbital periods shows of a void of BD detections below ~100d, while eccentricity and metallicity distributions agree with a transition between BDs similar to planets and BDs similar to stars in the range 40-50M_J_.
- ID:
- ivo://CDS.VizieR/J/A+A/493/565
- Title:
- Deuterated and ^15^N ethyl cyanides
- Short Name:
- J/A+A/493/565
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ethyl cyanide is an abundant molecule in hot molecular clouds. Its rotational spectrum is very dense and several hundreds of rotational transitions within the ground state have been identified in molecular clouds in the 40-900GHz frequency range. Lines from ^13^C isotopically substituted ethyl cyanide have been recently identified in Orion. To enable the search and the possible detection of other isotopologues of ethyl cyanide in interstellar objects we have studied the rotational spectrum of deuterated ethyl cyanide: CH_2_DCH_2_CN (in-plane and out-of-plane) and CH_3_CHDCN and the spectrum of ^15^N substituted ethyl cyanide CH_2_DCH_2_C^15^N. The rotational spectrum of these species in the ground state was measured in the microwave and millimeter-submillimeter wavelength range using waveguide Fourier transform spectrometers (4-40GHz) and a source-modulated spectrometer employing backward-wave oscillators (BWOs) (150-260 and 580-660GHz). More than 300 lines were identified for each species for J values up to 71-80 and K_a_ values up to 28-31 depending on the isotopologues. The experimental spectra were analysed using a Watson's Hamiltonian using A-reduction in I^r^ representation. From the fitting procedure, accurate spectroscopic constants were derived for each species. These new sets of spectroscopic constants enable us to compute reliable prediction of the rotational spectrum (lines frequency and intensity) in the 4-1000GHz frequency range and for J and K_a_ up to 80 and 31, respectively. This experimental study allowed us to detect for the first time ^15^N substituted ethyl cyanide CH_2_DCH_2_C^15^N in Orion. The derived column density and rotational temperature are 10^13^cm^-2^ and 150K for the plateau and 3x10^14^cm^-2^ and 300K for the hot core. The deuterated species were search for but are not detected. The upper limit on the column density of each deuterated isotopologues is 10^14^cm^-2^.
- ID:
- ivo://CDS.VizieR/J/ApJ/737/44
- Title:
- Deuterated chemistry of the early universe
- Short Name:
- J/ApJ/737/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A comprehensive chemistry of the highly deuterated species D_2_, D^+^_2_, D_2_H^+^, and D^+^_3_ in the early universe is presented. Fractional abundances for each are calculated as a function of redshift z in the recombination era. The abundances of the isotopologues are found to display similar behavior. Fractionation enhances the abundances of most of the more highly deuterated species as the redshift decreases due to the closing of some reaction channels as the gas temperature cools. Rate coefficients for the majority of the reactions involving the deuterated species are uncertain resulting in a corresponding uncertainty in their predicted abundances.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A36
- Title:
- Deuterated water in prestellar cores
- Short Name:
- J/A+A/585/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on new APEX observations of the ground state 1_0,1_-0_0,0_ HDO transition at 464.92452GHz toward the prestellar core L1544. The line is undetected and we present an extensive study on the conditions for its detectability in cold and dense cloud cores. The water and deuterated water abundances have been estimated using an advanced chemical model simplified for the limited number of reactions or processes that are active in cold regions (<15K). We use the LIME radiative transfer code to compute the expected intensity and profile of both H_2_O and HDO lines and compare them with the observations. We present several ad hoc profiles that best-fit the observations and compare the profiles with results from an astrochemical modeling, coupling gas phase and grain surface chemistry. Our comparison between observations, radiative transfer and chemical modeling shows the limits of detectability for singly deuterated water with single-dish telescopes as well as interferometric observations.
- ID:
- ivo://CDS.VizieR/J/A+A/575/A87
- Title:
- Deuteration in massive star formation process
- Short Name:
- J/A+A/575/A87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An ever growing number of observational and theoretical evidence suggests that the deuterated fraction (column density ratio between a species containing D and its hydrogenated counterpart, Dfrac) is an evolutionary indicator both in the low- and the high-mass star formation process. However, the role of surface chemistry in these studies has not been quantified from an observational point of view. In order to compare how the deuterated fractions of species formed only in the gas and partially or uniquely on grain surfaces evolve with time, we observed rotational transitions of CH_3_OH, ^13^CH_3_OH, CH_2_DOH, CH_3_OD at 3 and 1.3mm, and of NH_2_D at 3mm with the IRAM-30m telescope, and the inversion transitions (1,1) and (2,2) of NH_3_ with the GBT, towards most of the cores already observed by Fontani et al. (2011A&A...529L...7F, 2014MNRAS.440..448F) in N_2_H^+^, N_2_D^+^, HNC, DNC. NH_2_D is detected in all but two cores, regardless of the evolutionary stage. Dfrac(NH_3_) is on average above 0.1, and does not change significantly from the earliest to the most evolved phases, although the highest average value is found in the protostellar phase (~0.3). Few lines of CH_2_DOH and CH_3_OD are clearly detected, and only towards protostellar cores or externally heated starless cores. This work clearly confirms an expected different evolutionary trend of the species formed exclusively in the gas (N_2_D^+^ and N_2_H^+^) and those formed partially (NH_2_D and NH_3_) or totally (CH_2_DOH and CH_3_OH) on grain mantles. The study also reinforces the idea that Dfrac(N_2_H^+^) is the best tracer of massive starless cores, while high values of Dfrac(CH_3_OH) seem rather good tracers of the early protostellar phases, at which the evaporation/sputtering of the grain mantles is most efficient.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/2907
- Title:
- 3D extinction map of northern Galactic plane
- Short Name:
- J/MNRAS/443/2907
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a three dimensional map of extinction in the Northern Galactic Plane derived using photometry from the IPHAS survey. We construct the map using a method based on a hierarchical Bayesian model as previously described by Sale (2012MNRAS.427.2119S). In addition to mean extinction, we also measure differential extinction, which arises from the fractal nature of the ISM. The method applied also furnishes us with photometric estimates of the distance, extinction, effective temperature, surface gravity, and mass for ~38 million stars. Further details about the data as well as additional formats and data products are available via http://www.iphas.org/extinction.
4388. 6dF-DR2 Galaxy Survey
- ID:
- ivo://CDS.VizieR/VII/249
- Title:
- 6dF-DR2 Galaxy Survey
- Short Name:
- VII/249
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 6dF Galaxy Survey is measuring around 150000 redshifts and 15000 peculiar velocities from galaxies over the southern sky at |b|>10{deg}. When complete, it will be the largest survey of its kind by more than an order of magnitude. A total of 83014 sources now have their spectra, redshifts, and near-infrared and optical photometry available online and searchable through an Structured Query Language at www.wfau.roe.ac.uk/6dFGS/ .
- ID:
- ivo://CDS.VizieR/J/MNRAS/329/87
- Title:
- 2dF Galaxy Redshift Survey: galaxy clusters
- Short Name:
- J/MNRAS/329/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a study of known clusters within the 2dF Galaxy Redshift Survey (2dFGRS, Cat. <VII/226>) observed areas and have identified 431 Abell, 173 APM and 343 EDCC clusters. Precise redshifts, velocity dispersions and new centroids have been measured for the majority of these objects, and this information is used to study the completeness of these catalogues, the level of contamination from foreground and background structures along the cluster's line of sight, the space density of the clusters as a function of redshift, and their velocity dispersion distributions. We find that the Abell and EDCC catalogues are contaminated at the level of about 10 per cent, whereas the APM catalogue suffers only 5 per cent contamination. If we use the original catalogue centroids, the level of contamination rises to approximately 15 per cent for the Abell and EDCC catalogues, showing that the presence of foreground and background groups may alter the richness of clusters in these catalogues. There is a deficiency of clusters at z~0.05 hat may correspond to a large underdensity in the Southern hemisphere. From the cumulative distribution of velocity dispersions for these clusters, we derive a space density of {sigma}>1000km/s clusters of 3.6x10^-6^h^3^/Mpc^3^. This result is used to constrain models for structure formation; our data favour low-density cosmologies, subject to the usual assumptions concerning the shape and normalization of the power spectrum.
- ID:
- ivo://CDS.VizieR/J/MNRAS/329/227
- Title:
- 2dF Galaxy Redshift Survey. II.
- Short Name:
- J/MNRAS/329/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have cross-matched the 1.4-GHz NRAO VLA Sky Survey (NVSS, Condon 1998, Cat. <VIII/65>) with the first 210 fields observed in the 2dF Galaxy Redshift Survey (2dFGRS, Colless, 2001, Cat. <VII/226>), covering an effective area of 325{deg}^2^ (about 20 per cent of the final 2dFGRS area). This yields a set of optical spectra of 912 candidate NVSS counterparts, of which we identify 757 as genuine radio identifications - the largest and most homogeneous set of radio source spectra ever obtained. The 2dFGRS radio sources span the redshift range z=0.005 to 0.438, and are a mixture of active galaxies (60 per cent) and star-forming galaxies (40 per cent). About 25 per cent of the 2dFGRS radio sources are spatially resolved by NVSS, and the sample includes three giant radio galaxies with projected linear size greater than 1 Mpc. The high quality of the 2dF spectra means we can usually distinguish unambiguously between AGN and star-forming galaxies. We make a new determination of the local radio luminosity function at 1.4 GHz for both active and star-forming galaxies, and derive a local star formation density of 0.022+/-0.004M_{sun}_/yr/Mpc^3^ (H_0_=50km/s/Mpc)