- ID:
- ivo://CDS.VizieR/J/ApJ/846/159
- Title:
- Interferometric CO obs. of 126 CALIFA galaxies
- Short Name:
- J/ApJ/846/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present interferometric CO observations, made with the Combined Array for Millimeter-wave Astronomy (CARMA) interferometer, of galaxies from the Extragalactic Database for Galaxy Evolution survey (EDGE). These galaxies are selected from the Calar Alto Legacy Integral Field Area (CALIFA) sample, mapped with optical integral field spectroscopy. EDGE provides good-quality CO data (3{sigma} sensitivity {Sigma}_mol_~11M_{sun}/pc^2^ before inclination correction, resolution ~1.4kpc) for 126 galaxies, constituting the largest interferometric CO survey of galaxies in the nearby universe. We describe the survey and data characteristics and products, then present initial science results. We find that the exponential scale lengths of the molecular, stellar, and star-forming disks are approximately equal, and galaxies that are more compact in molecular gas than in stars tend to show signs of interaction. We characterize the molecular-to-stellar ratio as a function of Hubble type and stellar mass and present preliminary results on the resolved relations between the molecular gas, stars, and star-formation rate. We then discuss the dependence of the resolved molecular depletion time on stellar surface density, nebular extinction, and gas metallicity. EDGE provides a key data set to address outstanding topics regarding gas and its role in star formation and galaxy evolution, which will be publicly available on completion of the quality assessment.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/456/174
- Title:
- Intermediate-Mass Population in NGC 604
- Short Name:
- J/ApJ/456/174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometry of stars in the giant H II region NGC 604 in M33. The photometry is measured from Hubble Space Telescope images through the F336W, F555W, and F814W broadband filters. Color- magnitude diagrams of the stars in NGC 604 show a main sequence detected down to an M_F555W,0 of -1 (nearly 6M_{sun}_). In addition, there are luminous stars that are probably blue and red supergiants. Based on the previously known presence of Wolf-Rayet stars, we take the age of the cluster to be 3-5Myr. We measure an initial mass function for intermediate-mass stars (6.5-18M_{sun}_) that has a slope of -1.6+/-0.7. This slope is, within the uncertainties, similar to those found for OB associations in the Milky Way and Magellanic Clouds. The density of the luminous stars in NGC 604 is also comparable to that of OB associations in those galaxies even though the total number of stars is greater in NGC 604. A few subclamps have densities that are higher by as much as a factor of 10. A comparison with R136 in the LMC emphasizes that the formation of a large number of massive stars does not necessarily entail a high concentration of those stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/726/19
- Title:
- Intermediate-mass stars in IC 1805
- Short Name:
- J/ApJ/726/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of a study of the intermediate- and high-mass stars in the young, rich star-forming complex IC 1805, based on a combination of optical, near-infrared, and mid-infrared photometry, and classification spectra. These data provide the basis for characterizing the masses and ages for stars more massive than ~2M_{sun}_ and enable a study of the frequency and character of circumstellar disks associated with intermediate- and high-mass stars. Optically thick accretion disks among stars with masses 2<M/M_{sun}_<4 are rare (~2% of members) and absent among more massive stars. A larger fraction (~10%) of stars with masses 2<M/M_{sun}_<4 appear to be surrounded by disks that have evolved from the initial optically thick accretion phase. We identify four classes of such disks. These classes are based on spectral energy distributions (SEDs) of excess emission above photospheric levels: disks that are (1) optically thin based on the magnitude of the observed excess emission from 2 to 24um, (2) optically thin in their inner regions (r<20AU) and optically thick in their outer regions, (3) exhibit empty inner regions (r<10AU) and optically thin emission in their outer regions, and (4) exhibit empty inner regions and optically thick outer regions. We discuss, and assess the merits and liabilities of, proposed explanations for disks exhibiting these SED types and suggest additional observations that would test these proposals.
- ID:
- ivo://CDS.VizieR/J/MNRAS/493/2339
- Title:
- Internal motions in OB-associations
- Short Name:
- J/MNRAS/493/2339
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the motions inside 28 OB-associations with the use of Gaia DR2 proper motions. The average velocity dispersion calculated for 28 OB-associations including more than 20 stars with Gaia DR2 proper motion is sigma_v_=4.5km/s. The median virial and stellar masses of OB-associations are 8.9x10^5^ and 8.1x10^3^M_{sun}_, respectively. The median star-formation efficiency in parent giant molecular clouds appears to be epsilon=1.2%. Gaia DR2 proper motions confirm the expansion in the Per OB1, Car OB1 and Sgr OB1 associations found earlier with Gaia DR1 data. We also detect the expansion in Gem OB1, Ori OB1 and Sco OB1 associations which became possible for the first time now when analyzed with Gaia DR2 proper motions. The analysis of the distribution of OB-stars in the Per OB1 association shows the presence of a shell-like structure with the radius of 40 pc. Probably, the expansion of the Per OB1 association started with the velocity greater than the present-day expansion velocity equal to 5.0+/-1.7km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/421/455
- Title:
- Interplanetary Scintillation Pushchino Survey II
- Short Name:
- J/A+A/421/455
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of optical identification of 248 interplanetary scintillating (IPS) radio sources from the Pushchino Survey (PS) in the area of 0.11sr with the center at RA=10h28m, DE=+41{deg}. All 260 counterparts of IPS radio sources from the 7C and FIRST catalogues, which had been found in Paper I (Cat. <J/A+A/403/555>), were considered. We used USNO-B1.0 catalogue (limiting magnitude m_R_~21) for the optical identification and searched the literature to find optical data for fainter objects. Photometric and spectroscopic observations were conducted on the 1m and 6m telescopes of SAO RAS. Optical magnitudes or deep limits for 22 objects and redshifts for 26 ones have been obtained. In total, we collected optical data for 116 (68 with redshift) counterparts of the PS radio sources. For the subsample of the PS quasars (41 objects) the redshift distribution was compared to those of several other samples of quasars (BRL, 3CRR, MQS, B3-VLA, 7CRS I-III and PKS 0.25Jy) which have complete or nearly complete redshift information.
- ID:
- ivo://CDS.VizieR/J/A+A/275/549
- Title:
- Interstellar extinction curves
- Short Name:
- J/A+A/275/549
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The data are a decomposition of the extinction curves published by Aiello S., Barsella B., Chlewicki G., Greenberg J.M., Patriarchi P., and Perinotto M. (1988A&AS...73..195A) in the parameter scheme of Fitzpatrick E.L. and Massa D. (1988ApJ...328..734F). Each extinction curve k(x) = (A(lambda)-A(V))/(A(B)-A(V)) is given by: k(x) = c1 + c2*x + c3* D(x,x0,y) + c4*F(x) Where x = 1/wavelength (in inverse micron), D is a Drude profile: D(x,x0,y) = x^2^/((x^2^-x0^2^)^2^ + y^2^x^2^) and F is a polynomial of order 3: F(x) = 0.05392(x-5.9)^2^ + 0.0564(x-5.9)^3^ for 5.9<x<8.0 F(x) = 0 for x<5.9 In this scheme the parameters have the following meaning: c1: related directly to c2 because of normalisation k(x) c2: slope of the linear rise ( mag/E(B-V) ) y: width of the bump (inverse micron) c3: c3/y^2^ is bump height, pi*c3/(2.*y) is bump area x0: position of the bump (inverse micron) c4: amount of FUV non-linear rise contribution: at 8 mu^-1^: 2.9c4 (mag/E(B-V)) | * ^ | * 2.9c4 | ^ * * k(x)| c3/y^2 * * * .. v | *< y >* *.. | v * .. * * | *.. c2 1 | * 0 | * |^ * |Rv * |v____________________________|_____________________________ V B x0 5.9 8.0 x=1/wavelength (1/micron) Values of Rv, the ratio of total to selective extinction, can be found in Aiello et al. (1988A&AS...73..195A).
- ID:
- ivo://CDS.VizieR/J/BaltA/11/1
- Title:
- Interstellar extinction curves of OB stars
- Short Name:
- J/BaltA/11/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper presents a collection of 436 extinction curves covering the whole available range of wavelengths from satellite UV to near-IR. The data were taken from the ANS photometric catalogue (Cat. <II/97>) and from the compilations of IR photometric measurements. The data curves have been obtained with the aid of "artificial standards" Papaj et al. (1993A&A...273..575P) and Wegner (1994MNRAS.270..229W, 1995, Interstellar Absorption Structures in the Direction of Nearby OB stars, Wyd. Uczelniane WSP, Bydgoszcz, p. 1-383). The visual magnitudes and spectral classifications of O and B type stars with E_B-V_>=0.05 were taken from the SIMBAD database. The curves are given in the form of plots and tables E_{lambda}-V_/E_B-V_ versus 1/{lambda}. The observed variety of extinction laws among slightly reddened stars is apparently due to the various physical parameters of interstellar clouds.
- ID:
- ivo://CDS.VizieR/J/BaltA/17/125
- Title:
- Interstellar reddening in 3 HII regions
- Short Name:
- J/BaltA/17/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The slope of the interstellar reddening line in the J-H vs. H-Ks diagram of the 2MASS survey in the direction of the North America and Pelican nebulae, the L 935 dust cloud and the Cyg OB2 association is determined. The MK types were either classified by C.J. Corbally or collected from the literature. The ratio E(J-H)/E(H-Ks)=2.0 is obtained by taking the average for the four groups of spectral classes: O3-B1, B2-B6, B7-B9.5 and red clump giants. The obtained ratio is among the largest values of E(J-H)/E(H-Ks) determined till now.
- ID:
- ivo://CDS.VizieR/J/A+A/410/905
- Title:
- Interstellar reddening parameter measurements
- Short Name:
- J/A+A/410/905
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new measurements of the interstellar reddening parameter R_V_=A_V_/E(B-V) towards 185 O stars, using J, H, Ks photometry from the 2MASS project. The average R_V_ from these is of 3.19+/-0.50. All objects whose R_V_ departs from this value by more than 2 sigma have been recognized. Ten objects have R_V_ higher than this value and two lower. In the Cygnus region R_V_ values follow the behaviour of the general interstellar medium, while in the Carina arm, in spite of the relatively larger distance, local cloud effects prevail. The relatively few stars of our sample whose Hipparcos parallaxes are reliable, are found to have distances systematically smaller than the distances derived by the spectroscopic parallaxes. We argue that this effect is consistent with the recently claimed discovery of grey extinction towards OB stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/1300
- Title:
- Intranight optical variability of AGN
- Short Name:
- J/MNRAS/435/1300
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The incidence of intranight optical variability (INOV) is known to differ significantly among different classes of powerful active galactic nuclei (AGN). A number of statistical methods have been employed in the literature for testing the presence of INOV in the light curves, sometimes leading to discordant results. In this paper, we compare the INOV characteristics of six prominent classes of AGN, as evaluated using three commonly used statistical tests, namely the {chi}^2^-test, the modified C-test and the F-test, which has recently begun to gain popularity. The AGN classes considered are: radio-quiet quasars, radio-intermediate quasars, lobe-dominated quasars, low optical polarization core-dominated quasars, high optical polarization core-dominated quasars and TeV blazars. Our analysis is based on a large body of AGN monitoring data, involving 262 sessions of intranight monitoring of a total 77 AGN, using 1-2m class optical telescopes located in India. In order to compare the usefulness of the statistical tests, we have also subjected them to a 'sanity check' by comparing the number of false positives yielded by each test with the corresponding statistical prediction. The present analysis is intended to serve as a benchmark for future INOV studies of AGN of different classes.
