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401. ICRF stars near extragalactic radio sources
ID:
ivo://CDS.VizieR/J/other/KFNT/27.299
Title:
ICRF stars near extragalactic radio sources
Short Name:
J/other/KFNT/27.
Date:
21 Oct 2021
Publisher:
CDS
Description:
The compiled catalogue of 231044 stars was created from photographic and CCD observations of position catalogues observed by ground based telescopes. The catalogue destine for optical observations VLBI-ICRS astrometrical extragalactic radiosources (ERS) with telescopes equiped with CCD-cameras. The main purpose of this catalogue is to ensure the reference stars in optics for reducing positions of faint astrometrical ERS 17-22mag relative to more bright reference stars 14-17mag. The catalogue contains 231044 star positions in fields 40'x40' near 240 ERS. More than nine catalogues of stars coordinates were used for compiling the Pul-ERS catalogue. For 69% of stars the proper motions were taken from UCAC3 catalogue to convert the position stars to the common epoch. The number of position measurements for each star varies from one to more than ten records. The inner precision of positions of stars in Pul-ERS is from 4 to 150mas. 159331 stars of the compiled catalogue were identified with stars of the UCAC3. The average internal accuracy of positions on both coordinates is not worse 0.11".
402. Ilkhanid star table (1232)
ID:
ivo://CDS.VizieR/J/other/JHA/47.294
Title:
Ilkhanid star table (1232)
Short Name:
J/other/JHA/47.2
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Ilkhani zij compiled by Nasir al-Din al-Tusi and his colleagues in the first period of the astronomical activities (the 1260s and early 1270s) in the Maragha observatory includes a star table collecting important observations of Islamic astronomers from the early ninth century through the third quarter of the thirteenth century, including the Mumtahan astronomers, Ibn al-A'lam, Ibn Yunus, as well as the Maragha astronomers themselves. This table gives the ecliptical coordinates of 18 bright stars in comparison with Ptolemy's corresponding values. This medieval bright star table is especially interesting for two reasons: first, it provides reliable evidence for the examination of the accuracy of the observations made and the instruments employed (notably, an armillary sphere) in the Maragha observatory. Second, it facilitates a comparative study of the accuracy of stellar observations in medieval Middle Eastern astronomy in the period in question. We have obtained the result that the Maragha astronomers observed more accurate star longitudes than did their predecessors, while for the latitudes, all Islamic observers appear to have gained about the same degree of accuracy. We also discuss two delicate matters raised by this table: first, the problem of the use of the two different values for the rate of precession by the Maragha astronomers in order to convert earlier star longitudes to the epoch of the Ilkhani zij (1{deg}/66 years for Ptolemy's longitudes and 1{deg}/70 years for those measured by their Islamic predecessors); second, the change in the star latitudes essentially related to the various values measured by Ptolemy and the Islamic astronomers represented side-by-side in it. Finally, we briefly discuss a small celestial globe designed by the son of Mu'ayyad al-Din al-'Urdi, the instrument-maker of the Maragha observatory.
403. Image of Galaxies data-base II.
ID:
ivo://CDS.VizieR/J/A+AS/117/467
Title:
Image of Galaxies data-base II.
Short Name:
J/A+AS/117/467
Date:
21 Oct 2021
Publisher:
CDS
Description:
A preliminary list of 68.040 galaxies was built from extraction of 35.841 digitized images of the Palomar Sky Survey (Paper I, 1996A&A...311...12P). For each galaxy, the basic parameters are obtained: coordinates, diameter, axis ratio, total magnitude, position angle. On this preliminary list, we apply severe selection rules to get a catalog of 28.000 galaxies, well identified and well documented. For each parameter, a comparison is made with standard measurements. The accuracy of the raw photometric parameters is quite good despite of the simplicity of the method. Without any local correction, the standard error on the total magnitude is about 0.5 magnitude up to a total magnitude of B_T_=17. Significant secondary effects are detected concerning the magnitudes: distance to plate center effect and air-mass effect. The description of the construction of the catalog is given in Paturel et al. 1996 and Garnier et al. 1996. Galaxies are detected on POS-I and cross-identified with galaxies from the LEDA database (http://www-obs.univ-lyon1.fr/leda/)
404. Infall motions in massive star-forming regions
ID:
ivo://CDS.VizieR/J/MNRAS/450/1926
Title:
Infall motions in massive star-forming regions
Short Name:
J/MNRAS/450/1926
Date:
21 Oct 2021
Publisher:
CDS
Description:
Massive star-forming regions with observed infall motions are good sites for studying the birth of massive stars. In this paper, 405 compact sources have been extracted from the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) compact sources that also have been observed in the Millimetre Astronomy Legacy Team 90-GHz (MALT90) survey during years 1 and 2. These observations are complemented with Spitzer GLIMPSE/MIPSGAL mid-IR survey data to help classify the elected star-forming clumps into three evolutionary stages: pre-stellar, proto-stellar and UCHII regions. The results suggest that 0.05g/cm^2^ is a reliable empirical lower bound for the clump surface densities required for massive-star formation to occur. The optically thick HCO^+^(1-0) and HNC(1-0) lines, as well as the optically thin N_2_H^+^(1-0) line were used to search for infall motions towards these sources. By analysing the asymmetries of the optically thick HCO^+^(1-0) and HNC(1-0) lines and the mapping observations of HCO^+^(1-0), a total of 131 reliable infall candidates have been identified. The HCO^+^(1-0) line shows the highest occurrence of obvious asymmetric features, suggesting that it may be a better infall motion tracer than other lines such as HNC(1-0). The detection rates of infall candidates towards pre-stellar, proto-stellar and UCHII clumps are 0.3452, 0.3861 and 0.2152, respectively. The relatively high detection rate of infall candidates towards UCHII clumps indicates that many UCHII regions are still accreting matter. The peak column densities and masses of the infall candidates, in general, display an increasing trend with progressing evolutionary stages. However, the rough estimates of the mass infall rate show no obvious variation with evolutionary stage.
405. Infall motions in massive star-forming regions
ID:
ivo://CDS.VizieR/J/MNRAS/461/2288
Title:
Infall motions in massive star-forming regions
Short Name:
J/MNRAS/461/2288
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this work, we aim to characterize high-mass clumps with infall motions. We selected 327 clumps from the Millimetre Astronomy Legacy Team 90-GHz survey, and identified 100 infall candidates. Combined with the results of He et al. (2015, Cat. J/MNRAS/450/1926), we obtained a sample of 732 high-mass clumps, including 231 massive infall candidates and 501 clumps where infall is not detected. Objects in our sample were classified as pre-stellar, proto-stellar, HII or photodissociation region (PDR). The detection rates of the infall candidates in the pre-stellar, proto-stellar, HII and PDR stages are 41.2 per cent, 36.6 per cent, 30.6 per cent and 12.7 per cent, respectively. The infall candidates have a higher H_2_ column density and volume density compared with the clumps where infall is not detected at every stage. For the infall candidates, the median values of the infall rates at the pre-stellar, proto-stellar, HII and PDR stages are 2.6 x 10^-3^, 7.0x10^-3^, 6.5x10^-3^ and 5.5x10^-3^M_{sun}_/yr, respectively. These values indicate that infall candidates at later evolutionary stages are still accumulating material efficiently. It is interesting to find that both infall candidates and clumps where infall is not detected show a clear trend of increasing mass from the pre-stellar to proto-stellar, and to the HII stages. The power indices of the clump mass function are 2.04+/-0.16 and 2.17+/-0.31 for the infall candidates and clumps where infall is not detected, respectively, which agree well with the power index of the stellar initial mass function (2.35) and the cold Planck cores (2.0).
406. Infrared Photometry and 21cm data for nearby galaxies
ID:
ivo://CDS.VizieR/VII/75
Title:
Infrared Photometry and 21cm data for nearby galaxies
Short Name:
VII/75
Date:
21 Oct 2021
Publisher:
CDS
Description:
The catalogue is a compilation of magnitudes at 1.6um, 21cm velocity widths, and related data on 307 nearby galaxies.
407. Integrated radio continuum spectra of galaxies
ID:
ivo://CDS.VizieR/J/AJ/149/32
Title:
Integrated radio continuum spectra of galaxies
Short Name:
J/AJ/149/32
Date:
21 Oct 2021
Publisher:
CDS
Description:
We investigate the spectral shape of the total continuum radiation, between 74MHz and 5GHz (400-6cm in wavelength), for a large sample of bright galaxies. We take advantage of the overlapping survey coverage of the VLA Low-Frequency Sky Survey, the Westerbork Northern Sky Survey, the NRAO VLA Sky Survey, and the Green Bank 6cm Survey to achieve significantly better resolution, sensitivity, and sample size compared to prior efforts of this nature. For our sample of 250 bright galaxies we measure a mean spectral index, {alpha}, of -0.69 between 1.4 and 4.85GHz, -0.55 between 325MHz and 1.4GHz, and -0.45 between 74 and 325MHz, which amounts to a detection of curvature in the mean spectrum. The magnitude of this curvature is approximately {Delta}{alpha}=-0.2 per logarithmic frequency decade when fit with a generalized function having constant curvature. No trend in low-frequency spectral flattening versus galaxy inclination is evident in our data, suggesting that free-free absorption is not a satisfying explanation for the observed curvature. The ratio of thermal to non-thermal emission is estimated through two independent methods: (1) using the IRAS far-IR fluxes and (2) with the value of the total spectral index. Method (1) results in a distribution of 1.4GHz thermal fractions of 9%+/-3%, which is consistent with previous studies, while method (2) produces a mean 1.4GHz thermal fraction of 51% with dispersion 26%. The highly implausible values produced by method (2) indicate that the sum of typical power-law thermal and non-thermal components is not a viable model for the total spectral index between 325 and 1.4GHz. An investigation into relationships between spectral index, infrared-derived quantities, and additional source properties reveals that galaxies with high radio luminosity in our sample are found to have, on average, a flatter radio spectral index, and early types tend to have excess radio emission when compared to the radio-infrared ratio of later types. Early types also have radio emission that is more compact than later type galaxies, as compared to the optical size of the galaxy. Despite these differences, no relation between spectral index and galaxy type is detected.
408. Integrated spectroscopy of HRS galaxies
ID:
ivo://CDS.VizieR/J/A+A/550/A114
Title:
Integrated spectroscopy of HRS galaxies
Short Name:
J/A+A/550/A114
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present long-slit integrated spectroscopy of 238 late-type galaxies belonging to the Herschel Reference Survey, a volume-limited sample representative of the nearby universe. This sample has a unique legacy value since it was ideally defined for any statistical study of the multifrequency properties of galaxies spanning a wide range in morphological type and luminosity. The spectroscopic observations cover the spectral range 3600-6900{AA} at a resolution R~=1000 and are thus suitable for separating both the underlying absorption from the emission of the H{beta} line and the two [NII] lines from the H{alpha} emission. We measured the fluxes and the equivalent widths of the strongest emission lines ([OII]{lambda}3727, H{beta}, [OIII]{lambda}4959 and [OIII]{lambda}5007, [NII]{lambda}6548, H{alpha}, [NII]{lambda}6584, [SII]{lambda}6717, and [SII]{lambda}6731). We used the data to study the distribution of the equivalent width of all the emission lines, of the Balmer decrement C(H{beta}), and of the observed underlying Balmer absorption under H{beta} (EWH{beta}_abs_) in this sample. Combining these new spectroscopic data with those available at other frequencies, we also study the dependence of C(H{beta}) and EWH{beta}_abs_ on morphological type, stellar mass, stellar surface density, star formation rate, birthrate parameter, and metallicity in galaxies belonging to different environments (fields vs. Virgo cluster). The distribution of the equivalent width of all the emission lines, of C(H{beta}) (or equivalently of A(H{alpha}), and of EWH{beta}_abs_ are systematically different in cluster and field galaxies. The Balmer decrement increases with the stellar mass, stellar surface density, metallicity, and star formation rate of the observed galaxies, while it is unexpectedly almost independent of the column density of the atomic and molecular gas. The dependence of C(H{beta}) on stellar mass is steeper than previously found in other works. The underlying Balmer absorption does not significantly change with any of these physical parameters.
409. Interacting galaxies catalogue
ID:
ivo://CDS.VizieR/VII/236
Title:
Interacting galaxies catalogue
Short Name:
VII/236
Date:
21 Oct 2021
Publisher:
CDS
Description:
The present edition unifies two parts of Catalogue of interacting galaxies by B.A. Vorontsov-Velyaminov (1959VV....C......0V, 1970, 1977A&AS...28....1V). It contains 852 known interacting VV-systems and 1162 new objects taken from the comments on the galaxies in Morphological catalogues of galaxies by Vorotsov-Velyaminov et al. (1962, 1963, 1964, 1968, 1974, Cats. <VII/62>, <VII/100>) with numbers from VV853 to VV2014. The classification of interacting galaxies is given in accord with the suggestion s of Vorotsov-Velyaminov. The catalogue contains new information for the galaxies included taken from the NEDA-NASA/IPAC extragalactic data base.
410. International Celestial Reference Frame 2, ICRF2
ID:
ivo://CDS.VizieR/I/323
Title:
International Celestial Reference Frame 2, ICRF2
Short Name:
I/323
Date:
21 Oct 2021
Publisher:
CDS
Description:
This Technical Note describes the generation by an international team of the second realization of the International Celestial Reference Frame (ICRF2) at radio wavelengths using nearly 30 years of Very Long Baseline Interferometry (VLBI) observations. ICRF2 contains precise positions of 3414 compact radio astronomical sources, more than five times the number as in the first ICRF, hereafter ICRF1. Further, the ICRF2 is found to have a noise floor of only 40{mu}as, some 5-6 times better than ICRF1, and an axis stability of 10{mu}as, nearly twice as stable as ICRF1. Alignment of ICRF2 with the International Celestial Reference System (ICRS) was made using 138 stable sources common to both ICRF2 and ICRF1-Ext2. Future maintenance of ICRF2 will be made using a set of 295 new "defining" sources selected on the basis of positional stability and the lack of extensive intrinsic source structure. The stability of these 295 defining sources, and their more uniform sky distribution eliminates the two largest weaknesses of ICRF1.