- ID:
- ivo://CDS.VizieR/J/PASJ/52/631
- Title:
- Galactic plane VERA survey
- Short Name:
- J/PASJ/52/631
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to search for new VLBI sources in the galactic plane that can be used as phase reference sources in differential VLBI, we conducted 22GHz observations of radio sources in the galactic plane using the Japanese VLBI Network (J-Net). We have observed 267 VLBI source candidates selected from existing radio surveys and have detected 93 sources at a signal-to-noise ratio larger than 5. While 42 of the 93 detected sources had already been detected with VLBI at relatively lower frequency (typically 2 to 8GHz), the remaining 51 are found to be new VLBI sources detected for the first time. These are located within |b|<=5{deg}, and have a large number of galactic maser sources around them. Thus, they are potential candidates for phase reference sources for VLBI Exploration of Radio Astrometry (VERA), which is the first VLBI array dedicated to phase-referencing VLBI astrometry aimed at measuring the parallax and proper motion of maser sources in the whole Galaxy.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/96/1655
- Title:
- Galactic plane VLA survey
- Short Name:
- J/AJ/96/1655
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a continuum VLA snapshot survey of the galactic plane in the longitude range 0{deg}<=l<=90{deg} at 1.5GHz. Observations were taken every 0.5{deg} in longitude at b=0{deg}. Most fields are complete to about 30mJy peak flux density. The positions, peak, and total flux density of 471 compact sources (<30") have been measured. A complete sample of 329 sources is defined. An excess of sources above that expected from extragalactic source counts is seen for l<40{deg} at all flux-density intervals. We find 86 compact sources that are within 2.4arcmin of a source in the recent radio recombination-line survey of Lockman (1989ApJS...71..469L) Source counts excluding these 86 sources agree with extragalactic source counts for all flux-density and longitude intervals. there may only be a small number of galactic objects present in this survey that remain unidentified as such.
6783. Galactic PNe abundances
- ID:
- ivo://CDS.VizieR/J/MNRAS/349/793
- Title:
- Galactic PNe abundances
- Short Name:
- J/MNRAS/349/793
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New determinations of chemical abundances for He, N, O, Ne, Ar and S are derived for all galactic planetary nebulae (PNe) so far observed with a relatively high accuracy, in an effort to overcome differences in these quantities obtained over the years by different authors using different procedures.
- ID:
- ivo://CDS.VizieR/J/ApJS/98/659
- Title:
- Galactic PNe statistical distance scale
- Short Name:
- J/ApJS/98/659
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A statistical distance scale is proposed. It is based on the correlation between the ionized mass and the radius and the correlation between the radio continuum surface brightness temperature and the nebular radius. The proposed statistical distance scale is an average of the two distances obtained using the correlations. These correlations, calibrated on the 132 planetary nebulae with well-determined individual distances by Zhang, can reproduce not only the average distance of a sample of Galactic Bulge planetary nebulae exactly at the distance to the Galactic center, but also the expected gaussian distribution of their distances around the Galactic center. This new distance scale is applied to 647 Galactic planetary nebulae. It is estimated that this distance scale can be accurate on average to 35%-50%. Our statistical distance scale is in good agreement with the one recently proposed by Van de Steene and Zijlstra
- ID:
- ivo://CDS.VizieR/J/MNRAS/447/1673
- Title:
- Galactic post-AGB stars distances
- Short Name:
- J/MNRAS/447/1673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have commenced a detailed analysis of the known sample of Galactic post-asymptotic giant branch (PAGB) objects compiled in the Torun catalogue of Szczerba et al. (2007A&A...469..799S, Cat. J/A+A/469/799), and present, for the first time, homogeneously derived distance determinations for the 209 likely and 87 possible catalogued PAGB stars from that compilation. Knowing distances are essential in determining meaningful physical characteristics for these sources and this has been difficult to determine for most objects previously. The distances were determined by modelling their spectral energy distributions (SEDs) with multiple blackbody curves, and integrating under the overall fit to determine the total distance-dependent flux. This approach was undertaken for consistency as precise spectral types, needed for more detailed fitting, were unknown in the majority of cases. The SED method works because the luminosity of these central stars is very nearly constant from the tip of the AGB phase to the beginning of the white dwarf cooling track. This then enables us to use a standard-candle luminosity to estimate the SED distances. For Galactic thin-disc PAGB objects, we use three luminosity bins based on typical observational characteristics, ranging between 3500 and 12000L_{sun}_. We further adopt a default luminosity of 4000L_{sun}_ for bulge objects and 1700L_{sun}_ for the thick-disc and halo objects. We have also applied the above technique to a further sample of 54 related nebulae not in the current edition of the Torun catalogue. In a follow-up paper, we will estimate distances to the subset of RV Tauri variables using empirical period-luminosity relations, and to the R CrB stars, allowing a population comparison of these objects with the other subclasses of PAGB stars for the first time.
- ID:
- ivo://CDS.VizieR/J/AJ/130/156
- Title:
- Galactic radio compact HII regions at 1.4GHz
- Short Name:
- J/AJ/130/156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a new Very Large Array Galactic plane catalog at 1.4GHz (Cat. <J/AJ/130/586>) covering the first and second Galactic quadrants (340{deg}<=l<=120{deg}, |b|<=0.8{deg} with |b|<=1.8{deg} for 350{deg}<=l<=40{deg} and |b|<=2.5{deg} for 100{deg}<=l<=105{deg}) in conjunction with the MSX6C (Cat. <V/114>) Galactic plane mid-infrared catalog to supplement and better understand our 5GHz catalog (Cat. <J/ApJS/91/347>).
6787. Galactic reddening maps
- ID:
- ivo://CDS.VizieR/J/PASP/111/57
- Title:
- Galactic reddening maps
- Short Name:
- J/PASP/111/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate maps of Galactic reddening are important for a number of applications, such as mapping the peculiar velocity field in the nearby universe. Of particular concern are systematic errors which vary slowly as a function of position on the sky, as these would induce spurious bulk flow. We have compared the reddenings of Burstein & Heiles (BH, 1982, Cat. <J/AJ/87/1165>) and those of Schlegel, Finkbeiner, & Davis (1998ApJ...500..525S, SFD) to independent estimates of the reddening, for Galactic latitudes |b|>10{deg}. Our primary source of Galactic reddening estimates comes from comparing the difference between the observed B-V colors of early-type galaxies, and the predicted B-V color determined from the B-V-Mg_2_ relation. We have fitted a dipole to the residuals in order to look for large-scale systematic deviations. There is marginal evidence for a dipolar residual in the comparison between the SFD maps and the observed early-type galaxy reddenings. If this is due to an error in the SFD maps, then it can be corrected with a small (13%) multiplicative dipole term. We argue, however, that this difference is more likely to be due to a small (0.01mag) systematic error in the measured B-V colors of the early-type galaxies. This interpretation is supported by a smaller, independent data set (globular cluster and RR Lyrae stars), which yields a result inconsistent with the early-type galaxy residual dipole. BH reddenings are found to have no significant systematic residuals, apart from the known problem in the region 230{deg}<l<310{deg}, -20{deg}<b<20{deg}.
- ID:
- ivo://CDS.VizieR/J/A+A/564/A107
- Title:
- Galactic ridge X-ray emission
- Short Name:
- J/A+A/564/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We predict a thin diffuse component of the Galactic ridge X-ray emission (GRXE) arising from the scattering of the radiation of bright X-ray binaries (XBs) by the interstellar medium. This scattered component has the same scale height as that of the gaseous disk (~80pc) and is therefore thinner than the GRXE of stellar origin (scale height ~130pc). The morphology of the scattered component is furthermore expected to trace the clumpy molecular and HI clouds. We calculate this contribution to the GRXE from known Galactic XBs assuming that they are all persistent. The known XBs sample is incomplete, however, because it is flux limited and spans the lifetime of X-ray astronomy (~50-years), which is very short compared with the characteristic time of 1000-10000 years that would have contributed to the diffuse emission observed today due to time delays. We therefore also use a simulated sample of sources, to estimate the diffuse emission we should expect in an optimistic case assuming that the X-ray luminosity of our Galaxy is on average similar to that of other galaxies. In the calculations we also take into account the enhancement of the total scattering cross-section due to coherence effects in the elastic scattering from multi-electron atoms and molecules.
- ID:
- ivo://CDS.VizieR/J/PAZh/37/281
- Title:
- Galactic rotation curve from selected maser
- Short Name:
- J/PAZh/37/281
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on currently available observations of 28 maser sources in 25 star-forming regions with measured trigonometric parallaxes, proper motions, and radial velocities, we have constructed the rotation curve of the Galaxy. Taking different distances to the Galactic center R_0_, we have estimated the peculiar velocity of the Sun, the angular velocity of Galactic rotation, and its three derivatives.
- ID:
- ivo://CDS.VizieR/J/AJ/144/39
- Title:
- Galactic RRab stars from the GEOS RR Lyr Survey
- Short Name:
- J/AJ/144/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the GEOS database to study the Blazhko effect of galactic RRab stars. The database is continuously enriched by maxima supplied by amateur astronomers and by a dedicated survey by means of the two TAROT robotic telescopes. The same value of the Blazhko period is observed at different values of the pulsation periods and different values of the Blazhko periods are observed at the same value of the pulsation period. There are clues suggesting that the Blazhko effect is changing from one cycle to the next. The secular changes in the pulsation and Blazhko periods of Z CVn are anticorrelated. The diagrams of magnitudes against phases of the maxima clearly show that the light curves of Blazhko variables can be explained as modulated signals, both in amplitude and in frequency. The closed curves describing the Blazhko cycles in such diagrams have different shapes, reflecting the phase shifts between the epochs of the brightest maximum and the maximum O-C. Our sample shows that both clockwise and counterclockwise directions are possible for similar shapes. The improved observational knowledge of the Blazhko effect, in addition to some peculiarities of the light curves, has yet to be explained by a satisfactory physical mechanism.