- ID:
- ivo://CDS.VizieR/J/PASJ/71/6
- Title:
- Galactic infrared bubbles
- Short Name:
- J/PASJ/71/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Galactic infrared (IR) bubbles, which have shell-like structures in the mid-IR wavelengths, are known to contain massive stars near their centers. Infrared bubbles in inner Galactic regions (|l|<=65{deg}, |b|<=1{deg}) have so far been studied well to understand the massive star formation mechanisms. In this study, we expand the research area to the whole Galactic plane (0{deg}<=l<360{deg}, |b|<=5{deg}), using the AKARI all-sky survey data. We limit our study to large bubbles with angular radii of >1' to reliably identify and characterize them. For the 247 IR bubbles in total, we derived the radii and the covering fractions of the shells, based on the method developed by Y. Hattori et al. (2016PASJ...68...37H). We also created their spectral energy distributions, using the AKARI and Herschel photometric data, and decomposed them with a dust model to obtain the total IR luminosity and the luminosity of each dust component, i.e., polycyclic aromatic hydrocarbons (PAHs), warm dust, and cold dust. As a result, we find that there are systematic differences in the IR properties of the bubbles between the inner and outer Galactic regions. The total IR luminosities are lower in outer Galactic regions, while there is no systematic difference in the range of the shell radii between inner and outer Galactic regions. More IR bubbles tend to be observed as broken bubbles rather than closed ones and the fractional luminosities of the PAH emission are significantly higher in outer Galactic regions. We discuss the implications of these results for the massive stars and the interstellar environments associated with the Galactic IR bubbles.
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- ID:
- ivo://CDS.VizieR/J/ApJS/249/6
- Title:
- Galactic interstellar ratio ^18^O/^17^O. I.
- Short Name:
- J/ApJS/249/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The interstellar oxygen isotopic ratio of ^18^O/^17^O can reflect the relative amount of the secular enrichment by ejecta from high-mass versus intermediate-mass stars. Previous observations found a Galactic gradient of ^18^O/^17^O, i.e., low ratios in the Galactic center and large values in the Galactic disk, which supports the inside-out formation scenario of our Galaxy. However, there are not many observed objects and, in particular, there are not many at large galactocentric distances. For this reason, we started a systematic study on Galactic interstellar ^18^O/^17^O, through observations of C^18^O and C^17^O multi-transition lines toward a large sample of 286 sources (at least one order of magnitude larger than previous ones), from the Galactic center region to the far outer Galaxy (~22kpc). In this article, we present our observations of J=1-0 lines of C^18^O and C^17^O, with the 12m antenna of the Arizona Radio Observatory (ARO 12m) and the Institut de Radio Astronomie Millimetrique (IRAM) 30m telescopes. Among our IRAM 30m sample of 50 targets, we detected successfully both C^18^O and C^17^O 1-0 lines for 34 sources. Similarly, our sample of 260 targets for ARO 12m observations resulted in the detection of both lines for 166 sources. The C^18^O optical depth effect on our ratio results, evaluated by fitting results of C^17^O spectra with hyperfine components (assuming {tau}_C18O_=4{tau}_C17O_) and our radiative transfer and excitation model nonlocal thermodynamic equilibrium (non-LTE) model calculation for the strongest source, was found to be insignificant. Beam dilution does not seem to be a problem either, which was supported by the fact that there is no systematic variation between the isotopic ratio and the heliocentric distance, and ratios are consistently measured from two telescopes for most of those detected sources. With this study we obtained ^18^O/^17^O isotopic ratios for a large sample of molecular clouds with different galactocentric distances. Our results, though there are still very few detections made for sources in the outer Galaxy, confirm the apparent ^18^O/^17^O gradient of ^18^O/^17^O=(0.10+/-0.03)R_GC_+(2.95+/-0.30), with a Pearson's rank correlation coefficient of R=0.69. This is supported by the newest Galactic chemical evolution model including the impact of massive stellar rotators and novae.
- ID:
- ivo://CDS.VizieR/J/PAZh/39/601
- Title:
- Galactic kinematics from YSOs sample
- Short Name:
- J/PAZh/39/601
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on published sources, we have created a kinematic database on 220 massive (>10M_{sun}_) young Galactic star systems located within <3 kpcof the Sun. Out of them, approximately 100 objects are spectroscopic binary and multiple star systems whose components are massive OB stars; the remaining objects are massive Hipparcos B stars with parallax errors of no more than 10 percent. Based on the entire sample, we have constructed the Galactic rotation curve, determined the circular rotation velocity of the solar neighborhood around the Galactic center R_0_=8kpc, V_0_=259+/-16km/s, and obtained the following spiral density wave parameters: the amplitudes of the radial and azimuthal velocity perturbations f_R_=-10.8+/-1.2km/s, and f_{theta}_=7.9+/-1.3km/s, respectively; the pitch angle for a two-armed spiral pattern i=-6.0+/-0.4deg, with the wavelength of the spiral density wave near the Sun being {lambda}=2.6+/-0.2kpc; and the radial phase of the Sun in the spiral density wave {chi}_{sun}_=-120+/-4{deg}. We show that such peculiarities of the Gould Belt as the local expansion of the system, the velocity ellipsoid vertex deviation, and the significant additional rotation can be explained in terms of the density wave theory. All these effects decrease noticeably once the influence of the spiral density wave on the velocities of nearby stars has been taken into account. The influence of Gould Belt stars on the Galactic parameter estimates has also been revealed. Eliminating them from the kinematic equations has led to the following new values of the spiral density wave parameters: f_{theta}_=2.9+/-2.1km/s and {chi}_{sun}_=-104+/-6{deg}.
- ID:
- ivo://CDS.VizieR/J/A+A/518/A1
- Title:
- Galactic massive stars with AstraLux
- Short Name:
- J/A+A/518/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive stars have high-multiplicity fractions, and many of them have still undetected components, thus hampering the study of their properties. I study a sample of massive stars with high angular resolution to better characterize their multiplicity. I observed 138 fields that include at least one massive star with AstraLux, a lucky imaging camera at the 2.2m Calar Alto telescope. I also used observations of 3 of those fields with ACS/HRC on HST to obtain complementary information and to calibrate the AstraLux data. The results were compared with existing information from the Washington Double Star Catalog, Tycho-2, 2MASS, and other literature results.
- ID:
- ivo://CDS.VizieR/J/A+A/376/997
- Title:
- Galactic mass-losing AGB stars
- Short Name:
- J/A+A/376/997
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- AGB mass-losing sources are easy to identify and to characterize in the near-infrared range (1-5{mu}m). We make use of the near-infrared data acquired by the Japanese space experiment IRTS to study a sample of sources detected in the 2 celestial strips surveyed by the IRTS. Mass-loss rates and distances are estimated for 40 carbon-rich sources and 86 oxygen-rich sources of which 8 are probably of S-type. Although the sample is small, one sees a dependence of the relative contribution of the two kinds of sources to the replenishment of the interstellar medium (ISM) on the galactocentric distance. E.g. from 6 to 8kpc, oxygen-rich sources in our sample contribute 10-12 times as much as carbon rich sources, whereas from 10 to 12kpc, the latters contribute 3-4 times as much as the formers. Therefore, one would expect a gradient in the composition of the ISM between 6 and 12kpc from the Galactic Centre, especially in its dust component. Most of the replenishment (>50%) by AGB stars is due to sources with mass-loss rate larger than 10^-6^M_{sun}_/yr.
- ID:
- ivo://CDS.VizieR/J/ApJ/831/73
- Title:
- Galactic MCs associated with HII regions
- Short Name:
- J/ApJ/831/73
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The relations between star formation and properties of molecular clouds (MCs) are studied based on a sample of star-forming regions in the Galactic Plane. Sources were selected by having radio recombination lines to provide identification of associated MCs and dense clumps. Radio continuum emission and mid-infrared emission were used to determine star formation rates (SFRs), while ^13^CO and submillimeter dust continuum emission were used to obtain the masses of molecular and dense gas, respectively. We test whether total molecular gas or dense gas provides the best predictor of SFR. We also test two specific theoretical models, one relying on the molecular mass divided by the free-fall time, the other using the free-fall time divided by the crossing time. Neither is supported by the data. The data are also compared to those from nearby star-forming regions and extragalactic data. The star formation "efficiency," defined as SFR divided by mass, spreads over a large range when the mass refers to molecular gas; the standard deviation of the log of the efficiency decreases by a factor of three when the mass of relatively dense molecular gas is used rather than the mass of all of the molecular gas.
- ID:
- ivo://CDS.VizieR/J/MNRAS/509/421
- Title:
- Galactic metallicity gradient with open clusters
- Short Name:
- J/MNRAS/509/421
- Date:
- 26 Nov 2021 13:56:15
- Publisher:
- CDS
- Description:
- During the last years and decades, several individual studies and large-scale spectroscopic surveys significantly improved our knowledge of the Galactic metallicity distribution based on open clusters. The availability of Gaia data provided a further step forward in our knowledge. However, still some open issues remain, for example, the influence of radial migration on the interpretation of the observed gradients. We used spectroscopic metallicities from individual studies and from the APOGEE survey to compile a sample of 136 open clusters, with a membership verification based on Gaia DR2. Additionally, we present photometric metallicity estimates of 14 open clusters in a somewhat outer Galactic region. Eight age groups allow us to study the evolution of the metallicity gradient in detail, showing within the errors an almost constant gradient of about -0.06dex/kpc. Furthermore, using the derived gradients and an analysis of the individual objects, we estimate a mean migration rate of 1kpc/Gyr for objects up to about 2Gyr. Here, the change of the guiding radius is clearly the main contributor. For older and dynamically hotter objects up to 6Gyr we infer a lower migration rate of up to 0.5kpc/Gyr. The influence of epicyclic excursions increases with age and contributes already about 1 kpc to the total migration distance after 6Gyr. A comparison of our results with available models shows good agreement. However, there is still a lack of a suitable coverage of older objects, future studies are still needed to provide a better sampling in this respect.
- ID:
- ivo://CDS.VizieR/J/AJ/136/2413
- Title:
- Galactic midplane Spitzer red sources
- Short Name:
- J/AJ/136/2413
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a highly reliable flux-limited census of 18949 point sources in the Galactic midplane that have intrinsically red mid-infrared colors. These sources were selected from the Spitzer Space Telescope Galactic Legacy Infrared Midplane Survey Extraordinaire (GLIMPSE) I and II surveys of 274{deg}^2^ of the Galactic midplane, and consist mostly of high- and intermediate-mass young stellar objects (YSOs) and asymptotic giant branch (AGB) stars. The selection criteria were carefully chosen to minimize the effects of position-dependent sensitivity, saturation, and confusion. The distribution of sources on the sky and their location in the Infrared Array Camera and the Multiband Image Photometer for Spitzer 24um color-magnitude and color-color space are presented. Using this large sample, we find that YSOs and AGB stars can be mostly separated by simple color-magnitude selection criteria into approximately 50%-70% of YSOs and 30%-50% of AGB stars. Planetary nebulae and background galaxies together represent at most 2%-3% of all the red sources. 1004 red sources in the GLIMPSE II region, mostly AGB stars with high mass-loss rates, show significant (>=0.3mag) variability at 4.5 and/or 8.0um. With over 11,000 likely YSOs and over 7000 likely AGB stars, this is to date the largest uniform census of AGB stars and high- and intermediate-mass YSOs in the Milky Way Galaxy.
- ID:
- ivo://nasa.heasarc/duerbeck
- Title:
- Galactic Novae References Catalog
- Short Name:
- Nova
- Date:
- 27 Sep 2024
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table contains the Reference Catalog of Galactic Novae, Duerbeck, version 1990. It lists all objects known or believed to be novae at one time or other. Objects that were later found to be spurious have been omitted. Completeness was attempted only for novae and not for dwarf novae, X-ray novae, etc. This is a service provided by NASA HEASARC .
- ID:
- ivo://CDS.VizieR/J/ApJ/834/196
- Title:
- Galactic novae with m<=10 from 1900 to 2015
- Short Name:
- J/ApJ/834/196
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Despite its fundamental importance, a reliable estimate of the Galactic nova rate has remained elusive. Here, the overall Galactic nova rate is estimated by extrapolating the observed rate for novae reaching m<=2 to include the entire Galaxy using a two component disk plus bulge model for the distribution of stars in the Milky Way. The present analysis improves on previous work by considering important corrections for incompleteness in the observed rate of bright novae and by employing a Monte Carlo analysis to better estimate the uncertainty in the derived nova rates. Several models are considered to account for differences in the assumed properties of bulge and disk nova populations and in the absolute magnitude distribution. The simplest models, which assume uniform properties between bulge and disk novae, predict Galactic nova rates of ~50 to in excess of 100 per year, depending on the assumed incompleteness at bright magnitudes. Models where the disk novae are assumed to be more luminous than bulge novae are explored, and predict nova rates up to 30% lower, in the range of ~35 to ~75 per year. An average of the most plausible models yields a rate of 50_-23_^+31^yr^-1^, which is arguably the best estimate currently available for the nova rate in the Galaxy. Virtually all models produce rates that represent significant increases over recent estimates, and bring the Galactic nova rate into better agreement with that expected based on comparison with the latest results from extragalactic surveys.