- ID:
- ivo://CDS.VizieR/J/ApJ/809/10
- Title:
- Compact radio sources within 30" of Sgr A*
- Short Name:
- J/ApJ/809/10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent broadband 34 and 44GHz radio continuum observations of the Galactic center have revealed 41 massive stars identified with near-IR (NIR) counterparts, as well as 44 proplyd candidates within 30" of SgrA*. Radio observations obtained in 2011 and 2014 have been used to derive proper motions of eight young stars near Sgr A*. The accuracy of proper motion estimates based on NIR observations by Lu et al. (2009ApJ...690.1463L) and Paumard et al. (2006, J/ApJ/643/1011) have been investigated by using their proper motions to predict the 2014 epoch positions of NIR stars and comparing the predicted positions with those of radio counterparts in the 2014 radio observations. Predicted positions from Lu et al. show an rms scatter of 6mas relative to the radio positions, while those from Paumard et al. show rms residuals of 20mas. We also determine the mass-loss rates of 11 radio stars, finding rates that are on average ~2 times smaller than those determined from model atmosphere calculations and NIR data. Clumpiness of ionized winds would reduce the mass loss rate of WR and O stars by additional factors of 3 and 10, respectively. One important implication of this is a reduction in the expected mass accretion rate onto Sgr A* from stellar winds by nearly an order of magnitude to a value of a few x10^-7^m_{sun}_/yr. Finally, we present the positions of 318 compact radio sources within 30" of Sgr A*, 45 of which have stellar counterparts in the NIR K_s_ (2.18{mu}m) and L' (3.8{mu}m) bands.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/405/1293
- Title:
- Compact star clusters in M81
- Short Name:
- J/MNRAS/405/1293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the population of compact star clusters (CSCs) in M81, using the Hubble Space Telescope/Advanced Camera for Surveys (ACS) images in the filters F435W, F606W and F814W covering, for the first time, the entire optical extent of the galaxy. Our sample contains 435 clusters of full width at half-maximum less than 10 ACS pixels (9pc). The sample shows the presence of two cluster populations, a blue group of 263 objects brighter than B=22mag, and a red group of 172 objects, brighter than B=24mag. On the basis of analysis of colour-magnitude diagrams and making use of simple stellar population models,
- ID:
- ivo://CDS.VizieR/J/ApJ/824/71
- Title:
- Compact star clusters in M51 with HST
- Short Name:
- J/ApJ/824/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of 3816 compact star clusters in the grand design spiral galaxy M51 based on observations taken with the Hubble Space Telescope (HST). The age distribution of the clusters declines starting at very young ages, and can be represented by a power law, dN/d{tau}{propto}{tau}^gamma^, with {gamma}=-0.65+/-0.15. No significant changes in the shape of the age distribution at different masses is observed. The mass function of the clusters younger than {tau}~400Myr can also be described by a power law, dN/dM{propto}M^{beta}^, with {beta}~-2.1+/-0.2. We compare these distributions with the predictions from various cluster disruption models, and find that they are consistent with models where clusters disrupt approximately independent of their initial mass, but not with models where lower mass clusters are disrupted earlier than their higher mass counterparts. We find that the half-light radii of clusters more massive than M~3x10^4^M_{sun}_ and with ages between 100 and 400Myr are larger by a factor of ~3-4 than their counterparts that are younger than 10^7^ years old, suggesting that the clusters physically expand during their early life.
- ID:
- ivo://CDS.VizieR/J/PASJ/56/1025
- Title:
- Compact star clusters in SW field of M31
- Short Name:
- J/PASJ/56/1025
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A survey for compact clusters with a dimension of 10pc order was conducted in an area of about 500 square arc-minutes of the south-west part of the M31 disk, making use of the high-resolution capability of Suprime-Cam. Photometry in the B, V and R broad-bands, and in the R* medium-band centered around H{alpha} with varying apertures was carried out for about 1200 targets, which are related to about 300 compact objects detected in the survey. The results for 101 prominent compact objects are presented as photometric catalogues and morphological atlases, separately for samples with and without strong H{alpha} emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/703/1872
- Title:
- Compact star clusters in the M31 disk
- Short Name:
- J/ApJ/703/1872
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out a survey of compact star clusters (apparent size <~3") in the southwest part of the M31 galaxy, based on the high-resolution Suprime-Cam images (17.5'x28.5'), covering ~15% of the deprojected galaxy disk area. The UBVRI photometry of 285 cluster candidates (V<~20.5mag) was performed using frames of the Local Group Galaxies Survey. The final sample, containing 238 high probability star cluster candidates (typical half-light radius r_h_~1.5pc), was selected by specifying a lower limit of r_h_>~0.15" (>~0.6pc). We derived cluster parameters based on the photometric data and multiband images by employing simple stellar population models. The clusters have a wide range of ages from ~5Myr (young objects associated with 24um and/or H{alpha} emission) to ~10Gyr (globular cluster candidates), and possess mass in a range of 3.0<~log(m/m_{sun}_)<~4.3 peaking at m~4000m_{sun}_. Typical age of these intermediate-mass clusters is in the range of 30Myr<~t<~3Gyr, with a prominent peak at ~70Myr. These findings suggest a rich intermediate-mass star cluster population in M31, which appears to be scarce in the Milky Way galaxy.
- ID:
- ivo://CDS.VizieR/J/MNRAS/408/2261
- Title:
- Compact steep spectrum new sample
- Short Name:
- J/MNRAS/408/2261
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new sample of compact steep spectrum (CSS) sources with radio luminosity below 10^26^W/Hz at 1.4GHz; these are called low-luminosity compact (LLC) objects. The sources have been selected from the Faint Images of the Radio Sky at Twenty-cm (FIRST) survey and observed with the multi-element radio linked interferometer network (MERLIN) at the L and C bands. The main criterion used for selection was the luminosity of the objects, and approximately one-third of the CSS sources from the new sample have a value of radio luminosity comparable to Fanaroff-Riley type 1 sources (FR Is). About 80 per cent of the sources have been resolved and about 30 per cent have weak extended emission and disturbed structures when compared with the observations of higher-luminosity CSS sources. We have studied the correlation between radio power and linear size, and the redshift with a larger sample that also included published samples of compact objects and large-scale FR IIs and FR Is.
- ID:
- ivo://CDS.VizieR/J/MNRAS/382/1342
- Title:
- Compact stellar systems around NGC 1399
- Short Name:
- J/MNRAS/382/1342
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained spectroscopic redshifts of colour-selected point sources in four wide area VLT-FLAMES (Very Large Telescope-Fibre Large Array Multi Element Spectrograph) fields around the Fornax cluster giant elliptical galaxy NGC 1399, identifying as cluster members 27 previously unknown faint (-10.5<M_g'_<-8.8) compact stellar systems (CSS), and improving redshift accuracy for 23 previously catalogued CSS.
- ID:
- ivo://CDS.VizieR/J/MNRAS/315/839
- Title:
- Compact variable radio sources at 151MHz. I.
- Short Name:
- J/MNRAS/315/839
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cambridge Low-Frequency Synthesis Telescope has been used to produce a representative sample of low-frequency variable sources. 20 fields, each covering an area of approximately 9{deg}x9{deg}cosecDE, have been observed at 151MHz at between 2 and 10 epochs over the period from 1984 to 1996. At each epoch, maps were made with rms noise levels of typically 10^-15^mJy/beam. From a total of ~6000 sources detected on these maps, 207 are found for which the flux density variations between at least two epochs appear significant at greater than the 3{sigma} level. A numerical model is used to assess the true significance of the variability, given the analysis method adopted. This shows that for about half of the sources which appear to vary by >3{sigma} the variability is genuine. For the other half it is caused by random statistical fluctuations; most of the spurious variables vary by <=3.5{sigma} between a single pair of epochs. A catalogue of the variable sources is presented, which includes an estimate of the probability that a given source is a genuine variable. Fractional flux density variations of between 5 and 100% (typically 15-25%) have been detected on a range of time-scales from 1 to 12 years.
- ID:
- ivo://CDS.VizieR/J/ApJ/757/141
- Title:
- Companion IR detection limits in young associations
- Short Name:
- J/ApJ/757/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The frequency and properties of multiple star systems offer powerful tests of star formation models. Multiplicity surveys over the past decade have shown that binary properties vary strongly with mass, but the functional forms and the interplay between frequency and semimajor axis remain largely unconstrained. We present the results of a large-scale survey of multiplicity at the bottom of the initial mass function in several nearby young associations, encompassing 78 very low mass members observed with Keck laser guide star adaptive optics. Our survey confirms the overall trend observed in the field for lower-mass binary systems to be less frequent and more compact, including a null detection for any substellar binary systems with separations wider than ~7AU. Combined with a Bayesian re-analysis of existing surveys, our results demonstrate that the binary frequency and binary separations decline smoothly between masses of 0.5M_{sun}_ and 0.02M_{sun}_, though we cannot distinguish the functional form of this decline due to a degeneracy between the total binary frequency and the mean binary separation. We also show that the mass ratio distribution becomes progressively more concentrated at q~1 for declining masses, though a small number of systems appear to have unusually wide separations and low-mass ratios for their mass. Finally, we compare our results to synthetic binary populations generated by smoothed particle hydrodynamic simulations, noting the similarities and discussing possible explanations for the differences.
- ID:
- ivo://CDS.VizieR/J/AJ/126/1707
- Title:
- Companions of bright barred galaxies
- Short Name:
- J/AJ/126/1707
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Companion galaxy environment for a subset of 78 bright and nearby barred galaxies from the Shapley-Ames Catalog is presented. Among the spiral barred galaxies, there are Seyfert galaxies, galaxies with circumnuclear structures, galaxies not associated with any large-scale galaxy cloud structure, galaxies with peculiar disk morphology (crooked arms), and galaxies with normal disk morphology; the list includes all Hubble types. The companion galaxy list includes the number of companion galaxies within 20 diameters, their Hubble type, and projected separation distance.