- ID:
- ivo://CDS.VizieR/J/AJ/133/2764
- Title:
- M31 globular clusters structural parameters
- Short Name:
- J/AJ/133/2764
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The structures of globular clusters (GCs) reflect their dynamical states and past histories. High-resolution imaging allows the exploration of morphologies of clusters in other galaxies. Surface brightness profiles from new Hubble Space Telescope observations of 34 GCs in M31 are presented, together with fits of several different structural models to each cluster. M31 clusters appear to be adequately fit by standard King models and do not obviously require alternate descriptions with relatively stronger halos, such as are needed to fit many GCs in other nearby galaxies. The derived structural parameters are combined with corrected versions of those measured in an earlier survey in order to construct a comprehensive catalog of structural and dynamical parameters for M31 GCs with a sample size similar to that for the Milky Way. Clusters in M31, the Milky Way, Magellanic Clouds, the Fornax dwarf spheroidal, and NGC 5128 define a very tight fundamental plane with identical slopes. The combined evidence for these widely different galaxies strongly reinforces the view that old GCs have near-universal structural properties, regardless of host environment.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/803
- Title:
- M31 globular cluster system
- Short Name:
- J/MNRAS/402/803
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an updated catalogue of M31 globular clusters (GCs) based on images from the Wide Field Camera (WFCAM) on the United Kingdom Infrared Telescope and from the Sloan Digital Sky Survey (SDSS). Our catalogue includes new, self-consistent ugriz and K-band photometry of these clusters. We discuss the difficulty of obtaining accurate photometry of clusters projected against M31 due to small-scale background structure in the galaxy. We consider the effect of this on the accuracy of our photometry and provide realistic photometric error estimates. We investigate possible contamination in the current M31 GC catalogues using the excellent spatial resolution of these WFCAM images combined with the SDSS multicolour photometry. We identify a large population of clusters with very blue colours. Most of these have recently been proposed by other works as young clusters. We distinguish between these, and old clusters, in the final classifications. Our final catalogue includes 416 old clusters, 156 young clusters and 373 candidate clusters. We also investigate the structure of M31's old GCs using previously published King model fits to these WFCAM images. We demonstrate that the structure and colours of M31's old GC system are similar to those of the Milky Way. One GC (B383) is found to be significantly brighter in previous observations than observed here. We investigate all of the previous photometry of this GC and suggest that this variability appears to be genuine and short lived. We propose that the large increase in its luminosity may have been due to a classical nova in the GC at the time of the previous observations in 1989.
- ID:
- ivo://CDS.VizieR/J/AJ/134/1488
- Title:
- MG1 Variable Star Catalog (MG1-VSC)
- Short Name:
- J/AJ/134/1488
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of the first MOTESS-GNAT variable-star survey, a deep, wide-field variability survey conducted over 2yr with a total sky coverage of 300deg^2^. In this survey, we identified 26042 variable-star candidates with magnitudes R=13-19, including 5271 that are periodic at the 99% confidence level. We recovered 59 out of 68 members of the General Catalogue of Variable Stars (GCVS) that are in this brightness range. We discuss the implications for completeness and accuracy for both this survey and the GCVS; the implied completeness for distinctly classifiable variable stars in our survey is ~85%-90%. We also discuss some of the caveats of our survey results. We conclude that this instrument design is ideal for an inexpensive, longitudinally distributed telescope network that could be used to study faint or rare transient phenomena in a previously unexplored regime of parameter space.
3944. M31 Herschel images
- ID:
- ivo://CDS.VizieR/J/A+A/567/A71
- Title:
- M31 Herschel images
- Short Name:
- J/A+A/567/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dust and stars play a complex game of interactions in the interstellar medium and around young stars. The imprints of these processes are visible in scaling relations between stellar characteristics, star formation parameters, and dust properties. Aims. In the present work, we aim to examine dust scaling relations on a sub-kpc resolution in the Andromeda galaxy (M31). The goal is to investigate the properties of M31 on both a global and local scale and compare them to other galaxies of the local universe. Methods. New Herschel observations are combined with available data from GALEX, SDSS, WISE, and Spitzer to construct a dataset covering UV to submm wavelengths. All images were brought to the beam size and pixel grid of the SPIRE 500um frame. This divides M31 in 22437 pixels of 36 arcseconds in size on the sky, corresponding to physical regions of 137x608pc in the galaxy's disk. A panchromatic spectral energy distribution was modelled for each pixel and maps of the physical quantities were constructed. Several scaling relations were investigated, focussing on the interactions of dust with starlight. Results. We find, on a sub-kpc scale, strong correlations between Mdust/M* and NUV-r, and between Mdust/M* and mu* (the stellar mass surface density). Striking similarities with corresponding relations based on integrated galaxies are found. We decompose M31 in four macro-regions based on their FIR morphology; the bulge, inner disk, star forming ring, and the outer disk region. In the scaling relations, all regions closely follow the galaxy-scale average trends and behave like galaxies of different morphological types. The specific star formation characteristics we derive for these macro-regions give strong hints of an inside-out formation of the bulge-disk geometry, as well as an internal downsizing process. Within each macro-region, however, a great diversity in individual micro-regions is found, regardless of the properties of the macro-regions. Furthermore, we confirm that dust in the bulge of M31 is heated only by the old stellar populations. Conclusions. In general, the local dust scaling relations indicate that the dust content in M31 is maintained by a subtle interplay of past and present star formation. The similarity with galaxy-based relations strongly suggests that they are in situ correlations, with underlying processes that must be local in nature.
- ID:
- ivo://CDS.VizieR/J/MNRAS/462/1444
- Title:
- MHO catalogue for Cassiopeia and Auriga
- Short Name:
- J/MNRAS/462/1444
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of 35.5deg^2^ of images in the 1-0 S(1) line of H_2_ from the UK Widefield Infrared Survey for H_2_ (UWISH2) towards Cassiopeia and Auriga. We have identified 98 Molecular Hydrogen emission-line Objects (MHOs) driven by Young Stellar Objects, 60 per cent of which are bipolar outflows and all are new discoveries. We estimate that the UWISH2-extended emission object catalogue contains fewer than 2 per cent false positives and is complete at the 95 per cent level for jets and outflows brighter than the UWISH2 detection limit. We identified reliable driving source candidates for three quarters of the detected outflows, 40 per cent of which are associated with groups and clusters of stars. The driving source candidates are 20 per cent protostars, the remainder are Classical T-Tauri Stars. We also identified 15 new star cluster candidates near MHOs in the survey area. We find that the typical outflow identified in the sample has the following characteristics: the position angles are randomly orientated; bipolar outflows are straight within a few degrees; the two lobes are slightly asymmetrical in length and brightness; the length and brightness of the lobes are not correlated; typical time gaps between major ejections of material are 1-3 kyr, hence FU-Ori or EX-Ori eruptions are most likely not the cause of these, but we suggest MNors as a possible source. Furthermore, we find that outflow lobe length distributions are statistically different from the widely used total length distributions. There are a larger than expected number of bright outflows indicating that the flux distribution does not follow a power law.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/3257
- Title:
- MHO catalogue for Serpens and Aquila
- Short Name:
- J/MNRAS/421/3257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Jets and outflows from young stellar objects (YSOs) are important signposts of currently ongoing star formation. In order to study these objects, we are conducting an unbiased survey along the Galactic plane in the 1-0 S(1) emission line of molecular hydrogen at 2.122 um using the United Kingdom Infrared Telescope. In this paper, we are focusing on a 33-deg^2^-sized region in Serpens and Aquila (18{deg}<l<30{deg}; -1.5{deg}<b<+1.5{deg}). We trace 131 jets and outflows from YSOs, which results in a 15-fold increase in the total number of known molecular hydrogen outflows. Compared to this, the total integrated 1-0 S(1) flux of all objects just about doubles, since the known objects occupy the bright end of the flux distribution. Our completeness limit is 3x10^-18^W/m^2^ with 70 per cent of the objects having fluxes of less than 10^-17^W/m^2^.
- ID:
- ivo://CDS.VizieR/J/ApJ/844/38
- Title:
- MHOs toward 22 regions with H2 fluxes
- Short Name:
- J/ApJ/844/38
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a narrow-band near-infrared imaging survey for Molecular Hydrogen emission-line Objects (MHOs) toward 26 regions containing high-mass protostellar candidates and massive molecular outflows. We have detected a total of 236 MHOs, 156 of which are new detections, in 22 out of the 26 regions. We use H_2_2.12{mu}m/H_2_2.25{mu}m flux ratios, together with morphology, to separate the signatures of fluorescence associated with photo- dissociation regions (PDRs) from shocks associated with outflows in order to identify the MHOs. PDRs have typical low flux ratios of ~1.5-3, while the vast majority of MHOs display flux ratios typical of C-type shocks (~6-20). A few MHOs exhibit flux ratios consistent with expected values for J-type shocks (~3-4), but these are located in regions that may be contaminated with fluorescent emission. Some previously reported MHOs have low flux ratios, and are likely parts of PDRs rather than shocks indicative of outflows. We identify a total of 36 outflows across the 22 target regions where MHOs were detected. In over half these regions, MHO arrangements and fluorescent structures trace features present in CO outflow maps, suggesting that the CO emission traces a combination of dynamical effects, which may include gas entrained in expanding PDRs as well as bipolar outflows. Where possible, we link MHO complexes to distinct outflows and identify candidate driving sources.
- ID:
- ivo://CDS.VizieR/J/ApJS/159/242
- Title:
- 325MHz radio survey in M31. II.
- Short Name:
- J/ApJS/159/242
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have previously presented the results of a 325MHz radio survey of M31 (Cat. <J/ApJS/155/89>, conducted with the A configuration of the Very Large Array. In this survey, a total of 405 radio sources between <~6" and 170" in extent were mapped with a resolution of 6" and a sensitivity of ~0.6mJy/beam. Here we compare the resultant source list and image with other radio, IR, optical, and X-ray observations and catalogs of the region.
- ID:
- ivo://CDS.VizieR/J/ApJS/249/16
- Title:
- Microlensing event in the OGLE-IV GVS survey
- Short Name:
- J/ApJS/249/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Searches for gravitational microlensing events are traditionally concentrated on the central regions of the Galactic bulge but many microlensing events are expected to occur in the Galactic plane, far from the Galactic Center. Owing to the difficulty in conducting high-cadence observations of the Galactic plane over its vast area, which are necessary for the detection of microlensing events, their global properties were hitherto unknown. Here, we present results of the first comprehensive search for microlensing events in the Galactic plane. We searched an area of almost 3000 square degrees along the Galactic plane (|b|<7{deg}, 0{deg}<l<50{deg}, 190{deg}<l<360{deg}) observed by the Optical Gravitational Lensing Experiment (OGLE) during 2013-2019 and detected 630 events. We demonstrate that the mean Einstein timescales of Galactic plane microlensing events are on average three times longer than those of Galactic bulge events, with little dependence on the Galactic longitude. We also measure the microlensing optical depth and event rate as a function of Galactic longitude and demonstrate that they exponentially decrease with the angular distance from the Galactic Center (with the characteristic angular scale length of 32{deg}). The average optical depth decreases from 0.5x10^-6^ at l=10{deg} to 1.5x10^-8^ in the Galactic anticenter. We also find that the optical depth in the longitude range 240{deg}<l<330{deg} is asymmetric about the Galactic equator, which we interpret as a signature of the Galactic warp.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/29
- Title:
- Microlensing events toward the Galactic bulge
- Short Name:
- J/ApJS/244/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The number and properties of observed gravitational microlensing events depend on the distribution and kinematics of stars and other compact objects along the line of sight. In particular, precise measurements of the microlensing optical depth and event rate toward the Galactic bulge enable strict tests of competing models of the Milky Way. Previous estimates, based on samples of up to a few hundred events, gave larger values than expected from the Galactic models and were difficult to reconcile with other constraints on the Galactic structure. Here we used long-term photometric observations of the Galactic bulge by the Optical Gravitational Lensing Experiment (OGLE) to select a homogeneous sample of 8000 gravitational microlensing events. We created the largest and most accurate microlensing optical depth and event rate maps of the Galactic bulge. The new maps ease the tension between the previous measurements and Galactic models. They are consistent with some earlier calculations based on bright stars and are systematically ~30% smaller than the other estimates based on "all-source" samples of microlensing events. The difference is caused by the careful estimation of the source star population. The new maps agree well with predictions based on the Besancon model of the Galaxy. Apart from testing the Milky Way models, our maps may have numerous other applications, such as the measurement of the initial mass function or constraining the dark matter content in the Milky Way center. The new maps will also inform the planning of future space-based microlensing experiments by revising the expected number of events.
