- ID:
- ivo://CDS.VizieR/J/ApJ/830/17
- Title:
- Galactic Center secondary IR astrometric standards
- Short Name:
- J/ApJ/830/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new, more precise measurements of the mass and distance of our Galaxy's central supermassive black hole, Sgr A*. These results stem from a new analysis that more than doubles the time baseline for astrometry of faint stars orbiting Sgr A*, combining 2 decades of speckle imaging and adaptive optics data. Specifically, we improve our analysis of the speckle images by using information about a star's orbit from the deep adaptive optics data (2005-2013) to inform the search for the star in the speckle years (1995-2005). When this new analysis technique is combined with the first complete re-reduction of Keck Galactic Center speckle images using speckle holography, we are able to track the short-period star S0-38 (K-band magnitude=17, orbital period=19yr) through the speckle years. We use the kinematic measurements from speckle holography and adaptive optics to estimate the orbits of S0-38 and S0-2 and thereby improve our constraints of the mass (M_bh_) and distance (R_o_) of SgrA*: M_bh_=(4.02+/-0.16+/-0.04)x10^6^M_{sun}_ and 7.86+/-0.14+/-0.04kpc. The uncertainties in M_bh_ and R_o_ as determined by the combined orbital fit of S0-2 and S0-38 are improved by a factor of 2 and 2.5, respectively, compared to an orbital fit of S0-2 alone and a factor of ~2.5 compared to previous results from stellar orbits. This analysis also limits the extended dark mass within 0.01 pc to less than 0.13x10^6^M_{sun}_ at 99.7% confidence, a factor of 3 lower compared to prior work.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/143/211
- Title:
- Galactic Cepheids BVRI photometry
- Short Name:
- J/A+AS/143/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a new version of the catalogue of distances and light-curve parameters for Galactic classical Cepheids. The catalogue lists amplitudes, magnitudes at maximum light, and intensity means for 455 stars in BVRI filters of the Johnson system and (RI)_C_ filters of the Cron-Cousins system. The distances are based on our new multicolour set of Period/Luminosity relations and on our Cepheid-based solution for interstellar extinction law parameters and are referred to an LMC distance modulus of 18.25.
- ID:
- ivo://CDS.VizieR/J/A+A/493/785
- Title:
- Galactic disk stellar populations from ISOGAL
- Short Name:
- J/A+A/493/785
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identify the stellar populations (mostly red giants and young stars) detected in the ISOGAL survey at 7 and 15um towards a field (LN45) in the direction l=-45, b=0.0. The sources detected in the survey of the Galactic plane by the Infrared Space Observatory were characterised based on colour-colour and colour-magnitude diagrams. We combine the ISOGAL catalogue with the data from surveys such as 2MASS and GLIMPSE. Interstellar extinction and distance were estimated using the red clump stars detected by 2MASS in combination with the isochrones for the AGB/RGB branch. Absolute magnitudes were thus derived and the stellar populations identified from their absolute magnitudes and their infrared excess. A standard approach to analysing the ISOGAL disc observations has been established. We identify several hundred RGB/AGB stars and 22 candidate young stellar objects in the direction of this field in an area of 0.16deg^2^. An overdensity of stellar sources is found at distances corresponding to the distance of the Scutum-Crux spiral arm. In addition, we determined mass-loss rates of AGB-stars using dust radiative transfer models from the literature.
- ID:
- ivo://CDS.VizieR/J/A+A/474/121
- Title:
- Galactic globular cluster 2MASS GC02 JKs phot.
- Short Name:
- J/A+A/474/121
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained deep infrared images and K-band spectra of the Galactic globular cluster 2MASS GC02. A variable star search has also been carried out. Some basic physical properties of the cluster, such as metallicity, reddening, distance modulus and radial velocity, are derived. These measurements are based on an analysis of the J-Ks versus Ks color-magnitude diagram of the cluster. Spectroscopically derived metallicities and radial velocities of 15 stars are presented. In addition, periods and amplitudes are provided for five RR Lyrae stars discovered in the field. The cluster is moderately metal-rich and has a relatively high radial velocity. Its horizontal branch appears to be predominantly red, though our photometry cannot rule out the presence of a blue component as seen in NGC 6388 and NGC 6441. Similar to these two clusters, the detected RR Lyrae stars in GC02 have anomalously long periods for the cluster's moderately high metallicity, which suggests that it too is an Oosterhoff type III cluster. Comparison with the existing kinematic and abundance information for the Galactic globular clusters shows that GC02 most probably belongs to the bulge sub population, although an inner halo association cannot be ruled out.
- ID:
- ivo://CDS.VizieR/J/MNRAS/447/2307
- Title:
- Galactic HII region IRAS 16148-5011 content
- Short Name:
- J/MNRAS/447/2307
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An investigation of the IRAS 16148-5011 region - a cluster at a distance of 3.6kpc - is presented here, carried out using multiwavelength data in near-infrared (NIR) from the 1.4m Infrared Survey Facility telescope, mid-infrared (MIR) from the archival Spitzer GLIMPSE (Galactic Legacy Infrared Midplane Survey Extraordinaire) survey, far-infrared (FIR) from the Herschel archive, and low-frequency radio continuum observations at 1280 and 843MHz from the Giant Metrewave Radio Telescope and Molonglo Survey archive, respectively. A combination of NIR and MIR data is used to identify 7 Class I and 133 Class II sources in the region. Spectral energy distribution (SED) analysis of selected sources reveals a 9.6M_{sun}_ high-mass source embedded in nebulosity. However, Lyman continuum luminosity calculation using radio emission - which shows a compact HII region - indicates the spectral type of the ionizing source to be earlier than B0-O9.5. Free-free emission SED modelling yields the electron density as 138cm^-3^, and thus the mass of the ionized hydrogen as ~16.4M_{sun}_. Thermal dust emission modelling, using the FIR data from Herschel and performing modified blackbody fits, helped us construct the temperature and column density maps of the region, which show peak values of 30K and 3.3x10^22^cm^-2^, respectively. The column density maps reveal an A_V_>20mag extinction associated with the nebular emission, and weak filamentary structures connecting dense clumps. The clump associated with this IRAS object is found to have dimensions of ~1.1pcx0.8pc, and a mass of 10^23^M_{sun}_.
- 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.
- 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://CDS.VizieR/J/A+A/653/A133
- Title:
- GALACTICNUCLEUS IV. JHKs imaging survey
- Short Name:
- J/A+A/653/A133
- Date:
- 10 Mar 2022 11:26:04
- Publisher:
- CDS
- Description:
- The extreme extinction (A_V_~30mag) and its variation on arc-second scales towards the Galactic centre hamper the study of its stars. Their analysis is restricted to the near infrared (NIR) regime, where the extinction curve can be approximated by a broken power law for the JHKs bands. Therefore, correcting for extinction at these wavelengths is fundamental to analyse the structure and stellar population of the central regions of our Galaxy. We aim at: (1) Discussing different strategies to de-redden the photometry and checking the usefulness of extinction maps to deal with variable stars. (2) Building and making publicly available extinction maps for the NIR bands JHKs. (3) Creating a de-reddened catalogue of the GALACTICNUCLEUS (GNS) survey, identifying foreground stars. (4) Performing a preliminary analysis of the de-reddened $K_s$ luminosity functions (KLFs). We use photometry from the GNS survey to create extinction maps for the whole catalogue. We take red clump (RC) and red giant stars of similar brightness as a reference to build the maps, and de-redden the GNS photometry. We discuss the limitations of the process and analyse non-linear effects of the de-reddening. We create high resolution (~3'') extinction maps with low statistical and systematics uncertainties (<~5%), and compute average extinctions for each of the regions covered by the GNS. We check that our maps effectively correct the differential extinction reducing the spread of the RC features by a factor of ~2. We assess the validity of the broken power law approach computing two equivalent extinction maps A_H_ using either JH and HKs photometry for the same reference stars, and obtain compatible average extinctions within the uncertainties. Finally, we analyse de-reddened KLFs for different line-of-sights and find that the regions belonging to the NSD contain a homogeneous stellar population that is significantly different from the one in the innermost bulge regions.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A83
- Title:
- GALACTICNUCLEUS: JHKs imaging survey
- Short Name:
- J/A+A/610/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic Centre is of fundamental astrophysical interest, but existing near-infrared surveys fall short covering it adequately, either in terms of angular resolution, multi-wavelength coverage, or both. Here we introduce the GALACTICNUCLEUS survey, a JHKs imaging survey of the centre of the Milky Way with a 0.2" angular resolution. The purpose of this paper is to present the observations of Field 1 of our survey, centred approximately on SgrA* with an approximate size of 7.95'x3.43'. We describe the observational set-up and data reduction pipeline and discuss the quality of the data. Finally, we present the analysis of the data. The data were acquired with the near-infrared camera HAWK-I (High Acuity Wide field K-band Imager) at the ESO VLT (Very Large Telescope). Short readout times in combination with the speckle holography algorithm allowed us to produce final images with a stable, Gaussian PSF (point spread function) of 0.2" FWHM (full width at half maximum). Astrometric calibration is achieved via the VVV (VISTA Variables in the Via Lactea) survey and photometric calibration is based on the SIRIUS/IRSF (Infrared Survey Facility telescope) survey. The quality of the data is assessed by comparison between observations of the same field with different detectors of HAWK-I and at different times. We reach 5{sigma} uncertainties are less than 0.05" at J<=20, H<=17, and Ks<=16. We can distinguish five stellar populations in the colour-magnitude diagrams; three of them appear to belong to foreground spiral arms, and the other two correspond to high- and low-extinction star groups at the Galactic Centre. We use our data to analyse the near-infrared extinction curve and find some evidence for a possible difference between the extinction index between J-H and H-Ks. However, we conclude that it can be described very well by a power law with an index of JHKs=2.30+.-0.08. We do not find any evidence that this index depends on the position along the line of sight, or on the absolute value of the extinction. We produce extinction maps that show the clumpiness of the ISM (interstellar medium) at the Galactic Centre. Finally, we estimate that the majority of the stars have solar or super-solar metallicity by comparing our extinction-corrected colour-magnitude diagrams with isochrones with different metallicities and a synthetic stellar model with a constant star formation.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A20
- Title:
- GALACTICNUCLEUS JHKs imaging survey. II.
- Short Name:
- J/A+A/631/A20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The high extinction and extreme source crowding of the central regions of the Milky Way are serious obstacles to the study of the structure and stellar population of the Galactic centre (GC). Surveys that cover the GC region (2MASS, UKIDSS, VVV, SIRIUS) do not have the necessary high angular resolution. Therefore, a high angular resolution survey in the near infrared is crucial to improve the state of the art. Here, we present the GALACTICNUCLEUS catalogue, a near infrared JHKs high angular resolution (0.2") survey of the nuclear bulge of the Milky Way. We explain in detail the data reduction, data analysis, calibration, and uncertainty estimation of the GALACTICNUCLEUS survey. We assess the data quality comparing our results with previous surveys. We obtained accurate JHKs photometry ~3.3x10^6^ stars in the GC detecting around 20% in J, 65% in H and 90% in Ks. The survey covers a total area of ~0.3 square degrees, which corresponds to ~6000pc^2^. The GALACTICNUCLEUS survey reaches 5 sigma detections for J~22mag, H~21mag and Ks~21mag. The uncertainties are below 0.05mag at J~21mag, H~19mag and Ks~18mag. The zero point systematic uncertainty is <~0.04mag in all three bands. We present colour-magnitude diagrams for the different regions covered by the survey.
