- ID:
- ivo://CDS.VizieR/J/A+A/640/A83
- Title:
- Mass determination using microlensing by Gaia
- Short Name:
- J/A+A/640/A83
- Date:
- 15 Dec 2021 08:30:09
- Publisher:
- CDS
- Description:
- Astrometric gravitational microlensing can be used to determine the mass of a single star (the lens) with an accuracy of a few percent. To do so, precise measurements of the angular separations between lens and background star with an accuracy below 1 milli-arcsecond at different epochs are needed. Therefore only the most accurate instruments can be used. However, since the timescale is on the order of months to years, the astrometric deflection might be detected by Gaia, even though each star is only observed on a low cadence. We want to show how accurately Gaia can determine the mass of the lensing star. Using conservative assumptions based on the results of the second Gaia data release (GaiaDR2), we simulated the individual Gaia measurements for 501 predicted astrometric microlensing events during the Gaia era (2014.5 - 2026.5). For this purpose we used the astrometric parameters of Gaia DR2, as well as an approximative mass based on the absolute G magnitude. By fitting the motion of the lens and source simultaneously, we then reconstructed the 11 parameters of the lensing event. For lenses passing by multiple background sources, we also fitted the motion of all background sources and the lens simultaneously. Using a Monte-Carlo simulation we determined the achievable precision of the mass determination. We find that Gaia can detect the astrometric deflection for 114 events. Furthermore, for 13 events Gaia can determine the mass of the lens with a precision better than 15% and for 13 + 21 = 34 events with a precision of 30% or better.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/455/357
- Title:
- 2MASS J18212815+1414010 field stars
- Short Name:
- J/MNRAS/455/357
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used the OSIRIS camera at the 10.4m Gran Telescopio Canarias (GTC) to monitor the astrometric motion of the L4.5 dwarf 2M1821+14 over 17 months. The astrometric residuals of 11 epochs have an rms dispersion of 0.4mas, which is larger than the average precision of 0.23mas per epoch and hints towards an additional signal or excess noise. Comparison of the point-spread functions in OSIRIS and FORS2/VLT images reveals no differences critical for high-precision astrometry, despite the GTC's segmented primary mirror. We attribute the excess noise to an unknown effect that may be uncovered with additional data. For 2M1821+14, we measured a relative parallax of 10^6.15^+/-0.18mas and determined a correction of 0.50+/-0.05mas to absolute parallax, leading to a distance of 9.38+/-0.03pc. We excluded at 3{sigma} confidence the presence of a companion to 2M1821+14 down to a mass ratio of 0.1 (~5M_Jupiter_) with a period of 50-1000d and a separation of 0.1-0.7au. The accurate parallax allowed us to estimate the age and mass of 2M1821+14 of 120-700Myr and 0.049^+0.014^_-0.024_M_{sun}_, thus confirming its intermediate age and substellar mass. We complement our study with a parallax and proper motion catalogue of 587 stars (i'=~15.5-22) close to 2M1821+14, used as astrometric references. This study demonstrates submas astrometry with the GTC, a capability applicable for a variety of science cases including the search for extrasolar planets and relevant for future astrometric observations with E-ELT and TMT.
- ID:
- ivo://CDS.VizieR/J/AJ/106/773
- Title:
- Mass-luminosity relation
- Short Name:
- J/AJ/106/773
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mass-luminosity relations determined at infrared wavelengths are presented for stars with masses 1.0 to 0.08 solar masses. Using infrared speckle imaging techniques on a sample of nearby binaries, we have been able to concentrate on the lower main sequence (Mass<=0.5M_sun_), for which an accurate mass-luminosity calibration has remained problematic. In addition, the mass-visual luminosity relation for stars with 2.0>=Mass>=0.08M_sun_ is produced by implementing new photometric relations linking V to JHK wavelengths for the nearby stars, supplemented with eclipsing binary information. These relations predict that objects with masses ~0.08 solar masses have M(K)~=10 and M(V)~=18.
- ID:
- ivo://CDS.VizieR/I/272
- Title:
- M2000: Bordeaux Carte du Ciel zone +11<Dec<+18
- Short Name:
- I/272
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- During four years, systematic observations have been conducted in drift scan mode with the Bordeaux automated meridian circle in the declination band [+11 ; +18]. The resulting astrometric catalog includes about 2 300 000 stars down to the magnitude limit V_M_=16.3. Nearly all stars (96%) have been observed at least 6 times, the catalog being complete down to V_M_=15.4. The median internal standard error in position is about 35mas in the magnitude range 11<V_M_<15, which degrades to about 50mas when the faintest stars are considered. M2000 provides also one band photometry with a median internal standard error of 0.04mag. Comparisons with the Hipparcos and bright part of Tycho-2 catalogs have enabled to estimate external errors in position to be lower than 40mas. In this zone and at epoch 1998, the faint part of Tycho-2 is found to have an accuracy of 116mas in alpha instead of 82mas deduced from the model-based standard errors given in the catalog.
- ID:
- ivo://CDS.VizieR/J/A+A/649/A7
- Title:
- MC structure and properties
- Short Name:
- J/A+A/649/A7
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- This work is part of the Gaia Data Processing and Analysis Consortium papers published with the Gaia Early Data Release 3 (EDR3). It is one of the demonstration papers aiming to highlight the improvements and quality of the newly published data by applying them to a scientific case. We use the Gaia EDR3 data to study the structure and kinematics of the Magellanic Clouds. The large distance to the Clouds is a challenge for the Gaia astrometry. The Clouds lie at the very limits of the usability of the Gaia data, which makes the Clouds an excellent case study for evaluating the quality and properties of the Gaia data. The basis of our work are two samples selected to provide a representation as clean as possible of the stars of the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). The selection used criteria based on position, parallax, and proper motions to remove foreground contamination from the Milky Way, and allowed the separation of the stars of both Clouds. From these two samples we defined a series of subsamples based on cuts in the colour-magnitude diagram; these subsamples were used to select stars in a common evolutionary phase and can also be used as approximate proxies of a selection by age. We compared the Gaia Data Release 2 (DR2) and Gaia EDR3 performances in the study of the Magellanic Clouds and show the clear improvements in precision and accuracy in the new release. We also show that the systematics still present in the data make the determination of the 3D geometry of the LMC a difficult endeavour; this is at the very limit of the usefulness of the Gaia EDR3 astrometry, but it may become feasible with the use of additional external data. We derive radial and tangential velocity maps and global profiles for the LMC for the several subsamples we defined. To our knowledge, this is the first time that the two planar components of the ordered and random motions are derived for multiple stellar evolutionary phases in a galactic disc outside the Milky Way, showing the differences between younger and older phases. We also analyse the spatial structure and motions in the central region, the bar, and the disc, providing new insights into features and kinematics. Finally, we show that the Gaia EDR3 data allows clearly resolving the Magellanic Bridge, and we trace the density and velocity flow of the stars from the SMC towards the LMC not only globally, but also separately for young and evolved populations. This allows us to confirm an evolved population in the Bridge that is slightly shift from the younger population. Additionally, we were able to study the outskirts of both Magellanic Clouds, in which we detected some well-known features and indications of new ones.
- ID:
- ivo://CDS.VizieR/J/A+A/534/A109
- Title:
- MCXC Meta-Catalogue X-ray galaxy Clusters
- Short Name:
- J/A+A/534/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the compilation and properties of a meta-catalogue of X-ray detected clusters of galaxies, the MCXC. This very large catalogue is based on publicly available ROSAT All Sky Survey-based (NORAS, REFLEX, BCS, SGP, NEP, MACS, and CIZA) and serendipitous (160SD, 400SD, SHARC, WARPS, and EMSS) cluster catalogues. Data have been systematically homogenised to an overdensity of 500, and duplicate entries from overlaps between the survey areas of the individual input catalogues are carefully handled. The MCXC comprises 1743 clusters with virtually no duplicate entries. For each cluster the MCXC provides three identifiers, a redshift, coordinates, membership in the original catalogue, and standardised 0.1-2.4keV band luminosity L_500_, total mass M_500_, and radius R_500_. The meta-catalogue additionally furnishes information on overlaps between the input catalogues and the luminosity ratios when measurements from different surveys are available, and gives notes on individual objects.
- ID:
- ivo://CDS.VizieR/I/210
- Title:
- Mean Positions and proper motions of 995 FK4Sup stars
- Short Name:
- I/210
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalogue lists improved mean positions and proper motions for the 995 stars in the FK4 Supplement (Veroeff. Astron. Rechen-Inst. Heidelberg No 11, 1963) which were not included in the Fifth Fundamental Catalogue (Part I: "The Basic FK5", Fricke et al., 1988, Veroeff. Astron. Rechen-Inst. Heidelberg No 32, Catalogue I/149/; Part II: "The FK5 Extension", Fricke et al., 1991, Veroeff. Astron. Rechen-Inst. Heidelberg No 33, Catalogue I/175/). The main purpose of the FK4 Supplement was to stimulate further observations within absolute and differential programs of the stars listed in that catalogue with the aim of their inclusion as new fundamental stars into a future fundamental catalogue. The new fundamental stars should increase the star density without extending the magnitude limit to fainter magnitudes. Since the publication of the "Supplement-Katalog des FK3" (published in Astron-Geodaet. Jahrbuch 1954 and Astron-Geodaet. Jahrbuch 1956) these stars were included in many observing programs. Within work on deriving the FK5 Extension all stars in the FK4 Supplement had been treated in exactly the same way and improved mean positions and proper motions had thus been obtained for all FK4 Sup stars. For more details reference is made to the introduction of the FK5 Extension. FK4 Sup stars with the best astrometric data were included in the FK5 Extension for achieving a homogeneous distribution in magnitude and taking simultaneously into account an even distribution on the sky. This selection process included 992 of the 1987 FK4 Sup stars into the FK5 Extension. Although the astrometric precision of the stars given in the present catalogue is inferior to that of the FK4 Supplement stars included in the FK5 Extension, they deserve being published because a considerable number of observations has been obtained for these stars since about 1955, stimulated by the publication of the FK3 Supplement. The average mean epoch of observation of the stars given is therefore shifted to comparatively modern epochs (see the table in Section 2 of the publication). The astrometric precision of the stars presented here is better than for most other published star positions and proper motions, and the positions and proper motions are the best which could be derived from the available observations. These observations are published in the same catalogues as listed in the FK5, Part II on pages 139 ff. The apparent visual magnitudes are between 3.6 and 7.7 with a concentration around the mean value of 5.94. They are thus within the magnitude limit of the Basic FK5.
- ID:
- ivo://CDS.VizieR/V/126
- Title:
- MEGA-H proper motion catalog
- Short Name:
- V/126
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue MEGA-H is a result of a merging of star lists from the catalogue of stellar proper motions with respect to galaxies in 47 selected areas near the Main Meridional Section of the Galaxy (MEGA-G) (Kharchenko 1987) and from All-sky Compiled Catalogue of 2.5 Million Stars (ASCC-2.5) (Cat. <I/280>). Proper motions from the catalogue MEGA-G were reduced to the Hipparcos system by means of common with the ASCC-2.5 stars. The compiled proper motions in the Hipparcos system and their standard errors were computed as the weighted means. Equatorial coordinates are reduced to the equinox J2000 and epoch 1991.25. The catalogue MEGA-H contains 18169 stars. Stars are sorted in right ascension J2000 order.
- ID:
- ivo://CDS.VizieR/J/A+AS/102/643
- Title:
- Mesure d'etoiles doubles
- Short Name:
- J/A+AS/102/643
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/MNRAS/403/1625
- Title:
- Method for orientation angles of galaxies
- Short Name:
- J/MNRAS/403/1625
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A method is proposed for the determination of the position and inclination angles of the plane of a spiral galaxy based on the assumption that every spiral arm is a monotonic function of the radius against azimuthal angle. This method may yield more accurate results than the more commonly employed isophote method, which is subject to a number of drawbacks. Analytical study, calibration against other methods and examples of application of the proposed method to real galaxies are presented.
