- ID:
- ivo://CDS.VizieR/J/A+A/467/1025
- Title:
- JHK photometry of Fornax red giant branch
- Short Name:
- J/A+A/467/1025
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the evolved stellar populations in the dwarf spheroidal galaxy Fornax based on wide-area near-infrared observations, aimed at obtaining new independent estimates of its distance and metallicity distribution. Assessing the reliability of near-infrared methods is most important in view of future space- and ground-based deep near-infrared imaging of resolved stellar systems.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/456/905
- Title:
- JKs, i'g'r' photometry of C stars in NGC 6822
- Short Name:
- J/A+A/456/905
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a 2{deg}x2{deg} survey of NGC 6822 we have previously established that this Local Group dwarf irregular galaxy possesses a huge spheroid having more than one degree in length. This spheroid is in rotation but its rotation curve is known only within ~15' from the center. It is therefore critical to identify bright stars belonging to the spheroid to characterize, as far as possible, its outer kinematics. We use the new wide field near infrared imager CPAPIR, operated by the SMARTS consortium, to acquire J, K_s_ images of two 34.8'x34.8' areas in the outer spheroid to search for C stars. The colour diagram of the fields allows the identification of 192 C stars candidates but a study of the FWHM of the images permits the rejection of numerous non-stellar objects with colours similar to C stars. We are left with 75 new C stars, their mean K_s_ magnitude and mean colour are similar to the bulk of known NGC 6822 C stars. This outer spheroid survey confirms that the intermediate-age AGB stars are a major contributor to the stellar populations of the spheroid. The discovery of some 50 C stars well beyond the limit of the previously known rotation curve calls for a promising spectroscopic follow-up to a major axis distance of 40'.
- ID:
- ivo://CDS.VizieR/II/211
- Title:
- K-band survey in high galactic latitude
- Short Name:
- II/211
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The survey is a high galactic latitude, large area (552 square arcmin) blank-field sample to a 5{sigma} limit of K=17.3mag. Star-galaxy discrimination is performed. The infrared observations were made over the period 1987-1988, using the infrared camera IRCAM at the 3.8m UKIRTelescope at Mauna Kea, Hawai. The pixel size is 1.2arcsec. The redshift survey (spectro.dat) concerns 124 galaxies of the survey, and was carried out on the Anglo-Australian telescope and the William Herschel telescope at La Palma over the period 1990-1992, with a multi-fibre spectrograph for the brighter objects (R<19), long and multi-slit spectrographs for fainter objects.
- ID:
- ivo://CDS.VizieR/J/A+A/372/71
- Title:
- King 5 and Berkeley 20 UBVRI photometry
- Short Name:
- J/A+A/372/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multicolour CCD photometry for two poorly studied open clusters (King 5 and Be 20). Photometry for a field near King 5 was also carried out to estimate the contamination by field stars. The colour magnitude diagrams (CMD) of the clusters show a well defined main sequence extending to the limit of the photometry, V~=20mag. The reddening for King 5, estimated from the colour-colour diagram, is ~0.82, whereas that for Be 20 as estimated by comparing theoretical main-sequence (MS) with the observed MS is 0.10. The morphology of the CMDs indicates that these clusters are old. The CMD of Be 20 shows a globular cluster-like horizontal branch. In case of King 5 the comparison of observational CMDs with the standard isochrones of VandenBerg (1985ApJS...58..711V) indicates an apparent discrepancy between the shape of the turnoff and isochrones. The CMDs of King 5 seem to be better understood in terms of stellar models with convective overshoot. The comparison of the CMDs with the stellar models by Bertelli et al. (1985A&A...150...33B) with convective overshoot produces a good fit for a metallicity Z=0.008 and an age of 1Gyr for King 5 and 5Gyr for Be 20. An apparent distance modulus (m-M)=14.0 and 15.1 has been estimated for King 5 and Be 20 respectively. They correspond to a distance of 1900+/-100pc and 9026+/-480pc, respectively. The radial density distribution in King 5 indicates that there is an excess of low mass stars in the outer region of the cluster, whereas the density distribution in Be 20 shows a good fit with the empirical King (1962AJ.....67..471K) model. For both clusters, observations have also been carried out to search for variable stars.
- ID:
- ivo://CDS.VizieR/J/A+A/571/A37
- Title:
- KOI-1257 photometric and velocimetric data
- Short Name:
- J/A+A/571/A37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we report a new transiting warm giant planet: KOI-1257b. It was first detected in photometry as a planet-candidate by the Kepler space telescope and then validated thanks to a radial velocity follow-up with the SOPHIE spectrograph. It orbits its host star with a period of 86.647661d+/-3s and a high eccentricity of 0.772+/-0.045. The planet transits the main star of a metal-rich, relatively old binary system with stars of mass of 0.99+/-0.05M_{sun}_ and 0.70+/-0.07M_{sun}_ for the primary and secondary, respectively. This binary system is constrained thanks to a self-consistent modelling of the Kepler transit light curve, the SOPHIE radial velocities, line bisector and full-width half maximum (FWHM) variations, and the spectral energy distribution. However, future observations are needed to confirm it. The PASTIS fully-Bayesian software was used to validate the nature of the planet and to determine which star of the binary system is the transit host. By accounting for the dilution from the binary both in photometry and in radial velocity, we find that the planet has a mass of 1.45+/-0.35M_jup_, and a radius of 0.94+/-0.12R_jup_, and thus a bulk density of 2.1+/-1.2g/cm^3^. The planet has an equilibrium temperature of 511+/-50K, making it one of the few known members of the warm-Jupiter population. The HARPS-N spectrograph was also used to observe a transit of KOI-1257b, simultaneously with a joint amateur and professional photometric follow-up, with the aim of constraining the orbital obliquity of the planet. However, the Rossiter-McLaughlin effect was not clearly detected, resulting in poor constraints on the orbital obliquity of the planet.
- ID:
- ivo://CDS.VizieR/J/A+A/438/377
- Title:
- Kyiv Meridian Axial Circle Catalogue, KMAC1
- Short Name:
- J/A+A/438/377
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of astrometric observations of faint V<17mag stars in sky strip areas with ICRF objects obtained with the Kyiv meridian axial circle (D=180mm) equipped with a 1040x1160 CCD micrometer. Observations were carried out in a declination zone of 0+30 degrees. The work resulted in a compilation of a catalogue KMAC1 that presents an extension of the ICRF to faint stars in optical domain. The catalogue was obtained in the two versions: with reduction to the space catalogue Tycho2, <I/259>, (the version KMAC1-T, 159 ICRF fields, 104794 stars) and with reduction to the modern CCD catalogues CMC13 and UCAC2 (<I/289>) which are given also in the ICRF system (the version KMAC1-CU, 192 ICRF fields, 115032 stars). Due to a large number of CMC13 and UCAC2 stars used as reference, the version KMAC1-CU is of slightly better accuracy, though it may inherit local systematic errors of reference catalogues.
- ID:
- ivo://CDS.VizieR/J/AJ/121/2124
- Title:
- {lambda} Ori pre-main-sequence stars photometry
- Short Name:
- J/AJ/121/2124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The {lambda} Ori star-forming region presents a snapshot of a moderate-mass giant molecular cloud 1-2Myr after cloud disruption by OB stars, with the OB stars, the low-mass stellar population, remnant molecular clouds, and the dispersed gas all still present. We have used optical photometry and multiobject spectroscopy for lithium absorption to identify 266 pre-main-sequence stars in 8deg^2^ of the region. We also present new Stroemgren photometry for the massive stars, from which we derive a distance of 450pc and a turnoff age of 6-7Myr. Using these parameters and pre-main-sequence evolutionary models, we map the star formation history of the low-mass stars. We find that low-mass star formation started throughout the region at about the same time as the birth of the massive stars, and thereafter the birth rate accelerated. Within the last 1-2Myr star formation ceased in the center of the star-forming region, near the concentration of OB stars, while it continues in dark clouds 20pc away. We suggest that a supernova 1-2Myr ago destroyed the molecular cloud core from which the OB stars formed, but it did not terminate star formation in more distant reaches of the giant molecular cloud. We find no secure evidence for triggered or sequential star formation in the outer molecular clouds. The global star formation of the {lambda} Ori region has generated the field initial mass function, but local star formation in subregions shows large deviations from the expected ratio of high- to low-mass stars.
- ID:
- ivo://CDS.VizieR/J/MNRAS/366/645
- Title:
- LARCS. 11 X-ray luminous clusters
- Short Name:
- J/MNRAS/366/645
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the analysis of the spectroscopic and photometric catalogues of 11 X-ray luminous clusters at 0.07<z<0.16 from the Las Campanas/Anglo-Australian Telescope Rich Cluster Survey. Our spectroscopic data set consists of over 1600 galaxy cluster members, of which two-thirds are outside r_200_. These spectra allow us to assign cluster membership using a detailed mass model and expand on our previous work on the cluster colourmagnitude relation (CMR) where membership was inferred statistically.
- ID:
- ivo://CDS.VizieR/J/A+A/616/A118
- Title:
- Lensed QSOs light curves & spectral monitoring
- Short Name:
- J/A+A/616/A118
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the framework of the Gravitational LENses and DArk MAtter (GLENDAMA) project, we present a database of nine gravitationally lensed quasars (GLQs) that have two or four images brighter than r=20mag and are located in the northern hemisphere. This new database consists of a rich variety of follow-up observations included in the GLENDAMA global archive, which is publicly available online and contains 6557 processed astronomical frames of the nine lens systems over the period 1999-2016. In addition to the GLQs, our archive also incorporates binary quasars, accretion-dominated radio-loud quasars, and other objects, where about 50% of the non-GLQs were observed as part of a campaign to identify GLQ candidates. Most observations of GLQs correspond to an ongoing long-term macro-programme with 2-10m telescopes at the Roque de los Muchachos Observatory, and these data provide information on the distribution of dark matter at all scales. We outline some previous results from the database, and we additionally obtain new results for several GLQs that update the potential of the tool for astrophysical studies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/506/2122
- Title:
- Light curves and eclipse times of HW Vir
- Short Name:
- J/MNRAS/506/2122
- Date:
- 17 Jan 2022 00:24:15
- Publisher:
- CDS
- Description:
- A growing number of eclipsing binary systems of the HW Virginis (HW Vir) kind (i.e. composed by a subdwarf-B/O primary star and an M dwarf secondary) show variations in their orbital period, also called eclipse time variations (ETVs). Their physical origin is not yet known with certainty: While some ETVs have been claimed to arise from dynamical perturbations due to the presence of circumbinary planetary companions, other authors suggest that the Applegate effect or other unknown stellar mechanisms could be responsible for them. In this work, we present 28 unpublished high-precision light curves of one of the most controversial of these systems, the prototype HW Vir. We homogeneously analysed the new eclipse timings together with historical data obtained between 1983 and 2012, demonstrating that the planetary models previously claimed do not fit the new photometric data, besides being dynamically unstable. In an effort to find a new model able to fit all the available data, we developed a new approach based on a global-search genetic algorithm and eventually found two new distinct families of solutions that fit the observed timings very well, yet dynamically unstable at the 10^5^-yr time-scale. This serves as a cautionary tale on the existence of formal solutions that apparently explain ETVs but are not physically meaningful, and on the need of carefully testing their stability. On the other hand, our data confirm the presence of an ETV on HW Vir that known stellar mechanisms are unable to explain, pushing towards further observing and modeling efforts.
