- ID:
- ivo://CDS.VizieR/J/PAZh/37/120
- Title:
- Fast optical variability of SS 433
- Short Name:
- J/PAZh/37/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the variability of the optical flux from the peculiar Galactic source SS 433 based on observations with the Russian-Turkish 1.5-m telescope. We describe in detail the technique of high-quality photometric measurements with a time resolution of 0.3-1s using an ordinary CCD. Through test observations of non-variable stars, we show that atmospheric turbulence introduces no significant distortions into the light curves. Therefore, such data are well suited for studying the aperiodic variability of various objects.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/682/1205
- Title:
- Fast transients in the Fornax cluster
- Short Name:
- J/ApJ/682/1205
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The luminosity gap between novae (M_R_<=-10) and supernovae (M_R_>=-14) has been well known since the pioneering research of Zwicky and Hubble. Nearby galaxy clusters and concentrations offer an excellent opportunity to search for explosions brighter than classical novae and fainter than supernovae. Here we present the results of a B-band survey of 23 member galaxies of the Fornax Cluster, performed at the Las Campanas 2.5m Irenee du Pont telescope. Observations with a cadence of 32 minutes discovered no genuine fast transient to a limiting absolute magnitude of M_B_=-9.3mag. We provide a detailed assessment of the transient detection efficiency and the resulting upper limits on the event rate as function of peak magnitude. Further, we discuss the discoveries of five previously unknown foreground variables which we identified as two flare stars, two W UMa-type eclipsing binaries and a candidate {delta} Scuti/SX Phe star.
253. Field RR Lyrae stars
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/4360
- Title:
- Field RR Lyrae stars
- Short Name:
- J/MNRAS/459/4360
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents an extensive overview of known and proposed RR Lyrae stars in binaries. The aim is to revise and extend the list with new Galactic field systems. We utilized maxima timings for 11 RRab type stars with suspicious behaviour from the GEOS database, and determined maxima timings from data of sky surveys and our own observations. This significantly extended the number of suitable maxima timings. We modelled the proposed Light Time Effect (LiTE) in O-C diagrams to determine orbital parameters for these systems. In contrast to recent studies, our analysis focused on decades-long periods instead of periods in the order of years. Secondary components were found to be predominantly low-mass objects. However, for two of the stars, RZ Cet and AT Ser, the mass of the suspected companion of more than one solar mass suggests that it is a massive white dwarf, a neutron star or even a black hole. We found that the semi-major axes of the proposed orbits are between 1 and 20au. Because the studied stars belong to the closest RR Lyraes, maximal angular distances between components during orbit should at least be between 1 and 13mas and this improves the chance to detect both stars using current telescopes and interferometers. However, our interpretation of the O-C diagrams as a consequence of the LiTE should be considered as preliminary without reliable spectroscopic measurements. On the other hand, our models give a prediction of the period and radial velocity evolution which should be sufficient for plausible proof of binarity.
- ID:
- ivo://CDS.VizieR/J/AJ/144/19
- Title:
- Follow-up photometry for HAT-P-34 through HAT-P-37
- Short Name:
- J/AJ/144/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of four transiting extrasolar planets (HAT-P-34b-HAT-P-37b) with masses ranging from 1.05 to 3.33M_J_ and periods from 1.33 to 5.45days. These planets orbit relatively bright F and G dwarf stars (from V=10.16 to V=13.2). Of particular interest is HAT-P-34b which is moderately massive (3.33M_J_), has a high eccentricity of e=0.441+/-0.032 at a period of P=5.452654+/-0.000016days, and shows hints of an outer component. The other three planets have properties that are typical of hot Jupiters.
- ID:
- ivo://CDS.VizieR/J/ApJ/728/138
- Title:
- Follow-up photometry of HAT-P-26
- Short Name:
- J/ApJ/728/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery of HAT-P-26b, a transiting extrasolar planet orbiting the moderately bright V=11.744 K1 dwarf star GSC 0320-01027, with a period P=4.234516+/-0.000015 days, transit epoch T_c_=2455304.65122+/-0.00035 (BJD; Barycentric Julian dates throughout the paper are calculated from Coordinated Universal Time (UTC)), and transit duration 0.1023+/-0.0010 days. The host star has a mass of 0.82+/-0.03M_{sun}_, radius of 0.79^+0.10^_-0.04_R_{sun}_, effective temperature 5079+/-88K, and metallicity [Fe/H]=-0.04+/-0.08. The planetary companion has a mass of 0.059+/-0.007M_J_, and radius of 0.565^+0.072^_-0.032_R_J_ yielding a mean density of 0.40+/-0.10g/cm^3^. HAT-P-26b is the fourth Neptune-mass transiting planet discovered to date. It has a mass that is comparable to those of Neptune and Uranus, and slightly smaller than those of the other transiting Super-Neptunes, but a radius that is ~65% larger than those of Neptune and Uranus, and also larger than those of the other transiting Super-Neptunes. HAT-P-26b is consistent with theoretical models of an irradiated Neptune-mass planet with a 10M_{earth}_ heavy element core that comprises >~50% of its mass with the remainder contained in a significant hydrogen-helium envelope, though the exact composition is uncertain as there are significant differences between various theoretical models at the Neptune-mass regime. The equatorial declination of the star makes it easily accessible to both Northern and Southern ground-based facilities for follow-up observations.
- ID:
- ivo://CDS.VizieR/J/A+A/317/54
- Title:
- Fornax cluster 1 and 3 photometry
- Short Name:
- J/A+A/317/54
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed photometric CCD observations of the giant and horizontal branches of the globular cluster1, and of the giant branch of cluster3, in the Fornax dwarf spheroidal galaxy. The observations were performed in the V and I standard broad-band filters as well as through two narrow-band filters especially designed to distinguish between carbon and M type stars. The AGB is richly populated with carbon-rich stars, and all of them are considerably below the theoretical lower luminosity limit for such stars. If the Fornax clusters are interpreted as resembling an earlier epoch of the Galactic globular clusters, the low luminosities of the carbon stars therefore point to a larger role of the low-mass stars in the chemical enrichment of our Galaxy. The giant branches of the Fornax clusters are much broader than canonical giant branches in Galactic globulars, and the AGB is more well populated. We suggest that the morphology and stellar population of the giant branches indicate that the dwarf galaxies are =~3Gyr younger than the Galactic halo, which in turn seems to be =~3Gyr younger than the Galactic globular clusters. For a description of the N2-N3 photometric system, see e.g. <GCPD/39>
- ID:
- ivo://CDS.VizieR/J/A+A/603/A2
- Title:
- Gaia-ESO Survey abundances radial distribution
- Short Name:
- J/A+A/603/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spatial distribution of elemental abundances in the disc of our Galaxy gives insights both on its assembly process and subsequent evolution, and on the stellar nucleogenesis of the different elements. Gradients can be traced using several types of objects as, for instance, (young and old) stars, open clusters, HII regions, planetary nebulae. We aim to trace the radial distributions of abundances of elements produced through different nucleosynthetic channels - the {alpha}-elements O, Mg, Si, Ca and Ti, and the iron-peak elements Fe, Cr, Ni and Sc - by use of the Gaia-ESO IDR4 results for open clusters and young-field stars. From the UVES spectra of member stars, we have determined the average composition of clusters with ages >0.1Gyr. We derived statistical ages and distances of field stars. We traced the abundance gradients using the cluster and field populations and compared them with a chemo-dynamical Galactic evolutionary model. The adopted chemo-dynamical model, with the new generation of metallicity-dependent stellar yields for massive stars, is able to reproduce the observed spatial distributions of abundance ratios, in particular the abundance ratios of [O/Fe] and [Mg/Fe] in the inner disc (5kpc<R_GC_<7kpc), with their differences, that were usually poorly explained by chemical evolution models. Oxygen and magnesium are often considered to be equivalent in tracing {alpha}-element abundances and in deducing, for example, the formation timescales of different Galactic stellar populations. In addition, often [{alpha}/Fe] is computed combining several {alpha}-elements. Our results indicate, as expected, a complex and diverse nucleosynthesis of the various {alpha}-elements, in particular in the high metallicity regimes, pointing towards a different origin of these elements and highlighting the risk of considering them as a single class with common features.
- ID:
- ivo://CDS.VizieR/J/A+A/565/A11
- Title:
- Gaia photometry for white dwarfs
- Short Name:
- J/A+A/565/A11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia space mission, through its 5-6 years survey of the whole sky up to magnitude V=20-25, will drastically increase the sample of known white dwarfs allowing to address new science questions. In this paper we provide a characterisation of Gaia photometry for the case of white dwarfs to better prepare for the analysis of the scientific output of the mission including relationships among colours involving Gaia magnitudes (white light G, blue GBP, red GRP and GRVS passbands) and colours from other commonly used photometric systems (Johnson-Cousins, SDSS and 2MASS). We also present numbers of white dwarfs predicted by the Gaia Universe Model Snapshot and compare them with an alternative simulation calibrated with the local white dwarfs sample. In these online tables we provide the values used to fit the relationships in the paper, especially useful for those cases where the deviation from the established relationships is large. The most recent Gaia transmission curves and three different compositions for white dwarfs were considered here (pure hydrogen, pure helium and mixed composition with H/He=0.1).
- ID:
- ivo://CDS.VizieR/J/A+A/623/A117
- Title:
- Galactic Cepheids and RR Lyrae multiplicity. II
- Short Name:
- J/A+A/623/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The multiplicity of Classical Cepheids (CCs) and RR Lyrae stars (RRLs) is still imperfectly known, particularly for RRLs. In order to complement the close-in short orbital period systems presented in Paper I (Kervella et al., 2019, Cat. J/A+A/623/A16), we aim at detecting the wide, spatially resolved companions of the targets of our reference samples of Galactic CCs and RRLs. Angularly resolved common proper motion pairs are detected using a simple progressive selection algorithm to separate the most probable candidate companions from the unrelated field stars. We detect 27 resolved, high probability gravitationally bound systems with CCs out of 456 examined stars, and one unbound star embedded in the circumstellar dusty nebula of the long-period Cepheid RS Pup. We find 7 spatially resolved, probable bound systems with RRL primaries out of 789 investigated stars, and 22 additional candidate pairs. We report in particular new companions of three bright RRLs: OV And (companion of F4V spectral type), RR Leo (M0V) and SS Oct (K2V). In addition, we discovered resolved companions of 14 stars of various variability classes that were misclassified as RRLs. The detection of resolved common proper motion companions around CCs and RRLs facilitates the validation of their GDR2 parallaxes. The possibility to conduct a detailed analysis of the resolved coeval companions of CCs and old population RRLs will also be valuable to progress on our understanding of their evolutionary path.
260. Galaxies around M87
- ID:
- ivo://CDS.VizieR/J/A+A/635/A135
- Title:
- Galaxies around M87
- Short Name:
- J/A+A/635/A135
- Date:
- 07 Dec 2021 09:09:23
- Publisher:
- CDS
- Description:
- This work considers the Virgo cluster of galaxies, focusing on its structure, kinematics, and morphological landscape. Our principal aim is to estimate the virial mass of the cluster. For this purpose, we present a sample of 1537 galaxies with radial velocities V_LG_<2600km/s situated within a region of 30x20 degrees around M87. About half of the galaxies have distance estimates. We selected 398 galaxies with distances in the (17+/-5)Mpc range. Based on their 1D and 2D number-density profiles and their radial velocity dispersions, we made an estimate for the virial mass of the Virgo cluster. Results. We identify the infall of galaxies towards the Virgo cluster core along the Virgo Southern Extention filament. From a 1D profile of the cluster, we obtain the virial mass estimate of (6.3+/-0.9)x10^14^ solar masses, which is in tight agreement with its mass estimate via the external infall pattern of galaxies. We conclude that the Virgo cluster outskirts between the virial radius and the zero-velocity radius do not contain significant amounts of dark matter beyond the virial radius.
