- ID:
- ivo://CDS.VizieR/J/A+A/430/411
- Title:
- B-band photometry of ellipticals in Virgo
- Short Name:
- J/A+A/430/411
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a complete CCD imaging survey of 226 elliptical galaxies in the North-East quadrant of the Virgo cluster, representative of the properties of giant and dwarf elliptical galaxies in this cluster. We fit their radial light profiles with the Sersic r^1/n^ model of light distribution. We confirm the result of Graham & Guzman (2003AJ....125.2936G) that the apparent dichotomy between E and dE galaxies in the luminosity-<{mu}>_e_ plane no longer appears when other structural parameters are considered and can be entirely attributed to the onset of "core" galaxies at B_T_~-20.5mag. When "core" galaxies are not considered, E and dE form a unique family with n linearly increasing with the luminosity. For 90 galaxies we analyze the B-I color indices, both in the nuclear and in the outer regions. Both indices are bluer toward fainter luminosities. We find also that the outer color gradients do not show any significant correlation with the luminosity. The scatter in all color indicators increases significantly toward lower luminosities, e.g. galaxies fainter than B_T_~-15 have a B-I spread>0.5mag.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/299/834
- Title:
- Berkeley 21 BVI photometry
- Short Name:
- J/MNRAS/299/834
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD BVI photometry of the old open cluster Berkeley 21, one of the most distant clusters in the Galactic anticentre direction, and possibly the lowest metallicity object in the open clusters sample. Its position and metal abundance make it very important for the study of the Galactic disc. Using the synthetic colour-magnitude diagram method, we estimate values for the distance modulus (m-M)_0_=13.4-13.6, reddening E(B-V)=0.74-0.78 (with possible differential absorption), and age= 2.2-2.5Gyr.
- ID:
- ivo://CDS.VizieR/J/AJ/107/2101
- Title:
- Berkeley 93 RVB photometry
- Short Name:
- J/AJ/107/2101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- While performing galactic and extragalactic studies near the galactic plane in Cepheus. CCD frames in B, V, and R were taken of the faint (V>=16m), previously unstudied open star cluster Berkeley 93 (Be 93). Our results indicate that this object is the core of a larger aggregate, is slightly evolved, strongly reddened [E(B-V)~1.5], and shows a pronounced variable reddening that is probably due to the location of the cluster inside (near the border) a dust cloud. By far the reddest, and obviously most evolved star is a (variable) carbon star that-because of its reddening and location-appears to be a cluster member. We present arguments in favour of a large distance of more than 5kpc for Be 93 which possibly belongs to the galactic warp. As an addendum, we present six star concentrations discovered on the POSS or ESO/SERC atlas that might represent hitherto uncatalogued open star clusters of "Berkeley type."
- ID:
- ivo://CDS.VizieR/J/A+A/506/569
- Title:
- BEST-II periodic variables in CoRoT LRa02 field
- Short Name:
- J/A+A/506/569
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Berlin Exoplanet Search Telescope II (BEST II) is a small wide field-of-view photometric survey telescope system located at the Observatorio Cerro Armazones, Chile. The high duty cycle combined with excellent observing conditions and millimagnitude photometric precision makes this instrument suitable for ground based support observations for the CoRoT space mission. Photometric data of the CoRoT LRa02 target field collected between November 2008 and March 2009 were analysed for stellar variability. The presented results will help in the future analysis of the CoRoT data, particularly in additional science programs related to variable stars. BEST II observes selected CoRoT target fields ahead of the space mission. The photometric data acquired are searched for stellar variability, periodic variable stars are identified with time series analysis of the obtained stellar light curves. We obtained the light curves of 104335 stars in the CoRoT LRa02 field over 41 nights. Variability was detected in light curves of 3726 stars of which 350 showed a regular period. These stars are, with the exception of 5 previously known variable stars, new discoveries.
- ID:
- ivo://CDS.VizieR/J/AJ/143/140
- Title:
- BEST-II periodic variables in CoRoT LRa02 field. II.
- Short Name:
- J/AJ/143/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The CoRoT (Convection, Rotation and planetary Transit) field LRa02 has been observed with the Berlin Exoplanet Search Telescope II (BEST II) during the southern summer 2007/2008. A first analysis of stellar variability led to the publication of 345 newly discovered variable stars. Now, a deeper analysis of this data set was used to optimize the variability search procedure. Several methods and parameters have been tested in order to improve the selection process compared to the widely used J index for variability ranking. This paper describes an empirical approach to treat systematic trends in photometric data based upon the analysis of variance statistics that can significantly decrease the rate of false detections. Finally, the process of reanalysis and method improvement has virtually doubled the number of variable stars compared to the first analysis by Kabath et al. (Paper I, 2009, Cat. J/A+A/506/569). A supplementary catalog of 272 previously unknown periodic variables plus 52 stars with suspected variability is presented. Improved ephemerides are given for 19 known variables in the field. In addition, the BEST II results are compared with CoRoT data and its automatic variability classification.
- ID:
- ivo://CDS.VizieR/J/A+A/643/A110
- Title:
- beta Cas BRITE and SMEI light curves
- Short Name:
- J/A+A/643/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- F type stars are characterised by several physical processes such as different pulsation mechanisms, rotation, convection, diffusion, and magnetic fields. The rapidly rotating delta Scuti star beta Cas can be considered as a benchmark star to study the interaction of several of these effects. We investigate the pulsational and magnetic field properties of beta Cas. We also determine the star's apparent fundamental parameters and chemical abundances. Based on photometric time series obtained from three different space missions (BRITE-Constellation, SMEI, and TESS), we conduct a frequency analysis and investigate the stability of the pulsation amplitudes over four years of observations. We investigate the presence of a magnetic field and its properties using spectropolarimetric observations taken with the Narval instrument by applying the Least Square Deconvolution and Zeeman Doppler Imaging techniques. beta Cas shows only three independent p-mode frequencies down to the few ppm-level; its highest amplitude frequency is suggested to be a n=3, l=2, m=0 mode. Its magnetic field structure is quite complex and almost certainly of a dynamo origin. beta Cas' atmosphere is slightly deficient in iron peak elements and slightly overabundant in C, O, and heavier elements. Atypically for delta Scuti stars, we can only detect three pulsation modes down to exceptionally low noise levels for beta Cas.The star is also one of very few delta Scuti pulsators known to date to show a measurable magnetic field, and the first delta Scuti star with a dynamo magnetic field. These characteristics make beta Cas an interesting target for future studies of dynamo processes in the thin convective envelopes of F-type stars, of the transition region between fossil and dynamo fields, and the interaction between pulsations and magnetic field.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A28
- Title:
- beta Pic BRITE, bRing, SMEI light curves
- Short Name:
- J/A+A/627/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanet properties crucially depend on the parameters of their host stars: more accurate stellar parameters yield more accurate exoplanet characteristics. When the exoplanet host star shows pulsations, asteroseismology can be used for an improved description of the stellar parameters. We aim to revisit the pulsational properties of {beta} Pic and identify its pulsation modes from normalized amplitudes in five different passbands. We also investigate the potential presence of a magnetic field. We conducted a frequency analysis using three seasons of BRITE-Constellation observations in the two BRITE filters, the about 620-day-long bRing light curve, and the nearly 8-year-long SMEI photometric time series. We calculated normalized amplitudes using all passbands and including previously published values obtained from ASTEP observations. We investigated the magnetic properties of {beta} Pic using spectropolarimetric observations conducted with the HARPSpol instrument. Using 2D rotating models, we fit the normalized amplitudes and frequencies through Monte Carlo Markov chains. We identify 15 pulsation frequencies in the range from 34 to 55d^-1^, where two, F13 at 53.6917d^-1^ and F11 at 50.4921d^-1^, display clear amplitude variability. We use the normalized amplitudes in up to five passbands to identify the modes as three l=1, six l=2, and six l=3 modes. {beta} Pic is shown to be non-magnetic with an upper limit of the possible undetected dipolar field of 300 Gauss. Multiple fits to the frequencies and normalized amplitudes are obtained, including one with a near equator-on inclination for {beta} Pic, which corresponds to our expectations based on the orbital inclination of {beta} Pic b and the orientation of the circumstellar disk. This solution leads to a rotation rate of 27% of the Keplerian breakup velocity, a radius of 1.497+/-0.025R_{sun}_, and a mass of 1.797+/-0.035M_{sun}_. The ~2% errors in radius and mass do not account for uncertainties in the models and a potentially erroneous mode-identification.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A15
- Title:
- beta Pictoris photometry
- Short Name:
- J/A+A/648/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric monitoring of beta Pictoris in 1981 showed anomalous fluctuations of up to 4% over several days, consistent with foreground material transiting the stellar disk. The subsequent discovery of the gas giant planet beta Pictoris b and the predicted transit of its Hill sphere to within 0.1 au projected distance of the planet provided an opportunity to search for the transit of a circumplanetary disk in this 21+/-4Myr-old planetary system. Continuous broadband photometric monitoring of beta Pictoris requires ground- based observatories at multiple longitudes to provide redundancy and to provide triggers for rapid spectroscopic followup. These observatories include the dedicated beta Pictoris monitoring observatory bRing at Sutherland and Siding Springs, the ASTEP400 telescope at Concordia, and observations from the space observatories BRITE and Hubble Space Telescope. We search the combined light curves for evidence of short period transient events caused by rings and for longer term photometric variability due to diffuse circumplanetary material. We find no photometric event that matches with the event seen in November 1981, and there is no systematic photometric dimming of the star as a function of the Hill sphere radius. We conclude that the 1981 event was not caused by the transit of a circumplanetary disk around beta Pictoris b. The upper limit on the long term variability of beta Pictoris places an upper limit of 1.8x10^22^g of dust within the Hill sphere. Circumplanetary material is either condensed into a non-transiting disk, is condensed into a disk with moons that has a small obliquity, or is below our detection threshold. This is the first time that a dedicated international campaign has mapped the Hill sphere transit of a gas giant extrasolar planet at 10 au.
- ID:
- ivo://CDS.VizieR/J/A+AS/115/219
- Title:
- Bgr survey of Cl1613+3104 and Cl1600+4109
- Short Name:
- J/A+AS/115/219
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/465/965
- Title:
- BI light curves of NGC 2506 variables
- Short Name:
- J/A+A/465/965
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained photometric time-series observations of stars in the open cluster NGC 2506, in order to study pulsating blue stragglers and eclipsing binaries. The data were obtained during a bi-site campaign in early 2005 which involved the Danish 1.54-m telescope at ESO, La Silla, and the Flemish Mercator telescope at La Palma, Spain. Based on these data we increased the number of known variables in NGC 2506 from 5 to 28 through the detection of 3 new pulsating blue stragglers, 15 gamma Doradus stars and 4 new eclipsing binaries, while one variable is of unknown type. We derived orbital periods for two previously known binaries, we performed a tentative mode-identification of the pulsating blue stragglers, and compared B- and I amplitude ratios and phase differences for the gamma Doradus stars to seismic models.
