- ID:
- ivo://CDS.VizieR/J/AJ/154/30
- Title:
- Photometric study of fourteen low-mass binaries
- Short Name:
- J/AJ/154/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New CCD photometric observations of fourteen short-period low-mass eclipsing binaries (LMBs) in the photometric filters I, R, and V were used for a light curve analysis. A discrepancy remains between observed radii and those derived from the theoretical modeling for LMBs, in general. Mass calibration of all observed LMBs was performed using only the photometric indices. The light curve modeling of these selected systems was completed, yielding the new derived masses and radii for both components. We compared these systems with the compilation of other known double-lined LMB systems with uncertainties of masses and radii less then 5%, which includes 66 components of binaries where both spectroscopy and photometry were combined together. All of our systems are circular short-period binaries, and for some of them, the photospheric spots were also used. A purely photometric study of the light curves without spectroscopy seems unable to achieve high enough precision and accuracy in the masses and radii to act as meaningful test of the M-R relation for low-mass stars.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/1633
- Title:
- Photometric study of globular clusters
- Short Name:
- J/MNRAS/475/1633
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we describe the photometric and spectroscopic properties of multiple populations in seven northern globular clusters. In this study, we employ precise ground-based photometry from the private collection of Stetson, space photometry from the Hubble Space Telescope (HST), literature abundances of Na and O, and Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey abundances for Mg, Al, C, and N. Multiple populations are identified by their position in the C_U,B,I_-V pseudo colour-magnitude diagram (pseudo-CMD) and confirmed with their chemical composition determined using abundances. We confirm the expectation from previous studies that the red giant branches (RGBs) in all seven clusters are split and the different branches have different chemical compositions. The Mg-Al anticorrelations were well explored by the APOGEE and Gaia-ESO surveys for most globular clusters, some clusters showing bimodal distributions, while others continuous distributions. Even though the structure (i.e. bimodal versus continuous) of Mg-Al can greatly vary, the Al-rich and Al-poor populations do not seem to have very different photometric properties, agreeing with theoretical calculations. There is no one-to-one correspondence between the Mg-Al anticorrelation shape (bimodal versus continuous) and the structure of the RGB seen in the HST pseudo-CMDs, with the HSTphotometric information usually implying more complex formation/evolution histories than the spectroscopic ones. We report on finding two second-generation horizontal branch (HB) stars in M5, and five second-generation asymptotic giant branch (AGB) stars in M92, which is the most metal-poor cluster to date in which second-generation AGB stars have been observed.
- ID:
- ivo://CDS.VizieR/J/AcA/58/23
- Title:
- Photometric survey for M33 stellar clusters
- Short Name:
- J/AcA/58/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of 4780 extended sources from the outer field of M33. The catalog includes 73 previously identified clusters or planetary nebulae, 1153 likely background galaxies, and 3554 new candidate stellar clusters. The survey is based on deep ground-based images obtained with the MegaCam instrument on the CFHT telescope. We provide g'r'i' photometry for detected objects as well as estimates of the FWHM and ellipticity of their profiles. The sample includes 122 new, relatively bright, likely globular clusters. Follow-up observations of fainter candidates from our list may extend the faint-end of the observed luminosity function of globular clusters in M33 by up to 3 magnitudes. The catalog includes several cluster candidates located in the outskirts of the galaxy. These objects are promising targets for deep photometry with the HST. We present a color-magnitude diagram for one detected object, showing that it is an extended and low-surface-brightness old cluster located at an angular distance of 27' from the center of M33.
- ID:
- ivo://CDS.VizieR/J/AJ/153/252
- Title:
- Photometric variability of BeSS-KELT stars
- Short Name:
- J/AJ/153/252
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Be stars have generally been characterized by the emission lines in their spectra, and especially the time variability of those spectroscopic features. They are known to also exhibit photometric variability at multiple timescales, but have not been broadly compared and analyzed by that behavior. We have taken advantage of the advent of wide-field, long-baseline, and high-cadence photometric surveys that search for transiting exoplanets to perform a comprehensive analysis of brightness variations among a large number of known Be stars. The photometric data comes from the KELT transit survey, with a typical cadence of 30 minutes, a baseline of up to 10 years, photometric precision of about 1%, and coverage of about 60% of the sky. We analyze KELT light curves of 610 known Be stars in both the northern and southern hemispheres in an effort to study their variability. Consistent with other studies of Be star variability, we find most of the stars to be photometrically variable. We derive lower limits on the fraction of stars in our sample that exhibit features consistent with non-radial pulsations (25%), outbursts (36%), and long-term trends in the circumstellar disk (37%), and show how these are correlated with spectral sub-types. Other types of variability, such as those owing to binarity, are also explored. Simultaneous spectroscopy for some of these systems from the Be Star Spectra database allow us to better understand the physical causes for the observed variability, especially in cases of outbursts and changes in the disk.
- ID:
- ivo://CDS.VizieR/J/A+A/399/543
- Title:
- Photometry and Coravel observations of IC 2488
- Short Name:
- J/A+A/399/543
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new UBV photoelectric observations of 119 stars in the field of the southern open cluster IC 2488, supplemented by DDO and Washington photometry and Coravel radial velocities for a sample of red giant candidates. Nearly 50% of the stars sampled - including three red giants and one blue straggler - are found to be probable cluster members. Photometric membership probabilities of the red giant candidates show good agreement with those obtained from Coravel data. A mean radial velocity of -2.63+/-0.06km/s is derived for the cluster giants. The reddening across the cluster is found to be uniform, the mean value being E(B-V)=0.24+/-0.04. IC 2488, located at a distance of (1250+/-120) pc from the Sun and 96 pc below the Galactic plane, is most probably not related to the planetary nebula ESO 166-PN21. A metal abundance [Fe/H]=0.10+/-0.06 relative to the Sun is determined from DDO data of the red giant members, in good agreement with the [Fe/H] values derived from five independent Washington abundance indices. An age of 180Myr is determined from the fitting of isochrones computed with convective overshooting for Z=0.019. The isochrone for logt=8.25 reproduces remarkably well not only the morphology of the upper main sequence but also the observed red giant pattern.
- ID:
- ivo://CDS.VizieR/J/A+A/448/893
- Title:
- Photometry and lines of (z~0.2-1.0) galaxies
- Short Name:
- J/A+A/448/893
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectrophotometric properties of a sample of 141 emission-line galaxies at redshifts in the range 0.2<z<1.0 with a peak around 0.2<=z<=0.4. The analysis is based on medium resolution (Rs=500-600), optical spectra obtained at VLT and Keck. The targets are mostly "Canada-France Redshift Survey" (<VII/225>) emission-line galaxies, with the addition of field galaxies randomly selected behind lensing clusters. We complement this sample with galaxy spectra from the "Gemini Deep Deep Survey" (<J/AJ/127/2455>) public data release. We have computed absolute magnitudes of the galaxies and measured the line fluxes and equivalent widths of the main emission/absorption lines. The last two have been measured after careful subtraction of the fitted stellar continuum using the platefit software originally developed for the SDSS and adapted to our data. We present a careful comparison of this software with the results of manual measurements.
- ID:
- ivo://CDS.VizieR/V/52
- Title:
- Photometry and Proper Motions in M67
- Short Name:
- V/52
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Relative proper motions were determined for 1068 stars with limiting magnitude b=16.5 and located within an area 130'*130' centered at alpha=8h 47.7m,delta=+12 deg.00' and l=215.6deg.,b=+31.2deg.(1950.0). Five plate pairs taken with the Pulkovo normal astrograph with mean epoch difference of 62 years were used. The proper motions have a mean error of 0''.0020 per year and were measured relative to reference stars with 13.5<b<14.5. Photographic UBV magnitudes were determined using the photoelectric standards of Johnson, Sandage (1955ApJ...121..616J) and Eggen, Sandage (1964ApJ...140..130E). Three plates in each colour taken with the Schmidt telescope of the Radioastrophysical Observatory of the Latvian SSR were measured. In addition a plate taken with the Pulkovo 26inch telescope was used to determine v-magnitudes. The cluster members were selected on the basis of proper motion (vector point diagram) and photometric (V/B-V and U-B/B-V) criteria.
- ID:
- ivo://CDS.VizieR/J/ApJ/784/57
- Title:
- Photometry and proper motions in Praesepe
- Short Name:
- J/ApJ/784/57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Membership identification is the first step in determining the properties of a star cluster. Low-mass members in particular could be used to trace the dynamical history, such as mass segregation, stellar evaporation, or tidal stripping, of a star cluster in its Galactic environment. We identified member candidates of the intermediate-age Praesepe cluster (M44) with stellar masses ~0.11-2.4M_{sun}_, using Panoramic Survey Telescope And Rapid Response System and Two Micron All Sky Survey photometry, and PPMXL proper motions. Within a sky area of 3{deg} radius, 1040 candidates are identified, of which 96 are new inclusions. Using the same set of selection criteria on field stars, an estimated false positive rate of 16% was determined, suggesting that 872 of the candidates are true members. This most complete and reliable membership list allows us to favor the BT-Settl model over other stellar models. The cluster shows a distinct binary track above the main sequence, with a binary frequency of 20%-40%, and a high occurrence rate of similar mass pairs. The mass function is consistent with that of the disk population but shows a deficit of members below 0.3 solar masses. A clear mass segregation is evidenced, with the lowest-mass members in our sample being evaporated from this disintegrating cluster.
- ID:
- ivo://CDS.VizieR/V/125
- Title:
- Photometry and Spectroscopy for Luminous Stars
- Short Name:
- V/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- of the paper: The birthrate of stars of masses >=10M_{sun}_ is estimated from a sample of just over 400 O3-B2 dwarfs within 1.5kpc of the Sun and the result extrapolated to estimate the Galactic supernova rate contributed by such stars. The solar-neighborhood Galactic-plane massive star birthrate is estimated at ~176stars/kpc^3^/Myr. On the basis of a model in which the Galactic stellar density distribution comprises a "disk+central hole" like that of the dust infrared emission (as proposed by Drimmel and Spergel), the Galactic supernova rate is estimated at probably not less than ~1 nor more than ~2 per century and the number of O3-B2 dwarfs within the solar circle at ~200000.
- ID:
- ivo://CDS.VizieR/J/AJ/147/7
- Title:
- Photometry and spectroscopy of NGC 6520
- Short Name:
- J/AJ/147/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use CCD and photoelectric photometry with Stromgren filters along with medium resolution spectra to investigate NGC 6520, an open cluster very nearly in the direction of the galactic center. We find an age of 60Myr, a distance of 2kpc, and an average reddening E(b-y)=0.295, which increases toward the south. The average heliocentric radial velocity of the B stars is -29km/s, while the velocity of the nearby Barnard 86 is about 0 (heliocentric; -11km/s compared to the LSR). This velocity difference amounts to about 1.8kpc since the cluster formed, implying that it is extremely doubtful NGC6520 is related to Barnard 86.
