- ID:
- ivo://CDS.VizieR/J/MNRAS/375/1220
- Title:
- BVI photometry of young stars in 10 clusters
- Short Name:
- J/MNRAS/375/1220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have selected pre-main-sequence (PMS) stars in 12 groups of notional ages ranging from 1 to 35Myr, using heterogeneous membership criteria. Using these members we have constructed empirical isochrones in V, V-I colour-magnitude diagrams. This allows us to identify clearly the gap between the radiative main sequence and the convective PMS (the RC gap). We follow the evolution of this gap with age and show that it can be a useful age indicator for groups less than =15 Myr old. We also observe a reduction in absolute spreads about the sequences with age. Finally, the empirical isochrones allow us to place the groups in order of age, independently of theory. The youngest groups can be collated into three sets of similar ages. The youngest set is the ONC, NGC 6530 and IC 5146 (nominally 1Myr); next Cep OB3b, NGC 2362, Ori and NGC 2264 (nominally 3Myr); and finally Ori and IC 348 (nominally 45Myr). This suggests Cep OB3b is younger than previously thought, and IC 348 older. For IC 348 the stellar rotation rate distribution and fraction of stars with discs imply a younger age than we derive. We suggest this is because of the absence of O-stars in this cluster, whose winds and/or ionizing radiation may be an important factor in the removal of discs in other clusters.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/138/680
- Title:
- BVI TX Cnc light curves
- Short Name:
- J/AJ/138/680
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present B-, V-, and I-band CCD photometry of the W UMa-type binary system TX Cnc, which is a member star of the Praesepe open cluster. Based on the observations, new ephemeris and a revised photometric solution of the binary system were derived.
- ID:
- ivo://CDS.VizieR/J/ApJ/660/81
- Title:
- BViz photometry of TKRS blue galaxies in GOODS-N
- Short Name:
- J/ApJ/660/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the radius-luminosity (R-L) relation for blue galaxies in the Team Keck Redshift Survey (TKRS) of GOODS-N. We compare with a volume-limited, Sloan Digital Sky Survey sample and find that the R-L relation has evolved to lower surface brightness since z=1. Based on the detection limits of GOODS, this cannot be explained by incompleteness in low surface brightness galaxies. Number density arguments rule out a pure radius evolution. It can be explained by a radius-dependent decline in B-band luminosity with time.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A1
- Title:
- BVJH photometry of Andrews-Lindsay 1 field
- Short Name:
- J/A+A/567/A1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Andrews-Lindsay 1 is a pertinent open cluster because it may host the planetary nebula (PN) PHR 1315-6555, yet ambiguities linger concerning its fundamental parameters (>50% scatter). New multiband BVJHW_1-4_ photometry for cluster and field stars, in concert with observations of recently discovered classical Cepheids, were used to constrain the reddening and velocity-distance profiles along the sightline. That analysis yielded the following parameters for the cluster: E(J-H)=0.24+/-0.03, d=10.0+/-0.4kpc (d_JH_=9.9+/-0.6kpc, d_BV_=10.1+/-0.5kpc), and log{tau}=8.90+/-0.15. The steep velocity-distance gradient along l~305{deg} indicates that two remote objects sharing spatial and kinematic parameters (i.e., PHR 1315-6555 and Andrews-Lindsay 1) are associated, thus confirming claims that the PN is a cluster member. The new distance for PHR 1315-6555 is among the most precise established yet for a Galactic PN ({sigma}/d=4%).
- ID:
- ivo://CDS.VizieR/J/A+A/483/263
- Title:
- BV light curve of V570 Per
- Short Name:
- J/A+A/483/263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The orbit and physical parameters of the previously unsolved double-lined eclipsing binary V570 Per are derived using Asiago Echelle high-resolution and high S/N spectroscopy, and B, V photo-electric photometry. Effective temperatures, gravities, rotational velocities, and metallicities of both components are also obtained from atmospheric chi^2^ analysis. The observed properties of V570 Per components are compared to available families of stellar evolutionary tracks, in particular to BaSTI models computed on purpose for exactly the observed masses and varied chemical compositions.
- ID:
- ivo://CDS.VizieR/J/A+A/452/959
- Title:
- BV light curve of V781 Tau
- Short Name:
- J/A+A/452/959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze light curves of the W UMa type eclipsing binary V781 Tauri from three epochs and radial velocity curves from two epochs simultaneously, including previously unpublished B and V data. The overall time span is from 1983 to 2000 and the solution is done coherently in time (not phase) with five light curves and two sets of primary and secondary velocity curves. Minor systematic differences among the individual light curves are not large enough to undermine the value of a coherent solution that represents 18 years of observations. Times of minima confirm a period of 0.34491d and the general solution finds a small period change, dP/P, of (5.08+/-04)*10^-11^ that represents recent behavior. The eclipse timings cover the last half-century and find dP/P about four times smaller, corresponding to a period change time scale, P/(dP/dt) of about 6 million years. The system is over-contact with a filling factor of 0.205. The solution produces a temperature difference of about 260K between the components, an inclination of 65.9{deg}, and a mass ratio M_2_/M_1_=2.47. Separate solutions of the several light curves that incorporate dark spots find parameters that differ little from curve to curve. Absolute masses, luminosities, radii and the distance are derived, with luminosities and distance based on star 1 being of type G0V. The orbital angular momentum is compared with those of other W UMa type binaries and is normal. The star to star mass flow that one can infer from dP/dt is opposite to that expected from TRO (Thermal Relaxation Oscillator) theory, but pertains to a time span that is very short compared to the time scale of TRO oscillations.
- ID:
- ivo://CDS.VizieR/J/PAZh/35/44
- Title:
- BV light curves of 33 ASAS-3 Cepheids
- Short Name:
- J/PAZh/35/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cepheids, the principal distance indicators, point to the existence of two inner Galactic spiral arms in the immediate solar neighborhood (within 5kpc). However, the available Cepheids are clearly insufficient for a detailed study of the structure of these arms. Fortunately, southern-sky monitoring (the ASAS project) has led to the discovery of many new variable stars, more than one thousand of which have been identified as possible Cepheids. To improve the classification and to construct reliable light curves for new Cepheids, we have begun their regular photometric observations. Here, we present the first results: 1192 photoelectric BVIc observations were performed for 33 classicalCepheidswith the 76-cm telescope of the South-African Astronomical Observatory (SAAO, the South-African Republic) from December 2006 to January 2008.We provide tables of observations and V light and B-V and V-Ic color curves. The new observations together with ASAS-3 data have been used to improve the elements of the light variations.
- ID:
- ivo://CDS.VizieR/J/A+AS/131/115
- Title:
- BV light curves of AU Ser
- Short Name:
- J/A+AS/131/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the Table 1 shown are the Heliocentric Julian Days at the start and at the end of the observation runs and the numbers of the observations for each color. Since the observations in 1991 have been published in Li et al. (1992IBVS.3802....1L), only those in 1992 and 1995 are listed in Table 2a and 2b for yellow and blue light respectively, where the Heliocentric Julian Days and the magnitude differences(the variable minus the comparison) are given. The normal points producing the light curves in Fig. 2 can found in Table 3 through 5.
- ID:
- ivo://CDS.VizieR/J/AJ/134/642
- Title:
- BV light curves of BB Pegasi
- Short Name:
- J/AJ/134/642
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ground-based photometry of the low-temperature contact binary BB Peg. We collected all the times of mid-eclipse available in the literature and combined them with those obtained in this study.
- ID:
- ivo://CDS.VizieR/J/AJ/141/195
- Title:
- BV light curves of FT Ori
- Short Name:
- J/AJ/141/195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Accurate absolute properties are determined for the first time for the 3.15 day period eccentric eclipsing binary star FT Ori based on new absolute photometry, five differential light curves, and a radial velocity curve. The stars appear to be normal for their spectral types, A0+A2. The orbit is highly eccentric (e=0.409) and shows apsidal motion with a period of 536-years. The absolute properties and the degree of central mass concentration of the stars are consistent with current theoretical models at an age of 190Myr.
