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391. BV light curves of NN Vir
ID:
ivo://CDS.VizieR/J/A+A/415/283
Title:
BV light curves of NN Vir
Short Name:
J/A+A/415/283
Date:
21 Oct 2021
Publisher:
CDS
Description:
Photoelectric BV light curves of the recently discovered eclipsing binary NN Vir were studied for the first time to derive the physical parameters of the system. The light curves were obtained at the Ankara University Observatory during three nights in May, 2002. The solutions made by using Djurasevic's inverse problem method describe the NN Vir system as a high overcontact configuration (f_over_~58%) with a relatively small temperature differences between the components ({Delta}T=T_h_-T_c_~160K). These solutions suggest a significant mass and energy transfer from the more massive primary onto the less massive secondary. The hot area on the less massive star, near the neck region, can be taken as a consequence of this mass and energy exchange between the components through the connecting neck of the common envelope.
392. BV light curves of 11 RR Lyrae
ID:
ivo://CDS.VizieR/J/AJ/139/2014
Title:
BV light curves of 11 RR Lyrae
Short Name:
J/AJ/139/2014
Date:
21 Oct 2021
Publisher:
CDS
Description:
It is not easy to identify and classify low-amplitude variables, but it is important that the classification is done correctly. We use photometry and spectroscopy to classify low-amplitude variables in a 246deg^2^ part of the Akerlof et al. (2000, Cat. J/AJ/119/1901) field. Akerlof and Collaborators found that 38% of the RR Lyrae stars in their 2000deg^2^ test field were RR1 (type c). This suggests that these RR Lyrae stars belong to an Oosterhoff Type II population, while their period distribution is primarily Oosterhoff Type I. Our observations support their RR0 (type ab) classifications; however, six of the seven stars that they classified as RR1 (type c) are eclipsing binaries. Our classifications are supported by spectroscopic metallicities, line-broadening, and Galactic rotation measurements. Our 246deg^2^ field contains 16 RR Lyrae stars that are brighter than m_R_=14.5; only four of these are RR1 (type c). This corresponds to an Oosterhoff Type I population in agreement with the period distribution.
393. BV light curves of the Algol-type binary V1241 Tauri
ID:
ivo://CDS.VizieR/J/AJ/144/136
Title:
BV light curves of the Algol-type binary V1241 Tauri
Short Name:
J/AJ/144/136
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present new photometry for the eclipsing binary V1241 Tau, which was obtained on six nights between 2011 December and 2012 January using the 85cm telescope at the Xinglong station of the National Astronomical Observatories of China. By using the updated Wilson-Devinney code, photometric models with third lights were deduced from two sets of light curves. The result implies that V1241 Tau is an Algol-type near-contact binary (NCB), whose mass ratio and filling-out of the primary are q=0.545(+/-0.003) and f_1_=82.4% (+/-0.2%), respectively. Based on all available times of minimum light spanning over 80yr, the O-C curve of V1241 Tau appears to show a quasi-sinusoidal oscillation, i.e., a light-time orbit. The modulated period and amplitude are P_mod_=47.4(+/-1.7)yr and A=0.0087(+/-0.0005)days, respectively. This kind of period variation may be more likely attributed to the light-time effect via a presence of an unseen third body. From an analysis of 23 Algol-type NCBs with EB-type light curves, we determine that the fill-out for the primary f_1_ will increase as the orbital period P decreases. With angular momentum loss, the orbit of the binary will shrink, which causes f_1_ to increase. The primary component finally fills its Roche lobe, and the binary evolves into contact configuration. Therefore, this kind of Algol-type NCB with EB-type light curves, such as V1241 Tau, may be a progenitor of the A-type W UMa binary.
394. BV light curves of V511 Lyr in 1994-1996
ID:
ivo://CDS.VizieR/J/A+A/383/197
Title:
BV light curves of V511 Lyr in 1994-1996
Short Name:
J/A+A/383/197
Date:
21 Oct 2021
Publisher:
CDS
Description:
Our time series analysis of sixteen BV light curves of the chromospherically active binary V511 Lyr confirmed the 2.7days rotation period uniquely. The seasonal periodicity changes of 3.8% indicated the presence of detectable surface differential rotation. The significant 2.67455days periodicity in the light curve minimum epochs suggested that the strongest starspot formation in V511 Lyr was concentrated on one stable active longitude. The differential BV photometry of V511 Lyr was made between May 1994 and June 1996 with the Vanderbilt-Tennessee State 0.4m Automated Photoelectric Telescope (APT). The comparison and check stars were HDE 337663 (C1) and HD 179422 (C2).
395. BV light curves of XY Leo, EE Cet, AQ Psc
ID:
ivo://CDS.VizieR/J/other/PASA/23.154
Title:
BV light curves of XY Leo, EE Cet, AQ Psc
Short Name:
J/other/PASA/23.
Date:
21 Oct 2021
Publisher:
CDS
Description:
New photoelectric BV light curves of three close eclipsing binaries XY Leo, EE Cet and AQ Psc were observed at the Rozhen National Astronomical Observatory, Bulgaria in the period October 2004 - February 2005, by using the 0.6-m Cassegrain telescope, equipped with an UBV, single-channel, photon-counting, computer controlled photometer. Integration time of 10 seconds was chosen.
396. BV photometry and Li abundances in NGC3960
ID:
ivo://CDS.VizieR/J/A+A/475/539
Title:
BV photometry and Li abundances in NGC3960
Short Name:
J/A+A/475/539
Date:
21 Oct 2021
Publisher:
CDS
Description:
Old open clusters are very useful targets to investigate mechanisms responsible for lithium (Li) depletion during the main sequence. Comparison of the Li abundances in clusters of different age allows us to understand the efficiency of the Li destruction process. To determine the membership and Li abundance in a sample of candidate members of the open cluster NGC 3960 (age ~1Gyr), aiming to fill the gap between 0.6 and 2Gyr in the empirical description of the behavior of the average Li abundance as a function of the stellar age. We use VLT/FLAMES Giraffe spectra to determine the radial velocities and thus the membership of a sample of 113 photometrically selected candidate cluster members. From the analysis of the Li line we derive Li abundances for both cluster members and non-members. 39 stars have radial velocities consistent with membership, with an expected fraction of contaminating field stars of about 20%. Li is detected in 29 of the radial velocity members; we consider these stars as cluster members, while we make the reasonable assumption that the remaining 10 radial velocity members without Li are among the contaminating stars. Li abundances of the stars hotter than about 6000K are similar to those of stars in the Hyades, while they are slightly smaller for cooler stars. This confirms that NGC 3960 is older than the Hyades. The average Li abundance of stars cooler than about 6000K indicates that the Li Pop. I plateau might start at ~1Gyr, rather than 2Gyr, which is the upper limit previously derived in the literature. We also find that the fraction of field stars with high Li abundance (>1.5) is about one third of the whole sample, which is in agreement with previous estimates. The fraction of contaminating field stars is consistent with that previously derived by us from photometry.
397. BV photometry for components of HIP doubles
ID:
ivo://CDS.VizieR/J/A+A/356/141
Title:
BV photometry for components of HIP doubles
Short Name:
J/A+A/356/141
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using observations obtained with the Tycho instrument of the ESA Hipparcos satellite, a two-colour photometry is produced for components of more than 7000 Hipparcos double and multiple stars with angular separations 0.1 to 2.5 arcsec. We publish 9473 components of 5173 systems with separations above 0.3 arcsec. The majority of them did not have Tycho photometry in the Hipparcos catalogue. The magnitudes are derived in the Tycho B_T and V_T passbands, similar to the Johnson passbands. Photometrically resolved components of the binaries with statistically significant trigonometric parallaxes can be put on an HR diagram, the majority of them for the first time.
398. BV photometry in and around 5 globular clusters
ID:
ivo://CDS.VizieR/J/AJ/147/155
Title:
BV photometry in and around 5 globular clusters
Short Name:
J/AJ/147/155
Date:
21 Oct 2021
Publisher:
CDS
Description:
Homogeneous B, V photometry is presented for 19324 stars in and around 5 Magellanic Cloud globular clusters: NGC 1466, NGC 1841, NGC 2210, NGC 2257, and Reticulum. The photometry is derived from eight nights of CCD imaging with the Cerro Tololo Inter-American Observatory 0.9m SMARTS telescope. Instrumental magnitudes were transformed to the Johnson B, V system using accurate calibration relations based on a large sample of Landolt-Stetson equatorial standard stars, which were observed on the same nights as the cluster stars. Residual analysis of the equatorial standards used for the calibration, and validation of the new photometry using Stetson's sample of secondary standards in the vicinities of the five Large Magellanic Cloud clusters, shows excellent agreement with our values in both magnitudes and colors. Color-magnitude diagrams reaching to the main-sequence turnoffs at V~22mag, sigma-magnitude diagrams, and various other summaries are presented for each cluster to illustrate the range and quality of the new photometry. The photometry should prove useful for future studies of the Magellanic Cloud globular clusters, particularly studies of their variable stars.
399. (BV) photometry in Carina dSph
ID:
ivo://CDS.VizieR/J/A+A/572/A10
Title:
(BV) photometry in Carina dSph
Short Name:
J/A+A/572/A10
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present deep photometry of the Carina dwarf Spheroidal galaxy in the B,V filters from CTIO/MOSAIC, out to and beyond the tidal radius of r_ell_~0.48{deg}. The accurately calibrated photometry is combined with spectroscopic metallicity distributions of Red Giant Branch stars to determine the detailed star formation and chemical evolution history of Carina. The star formation history confirms the episodic formation history of Carina and quantifies the duration and strength of each episode in great detail, as a function radius from the centre. Two main episodes of star formation occurred at old (>8Gyr) and intermediate (2-8Gyr) ages, both enriching stars starting from low metallicities ([Fe/H]<-2dex). By dividing the SFH into two components, we determine that 60+/-9 percent of the total number of stars formed within the intermediate age episode. Furthermore, within the tidal radius (0.48{deg} or 888pc) a total mass in stars of 1.07+/-0.08x10^6^M_{sun}_ was formed, giving Carina a stellar mass-to-light ratio of 1.8+/-0.8. Combining the detailed star formation history with spectroscopic observations of RGB stars, we are able to determine the detailed age-metallicity relation of each episode and the timescale of alpha-element evolution of Carina from individual stars. The oldest episode displays a tight age-metallicity relation during ~6Gyr with steadily declining alpha-element abundances and a possible alpha-element knee visible at [Fe/H]~-2.5dex. The intermediate age sequence displays a more complex age-metallicity relation starting from low metallicity and a sequence in alpha-element abundances with a slope much steeper than observed in the old episode, starting from [Fe/H]=-1.8dex and [Mg/Fe]~0.4dex and declining to Mg-poor values ([Mg/Fe]<-0.5dex). This indicates clearly that both episodes of star formation formed from gas with different abundance patterns , inconsistent with simple evolution in an isolated system.
400. BV photometry in Carina dwarf galaxy
ID:
ivo://CDS.VizieR/J/AJ/115/1840
Title:
BV photometry in Carina dwarf galaxy
Short Name:
J/AJ/115/1840
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have analyzed deep B and V photometry of the Carina dwarf spheroidal galaxy reaching below the old main-sequence turnoff to V~25. Using simulated color-magnitude diagrams to model a range of star formation scenarios, we have extracted a detailed, global star formation history. Carina experienced three significant episodes of star formation at ~15, 7, and 3Gyr. Contrary to the generic picture of galaxy evolution, however, the bulk of star formation, at least 50%, occurred during the episode 7Gyr ago, which may have lasted as long as 2Gyr. For unknown reasons, Carina formed only 10%-20% of its stars at an ancient epoch and then remained quiescent for more than 4 Gyr. The remainder (~30%) formed relatively recently, only 3Gyr ago. Interest in the local population of dwarf galaxies has increased lately because of their potential importance in the understanding of faint galaxy counts. We surmise that objects like Carina, which exhibits the most extreme episodic behavior of any of the dwarf spheroidal companions to the Galaxy, are capable of contributing to the observed excess of blue galaxies at B~24 only if the star formation occurred instantaneously.