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981. Differential Stroemgren photometry of U Oph
ID:
ivo://CDS.VizieR/J/A+A/469/285
Title:
Differential Stroemgren photometry of U Oph
Short Name:
J/A+A/469/285
Date:
21 Oct 2021
Publisher:
CDS
Description:
We aim to determine absolute dimensions for the mid B-type eclipsing binary U Ophiuchi and compare the inferred ages and chemical compositions to those of other binary stars with masses near 5M_{sun}_. We determine masses, radii, logg, logT_eff_, and luminosities for the stars in U Oph from new radial velocities and uvby light curves. By improving the Wilson-Devinney code, we also derive precise apsidal-motion and light-time orbits of this triple system, using 353 times of minimum over 120 years. Finally, we compare the data for U Oph and similar systems with the predictions of stellar models.
982. Differential Stromgren photometry of 15 And
ID:
ivo://CDS.VizieR/J/A+A/480/187
Title:
Differential Stromgren photometry of 15 And
Short Name:
J/A+A/480/187
Date:
21 Oct 2021
Publisher:
CDS
Description:
The {lambda} Bootis stars are a chemically peculiar subgroup of main sequence A/F stars. Several of these fall into the instability strip of the {delta} Scuti stars and the whole spectroscopic group shows a high incidence of pulsational variability. We investigated the pulsational behaviour of the {lambda} Bootis star 15 And (HD 221756) to determine as many intrinsic mode frequencies as possible for asteroseismic applications.
983. Differential uvby photometry of HD 239276
ID:
ivo://CDS.VizieR/J/A+A/456/261
Title:
Differential uvby photometry of HD 239276
Short Name:
J/A+A/456/261
Date:
21 Oct 2021
Publisher:
CDS
Description:
The variability of HD 239276 was suspected photometrically nearly twenty years ago, but was confirmed with new observations obtained in 2001 during a two-site photometric campaign carried out from Spain, in uvby{beta} Stroemgren-Crawford photometry, and China, using the Johnson V filter. Two low-dispersion spectra were also collected. The results establish this star as a new multiperiodic gamma Dor-type pulsator with deficiency in metallicity.
984. Differential uvby photometry of HD 218427
ID:
ivo://CDS.VizieR/J/A+A/450/715
Title:
Differential uvby photometry of HD 218427
Short Name:
J/A+A/450/715
Date:
21 Oct 2021
Publisher:
CDS
Description:
Table 1 contents 845 simultaneous measurements collected in each of the four uvby colours of the Stromgren photometric system for the Gamma Doradus variable HD 218427. The data are magnitude differences (Du, Dv, Db, Dy, D(b-y), Dm1, Dc1) of the variable star minus comparison star in the standard system versus Heliocentric Julian Date. The comparison star is HD 219874. The origin in time is the Julian Day 2452839. The observations were carried out by the authors through the year 2003 using the 0.90m telescope at Sierra Nevada Observatory, Spain (Julian Days:0 to 69 in the table) and the 1.50m telescope at San Pedro Martir Observatory, Mexico (Julian Days: 122 to 128). Both telescopes are equipped with identical six-channel uvby-Hbeta spectrograph photometers for simultaneous measurements in uvby or in the narrow and wide H{beta} channels, respectively. Please note that a technical problem arose with the "u" filter in the 1.50m telescope, which made the "u" data collected with that telescope useless and they are named as 99.
985. Differential V-band phot. & RVs of V506 Oph
ID:
ivo://CDS.VizieR/J/ApJ/876/41
Title:
Differential V-band phot. & RVs of V506 Oph
Short Name:
J/ApJ/876/41
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report extensive differential V-band photometry and high-resolution spectroscopic observations of the early F-type, 1.06-day detached eclipsing binary V506 Oph. The observations, along with times of minimum light from the literature, are used to derive a very precise ephemeris and the physical properties for the components, with the absolute masses and radii being determined to 0.7% or better. The masses are 1.4153+/-0.0100M_{sun}_ and 1.4023+/-0.0094M_{sun}_ for the primary and secondary, the radii are 1.725+/-0.010R_{sun}_ and 1.692+/-0.012R_{sun}_, and the effective temperatures are 6840+/-150K and 6780+/-110K, respectively. The orbit is circular and the stars are rotating synchronously. The accuracy of the radii and temperatures is supported by the resulting distance estimate of 564+/-30pc, which is in excellent agreement with the value implied by the trigonometric parallax listed in the Gaia/Data Release 2 catalog. Current stellar evolution models from the Modules for Experiments in Stellar Astrophysics (MESA) Isochrones and Stellar Tracks series for a composition of [Fe/H]=-0.04 match the properties of both stars in V506 Oph very well at an age of 1.83Gyr and indicate they are halfway through their core hydrogen-burning phase.
986. Differential VRI photometry of HI Dra
ID:
ivo://CDS.VizieR/J/AJ/149/168
Title:
Differential VRI photometry of HI Dra
Short Name:
J/AJ/149/168
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a detailed investigation of the low-amplitude contact binary HI Dra based on the new VR_c_I_c_ CCD photometric light curves (LCs) combined with published radial velocity (RV) curves. Our completely covered LCs were analyzed using PHOEBE and revealed that HI Dra is an overcontact binary with low fill-out factor f=24+/-4(%) and temperature difference between the components of 330K. Two spotted models are proposed to explain the LC asymmetry, between which the A subtype of W UMa type eclipsing systems, with a cool spot on the less massive and cooler component, proves to be more plausible on evolutionary grounds. The results and stability of the solutions were explored by heuristic scan and parameter perturbation to provide a consistent and reliable set of parameters and their errors. Our photometric modeling and RV curve solution give the following absolute parameters of the hot and cool components, respectively: M_h_=1.72+/-0.08M_{sun}_ and M_c_=0.43+/-0.02M_{sun}_, R_h_=1.98+/-0.03R_{sun}_ and R_c_=1.08+/-0.02R_{sun}_, and L_h_=9.6+/-0.1L_{sun}_ and L_c_=2.4+/-0.1L_{sun}_. Based on these results the initial masses of the progenitors (1.11+/-0.03M_{sun}_ and 2.25+/-0.07M_{sun}_, respectively) and a rough estimate of the age of the system of 2.4Gyr are discussed.
987. Differential VRI photometry of WW Gem
ID:
ivo://CDS.VizieR/J/AJ/148/90
Title:
Differential VRI photometry of WW Gem
Short Name:
J/AJ/148/90
Date:
21 Oct 2021
Publisher:
CDS
Description:
WW Gem is a B-type eclipsing binary with a period of 1.2378days. The CCD photometry of this binary was performed in 2013 December using the 85cm telescope at the Xinglong Stations of the National Astronomical Observatories of China. Using the updated W-D program, the photometric model was deduced from the VRI light curves. The results imply that WW Gem is a near-contact eclipsing binary whose primary component almost fills its Roche lobe. The photometric mass ratio is q_ph_=0.48(+/-0.05). All collected times of minimum light, including two new ones, were used for the period studies. The orbital period changes of WW Gem could be described by an upward parabola, possibly overlaid by a light-time orbit with a period of P_mod_=7.41(+/-0.04)yr and a semi-amplitude of A=0.0079days(+/-0.0005days), respectively. This kind of cyclic oscillation may be attributed to the light-travel time effect via the third body. The long-term period increases at a rate of dP/dt=+3.47(+/-0.04)x10^-8^day/yr, which may be explained by the conserved mass transfer from the less massive component to the more massive one. With mass transfer, the massive binary WW Gem may be evolving into a contact binary.
988. Diffuse ionized gas in the Antennae galaxy
ID:
ivo://CDS.VizieR/J/A+A/611/A95
Title:
Diffuse ionized gas in the Antennae galaxy
Short Name:
J/A+A/611/A95
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Antennae galaxy (NGC 4038/39) is the closest major interacting galaxy system and is therefore often studied as a merger prototype. We present the first comprehensive integral field spectroscopic dataset of this system, observed with the MUSE instrument at the ESO VLT. We cover the two regions in this system which exhibit recent star formation: the central galaxy interaction and a region near the tip of the southern tidal tail. In these fields, we detect HII regions and diffuse ionized gas to unprecedented depth. About 15% of the ionized gas was undetected by previous observing campaigns. This newly detected faint ionized gas is visible everywhere around the central merger, and shows filamentary structure. We estimate diffuse gas fractions of about 60% in the central field and 10% in the southern region. We are able to show that the southern region contains a significantly different population of HII regions, showing fainter luminosities. By comparing HII region luminosities with the HST catalog of young star clusters in the central field, we estimate that there is enough Lyman-continuum leakage in the merger to explain the amount of diffuse ionized gas that we detect. We compare the Lyman-continuum escape fraction of each HII region against emission line ratios that are sensitive to the ionization parameter. While we find no systematic trend between these properties, the most extreme line ratios seem to be strong indicators of density bounded ionization. Extrapolating the Lyman-continuum escape fractions to the southern region, we conclude that simply from the comparison of the young stellar populations to the ionized gas there is no need to invoke other ionization mechanisms than Lyman-continuum leaking HII regions for the diffuse ionized gas in the Antennae.
989. Dimming event of RW Aurigae A
ID:
ivo://CDS.VizieR/J/A+A/625/A49
Title:
Dimming event of RW Aurigae A
Short Name:
J/A+A/625/A49
Date:
21 Oct 2021
Publisher:
CDS
Description:
RW Aur A is a classical T Tauri star that has suddenly undergone three major dimming events since 2010. The reason for these dimming events is still not clear. The two epochs of observations uploaded here are on the deep dimming events (2015) and immediate after the dimmin event (2016).
990. Direct variables in M33A field
ID:
ivo://CDS.VizieR/J/AJ/121/2032
Title:
Direct variables in M33A field
Short Name:
J/AJ/121/2032
Date:
21 Oct 2021
Publisher:
CDS
Description:
DIRECT is a project to directly obtain the distances to two Local Group galaxies, M31 and M33, which occupy a crucial position near the bottom of the cosmological distance ladder. As the first step of the DIRECT project, we have searched for detached eclipsing binaries (DEBs) and new Cepheids in the M31 and M33 galaxies with 1 m class telescopes. In this paper, we present a catalog of variable stars discovered in the data from the follow-up observations of the DEB system D33J013346.2+304439.9 in field M33A (RA=23.55{deg}, DE=30.72{deg}; J2000.0), collected with the Kitt Peak National Observatory's 2.1 m telescope. In our search covering an area of 108arcmin^2^, we have found 434 variable stars: 63 eclipsing binaries, 305 Cepheids, and 66 other periodic, possible long-period, or nonperiodic variables. Of these variables, 280 are newly discovered, mainly short-period and/or faint Cepheids. Their light curves were extracted using the ISIS image subtraction package. For 85% of the variables, we present light curves in standard V and B magnitudes, with the remaining 15% expressed in units of differential flux. We have discovered a population of first-overtone Cepheid candidates, and for eight of them we present strong arguments in favor of this interpretation. We also report on the detection of a nonlinearity in the KPNO T2KA and T1KA cameras.