- 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.
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- 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.
- 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.
- 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.
- 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).
- 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.
- ID:
- ivo://CDS.VizieR/J/AJ/122/2477
- Title:
- DIRECT variables in M33B field
- Short Name:
- J/AJ/122/2477
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- DIRECT is a project to obtain directly 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 1m class telescopes. In this eighth paper we present a catalog of variable stars discovered in the data from the follow-up observations of DEB system D33J013337.0+303032.8 in field M33B [(RA,DE)=(23.48{deg}, 30.57{deg}), J2000.0], collected with the Kitt Peak National Observatory 2.1m telescope. In our search covering an area of 108arcmin^2^ we have found 895 variable stars: 96 eclipsing binaries, 349 Cepheids, and 450 other periodic, possibly long-period or nonperiodic variables. Of these variables 612 are newly discovered. Their light curves were extracted using the ISIS image subtraction package. For 77% of the variables we present light curves in standard V and B magnitudes, with the remaining 23% expressed in units of differential flux. We have discovered a population of first-overtone Cepheid candidates, and for six of them we present strong arguments in favor of this interpretation. The catalog of variables, as well as their photometry (about 9.2x10^4^ BV measurements) and finding charts, is available electronically via anonymous ftp and the World Wide Web. The complete set of the CCD frames is available upon request.
- ID:
- ivo://CDS.VizieR/J/MNRAS/491/5524
- Title:
- Discovering Large-Scale Structure in ORELSE Survey
- Short Name:
- J/MNRAS/491/5524
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Observations of Redshift Evolution in Large-Scale Environments (ORELSE) survey is an ongoing imaging and spectroscopic campaign initially designed to study the effects of environment on galaxy evolution in high-redshift (z~1) large-scale structures. We use its rich data in combination with a powerful new technique, Voronoi tessellation Monte-Carlo (VMC) mapping, to search for serendipitous galaxy overdensities at 0.55<z<1.37 within 15 ORELSE fields, a combined spectroscopic footprint of ~1.4 square degrees. Through extensive tests with both observational data and our own mock galaxy catalogs, we optimize the method's many free parameters to maximize its efficacy for general overdensity searches. Our overdensity search yielded 402 new overdensity candidates with precisely measured redshifts and an unprecedented sensitivity down to low total overdensity masses M_tot_>5*10^13^M_{sun}_). Using the mock catalogs, we estimated the purity and completeness of our overdensity catalog as a function of redshift, total mass, and spectroscopic redshift fraction, finding impressive levels of both 0.92/0.83 and 0.60/0.49 for purity/completeness at z=0.8 and z=1.2, respectively, for all overdensity masses at spectroscopic fractions of ~20%. With VMC mapping, we are able to measure precise systemic redshifts, provide an estimate of the total gravitating mass, and maintain high levels of purity and completeness at z~1 even with only moderate levels of spectroscopy. Other methods (e.g., red-sequence overdensities and hot medium reliant detections) begin to fail at similar redshifts, which attests to VMC mapping's potential to be a powerful tool for current and future wide-field galaxy evolution surveys at z~1 and beyond.
- ID:
- ivo://CDS.VizieR/J/ApJ/697/1138
- Title:
- Discovery of PNe in M82
- Short Name:
- J/ApJ/697/1138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using an [OIII]{lambda}5007 on-band/off-band filter technique, we identify 109 planetary nebulae (PNe) candidates in the edge-on spiral galaxy M 82, using the FOCAS instrument at the 8.2m Subaru Telescope. The use of ancillary high-resolution Hubble Space Telescope Advanced Camera for Surveys H{alpha} imaging aided in confirming these candidates, helping to discriminate PNe from contaminants such as supernova remnants and compact HII regions. Once identified, these PNe reveal a great deal about the host galaxy; our analysis covers kinematics, stellar distribution, and distance determination. Radial velocities were determined for 94 of these PNe using a method of slitless spectroscopy, from which we obtain a clear picture of the galaxy's rotation.
- ID:
- ivo://CDS.VizieR/J/MNRAS/492/L40
- Title:
- Disentangling cataclysmic variables in Gaia DR2
- Short Name:
- J/MNRAS/492/L40
- Date:
- 07 Dec 2021 09:36:41
- Publisher:
- CDS
- Description:
- Cataclysmic Variables (CVs) are interacting binaries consisting of at least three components that control their colour and magnitude. Using Gaia we here investigate the influence of the physical properties of these binaries on their position in the Hertzsprung-Russell diagram (HR-diagram). The CVs are on average located between the main sequence and the white dwarf regime, the maximum density being at G_BP_-G_RP_~=0.56 and G_abs_~10.15. We nd a trend of the orbital period with colour and absolute brightness: with decreasing period, the CVs become bluer and fainter. We also identify the location of the various CV sub-types in the HR-diagram and discuss the possible location of detached CVs, going through the orbital period gap.
