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5621. R136 JKs photometry from VLT/SPHERE EAO
ID:
ivo://CDS.VizieR/J/A+A/602/A56
Title:
R136 JKs photometry from VLT/SPHERE EAO
Short Name:
J/A+A/602/A56
Date:
21 Oct 2021
Publisher:
CDS
Description:
This paper presents the sharpest near-IR images of the massive cluster R 136 to date, based on the extreme adaptive optics of the SPHERE focal instrument implemented on the ESO Very Large Telescope and operated in its IRDIS imaging mode. The crowded stellar population in the core of the R 136 starburst compact cluster remains still to be characterized in terms of individual luminosities, age, mass and multiplicity. SPHERE/VLT and its high contrast imaging possibilities open new windows to make progress on these questions. Stacking-up a few hundreds of short exposures in J and Ks spectral bands over a Field of View (FoV) of 10.9"x12.3" centered on the R136a1 stellar component, enabled us to carry a refined photometric analysis of the core of R136. We detected 1110 and 1059 sources in J and Ks images respectively with 818 common sources. Thanks to better angular resolution and dynamic range for 818 common sources being detected, we found that more than 62.6% (16.5%) of the stars, detected both in J and Ks data, have neighbours closer than 0.2" (0.1"). The closest stars are resolved down to the full width at half maximum (FWHM) of the point spread function (PSF) measured by Starfinder. Among newly resolved and/or detected sources R136a1 and R136c are found to have optical companions and R136a3 is resolved as two stars (PSF fitting) separated by 59+/-2mas. This new companion of R136a3 presents a correlation coefficient of 86% in J and 75% in Ks. The new set of detected sources were used to re-assess the age and extinction of R 136 based on 54 spectroscopically stars that have been recently studied with HST slit-spectroscopy (Crowther et al., 2016MNRAS.458..624C) of the core of this cluster. Over 90% of these 54 sources identified visual companions (closer than 0.2"). We found the most probable age and extinction for these sources are 1.8+1.2-0.8Myr, A_J_=(0.45+/-0.5)mag and A_K_=(0.2+/-0.5) mag within the photometric and spectroscopic error-bars. Additionally, using PARSEC evolutionary isochrones and tracks, we estimated the stellar mass range for each detected source (common in J and K data) and plotted the generalized histogram of mass (MF with error-bars). Using SPHERE data, we have gone one step further and partially resolved and studied the IMF covering mass range of (3-300)M_{sun}_ at the age of 1 and 1.5Myr. The density in the core of R 136 (0.1-1.4pc) is estimated and extrapolated in 3D and larger radii (up to 6pc). We show that the stars in the core are still unresolved due to crowding, and the results we obtained are upper limits. Higher angular resolution is mandatory to overcome these difficulties.
5622. RK photometry in 3C 336 field
ID:
ivo://CDS.VizieR/J/ApJ/480/568
Title:
RK photometry in 3C 336 field
Short Name:
J/ApJ/480/568
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present very deep WFPC2 images and FOS spectroscopy from the Hubble Space Telescope (HST) together with numerous supporting ground-based observations of the field of the quasar 3C 336 (z_em_=0.927). The observations are designed to investigate the nature of galaxies producing metal-line absorption systems in the spectrum of the QSO. Along a single line of sight, we find at least six metal-line absorption systems (of which three are newly discovered) ranging in redshift from 0.317 to 0.892. Through an extensive program of optical and IR imaging, QSO spectroscopy, and faint galaxy spectroscopy, we have identified five of the six metal-line absorption systems with luminous (L_K_>=0.1L^*^_K_) galaxies. These have morphologies ranging from very late-type spiral to S0, and they exhibit a wide range of inclination and position angles with respect to the QSO sight line. The only unidentified absorber, despite our intensive search, is a damped Lyman-{alpha} system at z_abs_=0.656. Analysis of the absorption spectrum suggests that the metal abundances ([Fe/H]=-1.2) in this system are similar to those in damped systems at z~2 and to the two other damped systems for which abundances have been determined at z<1. The absorption line system must either be associated with an underluminous, late-type spiral galaxy, which we find at a projected disk impact parameter of ~120h^-1^kpc, or with an as yet unseen, extremely faint galaxy (L<0.05L^*^_K_) near the QSO sight line that eludes detection despite our deep HST and high-resolution ground-based near-IR images. We have found no examples of intrinsically faint galaxies (L<0.1L^*^) at small impact parameters that might have been missed as absorber candidates in our previous ground-based imaging and spectroscopic programs on Mg II absorbing galaxies. We have, however, identified several intrinsically faint galaxies within ~50h^-1^kpc of the QSO sight line that do not produce detectable metal-line absorption. There are no bright galaxies (L>0.1L_K_) within 50h^-1^kpc that do not produce detectable metal lines (of Mg II {lambda}{lambda}2796, 2803 and/or C IV {lambda}{lambda}1548, 1550) in the QSO spectrum. All of these results generally support the inferences we have previously reached from a larger survey for absorption-selected galaxies at z<1. There are several other galaxies with redshifts near that of 3C 336, suggesting that the QSO is situated in an overdense region, perhaps a galaxy cluster. Previously published reports of a cluster around 3C 336 were largely misled by the presence of many foreground galaxies seen in projection near the QSO. It is possible that a reported measurement of weak shear gravitational lensing in this field may be produced by the QSO cluster itself, since there appear to be no other groups or clusters in the foreground. We find no evidence for a normal, bright QSO host galaxy, although there are several faint objects very close to the quasar and at similar redshift that might either be companions or part of a disorganized QSO host.
5623. R light curve of DO Dra
ID:
ivo://CDS.VizieR/J/A+A/486/855
Title:
R light curve of DO Dra
Short Name:
J/A+A/486/855
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the variability of the cataclysmic variable DO Dra, on time-scales of between minutes and decades. The observations were obtained at the Korean 1m telescope at the Mt. Lemmon in 2006-2007, 14 observational runs cover 45h. Additionally, we have used 1509 patrol observations from the international AFOEV and VSOLJ databases.
5624. R light-curve of TT Ari
ID:
ivo://CDS.VizieR/J/A+A/496/765
Title:
R light-curve of TT Ari
Short Name:
J/A+A/496/765
Date:
21 Oct 2021
Publisher:
CDS
Description:
We study the variability of the nova-like cataclysmic variable TT Ari, on time-scales of between minutes and months. The observations in the filter R were obtained at the 40-cm telescope of the Chungbuk National University (Korea), 51 observational runs cover 226 hours. In our analysis, we applied several methods: periodogram, wavelet, and scalegram analysis. TT Ari remained in a "negative superhump" state after its return from the "positive superhump" state, which lasted for 8 years. The ephemeris for 12 of the best pronounced minima is T_min_=BJD 2453747.0700(47)+0.132322(53)E, where numbers in digits are errors in units of the last digit. The phases of minima may reach 0.2, which reflects the non-eclipse nature of these minima. The quasi-periodic oscillations (QPO) are present with a mean "period" of 21.6min and mean semi-amplitude of 36mmag.This value is consistent with the range 15-25min reported for previous "negative superhump" states and does not support the hypothesis of secular decrease in the QPO period. Either the period, or the semi-amplitude show significant night-to-night variations. According to the position at the two-parameter diagrams (i.e. diagrams of pairs of parameters: time, mean brightness of the system, brightness of the source of QPO, amplitude, and timescale of the QPOs), the interval of observations was divided into 5 parts, showing different characteristics: 1) the "pre-outburst" stage, 2) the "rise to outburst", 3) "top of the outbursts", 4) "post- outburst QPO" state, and 5) "slow brightening". The the QPO source was significantly brighter during the 10-day outburst, than during the preceding interval. However, after the outburst, the large brightness of the QPO source still existed for about 30 days, producing the stage "4". The diagram for m_QPO_({bar}{m}) exhibits two groups in the brightness range 10.6-10.8, which correspond to larger and smaller amplitudes of the QPO. For the group "5" only, statistically significant correlations were found, for which, with increasing mean brightness, the period, amplitude, and brightness of the of QPO source also increase. The mean brightness at the "negative superhump state" varies within 10.3-11.2, so the system is brighter than at the "positive superhump" (11.3), therefore the "negative superhump" phenomenon may be interpreted by a larger accretion rate. The system is an excellent laboratory for studying processes resulting in variations on timescales of between seconds and decades and needs further monitoring at various states of activity.
5625. R light curves of 5 blazars
ID:
ivo://CDS.VizieR/J/AZh/81/925
Title:
R light curves of 5 blazars
Short Name:
J/AZh/81/925
Date:
21 Oct 2021
Publisher:
CDS
Description:
We monitored five active galactic nuclei in the R optical band with a CCD mounted on the 1-m Zeiss-1000 telescope of the Special Astrophysical Observatory from April 2001 to August 2003. Three sources displayed intraday variability on several nights. Stronger variability was detected on time scales from two days to a week. The two-year light curves are presented for four of the observed objects.
5626. R light curves of MN Dra
ID:
ivo://CDS.VizieR/J/A+A/603/A72
Title:
R light curves of MN Dra
Short Name:
J/A+A/603/A72
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of an extensive world-wide observing campaign of MN Draconis. MN Draconis is a poorly known active dwarf nova in the period gap and is one of the only two known cases of period gap SU UMa objects showing the negative superhumps. Photometric behaviour of MN Draconis poses a challenge for existing models of the superhump and superoutburst mechanisms. Therefore, thorough investigation of peculiar systems, such as MN Draconis, is crucial for our understanding of evolution of the close binary stars. To measure fundamental parameters of the system, we collected photometric data in October 2009, June-September 2013 and June-December 2015. Analysis of the light curves, O-C diagrams and power spectra was carried out. During our three observational seasons we detected four superoutburts and several normal outbursts. Based on the two consecutive superoutbursts detected in 2015, the supercycle length was derived P_sc_=74+/-0.5-days and it has been increasing with a rate of P_dot_=3.3x10^-3^ during last twelve years. Based on the positive and negative superhumps we calculated the period excess {epsilon}=5.6%+/-0.1%, the period deficit {epsilon}_=2.5%+/-0.6%, and in result, the orbital period P_orb_=0.0994(1)days (143.126+/-0.144min). We updated the basic light curve parameters of MN Draconis. MN Draconis is the first discovered SU UMa system in the period gap with increasing supercycle length.
5627. R light curves of NGC 6253 variables
ID:
ivo://CDS.VizieR/J/A+A/509/A17
Title:
R light curves of NGC 6253 variables
Short Name:
J/A+A/509/A17
Date:
21 Oct 2021
Publisher:
CDS
Description:
This work presents the first high-precision variability survey in the field of the intermediate-age, metal-rich open cluster NGC 6253. We discovered 595 variables and we also characterized most of them providing their variability classes, periods and amplitudes. The sample is complete at short periods: we classified 20 pulsating variables, 225 contact systems, 99 eclipsing systems (22 Beta Lyr type, 59 Beta Per type, 18 RS CVn type), and 77 rotational variables. The time-baseline hampered the precise characterization of 173 variables with periods longer than 4-5days. Moreover, we found a cataclysmic system undergoing an outburst of about 2.5mag.
5628. R Low-mass stars of beta Pic and AB Dor groups
ID:
ivo://CDS.VizieR/J/AJ/143/80
Title:
R Low-mass stars of beta Pic and AB Dor groups
Short Name:
J/AJ/143/80
Date:
21 Oct 2021
Publisher:
CDS
Description:
As part of our continuing effort to identify new, low-mass members of nearby, young moving groups (NYMGs), we present a list of young, low-mass candidates in the northern hemisphere. We used our proven proper-motion selection procedure and ROSAT X-ray and GALEX-UV activity indicators to identify 204 young stars as candidate members of the {beta} Pictoris and AB Doradus NYMGs. Definitive membership assignment of a given candidate will require a measurement of its radial velocity and distance. We present a simple system of indices to characterize the young candidates and help prioritize follow-up observations. New group members identified in this candidate list will be high priority targets for (1) exoplanet direct imaging searches, (2) the study of post-T-Tauri astrophysics, (3) understanding recent local star formation, and (4) the study of local galactic kinematics. Information available now allows us to identify eight likely new members in the list. Two of these, a late-K and an early-M dwarf, we find to be likely members of the {beta} Pic group. The other six stars are likely members of the AB Dor moving group. These include an M dwarf triple system, and three very cool objects that may be young brown dwarfs, making them the lowest-mass, isolated objects proposed in the AB Dor moving group to date.
5629. r' magnitudes and sizes of Oph cluster galaxies
ID:
ivo://CDS.VizieR/J/A+A/613/A20
Title:
r' magnitudes and sizes of Oph cluster galaxies
Short Name:
J/A+A/613/A20
Date:
21 Oct 2021
Publisher:
CDS
Description:
Ophiuchus is one of the most massive clusters known, but due to its low Galactic latitude its optical properties remain poorly known. We investigate the optical properties of Ophiuchus to obtain clues on the formation epoch of this cluster, and compare them to those of the Coma cluster, which is comparable in mass to Ophiuchus but much more dynamically disturbed. Based on a deep image of the Ophiuchus cluster in the r' band obtained at the Canada France Hawaii Telescope with the MegaCam camera, we have applied an iterative process to subtract the contribution of the numerous stars that, due to the low Galactic latitude of the cluster, pollute the image, and have obtained a photometric catalogue of 2818 galaxies fully complete at r'=20.5mag and still 91% complete at r'=21.5mag. We use this catalogue to derive the cluster Galaxy Luminosity Function (GLF) for the overall image and for a region (hereafter the "rectangle" region) covering exactly the same physical size as the region in which the GLF of the Coma cluster was previously studied. We then compute density maps based on an adaptive kernel technique, for different magnitude limits, and define three circular regions covering 0.08, 0.08, and 0.06 deg^2^, respectively, centred on the cluster (C), on northwest (NW) of the cluster, and southeast (SE) of the cluster, in which we compute the GLFs. The GLF fits are much better when a Gaussian is added to the usual Schechter function, to account for the excess of very bright galaxies. Compared to Coma, Ophiuchus shows a strong excess of bright galaxies. The properties of the two nearby very massive clusters Ophiuchus and Coma are quite comparable, though they seem embedded in different large-scale environments. Our interpretation is that Ophiuchus was built up long ago, as confirmed by its relaxed state (see paper I, Durret et al., 2015, Cat. J/A+A/583/A124) while Coma is still in the process of forming.
5630. R magnitudes in four ESO fields
ID:
ivo://CDS.VizieR/J/A+AS/120/357
Title:
R magnitudes in four ESO fields
Short Name:
J/A+AS/120/357
Date:
21 Oct 2021
Publisher:
CDS
Description:
The tables present a R-band CCD photometric sequence of stars for calibrating ESO/SERC(R) survey plates in the region of the Shapley supercluster of galaxies. The observations were carried out on 1993 Ferbruary 17 to 22 at the 0.6m telescope of the University of Toronto at Las Campanas Observatory in Chile, using a 513x516pix CCD with a resolution of 0.46''.