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4481. SLoWPoKES. II. Properties of wide, low-mass binaries
ID:
ivo://CDS.VizieR/J/AJ/143/67
Title:
SLoWPoKES. II. Properties of wide, low-mass binaries
Short Name:
J/AJ/143/67
Date:
21 Oct 2021
Publisher:
CDS
Description:
We report the results from spectroscopic observations of 113 ultra-wide, low-mass binary systems, largely composed of M0-M3 dwarfs, from the SLoWPoKES catalog of common proper motion pairs identified in the Sloan Digital Sky Survey (Dhital et al., 2010, Cat. J/AJ/139/2566). Radial velocities of each binary member were used to confirm that they are comoving and, consequently, to further validate the high fidelity of the SLoWPoKES catalog. Ten stars appear to be spectroscopic binaries based on broad or split spectral features, supporting previous findings that wide binaries are likely to be hierarchical systems. We measured the H{alpha} equivalent width of the stars in our sample and found that components of 81% of the observed pairs have similar H{alpha} levels. The difference in H{alpha} equivalent width among components with similar masses was smaller than the range of H{alpha} variability for individual objects. We confirm that the Lepine et al. (2007ApJ...669.1235L) {zeta}-index traces iso-metallicity loci for most of our sample of M dwarfs. However, we find a small systematic bias in {zeta}, especially in the early-type M dwarfs. We use our sample to recalibrate the definition of {zeta}. While representing a small change in the definition, the new {zeta} is a significantly better predictor of iso-metallicity for the higher-mass M dwarfs.
4482. SL2S galaxy-scale lens sample. III.
ID:
ivo://CDS.VizieR/J/ApJ/777/97
Title:
SL2S galaxy-scale lens sample. III.
Short Name:
J/ApJ/777/97
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Hubble Space Telescope (HST) imaging data and Canada-France-Hawaii Telescope (CFHT) near-infrared ground-based images for the final sample of 56 candidate galaxy-scale lenses uncovered in the CFHT Legacy Survey as part of the Strong Lensing in the Legacy Survey (SL2S) project. The new images are used to perform lens modeling, measure surface photometry, and estimate stellar masses of the deflector early-type galaxies (ETGs). Lens modeling is performed on the HST images (or CFHT when HST is not available) by fitting the spatially extended light distribution of the lensed features assuming a singular isothermal ellipsoid mass profile and by reconstructing the intrinsic source light distribution on a pixelized grid. Based on the analysis of systematic uncertainties and comparison with inference based on different methods, we estimate that our Einstein radii are accurate to ~3%. HST imaging provides a much higher success rate in confirming gravitational lenses and measuring their Einstein radii than CFHT imaging does. Lens modeling with ground-based images, however, when successful, yields Einstein radius measurements that are competitive with space-based images. Information from the lens models is used together with spectroscopic information from companion Paper IV (2013ApJ...777...98S) to classify the systems, resulting in a final sample of 39 confirmed (grade A) lenses and 17 promising candidates (grade B,C).
4483. SL2S galaxy-scale sample of lens candidates
ID:
ivo://CDS.VizieR/J/ApJ/785/144
Title:
SL2S galaxy-scale sample of lens candidates
Short Name:
J/ApJ/785/144
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present RINGFINDER, a tool for finding galaxy-scale strong gravitational lenses in multi-band imaging data. By construction, the method is sensitive to configurations involving a massive foreground ETG and a faint, background, blue source. RINGFINDER detects the presence of blue residuals embedded in an otherwise smooth red light distribution by difference imaging in two bands. The method is automated for efficient application to current and future surveys, having originally been designed for the 150 deg^2^ Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). We describe each of the steps of RINGFINDER. We then carry out extensive simulations to assess completeness and purity. For sources with magnification {mu}>4, RINGFINDER reaches 42% (25%) completeness and 29% (86%) purity before (after) visual inspection. The completeness of RINGFINDER is substantially improved in the particular range of Einstein radii 0.8"<=R_Ein_<=2.0" and lensed images brighter than g=22.5, where it can be as high as ~70%. RINGFINDER does not introduce any significant bias in the source or deflector population. We conclude by presenting the final catalog of RINGFINDER CFHTLS galaxy-scale strong lens candidates. Additional information obtained with Hubble Space Telescope and Keck adaptive optics high-resolution imaging, and with Keck and Very Large Telescope spectroscopy, is used to assess the validity of our classification and measure the redshift of the foreground and the background objects. From an initial sample of 640000 ETGs, RINGFINDER returns 2500 candidates, which we further reduce by visual inspection to 330 candidates. We confirm 33 new gravitational lenses from the main sample of candidates, plus an additional 16 systems taken from earlier versions of RINGFINDER. First applications are presented in the Strong Lensing Legacy Survey galaxy-scale lens sample paper series.
4484. SLUGGS globular clusters in early-type galaxies
ID:
ivo://CDS.VizieR/J/MNRAS/428/389
Title:
SLUGGS globular clusters in early-type galaxies
Short Name:
J/MNRAS/428/389
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a spectrophotometric survey of 2522 extragalactic globular clusters (GCs) around 12 early-type galaxies, nine of which have not been published previously. Combining space-based and multicolour wide-field ground-based imaging, with spectra from the Keck/DEep Imaging Multi-Object Spectrograph (DEIMOS) instrument, we obtain an average of 160 GC radial velocities per galaxy, with a high-velocity precision of ~15km/s per GC. After studying the photometric properties of the GC systems, such as their spatial and colour distributions, we focus on the kinematics of metal-poor (blue) and metal-rich (red) GC subpopulations to an average distance of ~8 effective radii from the galaxy centre.
4485. SLUGGS NGC 3607 and 3608 globular clusters
ID:
ivo://CDS.VizieR/J/MNRAS/458/105
Title:
SLUGGS NGC 3607 and 3608 globular clusters
Short Name:
J/MNRAS/458/105
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present an investigation of the globular cluster (GC) systems of NGC 3607 and NGC 3608 as part of the ongoing SLUGGS (SAGES Legacy Unifying Globulars and GalaxieS) survey. We use wide-field imaging data from the Subaru telescope in the g, r and i filters to analyse the radial density, colour and azimuthal distributions of both GC systems. With the complementary kinematic data obtained from the Keck II telescope, we measure the radial velocities of a total of 81 GCs. Our results show that the GC systems of NGC 3607 and NGC 3608 have a detectable spatial extent of ~15 and 13 galaxy effective radii, respectively. Both GC systems show a clear bimodal colour distribution. We detect a significant radial colour gradient for the GC subpopulations in both galaxies. NGC 3607 exhibits an overabundance of red GCs on the galaxy minor axis and NGC 3608 shows a misalignment in the GC subpopulation position angles with respect to the galaxy stellar component. With the aid of literature data, we discuss several relationships between the properties of GC systems and their host galaxies. A one-to-one relation between the ellipticities of red GCs and the galaxy stellar light emphasizes the evolutionary similarities between them. In our sample of four slowly rotating galaxies with kinematically decoupled cores, we observe a higher ellipticity for the blue GC subpopulation than their red counterparts. Also, we notice the flattening of negative colour gradients for the blue GC subpopulations with increasing galaxy stellar mass. Finally, we discuss the formation scenarios associated with the blue GC subpopulation.
4486. SMaSH+: observations and companion detection
ID:
ivo://CDS.VizieR/J/ApJS/215/15
Title:
SMaSH+: observations and companion detection
Short Name:
J/ApJS/215/15
Date:
21 Oct 2021
Publisher:
CDS
Description:
Multiplicity is one of the most fundamental observable properties of massive O-type stars and offers a promising way to discriminate between massive star formation theories. Nevertheless, companions at separations between 1 and 100 milliarcsec (mas) remain mostly unknown due to intrinsic observational limitations. At a typical distance of 2kpc, this corresponds to projected physical separations of 2-200AU. The Southern MAssive Stars at High angular resolution survey (SMaSH+) was designed to fill this gap by providing the first systematic interferometric survey of Galactic massive stars. We observed 117 O-type stars with VLTI/PIONIER and 162 O-type stars with NACO/Sparse Aperture Masking (SAM), probing the separation ranges 1-45 and 30-250mas and brightness contrasts of {Delta}H<4 and {Delta}H<5, respectively. Taking advantage of NACO's field of view, we further uniformly searched for visual companions in an 8" radius down to {Delta}H=8. This paper describes observations and data analysis, reports the discovery of almost 200 new companions in the separation range from 1mas to 8" and presents a catalog of detections, including the first resolved measurements of over a dozen known long-period spectroscopic binaries. Excluding known runaway stars for which no companions are detected, 96 objects in our main sample ({delta}<0{deg}; H<7.5) were observed both with PIONIER and NACO/SAM. The fraction of these stars with at least one resolved companion within 200mas is 0.53. Accounting for known but unresolved spectroscopic or eclipsing companions, the multiplicity fraction at separation {rho}<8" increases to f_m_=0.91+/-0.03. The nine non-thermal radio emitters observed by SMaSH+ are all resolved, including the newly discovered pairs HD 168112 and CPD-47{deg}2963.
4487. SMC Be stars candidates
ID:
ivo://CDS.VizieR/J/A+A/393/887
Title:
SMC Be stars candidates
Short Name:
J/A+A/393/887
Date:
21 Oct 2021
Publisher:
CDS
Description:
Recently the OGLE experiment has provided accurate light curves and colours for about 2 millions stars in the Small Magellanic Cloud. We have examined this database for its content of Be stars, applying some selection criteria, and we have found a sample of ~1000 candidates. Some of these stars show beautiful light curves with amazing variations never observed in any Galactic variable. We find outbursts in 13% of the sample (type-1 stars), high and low states in 15%, periodic variations in 7%, and the usual variations seen in Galactic Be stars in 65% of the cases. The Galactic counterparts of type-1 objects could be the outbursting Be stars found by Hubert & Floquet (1998, Cat. J/A+A/335/565) after the analysis of Hipparcos photometry. We discuss the possibility that type-1 stars could correspond to Be stars with accreting white dwarf companions or alternatively, blue pre-main sequence stars surrounded by thermally unstable accretion disks. We provide coordinates and basic photometric information for these stars and some examples of light curves.
4488. SMC blob N26 multiband photometry
ID:
ivo://CDS.VizieR/J/A+A/564/A31
Title:
SMC blob N26 multiband photometry
Short Name:
J/A+A/564/A31
Date:
21 Oct 2021
Publisher:
CDS
Description:
High-excitation compact HII regions of the Magellanic Clouds are sites of recent massive star formation in low metallicity environments. Detailed study of these regions and their environments using high-spatial resolution observations is necessary to better understand massive star formation, which is still an unsolved problem. We aim at a detailed study of the Small Magellanic Cloud compact HII region N26, which is only ~4" in diameter. This study is based on high spatial resolution imaging (~0.1"-0.3") in JHKs and L' bands, using the VLT equipped with the NAOS adaptive optics system. A larger region (~50pcx76pc) was also imaged at medium spatial resolution, using the ESO 2.2m telescope in optical wavelengths. We also used the JHKs archival data from the IRSF survey and the Spitzer Space Telescope SAGE-SMC survey.
4489. SMC BV photometry of 9 star cluster fields
ID:
ivo://CDS.VizieR/J/A+A/591/A11
Title:
SMC BV photometry of 9 star cluster fields
Short Name:
J/A+A/591/A11
Date:
21 Oct 2021
Publisher:
CDS
Description:
The evolution and structure of the Magellanic Clouds is currently under debate. The classical scenario in which both the Large and Small Magellanic Clouds (LMC, SMC) are orbiting the Milky Way has been challenged by an alternative in which the LMC and SMC are in their first close passage to our Galaxy. The clouds are close enough to us to allow spatially resolved observation of their stars, and detailed studies of stellar populations in the galaxies are expected to be able to constrain the proposed scenarios. In particular, the west halo (WH) of the SMC was recently characterized with radial trends in age and metallicity that indicate tidal disruption. We intend to increase the sample of star clusters in the west halo of the SMC with homogeneous age, metallicity, and distance derivations to allow a better determination of age and metallicity gradients in this region. Distances and positions are compared with the orbital plane of the SMC depending on the scenario adopted. Comparisons of observed and synthetic V(B-V) colour-magnitude diagrams were used to derive age, metallicity, distance, and reddening for star clusters in the SMC west halo. Observations were carried out using the 4.1m SOAR telescope. Photometric completeness was determined through artificial star tests, and the members were selected by statistical comparison with a control field. We derived an age of 1.23+/-0.07Gyr and [Fe/H]=-0.87+/-0.07 for the reference cluster NGC 152, compatible with literature parameters. Age and metallicity gradients are confirmed in the WH: 2.6+/-0.6Gyr/{deg} and -0.19+/-0.09dex/{deg}, respectively. The age-metallicity relation for the WH has a low dispersion in metallicity and is compatible with a burst model of chemical enrichment. All WH clusters seem to follow the same stellar distribution predicted by dynamical models, with the exception of AM-3, which should belong to the counter-bridge. Bruck 6 is the youngest cluster in our sample. It is only 130+/-40Myr old and may have been formed during the tidal interaction of SMC-LMC that created the WH and the Magellanic bridge. We suggest that it is crucial to split the SMC cluster population into groups: main body, wing and bridge, counter-bridge, and WH. This is the way to analyse the complex star formation and dynamical history of our neighbour. In particular, we show that the WH has clear age and metallicity gradients and an age-metallicity relation that is also compatible with the dynamical model that claims a tidal influence of the LMC on the SMC.
4490. SMC Cepheids K-band and RV curves
ID:
ivo://CDS.VizieR/J/A+A/620/A99
Title:
SMC Cepheids K-band and RV curves
Short Name:
J/A+A/620/A99
Date:
21 Oct 2021
Publisher:
CDS
Description:
The extragalactic distance scale builds on the Cepheid period-luminosity (PL) relation. Decades of work have not yet convincingly established the sensitivity of the PL relation to metallicity. This currently prevents a determination of the Hubble constant accurate to 1% from the classical Cepheid-SN Ia method. In this paper we carry out a strictly differential comparison of the absolute PL relations obeyed by classical Cepheids in the Milky Way (MW), LMC, and SMC galaxies. Taking advantage of the substantial metallicity difference among the Cepheid populations in these three galaxies, we want to establish a possible systematic trend of the PL relation absolute zero point as a function of metallicity, and to determine the size of such an effect in the optical and near-infrared photometric bands. We used a IRSB Baade-Wesselink-type method to determine individual distances to the Cepheids in our samples in the MW, LMC, and SMC. For our analysis, we used a greatly enhanced sample of Cepheids in the SMC (31 stars) compared to the small sample (5 stars) available in our previous work. We used the distances to determine absolute Cepheid PL relations in the optical and near-infrared bands in each of the three galaxies. Our distance analysis of 31 SMC Cepheids with periods of 4-69 days yields tight PL relations in all studied bands, with slopes consistent with the corresponding LMC and MW relations. Adopting the very accurately determined LMC slopes for the optical and near-infrared bands, we determine the zero point offsets between the corresponding absolute PL relations in the three galaxies. We find that in all bands the metal-poor SMC Cepheids are intrinsically fainter than their more metal-rich counterparts in the LMC and MW. In the K band the metallicity effect is -0.23+/-0.06mag/dex, while in the V,(V-I) Wesenheit index it is slightly stronger, -0.34+/-0.06mag/dex. We find suggestive evidence that the metallicity sensitivity of the PL relation might be nonlinear, being small in the range between solar and LMC Cepheid metallicity, and becoming steeper towards the lower-metallicity regime.