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4651. Walraven photometry of OB stars
ID:
ivo://CDS.VizieR/J/A+A/369/527
Title:
Walraven photometry of OB stars
Short Name:
J/A+A/369/527
Date:
21 Oct 2021
Publisher:
CDS
Description:
About 700 stars, mostly OB-stars, were observed by the author at the former Leiden Southern Station at Hartebees poortdam, South Africa, in the observing seasons 1965, 1968, 1969, 1974, 1977, 1978. Observations were made in the five channels of the Walraven photometric system. Due to weathering of the telescope mirror the W channel gave no reliable results for the faintest stars (m=11mag); in these cases the U-W colour index is not given. The change in sensitivity in the V channel, supposedly having occurred in 1968, was not recognised. For a description of the Walraven VBLUW photometric system, see e.g. <GCPD/11>
4652. Walraven Photometry of southern OB associations
ID:
ivo://CDS.VizieR/J/A+AS/85/915
Title:
Walraven Photometry of southern OB associations
Short Name:
J/A+AS/85/915
Date:
21 Oct 2021
Publisher:
CDS
Description:
Homogeneous Walraven (VBLUW) photometry is presented for 5260 stars in the region of five nearby southern OB associations: Sco-Cen (Sco OB2), Ori OB1, CMa OB1, Mon OB1, and Sct OB2. Note that the tables have been prepared at Lausanne/Geneve Observatory (star names in Lausanne/Geneva system, coordinates absent) For details about the Walraven photometric system, see <GCPD/11>
4653. Walraven photometry of WX Hyi
ID:
ivo://CDS.VizieR/J/A+A/242/401
Title:
Walraven photometry of WX Hyi
Short Name:
J/A+A/242/401
Date:
21 Oct 2021
Publisher:
CDS
Description:
The SU UMa-type dwarf nova WX Hyi was observed in the 5 passbands VBLUW (544, 430, 384, 362 and 324nm) during 15 nights on the 90cm telescope at ESO (La Silla), between July and November 1988, with an integration time of 16s.
4654. Warps of galaxies
ID:
ivo://CDS.VizieR/J/A+A/391/519
Title:
Warps of galaxies
Short Name:
J/A+A/391/519
Date:
21 Oct 2021
Publisher:
CDS
Description:
From a comparison of the different parameters of warped galaxies in the radio, and especially in the visible, we find that: a) No large galaxy (large mass or radius) has been found to have high amplitude in the warp, and there is no correlation of size/mass with the degree of asymmetry of the warp. b) The disc density and the ratio of dark to luminous mass show an opposing trend: smaller values give more asymmetric warps in the inner radii (optical warps) but show no correlation with the amplitude of the warp; however, in the external radii is there no correlation with asymmetry. c) A third anticorrelation appears in a comparison of the amplitude and degree of asymmetry in the warped galaxies. Hence, it seems that very massive dark matter haloes have nothing to do with the formation of warps but only with the degree of symmetry in the inner radii, and are unrelated to the warp shape for the outermost radii. Denser discs show the same dependence.
4655. Washington Photometry in NGC 5128
ID:
ivo://CDS.VizieR/J/AJ/128/712
Title:
Washington Photometry in NGC 5128
Short Name:
J/AJ/128/712
Date:
21 Oct 2021
Publisher:
CDS
Description:
To investigate the global properties of the globular cluster system (GCS) around NGC 5128, the central giant elliptical galaxy in the nearby Centaurus group, we have obtained deep CCD imaging for an area of almost 2{deg}^2^ centered on the galaxy. Our data, in the CMT_1_ Washington photometric system, reach an approximate limiting magnitude of T_1_~R~22 and contain magnitudes, colors, and coordinates for more than 100,000 objects. Of these, the vast majority (about 99%) are either foreground stars or faint background galaxies; the old-halo globular clusters make up the remaining tiny fraction of the sample. Our database, however, provides the material for understanding the large-scale features of the GCS, including its metallicity distribution (MDF), luminosity distribution, and spatial structure.
4656. Washington Photometry in NGC 5128. II
ID:
ivo://CDS.VizieR/J/AJ/128/723
Title:
Washington Photometry in NGC 5128. II
Short Name:
J/AJ/128/723
Date:
21 Oct 2021
Publisher:
CDS
Description:
Building on the CMT_1_ photometric database presented in Paper I (Cat. <J/AJ/128/712>), in this paper we derive the large-scale properties of the globular cluster system (GCS) in NGC 5128, the nearest giant elliptical and the dominant galaxy in the Centaurus group. Using the metallicity-sensitive C-T_1_ color index, we discuss the metallicity distribution function (MDF) for a subsample of 211 previously identified clusters, all on a homogeneous photometric system. We find the MDF to be strongly bimodal, with metallicity peaks at [Fe/H]=-1.55 and -0.55 and with nearly equal numbers of clusters in each of the metal-poor and metal-rich modes. Finally, we present a list of 327 new cluster candidates not identified in any previous surveys; most of these are in the less well studied bulge region of the galaxy and along the minor axis.
4657. Washington photometry of Bootes I stars
ID:
ivo://CDS.VizieR/J/AJ/136/2321
Title:
Washington photometry of Bootes I stars
Short Name:
J/AJ/136/2321
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present Washington CT_1_T_2_ photometry of a field central to the Bootes I dwarf spheroidal galaxy, which was discovered as a stellar overdensity in the Sloan Digital Sky Survey (DR5). We show that the Washington filters are much more effective than the Sloan filters in separating the metal-poor turn-off stars in the dwarf galaxy from the foreground stars. We detect 165 objects in the field, and statistically determine that just over 40% of the objects are nonmembers. Our statistical analysis mostly agrees with radial velocity measurements of the brighter stars. We find that there is a distinct main-sequence turn-off and subgiant branch, where there is some evidence of a spread in chemical abundance.
4658. WASP-31b and host star radius compared with IMACS
ID:
ivo://CDS.VizieR/J/AJ/160/230
Title:
WASP-31b and host star radius compared with IMACS
Short Name:
J/AJ/160/230
Date:
10 Dec 2021
Publisher:
CDS
Description:
We present a new optical (400-950nm) transmission spectrum of the hot Jupiter WASP-31b (M=0.48M_Jup_; R=1.54R_Jup_; P=3.41days), obtained by combining four transit observations. These transits were observed with IMACS on the Magellan Baade Telescope at Las Campanas Observatory as part of the ACCESS project. We investigate the presence of clouds/hazes in the upper atmosphere of this planet, as well as the contribution of stellar activity on the observed features. In addition, we search for absorption features of the alkali elements NaI and KI, with particular focus on KI, for which there have been two previously published disagreeing results. Observations with Hubble Space Telescope (HST)/STIS detected KI, whereas ground-based low- and high- resolution observations did not. We use equilibrium and nonequilibrium chemistry retrievals to explore the planetary and stellar parameter space of the system with our optical data combined with existing near-IR observations. Our best-fit model is that with a scattering slope consistent with a Rayleigh slope ({alpha}=5.3_-3.1_^+2.9^), high-altitude clouds at a log cloud top pressure of -3.6_-2.1_^+2.7^bars, and possible muted H2O features. We find that our observations support other ground-based claims of no KI. Clouds are likely why signals like H2O are extremely muted and Na or K cannot be detected. We then juxtapose our Magellan/IMACS transmission spectrum with existing VLT/FORS2, HST/WFC3, HST/STIS, and Spitzer observations to further constrain the optical-to-infrared atmospheric features of the planet. We find that a steeper scattering slope ({alpha}=8.3{+/-}1.5) is anchored by STIS wavelengths blueward of 400nm and only the original STIS observations show significant potassium signal.
4659. WASP-12b and WASP-43b griz light curves
ID:
ivo://CDS.VizieR/J/A+A/630/A89
Title:
WASP-12b and WASP-43b griz light curves
Short Name:
J/A+A/630/A89
Date:
21 Oct 2021
Publisher:
CDS
Description:
The TESS and PLATO missions are expected to find vast numbers of new transiting planet candidates. However, only a fraction of these candidates will be legitimate planets, and the candidate validation will require a significant amount of follow-up resources. Radial velocity (RV) follow-up study can be carried out only for the most promising candidates around bright, slowly rotating, stars. Thus, before devoting RV resources to candidates, they need to be vetted using cheaper methods, and, in the cases for which an RV confirmation is not feasible, the candidate's true nature needs to be determined based on these alternative methods alone. We study the applicability of multicolour transit photometry in the validation of transiting planet candidates when the candidate signal arises from a real astrophysical source (transiting planet, eclipsing binary, etc.), and not from an instrumental artefact. Particularly, we aim to answer how securely we can estimate the true uncontaminated star-planet radius ratio when the light curve may contain contamination from unresolved light sources inside the photometry aperture when combining multicolour transit observations with a physics-based contamination model in a Bayesian parameter estimation setting. More generally, we study how the contamination level, colour differences between the planet host and contaminant stars, transit signal-to-noise ratio, and available prior information affect the contamination and true radius ratio estimates. The study is based on simulations and ground-based multicolour transit observations. The contamination analyses were carried out with a contamination model integrated into the PYTRANSIT V2 transit modelling package, and the observations were carried out with the MuSCAT2 multicolour imager installed in the 1.5m Telescopio Carlos Sanchez in the Teide Observatory, in Tenerife. We show that multicolour transit photometry can be used to estimate the amount of flux contamination and the true radius ratio. Combining the true radius ratio with an estimate for the stellar radius yields the true absolute radius of the transiting object, which is a valuable quantity in statistical candidate validation, and enough in itself to validate a candidate whose radius falls below the theoretical lower limit for a brown dwarf.
4660. WASP-21b light curves
ID:
ivo://CDS.VizieR/J/MNRAS/497/5182
Title:
WASP-21b light curves
Short Name:
J/MNRAS/497/5182
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the optical transmission spectrum of the highly inflated Saturn- mass exoplanet WASP-21b, using three transits obtained with the ACAM instrument on the William Herschel Telescope through the LRG-BEASTS survey (Low Resolution Ground-Based Exoplanet Atmosphere Survey using Transmission Spectroscopy). Our transmission spectrum covers a wavelength range of 4635-9000{AA}, achieving an average transit depth precision of 197ppm compared to one atmospheric scale height at 246ppm. We detect NaI absorption in a bin width of 30{AA}, at >4{sigma} confidence, which extends over 100{AA}. We see no evidence of absorption from KI. Atmospheric retrieval analysis of the scattering slope indicates it is too steep for Rayleigh scattering from H_2, but is very similar to that of HD 189733b. The features observed in our transmission spectrum cannot be caused by stellar activity alone, with photometric monitoring of WASP-21 showing it to be an inactive star. We therefore conclude that aerosols in the atmosphere of WASP-21b are giving rise to the steep slope that we observe, and that WASP-21b is an excellent target for infra-red observations to constrain its atmospheric metallicity.