- ID:
- ivo://CDS.VizieR/J/AJ/120/3111
- Title:
- Stromgren photometry of NGC 6397
- Short Name:
- J/AJ/120/3111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry extending below the turnoff of the globular cluster NGC 6397 on the uvbyH{beta} system is presented and analyzed. Restricting the sample to stars with small photometric errors and highly probable cluster membership, the reddening from approximately 1500 stars at the turnoff is E(b-y)=0.127+/-0.002 (standard error of the mean), equivalent to E(B-V)=0.179+/-0.003. The photometric abundance for the same sample, on the revised spectroscopic scale for globular clusters, is [Fe/H]=-1.82+/-0.04 (standard error of the mean). From 220 cluster red giants, well-defined relations are established for m_1_ and c_1_ as a function of b-y.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/125/1383
- Title:
- Stromgren photometry of NGC 6253
- Short Name:
- J/AJ/125/1383
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry on the intermediate-band uvbyCaH system is presented for the old open cluster NGC 6253. Despite a high level of field star contamination because of its location toward the Galactic center, combination of the data from the multiple color indices with the core cluster sample derived from radial star counts leads to the identification of a set of highly probable, single cluster members.
- ID:
- ivo://CDS.VizieR/J/AJ/131/461
- Title:
- Stromgren photometry of NGC 2420
- Short Name:
- J/AJ/131/461
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- CCD photometry on the intermediate-band vbyCaH{beta} system is presented for the metal-deficient open cluster NGC 2420. Restricting the data to probable single members of the cluster using the CMD and the photometric indices alone generates a sample of 106 stars at the cluster turnoff.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A119
- Title:
- Stromgren v photometry of {sigma} Lup
- Short Name:
- J/A+A/545/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Magnetic early B-type stars are rare. Indirect indicators are needed to identify them before investing in time-intensive spectropolarimetric observations. We use the strongest indirect indicator of a magnetic field in B stars, which is periodic variability of ultraviolet (UV) stellar wind lines occurring symmetric about the approximate rest wavelength. Our aim is to identify probable magnetic candidates which would become targets for follow-up spectropolarimetry to search for a magnetic field. From the UV wind line variability the B1/B2V star sigma Lupi emerged as a new magnetic candidate star. AAT spectropolarimetric measurements with SEMPOL were obtained. The longitudinal component of the magnetic field integrated over the visible surface of the star was determined with the least- squares deconvolution method. The UV line variations of sigma Lupi are similar to what is known in magnetic B stars, but no periodicity could be determined. We detected a varying longitudinal magnetic field with amplitude of about 100G with error bars of typically 20G, which supports an oblique magnetic-rotator configuration. The equivalent width variations of the UV lines, the magnetic and the optical-line variations are consistent with the photometric period of 3.02d, which we identify with the rotation period of the star. Additional observations with ESPaDOnS attached to the CFHT confirmed this discovery, and allowed the determination of a precise magnetic period. Analysis revealed that sigma Lupi is a helium-strong star, with an enhanced nitrogen abundance and an underabundance of carbon, and has a chemically spotted surface. Conclusions. sigma Lupi is a magnetic oblique rotator, and is a He-strong star. Like in other magnetic B stars the UV wind emission appears to originate close to the magnetic equatorial plane, with maximum emission occurring when a magnetic pole points towards the Earth. The 3.01972+/-0.00043d magnetic rotation period is consistent with the photometric period, with maximum light corresponding to maximum magnetic field.
- ID:
- ivo://CDS.VizieR/J/ApJ/757/22
- Title:
- Strong and weak lensing analysis of A2261
- Short Name:
- J/ApJ/757/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We precisely constrain the inner mass profile of A2261 (z=0.225) for the first time and determine that this cluster is not "overconcentrated" as found previously, implying a formation time in agreement with {Lambda}CDM expectations. These results are based on multiple strong-lensing analyses of new 16-band Hubble Space Telescope imaging obtained as part of the Cluster Lensing and Supernova survey with Hubble (CLASH; Postman et al. 2012, Cat. J/ApJS/199/25). Combining this with revised weak-lensing analyses of Subaru wide-field imaging with five-band Subaru + KPNO photometry, we place tight new constraints on the halo virial mass M_vir_=(2.2+/-0.2)x10^15^M_{sun}_h^-1^_70_ (within r_vir_{approx}3Mpc.h^-1^_70_) and concentration c_vir_=6.2+/-0.3 when assuming a spherical halo. This agrees broadly with average c(M, z) predictions from recent {Lambda}CDM simulations, which span 5<~<c><~8. Our most significant systematic uncertainty is halo elongation along the line of sight (LOS). To estimate this, we also derive a mass profile based on archival Chandra X-ray observations and find it to be ~35% lower than our lensing-derived profile at r_2500_~600kpc. Agreement can be achieved by a halo elongated with a ~2:1 axis ratio along our LOS. For this elongated halo model, we find M_vir_=(1.7+/-0.2)x10^15^M_{sun}_h^-1^_70_ and c_vir_=4.6+/-0.2, placing rough lower limits on these values. The need for halo elongation can be partially obviated by non-thermal pressure support and, perhaps entirely, by systematic errors in the X-ray mass measurements. We estimate the effect of background structures based on MMT/Hectospec spectroscopic redshifts and find that these tend to lower M_vir_ further by ~7% and increase c_vir_by ~5%.
3606. Strong cyanogen stars
- ID:
- ivo://CDS.VizieR/II/46
- Title:
- Strong cyanogen stars
- Short Name:
- II/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A cyanogen index for late-type giants, insensitive to surface gravity but sensitive to metallicity, is presented in the David Dunlap Observatory (DDO) photometric system. Observations were made using conventional single-channel photometers with 1P21 photomultiplier tubes on the 40cm and 90cm telescopes of Kitt Peak National Observatory. The original DDO filter set C was used (see Paper I, 1968AJ.....73..313M). Table 1 contains DDO photometry on 52 bright late-type giants for calibration. Most G8 to M0 stars, luminosity class III, V<4.0mag, north of {delta}=-10{deg}, supplement the original stars from Paper I. Table 4 includes both DDO and UBV photometry for stars from Schmitt (1967 thesis, Univ. Michigan, Ann Arbor) and Spinrad and Taylor (1967AJ.....72S.320S). Reddening values were computed using the method of McClure and Racine (1969AJ.....74.1000M).
- ID:
- ivo://CDS.VizieR/J/ApJS/243/17
- Title:
- Strong DES lens candidates from neural networks
- Short Name:
- J/ApJS/243/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We search Dark Energy Survey (DES) Year 3 imaging for galaxy-galaxy strong gravitational lenses using convolutional neural networks, extending previous work with new training sets and covering a wider range of redshifts and colors. We train two neural networks using images of simulated lenses, then use them to score postage-stamp images of 7.9 million sources from DES chosen to have plausible lens colors based on simulations. We examine 1175 of the highest-scored candidates and identify 152 probable or definite lenses. Examining an additional 20000 images with lower scores, we identify a further 247 probable or definite candidates. After including 86 candidates discovered in earlier searches using neural networks and 26 candidates discovered through visual inspection of blue-near-red objects in the DES catalog, we present a catalog of 511 lens candidates.
- ID:
- ivo://CDS.VizieR/J/ApJ/894/78
- Title:
- Strong gravitational lenses from DECaLS
- Short Name:
- J/ApJ/894/78
- Date:
- 03 Dec 2021 00:50:48
- Publisher:
- CDS
- Description:
- We perform a semi-automated search for strong gravitational lensing systems in the 9000 deg2 Dark Energy Camera Legacy Survey (DECaLS), part of the Dark Energy Spectroscopic Instrument Legacy Imaging Surveys. The combination of the depth and breadth of these surveys are unparalleled at this time, making them particularly suitable for discovering new strong gravitational lensing systems. We adopt the deep residual neural network architecture developed by Lanusse+ (2018MNRAS.473.3895L) for the purpose of finding strong lenses in photometric surveys. We compile a training sample that consists of known lensing systems in the Legacy Surveys and the Dark Energy Survey as well as non-lenses in the footprint of DECaLS. In this paper we show the results of applying our trained neural network to the cutout images centered on galaxies typed as ellipticals in DECaLS. The images that receive the highest scores (probabilities) are visually inspected and ranked. Here we present 335 candidate strong lensing systems, identified for the first time.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/12
- Title:
- Strong lens models for 37 clusters from SGAS
- Short Name:
- J/ApJS/247/12
- Date:
- 08 Mar 2022 13:45:09
- Publisher:
- CDS
- Description:
- We present strong gravitational lensing models for 37 galaxy clusters from the Sloan Digital Sky Survey Giant Arcs Survey (SGAS). We combine data from multi-band Hubble Space Telescope Wide Field Camera 3 (WFC3) imaging, with ground-based imaging and spectroscopy from Magellan, Gemini, Apache Point Observatory, and the Multiple Mirror Telescope, in order to detect and spectroscopically confirm new multiply imaged lensed background sources behind the clusters. We report spectroscopic or photometric redshifts of sources in these fields, including cluster galaxies and background sources. Based on all available lensing evidence, we construct and present strong-lensing mass models for these galaxy clusters. The clusters span a redshift range of 0.176<z<0.66 with a median redshift of z=0.45, and sample a wide range of dynamical masses, 1.5<M_200_<35x10^14^M_{sun}_, as estimated from their velocity dispersions. As these clusters were selected as lenses primarily owing to a fortuitous alignment with background galaxies that results in giant arcs, they exhibit a wide range in Einstein radii, 1.3"<{theta}_E_<23.1" for a source at z=2, with a median {theta}_E_=10.8".
- ID:
- ivo://CDS.VizieR/J/A+A/631/A91
- Title:
- 2 strongly lensed galaxies MUSE & ALMA datacubes
- Short Name:
- J/A+A/631/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the molecular and ionized gas kinematics of two strongly lensed galaxies at z~1 that lie on the main sequence at this redshift, based on observations from ALMA and MUSE, respectively. We derive the CO and [OII] rotation curves and dispersion profiles of these two galaxies. We find a difference between the observed molecular and ionized gas rotation curves for one of the two galaxies, the Cosmic Snake, for which we obtain a spatial resolution of few hundred parsecs along the major axis. The rotation curve of the molecular gas is steeper than the rotation curve of the ionized gas. In the second galaxy, A521, the molecular and ionized gas rotation curves are consistent, but the spatial resolution is only of few kpc on the major axis. Using simulations, we investigate the effect of the thickness of the gas disk and effective radius on the observed rotation curves and find that a more extended and thicker disk smooths the curve. We also find that the presence of a strongly inclined (>70{deg}) thick disk (>1kpc) can smooth the rotation curve because it degrades the spatial resolution along the line of sight. By building a model using a stellar disk and two gas disks, we reproduce the rotation curves of the Cosmic Snake with a molecular gas disk that is more massive and more radially and vertically concentrated than the ionized gas disk. Finally, we also obtain an intrinsic velocity dispersion in the Cosmic Snake of 18.5+/-7km/s and 19.5+/-6km/s for the molecular and ionized gas, respectively, which is consistent with a molecular disk with a smaller and thinner disk. For A521, the intrinsic velocity dispersion values are 11+/-8km/s and 54+/-11km/s, with a higher value for the ionized gas. This could indicate that the ionized gas disk is thicker and more turbulent in this galaxy. These results highlight the diversity of the kinematics of galaxies at z~1 and the different spatial distribution of the molecular and ionized gas disks. It suggests the presence of thick ionized gas disks at this epoch and that the formation of the molecular gas is limited to the midplane and center of the galaxy in some objects.
