- ID:
- ivo://CDS.VizieR/J/MNRAS/459/1687
- Title:
- Ks light curve of 299 SMC new Cepheids
- Short Name:
- J/MNRAS/459/1687
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present K_s_-band light curves for 299 Cepheids in the Small Magellanic Cloud (SMC) of which 288 are new discoveries that we have identified using multi-epoch near-infrared photometry obtained by the VISTA survey of the Magellanic Clouds system (VMC). The new Cepheids have periods in the range from 0.34 to 9.1d and cover the magnitude interval 12.9<=<K_s_><=17.6mag. Our method was developed using variable stars previously identified by the optical microlensing survey OGLE. We focus on searching new Cepheids in external regions of the SMC for which complete VMC K_s_-band observations are available and no comprehensive identification of different types of variable stars from other surveys exists yet.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/777/82
- Title:
- Ks luminosity of AGB stars in LMC clusters
- Short Name:
- J/ApJ/777/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of K_s_-band luminosity evolution of the asymptotic giant branch (AGB) population in simple stellar systems using star clusters in the Large Magellanic Cloud (LMC). We determine physical parameters of LMC star clusters including center coordinates, radii, and foreground reddenings. Ages of 83 star clusters are derived from isochrone fitting with the Padova models, and those of 19 star clusters are taken from the literature. The AGB stars in 102 star clusters with log(age)=7.3-9.5 are selected using near-infrared color-magnitude diagrams based on Two Micron All Sky Survey photometry. Then we obtain the K_s_-band luminosity fraction of AGB stars in these star clusters as a function of ages. The K_s_-band luminosity fraction of AGB stars increases, on average, as age increases from log(age)~8.0, reaching a maximum at log(age)~8.5, and it decreases thereafter. There is a large scatter in the AGB luminosity fraction for given ages, which is mainly due to stochastic effects. We discuss this result in comparison with five simple stellar population models. The maximum K_s_-band AGB luminosity fraction for bright clusters is reproduced by the models that expect the value of 0.7-0.8 at log(age)=8.5-8.7. We discuss the implication of our results with regard to the study of size and mass evolution of galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/502/505
- Title:
- Ks photometry of LMC RR Lyrae
- Short Name:
- J/A+A/502/505
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- RR Lyrae variable stars are the primary Population II distance indicator. Likewise, the LMC constitutes a key step in the extragalactic distance scale. By combining near-IR photometry and spectroscopically measured metallicities for a homogeneous sample of 50 RR Lyr stars in the Large Magellanic Cloud (LMC), we investigate the metallicity dependence of the period-luminosity relation in the near-infrared (IR), use the newly derived relations to re-derive the distance to the LMC, and compare the distance moduli obtained from RR Lyr and red clump stars.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/28
- Title:
- K2 star parameters from Gaia & LAMOST
- Short Name:
- J/ApJS/247/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Previous measurements of stellar properties for K2 stars in the Ecliptic Plane Input Catalog (EPIC) largely relied on photometry and proper motion measurements, with some added information from available spectra and parallaxes. Combining Gaia DR2 distances with spectroscopic measurements of effective temperatures, surface gravities, and metallicities from the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) DR5, we computed updated stellar radii and masses for 26838 K2 stars. For 195250 targets without a LAMOST spectrum, we derived stellar parameters using random forest regression on photometric colors trained on the LAMOST sample. In total, we measured spectral types, effective temperatures, surface gravities, metallicities, radii, and masses for 222088 A, F, G, K, and M-type K2 stars. With these new stellar radii, we performed a simple reanalysis of 299 confirmed and 517 candidate K2 planet radii from Campaigns 1-13, elucidating a distinct planet radius valley around 1.9R_{Earth}_, a feature thus far only conclusively identified with Kepler planets, and tentatively identified with K2 planets. These updated stellar parameters are a crucial step in the process toward computing K2 planet occurrence rates.
- ID:
- ivo://CDS.VizieR/J/AJ/109/709
- Title:
- K survey of Ori A molecular cloud
- Short Name:
- J/AJ/109/709
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a 2.2{mu}m (limiting K about 14.5mag) survey of the northern portion of the Orion A molecular cloud. A total of 3548 sources were detected in the 1472arcmin^2^ area surveyed. We detect clustering of 2.2{mu}m sources at the locations of the Trapezium and OMC-2. No strict boundaries for these clusters could be drawn from our data because we find that the entire region surveyed shows an overabundance of sources when compared with background field levels. We find that the form of the observed K luminosity function (KLF) of stars near the Trapezium is consistent with that predicted from a Miller and Scalo (ApJS 41, 513 (1979) IMF, if the age of the cluster is about 1Myr. Away from the Trapezium and the OMC-2, the KLF of stars suggests that either this population contains more low mass stars or that it is older than the Trapezium stars. The survey was carried out using the Ohio State InfraRed Imaging System (OSIRIS) 256x256 HgCdTe array on the Perkins 1.8m telescope in November 1992. In survey mode OSIRIS provides a spatial resolution of 1.50arcsec/pixel; the total field of view of the camera is 6.4arcmin. The telescope was rastered on 4.2arcmin steps to produce a mosaic approximately 39x39arcmin, centered near the Trapezium. A total of 81 K-band images were obtained, each with an exposure time about 3s.
- ID:
- ivo://CDS.VizieR/J/AJ/162/101
- Title:
- K2 ugri & H{alpha} photometry in the Lagoon Nebula
- Short Name:
- J/AJ/162/101
- Date:
- 14 Mar 2022 06:42:13
- Publisher:
- CDS
- Description:
- Space observatories have provided unprecedented depictions of the many variability behaviors typical of low-mass, young stars. However, those studies have so far largely omitted more massive objects (~2M{sun} to 4-5M{sun}) and were limited by the absence of simultaneous, multiwavelength information. We present a new study of young star variability in the ~1-2Myr old, massive Lagoon Nebula region. Our sample encompasses 278 young, late B to K-type stars, monitored with Kepler/K2. Auxiliary u, g, r, i, H{alpha} time-series photometry, simultaneous with K2, was acquired at the Paranal Observatory. We employed this comprehensive data set and archival infrared photometry to determine individual stellar parameters, assess the presence of circumstellar disks, and tie the variability behaviors to inner disk dynamics. We found significant mass-dependent trends in variability properties, with B/A stars displaying substantially reduced levels of variability compared to G/K stars for any light-curve morphology. These properties suggest different magnetic field structures at the surface of early-type and later-type stars. We also detected a dearth of some disk-driven variability behaviors, particularly dippers, among stars earlier than G. This indicates that their higher surface temperatures and more chaotic magnetic fields prevent the formation and survival of inner disk dust structures corotating with the star. Finally, we examined the characteristic variability timescales within each light curve and determined that the day-to-week timescales are predominant over the K2 time series. These reflect distinct processes and locations in the inner disk environment, from intense accretion triggered by instabilities in the innermost disk regions to variable accretion efficiency in the outer magnetosphere.
- ID:
- ivo://CDS.VizieR/J/PAZh/25/276
- Title:
- KV Cyg, V435 Cyg, V699 Cyg UBVR photometry
- Short Name:
- J/PAZh/25/276
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a UBVR photometry observations are presented for eclipsing binaries KV Cyg, V435 Cyg and V699 Cyg. Each binary was observed 1989/91 with the 60 cm telescopes at Maidanak Observatory (Uzbekistan).
- ID:
- ivo://CDS.VizieR/J/A+A/526/A150
- Title:
- KV Vel and TW Crv JHK light curves
- Short Name:
- J/A+A/526/A150
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a number of known post common envelopes binaries (PCEB) only a handful have yet been observed at near-infrared (NIR) wavelengths, and even fewer have modeled NIR light curves. At shorter wavelengths one has access to the cooler and larger components of these systems and has a chance to detect emission from its faint and heavily irradiated atmospheres. By modeling NIR light curves of PCEBs, we intend to constrain their system parameters and study the properties of the system components.
- ID:
- ivo://CDS.VizieR/J/ApJS/234/5
- Title:
- LaCoSSPAr in the Southern Galactic Cap. I.
- Short Name:
- J/ApJS/234/5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a spectroscopic redshift catalog from the LAMOST Complete Spectroscopic Survey of Pointing Area (LaCoSSPAr) in the Southern Galactic Cap (SGC), which is designed to observe all sources (Galactic and extragalactic) by using repeating observations with a limiting magnitude of r=18.1mag in two 20deg^2^ fields. The project is mainly focusing on the completeness of LAMOST ExtraGAlactic Surveys (LEGAS) in the SGC, the deficiencies of source selection methods, and the basic performance parameters of the LAMOST telescope. In both fields, more than 95% of galaxies have been observed. A post-processing has been applied to the LAMOST 1D spectrum to remove the majority of remaining sky background residuals. More than 10000 spectra have been visually inspected to measure the redshift by using combinations of different emission/absorption features with an uncertainty of {sigma}_z_/(1+z)<0.001. In total, 1528 redshifts (623 absorption and 905 emission line galaxies) in Field A and 1570 redshifts (569 absorption and 1001 emission line galaxies) in Field B have been measured. The results show that it is possible to derive redshift from low S/N galaxies with our post-processing and visual inspection. Our analysis also indicates that up to one-fourth of the input targets for a typical extragalactic spectroscopic survey might be unreliable. The multi-wavelength data analysis shows that the majority of mid-infrared-detected absorption (91.3%) and emission line galaxies (93.3%) can be well separated by an empirical criterion of W2-W3=2.4. Meanwhile, a fainter sequence paralleled to the main population of galaxies has been witnessed both in Mr/W2-W3 and M*/W2-W3 diagrams, which could be the population of luminous dwarf galaxies but contaminated by the edge-on/highly inclined galaxies (~30%).
- ID:
- ivo://CDS.VizieR/J/ApJ/622/129
- Title:
- Lag-luminosity relationship in AGN
- Short Name:
- J/ApJ/622/129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determine interband lags between variations in the B band and variations in the V, R, and I bands for 14 active galactic nuclei observed at the Crimean Astrophysical Observatory. The computed lags range from tenths of a day to several days, and it is positive (that is, V, R, and I bands lag behind the B band) in most cases, except for a few cases for the V filter.
