- ID:
- ivo://CDS.VizieR/J/ApJ/898/46
- Title:
- NIR LCs of RRab stars from the VVV survey
- Short Name:
- J/ApJ/898/46
- Date:
- 21 Mar 2022 07:11:54
- Publisher:
- CDS
- Description:
- Aiming to extend the census of RR Lyrae stars to highly reddened low-latitude regions of the central Milky Way, we performed a deep near-IR variability search using data from the VISTA Variables in the Via Lactea (VVV) survey of the bulge, analyzing the photometric time series of over a hundred million point sources. In order to separate fundamental-mode RR Lyrae (RRab) stars from other periodically variable sources, we trained a deep bidirectional long short-term memory recurrent neural network (RNN) classifier using VVV survey data and catalogs of RRab stars discovered and classified by optical surveys. Our classifier attained a ~99% precision and recall for light curves with signal-to-noise ratio above 60, and is comparable to the best-performing classifiers trained on accurate optical data. Using our RNN classifier, we identified over 4300 hitherto unknown bona fide RRab stars toward the inner bulge. We provide their photometric catalog and VVV J,H,Ks photometric time series.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/160/220
- Title:
- NIR light curve of 234 RR Lyrae in Messier 3
- Short Name:
- J/AJ/160/220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new near-infrared (NIR), JHKs, time-series observations of RR-Lyrae variables in the Messier-3 (NGC5272) globular cluster using the WIRCam instrument at the 3.6m Canada-France-Hawaii Telescope. Our observations cover a sky area of ~21'x21' around the cluster center and provide an average of 20 epochs of homogeneous JHKs-band photometry. New homogeneous photometry is used to estimate robust mean magnitudes for 175 fundamental-mode (RRab), 47 overtone-mode (RRc), and 11 mixed-mode (RRd) variables. Our sample of 233 RR-Lyrae variables is the largest thus far obtained in a single cluster with time-resolved, multiband NIR photometry. NIR-to-optical amplitude ratios for RR-Lyrae in Messier-3 exhibit a systematic increase moving from RRc to short-period (P<0.6day) and long-period (P>~0.6day) RRab variables. We derive JHKs-band period-luminosity relations for RRab, RRc, and the combined sample of variables. Absolute calibrations based on the theoretically predicted period-luminosity-metallicity relations for RR Lyrae stars yield a distance modulus, {mu}=15.041{+/-}0.017(statistical){+/-}0.036(systematic)mag, to Messier-3. When anchored to trigonometric parallaxes for nearby RR-Lyrae stars from the Hubble Space Telescope and the Gaia mission, our distance estimates are consistent with those resulting from the theoretical calibrations, albeit with relatively larger systematic uncertainties.
- ID:
- ivo://CDS.VizieR/J/A+A/576/A30
- Title:
- NIR light-curve templates for classical Cepheids
- Short Name:
- J/A+A/576/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new near-infrared (NIR) light-curve templates for fundamental (FU, J, H, Ks) and first overtone (FO, J) classical Cepheids. The new templates together with period-luminosity and period-Wesenheit (PW) relations provide Cepheid distances from single-epoch observations with a precision only limited by the intrinsic accuracy of the method adopted. The templates rely on a very large set of Galactic and Magellanic Cloud Cepheids (FU, ~600; FO, ~200) with well-sampled NIR (IRSF data set) and optical (V, I; OGLE data set) light-curves. To properly trace the change in the shape of the light-curve as a function of pulsation period, we split the sample of calibrating Cepheids into ten different period bins. The templates for the first time cover FO Cepheids and the short-period range of FU Cepheids (P<=5-days). Moreover, the phase zero-point is anchored to the phase of the mean magnitude along the rising branch. The new approach has several advantages in sampling the light-curve of bump Cepheids when compared with the canonical phase of maximum light. We also provide new empirical estimates of the NIR-to-optical amplitude ratios for FU and FO Cepheids. We perform detailed analytical fits using seventh-order Fourier series and multi-Gaussian periodic functions. The latter are characterized by fewer free parameters (nine vs. fifteen). The mean NIR magnitudes based on the new templates are up to 80% more accurate than single-epoch NIR measurements and up to 50% more accurate than the mean magnitudes based on previous NIR templates, with typical associated uncertainties ranging from 0.015mag (J band) to 0.019mag (K_S_ band). Moreover, we find that errors on individual distance estimates for Small Magellanic Cloud Cepheids derived from NIR PW relations are essentially reduced to the intrinsic scatter of the adopted relations. Thus, the new templates are the ultimate tool for estimating precise Cepheid distances from NIR single-epoch observations, which can be safely adopted for future interesting applications, including deriving the 3D structure of the Magellanic Clouds.
- ID:
- ivo://CDS.VizieR/J/AJ/141/105
- Title:
- NIR-matched quasar catalog
- Short Name:
- J/AJ/141/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of over 130000 quasar candidates with near-infrared (NIR) photometric properties, with an areal coverage of approximately 1200deg^2^. This is achieved by matching the Sloan Digital Sky Survey (SDSS) in the optical ugriz bands to the UKIRT Infrared Digital Sky Survey (UKIDSS) Large Area Survey (LAS) in the NIR YJHK bands. We match the ~1 million SDSS DR6 Photometric Quasar catalog to Data Release 3 of the UKIDSS LAS (ULAS) and produce a catalog with 130827 objects with detections in one or more NIR bands, of which 74351 objects have optical and K-band detections and 42133 objects have the full nine-band photometry.
- ID:
- ivo://CDS.VizieR/J/A+A/550/A83
- Title:
- NIR observations of CG1 and CG2
- Short Name:
- J/A+A/550/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cometary globules CG1 and CG2 are "classical" cometary globules in the Gum Nebula region at a distance of ~300pc. The objective of this study is to examine the mass distribution and the structure of CG1 and CG2 through extinction, and to study the star formation activity in CG1 and CG2. The NIR JHKs photometry is used in creating visual extinction maps.
- ID:
- ivo://CDS.VizieR/J/ApJ/867/79
- Title:
- NIR observations of GF 9/LDN 1082C field stars
- Short Name:
- J/ApJ/867/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The orientation of the magnetic field (B field) in the filamentary dark cloud GF 9 was traced from the periphery of the cloud into the L1082C dense core that contains the low-mass, low-luminosity Class 0 young stellar object (YSO) GF 9-2 (IRAS 20503+6006). This was done using SOFIA HAWC+ dust thermal emission polarimetry (TEP) at 216{mu}m in combination with Mimir near-infrared background starlight polarimetry (BSP) conducted in the H band (1.6{mu}m) and K band (2.2{mu}m). These observations were augmented with published I-band (0.77{mu}m) BSP and Planck 850{mu}m TEP to probe B-field orientations with offset from the YSO in a range spanning 6000au to 3pc. No strong B-field orientation change with offset was found, indicating remarkable uniformity of the B-field from the cloud edge to the YSO environs. This finding disagrees with weak-field models of cloud core and YSO formation. The continuity of inferred B-field orientations for both TEP and BSP probes is strong evidence that both are sampling a common B field that uniformly threads the cloud, core, and YSO region. Bayesian analysis of Gaia DR2 stars matched to the Mimir BSP stars finds a distance to GF 9 of 270+/-10pc. No strong wavelength dependence of B-field orientation angle was found, contrary to previous claims.
- ID:
- ivo://CDS.VizieR/J/A+A/499/483
- Title:
- NIR observations of sources in galactic center
- Short Name:
- J/A+A/499/483
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a study that uses AO assisted observations obtained at the ESO VLT in the NIR H-band and 7 intermediate bands covering the NIR K-band. A comparison of the resulting SEDs with a blackbody of variable extinction then allows us to determine the presence and strength of a CO absorption feature to distinguish between early and late type stars. This new method is suitable for classifying K giants (and later), as well as B2 main sequence (and earlier) stars that are brighter than 15.5mag in the K band in the central parsec. Extremely red objects and foreground sources can also be reliably removed from the sample. Several results, such as the shape of the KLF and the spatial distribution of both early and late type stars, confirm and extend previous works. The distribution of the early type stars can be fitted with a steep power law (beta_1"_=-1.49+/-0.12), alternatively with a broken power law, beta_1-10"_=-1.08+/-0.12, beta_10-20"_=-3.46+/-0.58, since we find a drop in the early type density at ~10". We also detect early type candidates outside of 0.5pc in significant numbers for the first time. The late type density function shows an inversion in the inner 6", with a power-law slope of beta_R<6"_=0.17+/-0.09. The late type KLF has a power-law slope of 0.30+/-0.01, closely resembling the KLF obtained for the bulge of the Milky Way. The early type KLF has a much flatter slope of (0.14+/-0.02). Our results agree best with an in-situ star formation scenario.
- ID:
- ivo://CDS.VizieR/J/A+A/511/A18
- Title:
- NIR observations of stars near SgrA*
- Short Name:
- J/A+A/511/A18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nuclear star cluster of the Galaxy is an important template for understanding its extragalactic counterparts, which can currently not be resolved into individual stars. Important drawbacks of observations of the Galactic center are, however, the presence of strong and spatially highly variable interstellar extinction and extreme crowding of the sources, which makes the use of adaptive optics techniques necessary. Both points pose serious obstacles to precise photometry that is needed for analyzing the stellar population. The aims of this work are to provide accurate photometry in multiple near-infrared broadband filters, to determine the power-law index of the extinction-law toward the central parsec of the Galaxy, to provide measurements of the absolute extinction toward the Galactic center, and finally to measure the spatial variability of extinction on arcsecond scales.
- ID:
- ivo://CDS.VizieR/J/ApJS/239/22
- Title:
- NIR obs. of X-ray AGNs in COSMOS, SXDS & E-CDF-S
- Short Name:
- J/ApJS/239/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present near-IR spectroscopy in the J- and H-bands for a large sample of 243 X-ray-selected, moderate-luminosity Type 1 active galactic nuclei (AGNs) in the COSMOS, SXDS, and E-CDF-S survey fields using the multi-object spectrograph Subaru/FMOS. Our sample covers the redshift range 0.5<=z<=3.0 and X-ray luminosity range of 10^43^<=L_[2-10keV]_<=10^45^erg/s. We provide emission-line properties and derived virial black hole mass estimates, bolometric luminosities, and Eddington ratios, based on H{alpha} (211), H{beta} (63), and MgII (4). We compare line widths, luminosities, and black hole mass estimates from H{alpha} and H{beta}, and augment these with commensurate measurements of MgII and CIV detected in optical spectra. We demonstrate the robustness of using H{alpha}, H{beta}, and MgII as reliable black hole mass estimators for high-z moderate-luminosity AGNs, while the use of CIV is prone to large uncertainties (>=0.4dex). We extend a recently proposed correction based on the CIV blueshift to lower luminosities and black hole masses. While our sample shows an improvement in their CIV black hole mass estimates, the deficit of high blueshift sources reduces its overall importance for moderate-luminosity AGNs compared to the most luminous quasars. In addition, we revisit luminosity correlations between Lbol, L_[2-10keV]_, L[OIII], L5100, and LH{alpha} and find them to be consistent with a simple empirical model, based on a small number of well-established scaling relations. Finally, we highlight our highest redshift AGN, CID 781, at z=4.6, which has the lowest black hole mass (~10^8^M_{sun}_) among current near-IR samples at this redshift and is in a state of fast growth.
- ID:
- ivo://CDS.VizieR/J/ApJ/741/35
- Title:
- NIR photometry and polarization in NGC 2264
- Short Name:
- J/ApJ/741/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Near-infrared imaging polarimetry in the J, H, and Ks bands has been carried out for the protostellar cluster region around NGC 2264 IRS 2 in the Monoceros OB1 molecular cloud. Various infrared reflection nebula clusters (IRNCs) associated with NGC 2264 IRS 2 and the IRAS 12 S1 core, as well as local infrared reflection nebulae (IRNe), were detected. The illuminating sources of the IRNe were identified with known or new near- and mid-infrared sources. In addition, 314 point-like sources were detected in all three bands and their aperture polarimetry was studied. Using a color-color diagram, reddened field stars and diskless pre-main-sequence stars were selected to trace the magnetic field (MF) structure of the molecular cloud. The mean polarization position angle of the point-like sources is 81+/-29{deg} in the cluster core, and 58+/-24{deg} in the perimeter of the cluster core, which is interpreted as the projected direction on the sky of the MF in the observed region of the cloud. The Chandrasekhar-Fermi method gives a rough estimate of the MF strength to be about 100uG. A comparison with recent numerical simulations of the cluster formation implies that the cloud dynamics is controlled by the relatively strong MF. The local MF direction is well associated with that of CO outflow for IRAS 12 S1 and consistent with that inferred from submillimeter polarimetry. In contrast, the local MF direction runs roughly perpendicular to the Galactic MF direction.
