- ID:
- ivo://CDS.VizieR/J/A+A/531/A124
- Title:
- Visibilities of stellar oscillation modes
- Short Name:
- J/A+A/531/A124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Kepler produces a large amount of data used for asteroseismological analyses, particularly of solar-like stars and red giants. The mode amplitudes observed in the Kepler spectral band have to be converted into bolometric amplitudes to be compared to models. We give a simple bolometric correction for the amplitudes of radial modes observed with Kepler, as well as the relative visibilities of non-radial modes. We numerically compute the bolometric correction c_K-bol_ and mode visibilities, for different effective temperatures Teff within the range 4000-7500K, using a similar approach to a recent one from the literature. We derive a law for the correction to bolometric values: c_K-bol_=1+a_1_(Teff-To)+a_2_(Teff-To)^2^, with To=5934K, a_1_=1.349e-4K^-1^, and a_2_=-3.120e-9K^-2^ or, alternatively, as the power law c_K-bol_=(Teff/To)^alpha^ with alpha=0.80. We give tabulated values for the mode visibilities based on limb-darkening, computed from ATLAS9 model atmospheres for Teff in [4000,7500]K, logg in [2.5,4.5], and [M/H] in [-1.0,+1.0]. We show that using LD profiles already integrated over the spectral band provides quick and good approximations for visibilities. We point out the limits of these classical visibility estimations.
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- ID:
- ivo://CDS.VizieR/J/A+A/587/A65
- Title:
- Visible and near-infrared solar spectra
- Short Name:
- J/A+A/587/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new solar flux atlas with the aim of understanding wavelength precision and accuracy in solar benchmark data. The atlas covers the wavelength range 405-2300nm and was observed at the Institut fur Astrophysik, Gottingen (IAG), with a Fourier transform spectrograph (FTS). In contrast to other FTS atlases, the entire visible wavelength range was observed simultaneously using only one spectrograph setting. We compare the wavelength solution of the new atlas to the Kitt Peak solar flux atlases and to the HARPS frequency-comb calibrated solar atlas. Comparison reveals systematics in the two Kitt Peak FTS atlases resulting from their wavelength scale construction, and shows consistency between the IAG and the HARPS atlas. We conclude that the IAG atlas is precise and accurate on the order of +/-10m/s in the wavelength range 405-1065nm, while the Kitt Peak atlases show deviations as large as several ten to 100m/s. We determine absolute convective blueshift across the spectrum from the IAG atlas and report slight differences relative to results from the Kitt Peak atlas that we attribute to the differences between wavelength scales. We conclude that benchmark solar data with accurate wavelength solution are crucial to better understand the effect of convection on stellar radial velocity measurements, which is one of the main limitations of Doppler spectroscopy at m/s precision.
- ID:
- ivo://CDS.VizieR/J/A+A/577/A35
- Title:
- Visible colors of Centaurs and KBOs
- Short Name:
- J/A+A/577/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Since the discovery of the Kuiper Belt, broadband surface colors were thoroughly studied as a first approximation to the objects reflectivity spectra. Visible colors (BVRI) have proven to be a reasonable proxy for real spectra, which are rather linear in this range. On the contrary, near-IR colors (JHK bands) could be misleading when absorption features of ices are present in the spectra. Although the physical and chemical information provided by colors are rather limited, broadband photometry remains the best tool for establishing the bulk surface properties of KBOs and Centaurs. In this work, we explore for the first time general, recurrent effects in the study of visible colors that could affect the interpretation of the scientific results: i) how a correlation could be missed or weaken due to the data error bars, ii) the "risk" of missing-out an existing trend due to low sampling, and the possibility to make quantified predictions on the sample size needed to detect a trend at a given significance level, assuming the sample is unbiased, iii) the use of partial correlations to disentangle the mutual effect of two or more (physical) parameters, iv) the sensitivity of the "reddening line" tool to the central wavelength of the filters used. To illustrate and apply these new tools, we have compiled the visible colors and orbital parameters of about 370 objects available in the literature, assumed, by default, as unbiased samples, and carried-out the "traditional" analysis per dynamical family. Our results show in particular how: a) data error-bars impose a limit on the detectable correlations regardless of sample size and, therefore, once that limit is achieved it is important to diminish the error-bars but pointless to enlarge the sampling with the same or larger errors; b) almost all dynamical families still require larger samplings to "ensure" the detection of correlations stronger than +/-0.5, i.e. correlations that may "explain" ~25% or more of the color variability; c) the correlation strength between (V-R) vs. (R-I) is systematically lower than the one between (B-V) vs. (V-R) and not related with error-bar differences between these colors; d) it is statistically equivalent to use any of the different "flavors" of orbital excitation or collisional velocity parameters regarding the famous color-inclination correlation among Classical KBOs --- which no longer evidences to be a strong correlation --- whereas the inclination and Tisserand parameter relative to Neptune cannot be separated from one another; and e) Classical KBOs are the only dynamical family which evidences for neither (B-V) vs. (V-R) nor (V-R) vs. (R-I) correlations, being, therefore, the family with the most unpredictable visible surface reflectivities.
- ID:
- ivo://CDS.VizieR/J/ApJ/858/111
- Title:
- Visible obs. of GOT C+ Northern sightlines
- Short Name:
- J/ApJ/858/111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using visible, radio, microwave, and submillimeter data, we study several lines of sight toward stars generally closer than 1kpc on a component-by-component basis. We derive the component structure seen in absorption at visible wavelengths from CaII, CaI, KI, CH, CH+, and CN and compare it to emission from HI, CO and its isotopologues, and C+ from the GOT C+ (Galactic Observations of Terahertz C+) survey (Langer+ 2010A&A...521L..17L). The correspondence between components in emission and absorption helps create a more unified picture of diffuse atomic and molecular gas in the interstellar medium. We also discuss how these tracers are related to the CO-dark H2 gas probed by C+ emission and discuss the kinematic connections among the species observed.
- ID:
- ivo://CDS.VizieR/J/A+A/614/A65
- Title:
- VISION II. VISTA Orion A survey
- Short Name:
- J/A+A/614/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have investigated the shape of the extinction curve in the infrared up to ~25{mu}m for the Orion A star-forming complex. The basis of this work is near-infrared data acquired with the Visual and Infrared Survey Telescope for Astronomy, in combination with Pan-STARRS and mid-infrared Spitzer photometry. We obtain colour excess ratios for eight passbands by fitting a series of colour-colour diagrams. The fits are performed using Markov chain Monte Carlo methods, together with a linear model under a Bayesian formalism. The resulting colour excess ratios are directly interpreted as a measure of the extinction law. We show that the Orion A molecular cloud is characterized by flat mid-infrared extinction, similar to many other recently studied sightlines. Moreover, we find statistically significant evidence that the extinction law from ~1{mu}m to at least ~6{mu}m varies across the cloud. In particular, we find a gradient along galactic longitude, where regions near the Orion Nebula Cluster show a different extinction law compared to L1641 and L1647, the low-mass star-forming sites in the cloud complex. These variations are of the order of only 3% and are most likely caused by the influence of the massive stars on their surrounding medium. While the observed general trends in our measurements are in agreement with model predictions, both well-established and new dust grain models are not able to fully reproduce our infrared extinction curve. We also present a new extinction map featuring a resolution of 1' and revisit the correlation between extinction and dust optical depth. This analysis shows that cloud substructure, which is not sampled by background sources, affects the conversion factor between these two measures. In conclusion, we argue that specific characteristics of the infrared extinction law are still not well understood, but Orion A can serve as an unbiased template for future studies.
- ID:
- ivo://CDS.VizieR/J/A+A/587/A153
- Title:
- VISION I. VISTA Orion A Survey
- Short Name:
- J/A+A/587/A153
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Orion A hosts the nearest massive star factory, thus offering a unique opportunity to resolve the processes connected with the formation of both low- and high-mass stars. Here we present the most detailed and sensitive near-infrared (NIR) observations of the entire molecular cloud to date. With the unique combination of high image quality, survey coverage, and sensitivity, our NIR survey of Orion A aims at establishing a solid empirical foundation for further studies of this important cloud. In this first paper we present the observations, data reduction, and source catalog generation. To demonstrate the data quality, we present a first application of our catalog to estimate the number of stars currently forming inside Orion A and to verify the existence of a more evolved young foreground population. We used the European Southern Observatory's (ESO) Visible and Infrared Survey Telescope for Astronomy (VISTA) to survey the entire Orion A molecular cloud in the NIR J, H, and K_S_ bands, covering a total of ~18.3deg^2^. We implemented all data reduction recipes independently of the ESO pipeline. Estimates of the young populations toward Orion A are derived via the K_S_-band luminosity function. Our catalog (799995 sources) increases the source counts compared to the Two Micron All Sky Survey by about an order of magnitude. The 90% completeness limits are 20.4, 19.9, and 19.0mag in J, H, and K_S_, respectively. The reduced images have 20% better resolution on average compared to pipeline products. We find between 2300 and 3000 embedded objects in Orion A and confirm that there is an extended foreground population above the Galactic field, in agreement with previous work. The Orion A VISTA catalog represents the most detailed NIR view of the nearest massive star-forming region and provides a fundamental basis for future studies of star formation processes toward Orion.
- ID:
- ivo://CDS.VizieR/J/A+A/473/369
- Title:
- VISIR/VLT mid-infrared imaging of Seyfert nuclei
- Short Name:
- J/A+A/473/369
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Half of the Seyfert-2 galaxies escaped detection of broad lines in their polarised spectra observed so far. Some authors have suspected that these non-HBLRs contain real Sy2 nuclei without intrinsic broad line region hidden behind a dust torus. If this were true, then their nuclear structure would fundamentally differ from that of Sy2s with polarised broad lines: in particular, they would not be explained by orientation-based AGN unification. Further arguments for two physically different Sy2 populations have been derived from the warm and cool IRAS F25/F60 ratios. These ratios, however, refer to the entire host galaxies and are unsuitable to conclusively establish the absence of a nuclear dust torus. Instead, a study of the Seyfert-2 dichotomy should be performed on the basis of nuclear properties only. Here we present the first comparison between [OIII] {lambda} 5007{AA} and mid-infrared imaging at matching spatial resolution. The aim is to check whether the nuclear dust emission scales with AGN luminosity as traced by [OIII].
- ID:
- ivo://CDS.VizieR/J/MNRAS/503/2265
- Title:
- VISTA and Subaru/HSC obs. of Upper Scorpius
- Short Name:
- J/MNRAS/503/2265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim at identifying very low-mass isolated planetary-mass member candidates in the nearest OB association to the Sun, Upper Scorpius (145pc; 5-10Myr), to constrain the form and shape of the luminosity function and mass spectrum in this regime. We conducted a deep multi-band (Y=21.2, J=20.5, Z=22.0mag) photometric survey of six square degrees in the central region of Upper Scorpius. We extend the current sequence of astrometric and spectroscopic members by about two magnitudes in Y and one magnitude in J, reaching potentially T-type free-floating members in the association with predicted masses below 5 Jupiter masses, well into the planetary-mass regime. We extracted a sample of 57 candidates in this area and present infrared spectroscopy confirming two of them as young L-type members with characteristic spectral features of 10Myr-old brown dwarfs. Among the 57 candidates, we highlight 10 new candidates fainter than the coolest members previously confirmed spectroscopically. We do not see any obvious sign of decrease in the mass spectrum of the association, suggesting that star processes can form substellar objects with masses down to 4-5 Jupiter masses.
- ID:
- ivo://CDS.VizieR/III/334
- Title:
- VISTA Deep Extragalactic Observations (VIDEO)
- Short Name:
- III/334
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- VIDEO is a ~12 square degrees survey in the near-infrared Z, Y, J, H and Ks bands,over the ELAIS-S1, XMMLS, and ECDFS extragalactic fields. This document describes the catalog released for the deep stracked data in the VIDEO-XMM3 field, which also covers the Canada-France-Hawaii Telescope Legacy Survey Deep-1 field (CFHTLS-D1).
- ID:
- ivo://CDS.VizieR/J/ApJ/754/30
- Title:
- VISTA IR photometry of {sigma} Ori cluster
- Short Name:
- J/ApJ/754/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on our analysis of the VISTA Orion ZY JHK_s_ photometric data (completeness magnitudes of Z=22.6 and J=21.0 mag) focusing on a circular area of 2798.4arcmin^2^ around the young {sigma} Orionis star cluster (~3Myr, ~352pc, and solar metallicity). The combination of the VISTA photometry with optical, WISE and Spitzer data allows us to identify a total of 210 {sigma} Orionis member candidates with masses in the interval 0.25-0.004M_{sun}_, 23 of which are new planetary-mass object findings. These discoveries double the number of cluster planetary-mass candidates known so far. One object has colors compatible with a T spectral type. The {sigma} Orionis cluster harbors about as many brown dwarfs (69, 0.072-0.012M_{sun}_) and planetary-mass objects (37, 0.012-0.004M_{sun}_) as very low mass stars (104, 0.25-0.072M_{sun}_). Based on Spitzer data, we derive a disk frequency of ~40% for very low mass stars, brown dwarfs, and planetary-mass objects in {sigma} Orionis. The radial density distributions of these three mass intervals are alike: all are spatially concentrated within an effective radius of 12' (1.2pc) around the multiple star {sigma} Ori, and no obvious segregation between disk-bearing and diskless objects is observed.
