- ID:
- ivo://CDS.VizieR/J/A+A/621/A133
- Title:
- ABYSS HUDF WFC3 IR mosaics
- Short Name:
- J/A+A/621/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hubble Ultra Deep field (HUDF) is the deepest region ever observed with the Hubble Space Telescope. With the main objective of unveiling the nature of galaxies up to z~7-8, the observing and reduction strategy have focused on the properties of small and unresolved objects, rather than the outskirts of the largest objects, which are usually over-subtracted. We aim to create a new set of WFC3 IR mosaics of the HUDF using novel techniques to preserve the properties of the low surface brightness regions. We created ABYSS a pipeline that optimises the estimate and modelling of low-level systematic effects to obtain a robust background subtraction. We have improved four key points in the reduction: 1) creation of new absolute sky flat fields, 2) extended persistence models, 3) dedicated sky background subtraction and 4) robust co-adding. The new mosaics successfully recover the low surface brightness structure removed on the previous HUDF published reductions. The amount of light recovered with a mean surface brightness dimmer than mu=26mag/arcsec^2^ is equivalent to a m=19 mag source when compared to the XDF and a m=20mag compared to the HUDF12. We present a set of techniques to reduce ultra-deep images (mu>32.5mag/arcsec^2^, 3 sigma in 10x10 arcsec boxes), that successfully allow to detect the low surface brightness structure of extended sources on ultra deep surveys. The developed procedures are applicable to HST, JWST, EUCLID and many other space and ground-based observatories. We made the final ABYSS WFC3 IR HUDF mosaics publicly available at http://www.iac.es/proyecto/abyss/.
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- ID:
- ivo://CDS.VizieR/J/A+A/643/A110
- Title:
- beta Cas BRITE and SMEI light curves
- Short Name:
- J/A+A/643/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- F type stars are characterised by several physical processes such as different pulsation mechanisms, rotation, convection, diffusion, and magnetic fields. The rapidly rotating delta Scuti star beta Cas can be considered as a benchmark star to study the interaction of several of these effects. We investigate the pulsational and magnetic field properties of beta Cas. We also determine the star's apparent fundamental parameters and chemical abundances. Based on photometric time series obtained from three different space missions (BRITE-Constellation, SMEI, and TESS), we conduct a frequency analysis and investigate the stability of the pulsation amplitudes over four years of observations. We investigate the presence of a magnetic field and its properties using spectropolarimetric observations taken with the Narval instrument by applying the Least Square Deconvolution and Zeeman Doppler Imaging techniques. beta Cas shows only three independent p-mode frequencies down to the few ppm-level; its highest amplitude frequency is suggested to be a n=3, l=2, m=0 mode. Its magnetic field structure is quite complex and almost certainly of a dynamo origin. beta Cas' atmosphere is slightly deficient in iron peak elements and slightly overabundant in C, O, and heavier elements. Atypically for delta Scuti stars, we can only detect three pulsation modes down to exceptionally low noise levels for beta Cas.The star is also one of very few delta Scuti pulsators known to date to show a measurable magnetic field, and the first delta Scuti star with a dynamo magnetic field. These characteristics make beta Cas an interesting target for future studies of dynamo processes in the thin convective envelopes of F-type stars, of the transition region between fossil and dynamo fields, and the interaction between pulsations and magnetic field.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A28
- Title:
- beta Pic BRITE, bRing, SMEI light curves
- Short Name:
- J/A+A/627/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Exoplanet properties crucially depend on the parameters of their host stars: more accurate stellar parameters yield more accurate exoplanet characteristics. When the exoplanet host star shows pulsations, asteroseismology can be used for an improved description of the stellar parameters. We aim to revisit the pulsational properties of {beta} Pic and identify its pulsation modes from normalized amplitudes in five different passbands. We also investigate the potential presence of a magnetic field. We conducted a frequency analysis using three seasons of BRITE-Constellation observations in the two BRITE filters, the about 620-day-long bRing light curve, and the nearly 8-year-long SMEI photometric time series. We calculated normalized amplitudes using all passbands and including previously published values obtained from ASTEP observations. We investigated the magnetic properties of {beta} Pic using spectropolarimetric observations conducted with the HARPSpol instrument. Using 2D rotating models, we fit the normalized amplitudes and frequencies through Monte Carlo Markov chains. We identify 15 pulsation frequencies in the range from 34 to 55d^-1^, where two, F13 at 53.6917d^-1^ and F11 at 50.4921d^-1^, display clear amplitude variability. We use the normalized amplitudes in up to five passbands to identify the modes as three l=1, six l=2, and six l=3 modes. {beta} Pic is shown to be non-magnetic with an upper limit of the possible undetected dipolar field of 300 Gauss. Multiple fits to the frequencies and normalized amplitudes are obtained, including one with a near equator-on inclination for {beta} Pic, which corresponds to our expectations based on the orbital inclination of {beta} Pic b and the orientation of the circumstellar disk. This solution leads to a rotation rate of 27% of the Keplerian breakup velocity, a radius of 1.497+/-0.025R_{sun}_, and a mass of 1.797+/-0.035M_{sun}_. The ~2% errors in radius and mass do not account for uncertainties in the models and a potentially erroneous mode-identification.
- ID:
- ivo://CDS.VizieR/J/A+A/608/A103
- Title:
- 43 Cyg decorrelated 156-day light curve
- Short Name:
- J/A+A/608/A103
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Photometric time series of the gamma Doradus star 43 Cyg obtained with the BRITE-Constellation nano-satellites allow us to study its pulsational properties in detail and to constrain its interior structure. We aim to find a g-mode period spacing pattern that allows us to determine the near-core rotation rate of 43 Cyg and redetermine the star's fundamental atmospheric parameters and chemical composition. We conducted a frequency analysis using the 156-days long data set obtained with the BRITE-Toronto satellite and employed a suite of MESA/GYRE models to derive the mode identification, asymptotic period spacing and near-core rotation rate. We also used high-resolution, high signal-to-noise ratio spectroscopic data obtained at the 1.2m Mercator telescope with the HERMES spectrograph to redetermine the fundamental atmospheric parameters and chemical composition of 43 Cyg using the software Spectroscopy Made Easy (SME). We detected 43 intrinsic pulsation frequencies and identified 18 of them to be part of a period spacing pattern consisting of prograde dipole modes with an asymptotic period spacing of 2970(+700,-570)s. The near-core rotation rate was determined to be 0.56(+0.12,-0.14)c/d. The atmosphere of 43 Cyg shows solar chemical composition at an effective temperature of 7150+/-150K, a logg of 4.2+/-0.6dex and a projected rotational velocity, vsini, of 44+/-4km/s. The morphology of the observed period spacing patterns shows indications of the presence of a significant chemical gradient in the stellar interior.
- ID:
- ivo://CDS.VizieR/V/51
- Title:
- Data Inventory of Space-Based Obs, Ver 1.1
- Short Name:
- V/51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The "Data Inventory of Space-Based Celestial Observations Version 1.0" (DISCO) is a directory to data contained in sixteen catalogs dealing with observations from space. (Sounding rocket, solar, and planetary observations have been excluded.) The information extracted from the catalogs includes names of objects observed, 1950 equatorial coordinates, and the name of the catalog or instrument. A second file contains full references to the source catalogs and other pertinent information. The purpose of creating DISCO is (1) to unify astronomical observations from space, which are at present scattered and hard to locate, and then (2) to provide a machine-readable index to these observations, thus enabling easy access by computer. Such a directory will permit an astronomer to find out what objects have been observed from space, which spacecraft and instruments made the observations, and where to go to find the data themselves.
- ID:
- ivo://CDS.VizieR/J/ApJ/884/162
- Title:
- HaloSat targets to study the hot Galactic halo
- Short Name:
- J/ApJ/884/162
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- HaloSat is a small satellite (CubeSat) designed to map soft X-ray oxygen line emission across the sky in order to constrain the mass and spatial distribution of hot gas in the Milky Way. The goal of HaloSat is to help determine if hot gas gravitationally bound to individual galaxies makes a significant contribution to the cosmological baryon budget. HaloSat was deployed from the International Space Station in 2018 July and began routine science operations in 2018 October. We describe the goals and design of the mission, the on-orbit performance of the science instrument, and initial observations.
- ID:
- ivo://CDS.VizieR/J/A+A/606/A107
- Title:
- K2/HARPS measurements for 8 stars
- Short Name:
- J/A+A/606/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- One of the best ways to improve our understanding of the stellar activity-induced signal in radial velocity (RV) measurements is through simultaneous high-precision photometric and RV observations. This is of prime importance to mitigate the RV signal induced by stellar activity and therefore unveil the presence of low-mass exoplanets. The K2 Campaign 7 and 8 fields of view were located in the southern hemisphere, and provided a unique opportunity to gather unprecedented simultaneous high-precision photometric observation with K2 and high-precision RV measurements with the HARPS spectrograph to study the relationship between photometric variability and RV jitter. We observed nine stars with different levels of activity, from quiet to very active. We first probed the presence of any meaningful relation between measured RV jitter and the simultaneous photometric variation, and also other activity indicators (such as BIS, FWHM, logR0'HK, and F8) by evaluating the strength and significance of the monotonic correlation between RVs and each indicator. We found that for the case of very active stars, strong and significant correlations exist between almost all the observables and measured RVs; however, when we move towards lower activity levels the correlations become random, and we could not reach any conclusion regarding the tendency of correlations depending on the stellar activity level. Except for the F8 whose strong correlation with RV jitter persists over a wide range of stellar activity level, and thus our result suggests that F8 might be a powerful proxy for activity-induced RV jitter over a wide range of stellar activity. Moreover, we examine the capability of two state-of-the-art modeling techniques, namely the FF' method and SOAP2.0, to accurately predict the RV jitter amplitude using the simultaneous photometric observation. We found that for the very active stars both techniques can predict the amplitude of the RV jitter reasonably well; however, at lower activity levels the FF' method underpredicts the RV jitter amplitude.
- ID:
- ivo://CDS.VizieR/J/PASJ/65/119
- Title:
- Low-resolution NIR spectra of zodiacal light
- Short Name:
- J/PASJ/65/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains the 278 low-resolution (R~20) near-infrared (1.8-5.3micron) spectra of diffuse sky covering a wide range of galactic and ecliptic latitudes with the Infrared Camera (IRC) on board AKARI before the exhaustion of liquid-helium (from September 2006 to May 2007). Advanced reduction methods specialized for the slit spectroscopy of diffuse sky spectra are developed for constructing this spectral catalog. Filter wheel of the IRC instrument has dark position to measure the dark current, and uncertainty due to dark current subtraction is estimated to be <3nW/m2/sr at 2micron (Tsumura & Wada, 2011PASJ...63..755T). Point sources brighter than mK(Vega)=19 were detected on the slit and masked for deriving the diffuse spectrum. It was confirmed that the brightness due to unresolved galactic stars under this detection limit is negligible (<0.5% of the sky brightness at 2.2 micron) by a Milky Way star count model (TRILEGAL; Girardi et al., 2005A&A...436..895G). Cumulative brightness contributed by unresolved galaxies can be estimated by the deep galaxy counts, being <4nW/m2/sr at K band in the case of limiting magnitude of mK=19 (Keenan et al., 2010ApJ...723...40K).
- ID:
- ivo://CDS.VizieR/J/A+A/613/A40
- Title:
- PACS photometry of FIR faint stars
- Short Name:
- J/A+A/613/A40
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Our aims are to determine flux densities and their photometric accuracy for a set of seventeen stars that range in flux from intermediately bright (<~2.5Jy) to faint (>~5mJy) in the far-infrared (FIR). We also aim to derive signal-to-noise dependence with flux and time, and compare the results with predictions from the Herschel exposure-time calculation tool. We obtain aperture photometry from Herschel-PACS high-pass-filtered scan maps and chop/nod observations of the faint stars. The issues of detection limits and sky confusion noise are addressed by comparison of the field-of-view at different wavelengths, by multi-aperture photometry, by special processing of the maps to preserve extended emission, and with the help of large-scale absolute sky brightness maps from AKARI. This photometry is compared with flux-density predictions based on photospheric models for these stars. We obtain a robust noise estimate by fitting the flux distribution per map pixel histogram for the area around the stars, scaling it for the applied aperture size and correcting for noise correlation.
- ID:
- ivo://CDS.VizieR/J/A+A/568/L12
- Title:
- Rotational frequency splitting in Sun-like stars
- Short Name:
- J/A+A/568/L12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroseismology offers the prospect of constraining differential rotation in Sun-like stars. Here we have identified six high signal-to-noise main-sequence Sun-like stars in the Kepler field, which all have visible signs of rotational splitting of their p-mode frequencies. For each star, we extract the rotational frequency splitting and inclination angle from separate mode sets (adjacent modes with l=2, 0, and 1) spanning the p-mode envelope. We use a Markov chain Monte Carlo method to obtain the best fit and errors associated with each parameter. We are able to make independent measurements of rotational splittings of ~8 radial orders for each star. For all six stars, the measured splittings are consistent with uniform rotation, allowing us to exclude large radial differential rotation. This work opens the possibility of constraining internal rotation of Sun-like stars.
