- ID:
- ivo://CDS.VizieR/J/A+A/338/340
- Title:
- Asteroids as IR Standards for ISOPHOT
- Short Name:
- J/A+A/338/340
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroids are used as far-IR calibrators for the imaging photopolarimeter ISOPHOT on board the Infrared Space Observatory ISO. For the 10 selected objects we compiled a large uniform database of 678 individual observations, ranging from 7-2000{mu}m. Applying a new thermophysical model to the observations we derived thermal properties of the selected asteroids, based on spin-vector solutions, direct size measurements and the HG-magnitude system. Our investigations indicate very rough surfaces, reflected in the beaming effect, and very low levels of heat conduction, expressed in thermal inertias between 5 and 25J/m^2^/s^0.5^/K. Due to scattering processes in the porous regolith, the emissivity varies significantly with wavelength. In case of Vesta we find emissivities as low as 0.6 in the far-IR/submillimetre region. By entering the combined results into the thermophysical model we defined new photometric standards for the far-IR. The absolute accuracy for thermal flux or lightcurve predictions is 5-10% for the first category objects and 10-20% for the secondaries. The methods and procedures discussed here are included in the first update of the ISOPHOT calibration in 1998.
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- ID:
- ivo://CDS.VizieR/J/A+A/572/A29
- Title:
- Asteroids for a targeted spectroscopic survey
- Short Name:
- J/A+A/572/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroid spectroscopy reflects surface mineralogy. There are few thousand asteroids whose surfaces have been observed spectrally. Determining the surface properties of those objects is important for many practical and scientific applications, such as for example developing impact deflection strategies or studying history and evolution of the Solar System and planet formation. The aim of this study is to develop a pre-selection method that can be utilized in searching for asteroids of any taxonomic complex. The method could then be utilized im multiple applications such as searching for the missing V-types or looking for primitive asteroids. We used the Bayes Naive Classifier combined with observations obtained in the course of the Sloan Digital Sky Survey and the Wide-field Infrared Survey Explorer surveys as well as a database of asteroid phase curves for asteroids with known taxonomic type. Using the new classification method we have selected a number of possible V-type candidates. Some of the candidates were than spectrally observed at the Nordic Optical Telescope and South African Large Telescope. We have developed and tested the new pre-selection method. We found three asteroids in the mid/outer Main Belt that are likely of differentiated type. Near-Infrared are still required to confirm this discovery. Similarly to other studies we found that V-type candidates cluster around the Vesta family and are rare in the mid-to-outer Main Belt. The new method shows that even largely explored large databases combined together could still be further exploited in for example solving the missing dunite problem.
- ID:
- ivo://CDS.VizieR/VII/108C
- Title:
- Asteroids II Machine-Readable Data Base
- Short Name:
- VII/108C
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This data set was assembled by E. F. Tedesco, Jet Propulsion Laboratory, in March 1988 from files provided by the contributors to the above reference. Included are asteroid names and discovery circumstances, proper elements and family identifications, asteroid lightcurve parameters, asteroid pole determinations, taxonomic classes, absolute magnitudes and slope parameters, UBV color indices, and albedos and diameters from the IRAS Asteroid and Comet Survey. The asteroid discovery tables were updated by F. Pilcher in 1994.
1284. Asteroids in GALEX
- ID:
- ivo://CDS.VizieR/J/ApJ/809/92
- Title:
- Asteroids in GALEX
- Short Name:
- J/ApJ/809/92
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ultraviolet (UV) photometry (near-UV (NUV) band, 180-280nm) of 405 asteroids observed serendipitously by GALEX from 2003 to 2012. All asteroids in this sample were detected by GALEX at least twice. Unambiguous visible-color-based taxonomic labels (C type versus S type) exist for 315 of these asteroids; of these, thermal-infrared-based diameters are available for 245. We derive NUV-V color using two independent models to predict the visual magnitude V at each NUV-detection epoch. Both V models produce NUV-V distributions in which the S types are redder than C types with more than 8{sigma} confidence. This confirms that the S types' redder spectral slopes in the visible remain redder than the C types' into the NUV, this redness being consistent with absorption by silica-containing rocks. The GALEX asteroid data confirm earlier results from the International Ultraviolet Explorer, which two decades ago produced the only other sizeable set of UV asteroid photometry. The GALEX-derived NUV-V data also agree with previously published Hubble Space Telescope (HST) UV observations of asteroids 21 Lutetia and 1 Ceres. Both the HST and GALEX data indicate that NUV band is less useful than u band for distinguishing subgroups within the greater population of visible-color-defined C types (notably, M types and G types).
- ID:
- ivo://CDS.VizieR/J/A+A/556/A8
- Title:
- 100 asteroids rotational parameters
- Short Name:
- J/A+A/556/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compute for a set of 100 asteroids their rotational parameters: the moments of inertia along the principal axes of the object, the obliquity of the axis of rotation with respect to the orbital plane, the precession rates, and the nutation coefficients. We select 100 asteroids for which the parameters for the study are well-known from observations or space missions. For each asteroid, we determine the moments of inertia, assuming an ellipsoidal shape. We calculate their obliquity from their orbit (instead of the ecliptic) and the orientation of the spin-pole. Finally, we calculate the precession rates and the largest nutation components. The number of asteroids concerned leads to some statistical studies of the output. We provide a table of rotational parameters for our set of asteroids. The table includes the obliquity, their axes ratio, their dynamical ellipticity H_d_, and the scaling factor K. We compute the precession rate {psi} and the leading nutation coefficients {Delta}{psi} and {Delta}{epsilon}. We observe similar characteristics, as observed by previous authors that is, a significantly larger number of asteroids rotates in the prograde mode (~60%) than in the retrograde one with a bimodal distribution. In particular, there is a deficiency of objects with a polar axis close to the orbit. The precession rates have a mean absolute value of 18"/y, and the leading nutation coefficients have an average absolute amplitude of 5.7" for {Delta}{psi} and 5.2" for {Delta}{epsilon}. At last, we identify and characterize some cases with large precession rates, as seen in 25143 Itokawa, with has a precession rate of about - 475"/y.
- ID:
- ivo://CDS.VizieR/J/A+A/506/79
- Title:
- Asteroseismic analysis of HD 174936
- Short Name:
- J/A+A/506/79
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the {delta}-Scuti star HD 174936 (ID 7613) observed by CoRoT during the first short run SRc01 (27 days). A total number of 422 frequencies were extracted from the light curve using standard prewhitening techniques. This number of frequencies was obtained by considering a spectral significance limit of sig=10 using the software package SigSpec. Our analysis of the oscillation frequency spectrum reveals a spacing periodicity around 52muHz. Although modes considered here are not in the asymptotic regime, a comparison with stellar models confirms that this signature may stem from a quasi-periodic pattern similar to the so-called large separation in solar-like stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/838/115
- Title:
- Asteroseismic analysis of 8 Kepler red giants
- Short Name:
- J/ApJ/838/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using data from the NASA spacecraft Kepler, we study solar-like oscillations in red giant stars in the open cluster NGC 6811. We determine oscillation frequencies, frequency separations, period spacings of mixed modes, and mode visibilities for eight cluster giants. The oscillation parameters show that these stars are helium-core-burning red giants. The eight stars form two groups with very different oscillation power spectra; the four stars with the lowest {Delta}{nu} values display rich sets of mixed l=1 modes, while this is not the case for the four stars with higher {Delta}{nu}. For the four stars with lowest {Delta}{nu}, we determine the asymptotic period spacing of the mixed modes, {Delta}P, which together with the masses we derive for all eight stars suggest that they belong to the so-called secondary clump. Based on the global oscillation parameters, we present initial theoretical stellar modeling that indicates that we can constrain convective-core overshoot on the main sequence and in the helium-burning phase for these ~2M_{sun}_ stars. Finally, our results indicate less mode suppression than predicted by recent theories for magnetic suppression of certain oscillation modes in red giants.
- ID:
- ivo://CDS.VizieR/J/ApJ/749/152
- Title:
- Asteroseismic analysis of 22 solar-type stars
- Short Name:
- J/ApJ/749/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Asteroseismology with the Kepler space telescope is providing not only an improved characterization of exoplanets and their host stars, but also a new window on stellar structure and evolution for the large sample of solar-type stars in the field. We perform a uniform analysis of 22 of the brightest asteroseismic targets with the highest signal-to-noise ratio observed for 1 month each during the first year of the mission, and we quantify the precision and relative accuracy of asteroseismic determinations of the stellar radius, mass, and age that are possible using various methods. We present the properties of each star in the sample derived from an automated analysis of the individual oscillation frequencies and other observational constraints using the Asteroseismic Modeling Portal (AMP), and we compare them to the results of model-grid-based methods that fit the global oscillation properties. We find that fitting the individual frequencies typically yields asteroseismic radii and masses to ~1% precision, and ages to ~2.5% precision (respectively, 2, 5, and 8 times better than fitting the global oscillation properties). The absolute level of agreement between the results from different approaches is also encouraging, with model-grid-based methods yielding slightly smaller estimates of the radius and mass and slightly older values for the stellar age relative to AMP, which computes a large number of dedicated models for each star. The sample of targets for which this type of analysis is possible will grow as longer data sets are obtained during the remainder of the mission.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/L41
- Title:
- Asteroseismic classification of KIC objects
- Short Name:
- J/ApJ/765/L41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Of the more than 150000 targets followed by the Kepler Mission, about 10% were selected as red giants. Due to their high scientific value, in particular for Galaxy population studies and stellar structure and evolution, their Kepler light curves were made public in late 2011. More than 13000 (over 85%) of these stars show intrinsic flux variability caused by solar-like oscillations making them ideal for large-scale asteroseismic investigations. We automatically extracted individual frequencies and measured the period spacings of the dipole modes in nearly every red giant. These measurements naturally classify the stars into various populations, such as the red giant branch, the low-mass (M/M_{sun}_<~1.8) helium-core-burning red clump, and the higher-mass (M/M_{sun}_>~1.8) secondary clump. The period spacings also reveal that a large fraction of the stars show rotationally induced frequency splittings. This sample of stars will undoubtedly provide an extremely valuable source for studying the stellar population in the direction of the Kepler field, in particular when combined with complementary spectroscopic surveys.
- ID:
- ivo://CDS.VizieR/J/AJ/158/227
- Title:
- Asteroseismic parameters of RGB stars
- Short Name:
- J/AJ/158/227
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Every Sun-like star will eventually evolve into a red giant, a transition which can profoundly affect the evolution of a surrounding planetary system. The timescale of dynamical planet evolution and orbital decay has important implications for planetary habitability, as well as post-main-sequence star and planet interaction, evolution, and internal structure. Here, we investigate these effects by estimating planet occurrence around 2476 low-luminosity red giant branch (LLRGB) stars observed by the NASA K2 mission. We measure stellar masses and radii using asteroseismology, with median random uncertainties of 3.7% in mass and 2.2% in radius. We compare this planet population to the known population of planets around dwarf Sun-like stars, accounting for detection efficiency differences between the stellar populations. We find that 0.49%+/-0.28% of LLRGB stars host planets larger than Jupiter with orbital periods less than 10 days, tentatively higher than main-sequence stars hosting similar planets (0.15%+/-0.06%). Our results suggest that the effects of stellar evolution on the occurrence of close-in planets larger than Jupiter are not significant until stars have begun ascending substantially up the red giant branch (>~5-6 R_{sun}_).
