3 results on '"DUST TEMPERATURES"'
Search Results
2. Thermal evolution of protoplanetary disks: from β-cooling to decoupled gas and dust temperatures
- Author
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Eduard I. Vorobyov, Ryoki Matsukoba, Manuel Guedel, and Kazuyuki Omukai
- Subjects
Radiative cooling ,Metallicity ,DUST ,Astrophysics ,GASES ,NUMERICAL HYDRODYNAMICS ,01 natural sciences ,HYDRODYNAMICS ,COMPRESSIONAL HEATING ,DUST TEMPERATURES ,0103 physical sciences ,Thermal ,Astrophysics::Solar and Stellar Astrophysics ,Irradiation ,LONG TERM EVOLUTION (LTE) ,SUB-SOLAR METALLICITY ,010303 astronomy & astrophysics ,Chemical composition ,Astrophysics::Galaxy Astrophysics ,Envelope (waves) ,Physics ,PROTOSTARS [STARS] ,CHEMICAL COMPOSITIONS ,010308 nuclear & particles physics ,Computer Science::Information Retrieval ,THERMAL EVOLUTION ,Astronomy and Astrophysics ,Mechanics ,Decoupling (cosmology) ,Astrophysics - Astrophysics of Galaxies ,IRRADIATION ,Astrophysics - Solar and Stellar Astrophysics ,EXCHANGE OF ENERGY ,13. Climate action ,Space and Planetary Science ,Astrophysics::Earth and Planetary Astrophysics ,PROTOPLANETARY DISKS ,RADIATIVE COOLING ,Astrophysics - Earth and Planetary Astrophysics - Abstract
Aims: We explore the long-term evolution of young protoplanetary disks with different approaches to computing the thermal structure determined by various cooling and heating processes in the disk and its surroundings. Methods: Numerical hydrodynamics simulations in the thin-disk limit were complemented with three thermal evolution schemes: a simplified $\beta$-cooling approach with and without irradiation, in which the rate of disk cooling is proportional to the local dynamical time, a fiducial model with equal dust and gas temperatures calculated taking viscous heating, irradiation, and radiative cooling into account, and also a more sophisticated approach allowing decoupled dust and gas temperatures. Results: We found that the gas temperature may significantly exceed that of dust in the outer regions of young disks thanks to additional compressional heating caused by the infalling envelope material in the early stages of disk evolution and slow collisional exchange of energy between gas and dust in low-density disk regions. The outer envelope however shows an inverse trend with the gas temperatures dropping below that of dust. The global disk evolution is only weakly sensitive to temperature decoupling. Nevertheless, separate dust and gas temperatures may affect the chemical composition, dust evolution, and disk mass estimates. Constant-$\beta$ models without stellar and background irradiation fail to reproduce the disk evolution with more sophisticated thermal schemes because of intrinsically variable nature of the $\beta$-parameter. Constant-$\beta$ models with irradiation can better match the dynamical and thermal evolution, but the agreement is still incomplete. Conclusions: Models allowing separate dust and gas temperatures are needed when emphasis is placed on the chemical or dust evolution in protoplanetary disks, particularly in sub-solar metallicity environments., Comment: 19 pages, 21 Figures, accepeted for publication in Astronomy & Astrophysics
- Published
- 2020
3. Correlations between the stellar, planetary, and debris components of exoplanet systems observed byHerschel
- Author
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G. Olofsson, A. Mora, Brenda C. Matthews, B. Sibthorpe, Jonathan P. Marshall, Grant M. Kennedy, Jesús E. Maldonado, G. Bryden, Jonathan Horner, Jorge Sanz-Forcada, Gwendolyn Meeus, Jane Greaves, Rob Ivison, J.-F. Lestrade, C. del Burgo, Carlos Eiroa, Göran Pilbratt, Amaya Moro-Martin, Mark C. Wyatt, Benjamin Montesinos, G. J. White, Science & Technology Facilities Council, and University of St Andrews. School of Physics and Astronomy
- Subjects
Solar System ,010504 meteorology & atmospheric sciences ,Metallicity ,FOS: Physical sciences ,planetary systems [Infrared] ,Astrophysics::Cosmology and Extragalactic Astrophysics ,Astrophysics ,01 natural sciences ,Luminosity ,Effective temperature ,Infrared: planetary systems ,Planet ,0103 physical sciences ,Hot Jupiter ,QB Astronomy ,Astrophysics::Solar and Stellar Astrophysics ,010303 astronomy & astrophysics ,Astrophysics::Galaxy Astrophysics ,QB ,0105 earth and related environmental sciences ,Earth and Planetary Astrophysics (astro-ph.EP) ,Infrared: star ,Planet formation ,Physics ,Second generation ,Dust ,Astronomy and Astrophysics ,Circumstellar matter ,Stars ,Exoplanet ,Extrasolar planets ,Circumstellar matters ,Dust temperatures ,Luminance ,13. Climate action ,Space and Planetary Science ,stars [Infrared] ,Debris ,Astrophysics::Earth and Planetary Astrophysics ,Astrophysics - Earth and Planetary Astrophysics ,Solar system ,Planet-disk interactions - Abstract
The $\textit{Herschel}$ DEBRIS, DUNES and GT programmes observed 37 exoplanet host stars within 25 pc at 70, 100 and 160 $\mu$m with the sensitivity to detect far-infrared excess emission at flux density levels only an order of magnitude greater than that of the Solar system's Edgeworth-Kuiper belt. Here we present an analysis of that sample, using it to more accurately determine the (possible) level of dust emission from these exoplanet host stars and thereafter determine the links between the various components of these exoplanetary systems through statistical analysis. We have fitted the flux densities measured from recent \textit{Herschel} observations with a simple two parameter ($T_{d}$, $L_{\rm IR}/L_{\star}$) black body model (or to the 3-$\sigma$ upper limits at 100 $\mu$m). From this uniform approach we calculate the fractional luminosity, radial extent, dust temperature and disc mass. We then plotted the calculated dust luminosity or upper limits against the stellar properties, e.g. effective temperature, metallicity, age, and identified correlations between these parameters. A total of eleven debris discs are identified around the 37 stars in the sample. An incidence of ten cool debris discs around the Sun-like exoplanet host stars (29 $\pm$ 9 %) is consistent with the detection rate found by DUNES (20.2 $\pm$ 2.0 %). For the debris disc systems, the dust temperatures range from 20 to 80 K, and fractional luminosities ($L_{\rm IR}/L_{\star}$) between 2.4 $\times$10$^{-6}$ and 4.1 $\times$10$^{-4}$. In the case of non-detections, we calculated typical 3-$\sigma$ upper limits to the dust fractional luminosities of a few $\times10^{-6}$. We recover the previously identified correlation between stellar metallicity and hot Jupiter planets in our data set. We find a correlation between the increased presence of dust, lower planet masses and lower stellar metallicities. (abridged), Comment: 14 pages, 2 figures, 4 tables, A&A accepted
- Published
- 2014
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