Heating and cooling processes in disks

Woitke, P.

doi:10.1051/epjconf/201510200011

Cited by 17 publications

(16 citation statements)

References 45 publications

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“…For the quiescence data, the emission is close to being optically thin in the weak line for both the Fe I 6256/6191 Å and the Fe I 6462/6393 Å pairs. This is significantly different from what has been observed in EX Lupi (Sicilia-Aguilar et al 2012, 2015 and DR Tau (Beristain et al 1998), where narrow lines are optically thicker than the broad components and can be traced back to dense, hot spots on the stellar surface 8 , and suggests a disk origin.…”

Section: Line Ratio Constraints On the Inner Diskcontrasting

confidence: 96%

“…The emission lines were visually selected and classified using the NIST database (Ralchenko et al 2010;Kramida et al 2018) and the list of lines observed in Z CMa and other outbursting objects (van den Ancker et al 2004;Sicilia-Aguilar et al 2012, 2015. The narrow neutral metallic emission lines in quiescence 1 http://www.astrouw.edu.pl/asas/explanations.html reveal a radial velocity ∼27 ± 3 km s −1 , which is consistent with previous estimates (∼30 km s −1 ; Hartmann et al 1989).…”

Section: Emission Line Classificationmentioning

confidence: 99%

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Reading between the lines

Sicilia‐Aguilar

Bouvier

Dougados

et al. 2020

A&A

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Aims. We use optical spectroscopy to investigate the disk, wind, and accretion during the 2008 Z CMa NW outburst. Methods. Emission lines were used to constrain the locations, densities, and temperatures of the structures around the star. Results. More than 1000 optical emission lines reveal accretion, a variable, multicomponent wind, and double-peaked lines of disk origin. The variable, non-axisymmetric, accretion-powered wind has slow (~0 km s−1), intermediate (approximately −100 km s−1), and fast (≥−400 km s−1) components. The fast components are of stellar origin and disappear in quiescence, while the slow component is less variable and could be related to a disk wind. The changes in the optical depth of the lines between outburst and quiescence reveal that increased accretion is responsible for the observed outburst. We derive an accretion rate of 10−4 M⊙ yr−1 in outburst. The Fe I and weak Fe II lines arise from an irradiated, flared disk at ~0.5–3 × M*/16 M⊙ au with asymmetric upper layers, revealing that the energy from the accretion burst is deposited at scales below 0.5 au. Some line profiles have redshifted asymmetries, but the system is unlikely to be sustained by magnetospheric accretion, especially in outburst. The accretion-related structures extend over several stellar radii and, like the wind, are likely to be non-axisymmetric. The stellar mass may be ~6–8 M⊙, lower than previously thought (~16 M⊙). Conclusions. Emission line analysis is found to be a powerful tool to study the innermost regions and accretion in stars within a very large range of effective temperatures. The density ranges in the disk and accretion structures are higher than in late-type stars, but the overall behavior, including the innermost disk emission and variable wind, is very similar for stars with different spectral types. Our work suggests a common outburst behavior for stars with spectral types ranging from M type to intermediate mass.

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Section: Line Ratio Constraints On the Inner Diskcontrasting

confidence: 96%

Section: Emission Line Classificationmentioning

confidence: 99%

Reading between the lines

Sicilia‐Aguilar

Bouvier

Dougados

et al. 2020

A&A

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“…PAH heating and grain radiative cooling), chemical processes (e.g. exothermic reactions), hydrodynamic work/viscous heating and cosmic rays (a review is given by Woitke 2015). Many of these heating/cooling terms are linked to the composition of the gas, requiring chemical and thermal calculations to be solved iteratively.…”

Section: Reactionmentioning

confidence: 99%

Grand Challenges in Protoplanetary Disc Modelling

Haworth

Ilee

Forgan

et al. 2016

Publ. Astron. Soc. Aust.

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The Protoplanetary Discussions conference-held in Edinburgh, UK, from 2016 March 7th-11th-included several open sessions led by participants. This paper reports on the discussions collectively concerned with the multi-physics modelling of protoplanetary discs, including the self-consistent calculation of gas and dust dynamics, radiative transfer, and chemistry. After a short introduction to each of these disciplines in isolation, we identify a series of burning questions and grand challenges associated with their continuing development and integration. We then discuss potential pathways towards solving these challenges, grouped by strategical, technical, and collaborative developments. This paper is not intended to be a review, but rather to motivate and direct future research and collaboration across typically distinct fields based on community-driven input, to encourage further progress in our understanding of circumstellar and protoplanetary discs.

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“…As heating effectively occurs throughout the spectrum, cooling of dust is, on the other hand, temperature dependent. Therefore, due to the ice bands in especially the near-IR (NIR) and the far-IR (FIR), the dust grain is either cooled or heated more depending on its temperature (see for a review Woitke 2015).…”

Section: Icy Grainsmentioning

confidence: 99%

Parameterizing the interstellar dust temperature

Hocuk

Szücs

Caselli

et al. 2017

A&A

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The temperature of interstellar dust particles is of great importance to astronomers. It plays a crucial role in the thermodynamics of interstellar clouds, because of the gas-dust collisional coupling. It is also a key parameter in astrochemical studies that governs the rate at which molecules form on dust. In 3D (magneto)hydrodynamic simulations often a simple expression for the dust temperature is adopted, because of computational constraints, while astrochemical modelers tend to keep the dust temperature constant over a large range of parameter space. Our aim is to provide an easy-to-use parametric expression for the dust temperature as a function of visual extinction (A V ) and to shed light on the critical dependencies of the dust temperature on the grain composition. We obtain an expression for the dust temperature by semi-analytically solving the dust thermal balance for different types of grains and compare to a collection of recent observational measurements. We also explore the effect of ices on the dust temperature. Our results show that a mixed carbonaceous-silicate type dust with a high carbon volume fraction matches the observations best. We find that ice formation allows the dust to be warmer by up to 15% at high optical depths (A V > 20 mag) in the interstellar medium. Our parametric expression for the dust temperature is presented as T d = 11 + 5.7 × tanh 0.61 − log 10 (A V ) χ 1/5.9 uv , where χ uv is in units of the Draine (1978) UV field.

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Heating and cooling processes in disks

Cited by 17 publications

References 45 publications

Reading between the lines

Reading between the lines

Grand Challenges in Protoplanetary Disc Modelling

Parameterizing the interstellar dust temperature

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