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Low EUV Luminosities Impinging on Protoplanetary Disks

Pascucci, I. and Ricci, L. and Gorti, U. and Hollenbach, D. and Hendler, N. P. and Brooks, K. J. and Contreras, Y. (2014) Low EUV Luminosities Impinging on Protoplanetary Disks. . (Submitted)

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The amount of high-energy stellar radiation reaching the surface of protoplanetary disks is essential to determine their chemistry and physical evolution. Here, we use millimetric and centimetric radio data to constrain the EUV luminosity impinging on 14 disks around young (~2-10Myr) sun-like stars. For each object we identify the long-wavelength emission in excess to the dust thermal emission, attribute that to free-free disk emission, and thereby compute an upper limit to the EUV reaching the disk. We find upper limits lower than 10^(42) photons/s for all sources without jets and lower than 5×10^(40) photons/s for the three older sources in our sample. These latter values are low for EUV-driven photoevaporation alone to clear out protoplanetary material in the timescale inferred by observations. In addition, our EUV upper limits are too low to reproduce the [NeII] 12.81 µm luminosities from three disks with slow [NeII]-detected winds. This indicates that the [NeII] line in these sources primarily traces a mostly neutral wind where Ne is ionized by 1 keV X-ray photons, implying higher photoevaporative mass loss rates than those predicted by EUV-driven models alone. In summary, our results suggest that high-energy stellar photons other than EUV may dominate the dispersal of protoplanetary disks around sun-like stars.

Item Type:Report or Paper (Discussion Paper)
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URLURL TypeDescription
Pascucci, I.0000-0001-7962-1683
Hendler, N. P.0000-0002-3164-0428
Additional Information:The authors thank the anonymous referee for a prompt and useful report. I.P. thanks Cathie Clarke for stimulating discussion. I.P., U.G., and D.H. acknowledge support from an NSF Astronomy & Astrophysics Research Grant (ID: 1312962). Facilities: ATCA
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Record Number:CaltechAUTHORS:20141217-103128286
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:52952
Deposited By: Tony Diaz
Deposited On:17 Dec 2014 19:40
Last Modified:09 Mar 2020 13:19

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