|Direct measurements of the warm gas distribution and vertical temperature gradient in protoplanetary disks.
|Recent observations of protoplanetary disks with Herschel have revealed the presence of high-J CO lines. State-of-the-art disk models predicts that this emission arises from intermediate layers below the disk surface and above the mid-plane. These layers are shielded from the photodissociative (UV) radiation emitted by the pre-main-sequence star and are thus very important for the chemical evolution of the disk. Previous observations with PACS allows us to determine the temperature and density of the gas in these layers. The low-resolution spectra of PACS, however, does not provide direct information on the distribution of the gas. We propose follow-up observations with HIFI of the J=16-15 CO line previously detected with PACS in 8 disks. The high-spectral resolution of HIFI will allow us to directly measure the radial distribution of the emitting gas. This modest (14 hours) HIFI proposal will complement the previous PACS observations allowing to fully characterize the properties of the warm gas (temperature, density and radial distribution). The second goal of this project is to address the vertical temperature gradient inside the disk. This will be achieved by comparing the HIFI observation of CO J=16-15 line to spectrally-resolved ro-vibrational and low-J CO emission lines observed from the ground. For this we will implement thermo-chemical disk models developed in our group. We also propose follow-up HIFI observations of the strong [CII] emission detected with PACS in three protoplanetary disks. According to disk models this line is expected to emerge from the ionised disk surface of the disk and is linked to the CO chemistry (photodissociation). However, the measured line flux in HD 100546, HD 97048 and IRS 48 is high and might not all come from the disk but rather from an outflow or a remnant envelope. HIFI will allow to resolve to resolve the velocity profile of the line and in turn to disentangle its origin.
|Probing the 2D temperature structure of protoplanetary disks with Herschel observations of high-J CO lines . Fedele D. et al. . Astronomy & Astrophysics, Volume 591, id.A95, 13 pp. . 591 . 10.1051/0004-6361/201526948 . 2016A&A...591A..95F ,
Probing the Radial Temperature Structure of Protoplanetary Disks with Herschel-HIFI . Fedele D. et al. . The Astrophysical Journal Letters, Volume 776, Issue 1, article id. L3, 5 pp. (2013). . 776 . 10.1088/2041-8205/776/1/L3 . 2013ApJ...776L...3F ,
|Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
|Publisher And Registrant
|European Space Agency
|European Space Agency, 2013, OT2_dfedele_2, SPG v14.1.0. https://doi.org/10.5270/esa-fpl980w