Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. However, there is a very small interesting group of stars in our neighbourhood (49 Ceti, and our discovery HD 21997), which may represent the missing link between these phases as indicated by the unexpected presence of debris-like dust content and measurable CO gas component. With the aim of discovering and characterizing more of these spectacular objects here we propose to obtain O I 63 micron observations of a sample of carefully selected young (<50Myr) debris disks of high fractional luminosity with Herschel/PACS. Our objectives are to 1) discover and determine the incidence of 49 Ceti-like gaseous debris disks; 2) characterize disk structure; 3) determine the timescale of gas dispersal; 4) perform a detailed investigation of HD 21997. New discoveries would lead to the definition of a new subclass of circumstellar disks, the gaseous debris disks. We required 17.2h of Herschel time for the observations.
Publication
Herschel-PACS observations of far-IR lines in young stellar objects. I. OI and H2O at 63 mm | Riviere-Marichalar P. et al. | Astronomy & Astrophysics Volume 594 id.A59 25 pp. | 594 | 10.1051/0004-6361/201527829 | 2016A&A...594A..59R | http://adsabs.harvard.edu/abs/2016A%26A...594A..59R
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.
European Space Agency, kiss et al., 2013, 'Exploring the gaseous component of debris disks of high fractional luminosity :a deep [O I] 63.2 micron survey with Herschel.', SPG v14.2.0, European Space Agency, https://doi.org/10.5270/esa-o9n2kjw
