Because the formation of protostars is believed to be closely tied to the angular momentum problem of star formation, characterizing the properties of the youngest disks around Class 0 objects is crucial. However, not much is known on the structure of the youngest protostellar envelopes, on the small scales at which disks and multiple systems are observed around more evolved YSOs, due to a lack of comprehensive high angular resolution observations (probing <100 AU). In order to tackle this issue, we conducted a large observing program with the IRAM Plateau de Bure interferometer (PdBI): the CALYPSO survey, providing us with detailed maps of molecular lines and millimeter continuum emission, probing scales down to ~30–50 au towards a sample of 17 Class 0 protostars. Here we present our analysis of the CALYPSO dust continuum emission maps, constraining disk properties of the Class 0 protostars in our sample. We show that large, r > 50 au, disk structures are not observed in most Class 0 protostars from our sample, which can be described by various envelope models reproducing satisfactorily the intensity distribution of the dust emission at all scales from 50 au to 5000 au.

SEEDS is the first Subaru Strategic Program, whose aim is to conduct a direct imaging survey for giant planets as well as protoplanetary/debris disks at a few to a few tens of AU region around 500 nearby solar-type or more massive young stars devoting 120 Subaru nights for 5 years. The targets are composed of five categories spanning the ages of ~1 Myr to ~1 Gyr. Some RV-planet targets with older ages are also observed. The survey employs the new high-contrast instrument HiCIAO, a successor of the previous NIR coronagraph camera CIAO for the Subaru Telescope. We describe the outline of this survey and present its first three years of results. The survey has published ~20 refereed papers by now. The main results are as follows: (1) detection and characterization of the most unequivocal and lowest-mass planet via direct imaging. (2) detection of a super-Jupiter around the most massive star ever imaged, (3) detection of companions around a retrograde exoplanet system, which supports the Kozai mechanism for the origin of retrograde orbit (not in this proceedings, but see Narita et al. 2010, 2012). We also report (4) the discovery of unprecedentedly detailed structures of more than a dozen of protoplanetary disks and some debris disks. The detected structures such as wide gaps and spirals arms of a Solar-system scale could be signpost of planet.

The existence of circumstellar disks around young stellar objects like T Tauri stars is now well accepted. Such disks would have solar system sizes and, at the distance of the nearest star forming cloud, an angular diameter of 0.01 to 1 arcsecond at most, requiring very high angular resolution to be detected. Due to the nature of the emission process in circumstellar disks and to chromatic properties of ground based observations, disk imaging is expected to be more efficient in the near infrared. Also, multi-aperture interferometry in this wavelength range (1 – 10 μm) is expected to bring considerable insight into the disks properties and evolution in revealing their inner physical structure.

In this paper, we present synthetic images of circumstellar accretion disks. The images have been computed from a complete disk vertical structure model.