The  2017 edition of the Evry Schatzman school of the French national program of stellar Physics (PNPS) will focus on high angular resolution imaging (HAR). HAR is a very dynamic topic with a lot of new instruments such as SPHERE/VLT,  the  JWST and later EELT-CAM, EELT-EPICS, together with  interferometry with JouFlu (CHARA), PIONIER (VLTI), VEGA (CHARA), GRAVITY (VLTI), MATISSE (VLTI)..., or at longer wavelenghths with  ALMA and NOEMA. This fast moving topic is the key to study star forming regions, protoplanetary discs, stellar surfaces and circumstellar environments. France is an historical  key actor in the world to develop high angular resolution, imaging instruments and HAR imaging is a topic of high priority for the french national propgram of stellar physics (PNPS). It is also essential for the study of extrasolar planets and thus a key topic for the planets national program  (PNP).

Scientific context:

The field of high angular resolution imaging in France is structured by ASHRA. The main aim of the different high angular resolution themes is to reach one goal: control the wavefront to reach the angular resolution limit. This field of research steadily broadened thanks to new techniques such as optical interferometry, adaptive optics, very high dynamics, data processing, the study of atmospheric turbulence and innovative optical concepts.

For instance, the impact of optical interferometry on stellar physics (and other topics) is very various. One can i.e. mention the measurements of planetary and stellar fondamental parameters, asteroseismology, the distance to Cepheids, the study of protoplanetary discs, fast rotators and the convection structure of supergiant stars. Since 2009, optical interferometry can even produce images.

In the meantime, thanks to the developments of adaptive optics, it is now feasible to directly image the close circumstellar environments of red giants and supergiants (e.g. Betelgeuse and L2 Pup) to study dust and gas around it with single telescopes (with NACO on the VLT for example).  Today, SPHERE is producing similar results. On the long term, direct imaging of stellar surfaces will be feasible with the E-ELT, leading to a better understanding of stellar convection, of the environments of massive stars or evolved stars and their mass loss...

Goals of the school:

High angular resolution studies require an instrumental expertise which has to take into account technical and scientific  constraints. The fast evolution of this topic in the field of stellar physics planetary sciences requires a very good interaction between different communities:

• Instrument designers on one side and users on the other (stellar physicists or (exo)planetary scientists).  The school aims at reaching these two communities first
• A very strong complementarity merges between optical and radio with the apparition of ALMA. (see e.g. the recent conference: "Resolving planet formation in the era of ALMA and extreme AO" http://www.eso.org/sci/meetings/2016/Planet-Formation2016.html.  This will be the subject of studies during this school
• Another goal of the school is to show the complementarity between single telescope imaging and interferometry

One of the goal will finally be to make high angular resolution reachable  for as many people as possible, to make it as useful as possible for stellar physics and planetary sciences.

Program of the school:

The school will be structured around 5 key lectures, organized as followed:

• History and introduction to the technique,
• An overview of existing and forthcoming instruments,
• A description of the most spectacular astrophysical applications,
• All this will be completed by personal labwork (TP)

Lectures will start on monday morning and will end on Friday at noon. Welcoming will take place on Sunday from 2pm onwards.

Lectures titles/speakers:

Part I: Direct imaginfg

• Lecture - Introduction to direct imaging (F. Martinache)
• TP on atmospheric distortion and image analysis techniques (F. Martinache)
  
• Lecture - Current instrumentation and future with direct imaging (A. M. Lagrange)
• TP  on reduction and analysis of SPHERE data (E. Lagadec)

Part II: Interférometry

• Lecture - Introduction to interférometry. History, principles (J. Surdej)
• Lecture - Optical interferometry. Current and forthcoming instruments and their specificities (D. Mourard)
  
• TP  on « Jean-Marie Mariotti Center » (JMMC) tools.  Data reduction and image reconstruction with GRAVITY (A. Meilland, F. Millour)
  
• Lecture - Radio/mm interferometry. Current and forthcoming instruments and their specificities (A. Maury)

Specific seminars spécifiques:

• Seminar on E-ELT (to be confirmed)
  
• First results from Gravity. Perspectives. (P. Kervella, UMi)