Abstract

The DENIS survey will survey the southern sky in the near-IR J (1.2 micron) and K (2.2 microns) bands at 3” resolution and to limiting magnitudes in J and K of respectively 16 and 14.5 (lmJy in both cases), and at 1” resolution in the red I band (0.9 microns). Astrophysical motivation is provided by basic problems concerning structure and evolution of galaxies, of types ranging from our own to active galaxies, and concerning specific stellar populations including stars with low temperature photospheres, those still embedded in their protostellar envelopes, and those currently losing mass on the AGB.

Scientific objectives

The release of large 2D detector arrays sensitive in the near infrared provides the first opportunity to undertake a deep survey of the sky in the non-thermal infrared range (1 to 2.5 microns). This underexplored spectral range will provide crucial insights into fundamental problems in stellar and galactic astrophysics. Theere is no recent all-sky atlas of data between the visible and the IRAS 12 microns band. The 25 year-old IRC catalog remains the state of the art effort in the near IR despite its limitations. Our objective is to carr y a 3 colour (IJK) survey of the complete southern sky, improving on the pioneering IRC sensitivity by 4 orders of magnitude and improving on its spatial resolution by a factor of 20.

There are two main motivations for a deep near IR sky survey: the near IR brightness is the best tracer of mass in stellar form, and the interstellar extinction is reduced by a factor of 10 with respect to the visible V band.