We examine the implications for the distribution of extrasolar planets based on the null results from two of the largest direct imaging surveys published to date. Combining the measured contrast curves from Masciadri et al.  (2005) and Biller et al.  (2007), we consider what distributions of planet masses and semi-major axes can be ruled out by these data, based on Monte Carlo simulations of planet populations. We can set the following upper limit with 95% confidence: the fraction of stars with planets with semi-major axis between 20 and 100 AU, and mass above 4 MJup, is 20% or less. Also, with a distribution of planet mass of $\frac{{\rm d}N}{{\rm d}M} \propto M^{-1.16}$ in the range of 0.5–13 MJup, we can rule out a power-law distribution for semi-major axis ($\frac{{\rm d}N}{{\rm d}a} \propto a^{\alpha}$) with index 0 and upper cut-off of 18 AU, and index –0.5 with an upper cut-off of 48 AU. For the distribution suggested by Cumming et al.  (2008), a power-law of index –0.61, we can place an upper limit of 75 AU on the semi-major axis distribution.


Binary brown dwarfs are important because their dynamical masses can be determined in a model-independent way. If a main sequence star is also involved, the age and metallicity for the system can be determined, making it possible to break the sub-stellar mass-age degeneracy. The most suitable benchmark system for intermediate age T dwarfs is ε Indi Ba,b, two T dwarfs (spectral types T1 and T6; McCaughrean et al. (2004)) orbiting a K4.5V star, ε Indi A, at a projected separation of 1460AU. At a distance of 3.6224pc (HIPPARCOS distance to ε Indi A; van Leeuwen (2007)), these are the closest brown dwarfs to the Earth, and thus both components are bright and the system is well-resolved. The system has been monitored astrometrically with NACO and FORS2 on the VLT since June 2004 and August 2005, respectively, in order to determine the system and individual masses independent of evolutionary models. We have obtained a preliminary system mass of 121±1MJup. We have also analysed optical/near-IR spectra (0.6-5.0μm at a resolution up to R~5000; King et al. (2009)) allowing us to determine bolometric luminosities, compare and calibrate evolutionary and atmospheric models of T dwarfs at an age of 4-8Gyr.

We present the adaptive optics assisted, near-infrared VLTI instrument GRAVITY for precision narrow-angle astrometry and interferometric phase referenced imaging of faint objects. With its two fibers per telescope beam, its internal wavefront sensors and fringe tracker, and a novel metrology concept, GRAVITY will not only push the sensitivity far beyond what is offered today, but will also advance the astrometric accuracy for UTs to 10 μas. GRAVITY is designed to work with four telescopes, thus providing phase referenced imaging and astrometry for 6 baselines simultaneously. Its unique capabilities and sensitivity will open a new window for the observation of a wide range of objects, and — amongst others — will allow the study of motion within a few times the event horizon size of the Galactic Center black hole.

A Mid-IR instrumentation study for OWL has been performed by the Max-Planck-Institut für Astronomie in Heidelberg (Germany), and a Dutch consortium led by the Leiden Observatory (The Netherlands). MIR imaging and spectroscopic observational capabilities are compared to contemporary IR to sub-millimeter facilities, especially concentrating on the MIR-capabilities of JWST(MIRI). Our best effort calculation of the sensitivity for both MIR imager and spectrograph indicate a huge discovery potential in numerous areas from our planetary system to the high redshift Universe. Here we focus on the field of exo-planets and nearby star formation. Starting with the science cases, top level requirements are deduced and summarized including MIR instrumental constrains for the telescope itself.

We expand upon the results of Close et al. 2005 regarding the young, low-mass object AB Dor C and its role as a calibration point for theoretical tracks. We argue for a new 70$\pm$30 Myr age estimate and present two additional detections of C with the Simultaneous Differential Imaging (SDI) camera. Our improved analysis (Nielsen et al. 2005) confirms our spectral type of M8 ($\pm$1) and mass of 0.090 $\pm$0.003 M$_{\hbox{\it \scriptsize sun}}$ for AB Dor C. However, Luhman & Potter (2006) argue for a hotter spectral type (M6$\pm$1). Here we adopt the consistent spectral range of M7$\pm$1 in this paper as a final spectral type. Plotting AB Dor C (and all other young (${<}0.12$ Myr), low-mass ($0.3-0.05 M_{\hbox{\it \scriptsize sun}}$) objects with accurate dynamical masses) on the HR diagram suggests a trend where current evolutionary models tend to over-predict the temperature (or under-predict the mass) for young low-mass stars and high-mass brown dwarfs. With our uncertainties, there is a $\sim$90% chance that the mass of AB Dor C is underestimated by the DUSTY tracks in the HR diagram.

Light reflected from planets is polarized. This basic property of planets provides the possibility for detecting and characterizing extra-solar planets using polarimetry. The expected polarization properties of extra-solar planets are discussed that can be inferred from polarimetry of “our” solar system planets. They show a large variety of characteristics depending on the atmospheric and/or surface properties. Best candidates for a polarimetric detection are extra-solar planets with an optically thick Rayleigh scattering layer.

Even the detection of highly polarized extra-solar planets requires a very sophisticated instrument. We present the results from a phase A (feasibility) study for a polarimetric arm in the ESO VLT planet finder instrument. It is shown that giant planets around nearby stars can be searched and investigated with an imaging polarimeter, combined with a powerful AO system and a coronagraph at an 8 m class telescope.

A similar type of polarimeter is also considered for the direct detection of terrestrial planets using an AO system on one of the future Extremely Large Telescopes.

This paper presents the status of the EPICS project, an Earth-like Planets Imaging Camera Spectrograph for OWL. We present the Top-Level-Requirements of the instrument and we describe the baseline of the Adaptive Optics system with optimized wave-front sensor. The expected performance in rejection of starlight in the near infrared and in the visible is given. The instruments concepts for detection and characterization of exo-planets will be briefly described. The Signal-to-Noise ratio estimation shows that Earth-like planets can be detected up to 20 pc in a reasonable amount of time. The extremely challenging requirements in terms of static residual errors and differential aberrations are discussed.

We surveyed all stars in Taurus (3h 45m < α < 4h 15m, 15° < δ < 35°) for multiplicity which are contained in the Herbig-Bell catalogue of young stars and have a 2 micron brightness of K ≤ 9.5 mag. This sample consists of 106 stellar systems (single or multiple), of which 43 are double or multiple according to the criteria of our survey, i.e. with separations of ≈0″.2 ≤ d ≤ 10″. Of these, 23 binaries are new detections found in this survey. The resulting degree of multiplicity, 43/106 = 41±6%, is higher than found for main-sequence stars. Provided that the period distribution is the same for young stars as on the main sequence, our result implies that the vast majority of stars are born in binary or multiple systems.

0.9 μm CCD images and 2.2 μm slit scan observations reveal the double character of the infrared source Serpens - SVS20; the separation, position angle and brightness ratio are 1.″6, 10°, and Δm ≍ 1.6 mag respectively. The southern source is the brightest at both spectral ranges. At 0.9 μm the observed polarization of each component is p = 9.0 %, ⊙ = 155° and p = 10.4 %, ⊙ = 135° for SVS20-South and SVS20-North respectively. These results combined with 2.2 μm polarimetry and JHKLM photometry suggest that both SVS20 sources are in fact low mass, probably PMS, stars.

Deep direct 1 μm images and polarization maps have been taken for several objects of bipolar molecular outflow, using a CCD camera at the prime-focus of the 3.5 m telescope on Calar Alto/Spain. Compact reflection nebulae are found near GL2591, GL2884 = S140/IRS1, GL2789 = V645 Cyg, L1551/IRS5 and within the red reflection nebula in Serp. The position angles of polarization vectors coincide in all cases with that of the 2.2 μm polarization of the central source itself, and it is perpendicular to the direction of mass outflow (if it is well defined). The visual extinction in front of the central source, is at least 20 mag higher than that which is affecting the scattered light. This is consistent with a model of bipolar outflow, where the active source is surrounded by a dust torus or ring.

Photometry and first results of extensive CCD-spectroscopy of the UX UMa system RW Sex are presented. The period is found to be P = 0.24486 days and the semi-amplitude of the radial velocity is K1 = 101 km s−1. The mass of a Roche-lobe filling secondary is M2 = (0.54±0.09) Mo and, for M1 ≧ M2, the mass ratio is M1/M2 = 1.5±0.5. The accretion rate is about (2–3) 1017 g/s. The model for RW Sex by Greenstein and Oke is discussed and rejected.