We present a detailed study of SMM 02399-0136, a hyperluminous, active galaxy selected from a sub-mm survey of the distant Universe. This galaxy is the brightest source in the fields of seven rich, lensing clusters - total area 0.01 deg^2 - that we have mapped with a sensitivity of ~2 mJy/bm at 850um. We identify a compact optical counterpart with B ~ 23 and a LSB companion 3" away. Our spectroscopy shows that components have the same redshift; z = 2.803 +/- 0.003. The emission lines widths, FWHM ~ 1000-1500 km/s, and line ratios, along with the compact morphology and high luminosity (M_B ~ -24.0) of the galaxy indicate that SMM 02399-0136 contains a rare dust-embedded, narrow-line or type-2 AGN. The source is lensed by the foreground cluster, amplifying its apparent luminosity by a factor of 2.5. Taking this into account, we estimate that SMM 02399-0136 is five times more luminous than F10214+4724. Its far-IR and H-alpha luminosities and LSB radio emission are indicative of an extremely high SFR - several thousand Mo/yr. This assumes that a starburst is the dominant source of energy, but we cannot yet determine the relative contributions of the starburst and the buried AGN. A dust mass of 5-7 x 10^8 Mo is indicated by our data for T(dust) ~ 40-50K, independent of whether the dominant energy source is an AGN or a starburst. We estimate the possible space density of such luminous sub-mm sources and find that while a very large population of these obscured sources could be detected in future wide-field sub-mm surveys, they are unlikely to dominate the faint counts in this waveband. Galaxies such as SMM 02399-0136 and F10214+4724 cannot be easily detected in conventional AGN/QSO surveys, and so estimates of the prevalence of AGN in the early Universe may require significant revision.Comment: 11 pages, 5 figures. Accepted for MNRAS. Full survey discussed briefl

Abstract. In this paper we present the first comprehensive results extracted from the spectroscopic campaigns carried out by the EXPORT (EXoPlanetary Observational Research Team) consortium. During 1998-1999, EXPORT carried out an intensive observational effort in the framework of the origin and evolution of protoplanetary systems in order to obtain clues on the evolutionary path from the early stages of the pre-main sequence to stars with planets already formed. The spectral types of 70 stars, and the projected rotational velocities, v sin i, of 45 stars, mainly Vega-type and pre-main sequence, have been determined from intermediate-and high-resolution spectroscopy, respectively. The first part of the work is of fundamental importance in order to accurately place the stars in the HR diagram and determine the evolutionary sequences; the second part provides information on the kinematics and dynamics of the stars and the evolution of their angular momentum. The advantage of using the same observational configuration and methodology for all the stars is the homogeneity of the set of parameters obtained. Results from previous work are revised, leading in some cases to completely new determinations of spectral types and projected rotational velocities; for some stars no previous studies were available.

Abstract. This paper presents optical UBVRI broadband photo-polarimetry of the EXPORT sample obtained at the 2.5m Nordic Optical Telescope. The database consists of multi-epoch photo-polarimetry of 68 pre-mainsequence and main-sequence stars. An investigation of the polarization variability indicates that 22 objects are variable at the 3σ level in our data. All these objects are pre-main sequence stars, consisting of both T Tauri and Herbig Ae/Be objects while the main sequence, Vega type and post-T Tauri type objects are not variable. The polarization properties of the variable sources are mostly indicative of the UXOR-type behaviour; the objects show highest polarization when the brightness is at minimum. We add nine new objects to the class of UXOR variables (BH Cep, VX Cas, DK Tau, HK Ori, LkHα 234, KK Oph and RY Ori). The main reason for their discovery is the fact that our data-set is the largest in its kind, indicating that many more young UXOR-type pre-main sequence stars remain to be discovered. The set of Vega-like systems has been investigated for the presence of intrinsic polarization. As they lack variability, this was done using indirect methods, and apart from the known case of BD +31 o 643, the following stars were found to be strong candidates to exhibit polarization due to the presence of circumstellar disks: 51 Oph, BD +31 o 643C, HD 58647 and HD 233517.

Abstract. For a complete understanding of the physical processes causing the photometric variability of pre-main sequence systems, simultaneous optical and near-IR observations are required to disentangle the emission from the stars and that from their associated circumstellar disks. Data of this sort are extremely rare and little systematic work has been reported to date. The work presented in this paper is a systematic attempt in this direction. It presents an analysis of the simultaneous optical and near-IR photometric variability of 18 Herbig Ae/Be and T Tauri stars which were observed in October 98 by the EXPORT collaboration. The time difference between the UBVRI and JHK measurements is less than 1 hour in ≈50% of the data and the largest difference is around 2 hours in only ≈10% of the data. Twelve stars appear to show a correlation between the optical and near-IR variability trends, which suggests a common physical origin such as spots and/or variable extinction. The optical and near-IR variability is uncorrelated in the rest of the objects, which suggests it originates in distinctly different regions. In general, the optical variability qualitatively follows the predictions of starspots or variable extinction. As far as the near-IR is concerned, the simultaneity of the observations demonstrates that for most objects the flux is largely produced by their circumstellar disks and, consequently, in many cases the near-IR fluctuations must be attributed to structural variations of such disks producing variations of their thermal emission and/or scattered light. The observed near-IR changes of up to around 1 mag on timescales of 1-2 days provide interesting challenges for understanding the mechanisms generating such remarkable variabilities, an issue insufficiently investigated until now but one which deserves further theoretical and modeling efforts.