Context. The spectacular outflow of HH 46/47 is driven by HH 46 IRS 1, an embedded Class I Young Stellar Object (YSO). Although much is known about this region from extensive optical and infrared observations, the properties of its protostellar envelope and molecular outflow are poorly constrained. Aims. Our aim is to characterize the size, mass, density and temperature profiles of the protostellar envelope of HH 46 IRS 1 and its surrounding cloud material as well as the effect the outflow has on its environment. Methods. The newly commisioned CHAMP + and LABOCA arrays on the APEX telescope, combined with lower frequency line receivers, are used to obtain a large (5 × 5 , 0.6 × 0.6 pc) continuum map and smaller (80 × 80 , 36 000 × 36 000 AU) heterodyne maps in various isotopologues of CO and HCO + . The high-J lines of CO (6-5 and 7-6) and its isotopologues together with [C I] 2-1, observed with CHAMP + , are used to probe the warm molecular gas in the inner few hundred AU and in the outflowing gas. The data are interpreted with continuum and line radiative transfer models. Results. Broad outflow wings are seen in CO low-and high-J lines at several positions, constraining the gas temperatures to a constant value of ∼100 K along the red outflow axis and to ∼60 K for the blue outflow. The derived outflow mass is of order 0.4-0.8 M , significantly higher than previously found. The bulk of the strong high-J CO line emission has a surprisingly narrow width, however, even at outflow positions. These lines cannot be fit by a passively heated model of the HH 46 IRS envelope. We propose that it originates from photon heating of the outflow cavity walls by ultraviolet photons originating in outflow shocks and the accretion disk boundary layers. At the position of the bow shock itself, the UV photons are energetic enough to dissociate CO. The envelope mass of ∼5 M is strongly concentrated towards HH 46 IRS with a density power law of −1.8. Conclusions. The fast mapping speed offered by CHAMP + allows the use of high-J CO lines and their isotopes to generate new insights into the physics of the interplay between the molecular outflow and protostellar envelope around low-mass protostars. The UV radiation inferred from the high-J CO and [C I] data will affect the chemistry of other species.

We report the discovery of 16 detached M dwarf eclipsing binaries with J < 16 mag and provide a detailed characterization of three of them, using high-precision infrared light curves from the WFCAM Transit Survey (WTS). Such systems provide the most accurate and modelindependent method for measuring the fundamental parameters of these poorly understood yet numerous stars, which currently lack sufficient observations to precisely calibrate stellar evolution models. We fully solve for the masses and radii of three of the systems, finding orbital periods in the range 1.5 < P < 4.9 d, with masses spanning 0.35-0.50 M and radii between 0.38 and 0.50 R , with uncertainties of ∼3.5-6.4 per cent in mass and ∼2.7-5.5 per cent in radius. Close companions in short-period binaries are expected to be tidally locked into fast rotational velocities, resulting in high levels of magnetic activity. This is predicted to inflate their radii by inhibiting convective flow and increasing starspot coverage. The radii of the WTS systems are inflated above model predictions by ∼3-12 per cent, in agreement with the observed trend, despite an expected lower systematic contribution from starspot signals at infrared wavelengths. We searched for correlation between the orbital period and radius inflation by combining our results with all existing M dwarf radius measurements of comparable precision, but we found no statistically significant evidence for a decrease in radius inflation for longer period, less active systems. Radius inflation continues to exists in non-synchronized systems, indicating that the problem remains even for very low activity M dwarfs. Resolving this issue is vital not only for understanding the most populous stars in the Universe, but also for characterizing their planetary companions, which hold the best prospects for finding Earth-like planets in the traditional habitable zone.

The mid-infrared (MIR) ratio [Ne III] 15.6 μm /[Ne II] 12.8 μm is a strong diagnostic of the ionization state of emission-line objects, due to its use of only strong neon emission lines only weakly affected by extinction. However, this ratio is not available to ground-based telescopes as only a few spectroscopic windows are available in the MIR. To deal with this problem, we aimed to verify if there exists a conversion law between the ground-accessible, strong MIR line ratio [S IV]/[Ne II] and the diagnostic [Ne III]/[Ne II] ratio that can serve as a reference for future ground-based observations. We collated the [S IV] 10.5 μm , [Ne II] 12.8 μm , [Ne III] 15.6 μm and [S III] 18.7 μm emission-line fluxes from a wide range of sources in the rich Spitzer and Infrared Space Observatory archives, and compared the [Ne III]/[Ne II], [S IV]/[S III] and [S IV]/[Ne II] ratios. We find a strong correlation between the [S IV]/[Ne II] and [Ne III]/[Ne II] ratios, with a linear fit of log([Ne III]/[Ne II]) = 0.81 log([S IV]/[Ne II]) + 0.36, accurate to a factor of ∼2 over four orders of magnitude in the line ratios. This demonstrates clearly the ability of ground-based infrared spectrographs to do ionization studies of nebulae.

The WFCAM Transit Survey (WTS) is a near-infrared transit survey running on the United Kingdom Infrared Telescope (UKIRT), designed to discover planets around M dwarfs. The WTS acts as a poor-seeing backup programme for the telescope, and represents the first dedicated wide-field near-infrared transit survey. Observations began in 2007 gathering J-band photometric observations in four (seasonal) fields. In this paper we present an analysis of the first of the WTS fields, covering an area of 1.6 square degrees. We describe the observing strategy of the WTS and the processing of the data to generate lightcurves. We describe the basic properties of our photometric data, and measure our sensitivity based on 950 observations. We show that the photometry reaches a precision of ∼ 4 mmag for the brightest unsaturated stars in lightcurves spanning almost 3 years. Optical (SDSS griz) and near-infrared (UKIRT ZY JHK) photometry is used to classify the target sample of 4600 M dwarfs with J magnitudes in the range 11-17. Most have spectral-types in the range M0-M2. We conduct Monte Carlo transit injection and detection simulations for short period (<10 day) Jupiterand Neptune-sized planets to characterize the sensitivity of the survey. We investigate the recovery rate as a function of period and magnitude for 4 hypothetical star-planet cases: M0-2+Jupiter, M2-4+Jupiter, M0-2+Neptune, M2-4+Neptune. We find that the WTS lightcurves are very sensitive to the presence of Jupiter-sized short-period transiting planets around M dwarfs. Hot Neptunes produce a much weaker signal and suffer a correspondingly smaller recovery fraction. Neptunes can only be reliably recovered with the correct period around the rather small sample (∼ 100) of the latest M dwarfs (M4-M9) in the WTS. The non-detection of a hot-Jupiter around an M dwarf by the WFCAM Transit Survey allows us to place an upper limit of 1.7-2.0 per cent (at 95 per cent confidence) on the planet occurrence rate.

Abstract. The WFCAM Transit Survey (WTS) is a near-infrared transit survey running on the United Kingdom Infrared Telescope (UKIRT). We conduct Monte Carlo transit injection and detection simulations for short period (<10 day) Jupiter-sized planets to characterize the sensitivity of the survey. We investigate the recovery rate as a function of period and magnitude in 2 hypothetical star-planet cases: M0-2 + hot Jupiter, M2-4 + hot Jupiter. We find that the WTS lightcurves are very sensitive to the presence of Jupitersized short-period transiting planets around M dwarfs. The non-detection of a hot-Jupiter around an M dwarf by the WFCAM Transit Survey allows us to place a firm upper limit of 1.9 per cent (at 95 per cent confidence) on the planet occurrence rate.