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In a continuing effort to investigate the role of magnetic fields in evolved low and intermediate mass stars (principally regarding the shaping of their envelopes), we present new ALMA high resolution polarization data obtained for the nebula OH 231.8+4.2. We found that the polarized emission likely arises from aligned grains in the presence of magnetic fields rather than radiative alignment and self scattering. The ALMA data show well organized electric field orientations in most of the nebula and the inferred magnetic field vectors (rotated by 90 degrees) trace an hourglass morphology centred on the central system of the nebula. One region in the southern part of OH 231.8+4.2 shows a less organized distribution probably due to the shocked environment. These findings, in conjunction with earlier investigations (maser studies and dust emission analysis at other scales and wavelengths) suggest an overall magnetic hourglass located inside a toroidal field. We propose the idea that the magnetic field structure is closely related to the architecture of a magnetic tower and that the outflows were therefore magnetically launched. While the current dynamical effect of the fields might be weak in the equatorial plane principally due to the evolution of the envelope, it would still be affecting the outflows. In that regard, the measurement of the magnetic field at the stellar surface, which is still missing, combined with a full MHD treatment are required to better understand and constrain the events occurring in OH 231.8+4.2., 9 pages, 7 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society Main Journal

We present medium-resolution K-band long-slit spectroscopy of 29 true, likely, possible and candidate Galactic Plane planetary nebulae (PNe) from the UWISH2 survey - many of which have only been recently discovered. These objects are bright in molecular hydrogen (H2) emission, and many have bipolar morphologies. Through the detection of the Br{\gamma} emission line, which traces ionized hydrogen, we find that the majority of the candidate PNe are indeed likely to be PNe, while 2 of the targets are more likely young stellar objects (YSOs) or pre-planetary nebulae (pPNe). We detect Br{\gamma} in 13 objects which have no detection in IPHAS or SHS H{\alpha} surveys. This implies they are potential members of the little-known optically-obscured PN population, hidden from wide-field optical surveys. We use the spatial extent of the H2 1-0 S(1) and Br{\gamma} lines to estimate the evolutionary stage of our targets, and find that W-BPNe (bipolar PNe with pinched waist morphologies) are likely to be younger objects, while R-BPNe (bipolar PNe with large ring structures) are more evolved. We use line ratios to trace the excitation mechanism of the H2, and find the 1-0 S(1) / 2-1 S(1) and 1-0 S(1) / Br{\gamma} ratios are higher for R-BPNe, implying the H2 is thermally excited. However, in W-BPNe, these ratios are lower, and so UV-fluorescence may be contributing to the excitation of H2., Comment: 17 pages, 4 figures, accepted for MNRAS

Near-infrared imaging in the 1 - 0 S(1) emission line of molecular hydrogen is able to detect planetary nebulae (PNe) that are hidden from optical emission line surveys. We present images of 307 objects from the UWISH2 survey of the northern Galactic Plane, and with the aid of mid-infrared colour diagnostics draw up a list of 291 PN candidates. The majority, 183, are new detections and 85 per cent of these are not present in H$\alpha$ surveys of the region. We find that more than half (54 per cent) of objects have a bipolar morphology and that some objects previously considered as elliptical or point-source in H$\alpha$ imaging, appear bipolar in UWISH2 images. By considering a small subset of objects for which physical radii are available from the H$\alpha$ surface brightness-radius relation, we find evidence that the H2 surface brightness remains roughly constant over a factor 20 range of radii from 0.03 to 0.6 pc, encompassing most of the visible lifetime of a PN. This leads to the H$\alpha$ surface brightness becoming comparable to that of H2 at large radius (> 0:5 pc). By combining the number of UWISH2 PNe without H$\alpha$ detection with an estimate of the PN detection efficiency in H2 emission, we estimate that PN numbers from H$\alpha$ surveys may underestimate the true PN number by a factor between 1.5 and 2.5 within the UWISH2 survey area., Comment: 20 pages, 8 figures. Appendices B and C are available as supplementary material from http://star.herts.ac.uk/~tmg/uwish2

Full paper with higher resolution figures and entire Appendix can be found at http://astro.kent.ac.uk/~df/

We present 2 to 2.4 micron integral field spectroscopy of a sample of hot post-AGB stars with early-B spectral types, using the NIFS instrument on Gemini North. These stars are just beginning to ionize their immediate environments and turn into planetary nebulae (PNe).We use molecular hydrogen emission lines together with hydrogen and helium recombination lines to explore the distribution of molecular and atomic gas and the extent of the developing ionized region. We see a range of evolutionary stages: IRAS 18062+2410 and IRAS 18379-1707 have recently developed compact and unresolved regions of photoionized H within axisymmetric molecular envelopes, with the former object increasing its Br-Gamma flux by a factor of 5.3 in 14 years; IRAS 22023+5249 and IRAS 20462+3416 have extended Br-Gamma nebulae and in the latter object only weak H2 emission remains; IRAS 19336-0400 is at a more advanced stage of PN formation where H2 is mostly dissociated and we see structure in both the H and He recombination line nebulae. IRAS 19200+3457 is the only object not to show the He I line at 2.058 micron and is probably the least evolved object in our sample; the H2 emission forms a ring around the star and we suggest that this object may be a rare example of a "round" pre-PN in transition to a "round" PN., Comment: 17 pages, 11 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society

We present the discovery of 816 high amplitude infrared variable stars ($\Delta K_{\rm s} >$ 1 mag) in 119 deg$^2$ of the Galactic midplane covered by the Vista Variables in the Via Lactea (VVV) survey. Almost all are new discoveries and about 50$\%$ are YSOs. This provides further evidence that YSOs are the commonest high amplitude infrared variable stars in the Galactic plane. In the 2010-2014 time series of likely YSOs we find that the amplitude of variability increases towards younger evolutionary classes (class I and flat-spectrum sources) except on short timescales ($$100 days) and 162 short-term variables. Eruptive YSOs and faders tend to have the highest amplitudes and eruptive systems have the reddest SEDs. Follow up spectroscopy in a companion paper verifies high accretion rates in the eruptive systems. Variable extinction is disfavoured by the 2 epochs of colour data. These discoveries increase the number of eruptive variable YSOs by a factor of at least 5, most being at earlier stages of evolution than the known FUor and EXor types. We find that eruptive variability is at least an order of magnitude more common in class I YSOs than class II YSOs. Typical outburst durations are 1 to 4 years, between those of EXors and FUors. They occur in 3 to 6\% of class I YSOs over a 4 year time span., Comment: Accepted for publication in MNRAS, 51 pages, 23 figures

We present a study of the radial distribution of dust species in young brown dwarf disks. Our work is based on a compositional analysis of the 10 and 20 micron silicate emission features for brown dwarfs in the Taurus-Auriga star-forming region. A fundamental finding of our work is that brown dwarfs exhibit stronger signs of dust processing in the cold component of the disk, compared to the higher mass T Tauri stars in Taurus. For nearly all of our targets, we find a flat disk structure, which is consistent with the stronger signs of dust processing observed in these disks. For the case of one brown dwarf, 2M04230607, we find the forsterite mass fraction to be a factor of ~3 higher in the outer disk compared to the inner disk region. Simple large-scale radial mixing cannot account for this gradient in the dust chemical composition, and some local crystalline formation mechanism may be effective in this disk. The relatively high abundance of crystalline silicates in the outer cold regions of brown dwarf disks provides an interesting analogy to comets. In this context, we have discussed the applicability of the various mechanisms that have been proposed for comets on the formation and the outward transport of high-temperature material. We also present Chandra X-ray observations for two Taurus brown dwarfs, 2M04414825 and CFHT-BD-Tau 9. We find 2M04414825, which has a ~12% crystalline mass fraction, to be more than an order of magnitude brighter in X-ray than CFHT-BD-Tau 9, which has a ~35% crystalline mass fraction. Combining with previous X-ray data, we find the inner disk crystalline mass fractions to be anti-correlated with the X-ray strength.

Post-AGB stars are key objects for the study of the dramatic morphological changes of low- to intermediate-mass stars on their evolution from the Asymptotic Giant Branch (AGB) towards the Planetary Nebula stage. There is growing evidences that binary interaction processes may very well have a determining role in the shaping process of many objects, but so far direct evidence is still weak. We aim at a systematic study of the dust distribution around a large sample of Post-AGB stars as a probe of the symmetry breaking in the nebulae around these systems. We used imaging in the mid-infrared to study the inner part of these evolved stars to probe direct emission from dusty structures in the core of Post-AGB stars in order to better understand their shaping mechanisms. We imaged a sample of 93 evolved stars and nebulae in the mid-infrared using VISIR/VLT, T-Recs/Gemini South and Michelle/Gemini North. We found that all the the Proto-Planetary Nebulae we resolved show a clear departure from spherical symmetry. 59 out of the 93 observed targets appear to be non resolved. The resolved targets can be divided in two categories. The nebulae with a dense central core, that are either bipolar and multipolar. The nebulae with no central core have an elliptical morphology. The dense central torus observed likely host binary systems which triggered fast outflows that shaped the nebulae.

We present K-band integral field spectroscopy of the bipolar post-AGB object IRAS 18276-1431 (OH 17.7-2.0) using SINFONI on the VLT. This allows us to image both the continuum and molecular features in this object from 1.95-2.45{\mu}m with a spatial resolution down to 70 mas and a spectral resolution of approx. 5000. We detect a range of H2 ro-vibrational emission lines which are consistent with shock excitation in regions of dense (approx. 10^7 cm^-3) gas with shock velocities in the range 25 - 30 km/s. The distribution of H2 emission in the bipolar lobes suggests that a fast wind is impinging on material in the cavity walls and tips. H2 emission is also seen along a line of sight close to the obscured star as well as in the equatorial region to either side of the stellar position which has the appearance of a ring with radius 0.3 arcsec. This latter feature may be radially cospatial with the boundary between the AGB and post-AGB winds. The first overtone 12^CO bandheads are observed longward of 2.29 {\mu}m with the v = 2-0 bandhead prominently in emission. The CO emission has the same spatial distribution as the K-band continuum and therefore originates from an unresolved central source close to the star. We interpret this as evidence for ongoing mass loss in this object. This conclusion is further supported by a rising K-band continuum indicating the presence of warm dust close to the star, possibly down to the condensation radius. The red-shifted scattered peak of the CO bandhead is used to estimate a dust velocity along the bipolar axis of 95 km/s for the collimated wind. This places a lower limit of approx. 125 yr on the age of the bipolar cavities, meaning that the collimated fast wind turned on very soon after the cessation of AGB mass loss.

Imaging polarimetry through J and H broad-band filters and a 3.4 � m narrow-band filter is used to highlight regions of scattered light in the Red Rectangle. We find that the scattered light identifies the circumbinary dust component of the molecular disc seen in CO emission. This region also appears to be the origin of the recently discovered Blue Luminescence. We find that the degrees of polarization are consistent with the amorphous carbon dust model invoked by Men’shchikov et al. (2002). Spectropolarimetry from 1.4 to 2.5 � m confirms that the degree of polarization in the central arcsecond region is very low. This suggests that the central bicone seen in the nearinfrared is due predominantly to emission from hot dust and/or from stochastically heated nanoparticles, rather than due to scattering by large grains.

We present near-infrared polarimetric images of the dusty circumstellar envelope (CSE) of IRAS 19306+1407, acquired at the United Kingdom Infrared Telescope (UKIRT) using the UKIRT 1-5 µm Imager Spectrometer (UIST) in conjunction with the half-waveplate module IRPOL2. We present additional 450 and 850 µm photometry obtained with the Sub-mm Common User Bolometer Array (SCUBA) at the James Clerk Maxwell Telescope (JCMT), as well as archived Hubble Space Telescope (HST) F606W- and F814W-filter images. The CSE structure in polarized flux at J- and Kbands shows an elongation NNE-SSW with two bright scattering shoulders NW-SE. These features are not perpendicular to each other and could signify a recent ‘twist’ in the outflow axis. We model the CSE using an axisymmetric light scattering (ALS) code to investigate the polarization produced by the CSE, and an axisymmetric radiation transport (DART) code to fit the SED. A good fit was achieved with the ALS and DART models using silicate grains, 0.1-0.4 µm with a power-law size distribution of a 3.5 , and an axisymmetric shell geometry with an equator-to-pole contrast of 7:1. The spectral type of the central star is determined to be B1I supporting previous suggestions that the object is an early PN. We have constrained the CSE and interstellar extinction as 2.0 and 4.2 mag respectively, and have estimated a distance of 2.7 kpc. At this distance the stellar luminosity is ∼4500 L⊙ and the mass of the CSE ∼0.2 M⊙. We also determine that the mass loss lasted ∼5300 yrs with a mass-loss rate of ∼3.4×10 5 M ⊙ yr 1 .

We have carried out JHK polarimetric observations of eleven dusty young stars, by using the polarimeter module IRPOL2 with the near-IR camera UIST on the 3.8-m United Kingdom Infrared Telescope (UKIRT). Our sample targeted systems for which UKIRT-resolvable discs had been predicted by model fits to their spectral energy distributions. Our observations have confirmed the presence of extended polarized emission around TW Hya and around HD 169142. HD 150193 and HD 142666 show the largest polarization values among our sample, but no extended structure was resolved. By combining our observations with HST coronographic data from the literature, we derive the J- and H-band intrinsic polarization radial dependences of TW Hya's disc. We find the disc's polarizing efficiency is higher at H than at J, and we confirm that the J- and H-band percentage polarizations are reasonably constant with radius in the region between 0.9 and 1.3 arcseconds from the star. We find that the objects for which we have detected extended polarizations are those for which previous modelling has suggested the presence of flared discs, which are predicted to be brighter than flat discs and thus would be easier to detect polarimetrically.

Echelle spectroscopy of H2, [FeII] and Br-gamma line emission from a very young planetary nebula, IRAS 21282+5050, and from four proto-planetary nebulae, IRAS 19343+2926 (M 1-92), IRAS 17150-3224 (AFGL 6815), IRAS 17423-1755 (Hen 3-1475), and IRAS 17441-2411 is presented. H2 line emission is detected in discrete shock fronts in the lobes of each nebula, regardless of source spectral type. In IRAS 17150-3224 we also uncover possible signs of rotation, as would be expected if the H2 features were excited in a magneto-centrifugal disk wind. [FeII] emission was detected in only one source, M 1-92. The H2 and [FeII] observations of M 1-92, and the complex H2 profiles in IRAS 21282+5050, are explained using the shock models of Smith and collaborators. J-type bow models are adequate in each case, i.e. a strongly-magnetised wind is not required. Finally, Br-gamma is detected in each of the five targets; in absorption in the G-type PPN though in emission in the O and B-type sources. Br-gamma emission is detected predominantly toward the near-IR continuum peak in each PPN. Low peak velocities, though very broad profile widths, are measured in each target. The emission must therefore derive from ionised regions in a fast wind very close to the central star, or, in the late-type sources, from absorption in an equatorial torus., Comment: 17 pages, 13 figures

In an imaging polarimetry survey of candidate post-AGB stars, scattering envelopes are detected around 20 objects. These envelopes represent the final mass-loss phases at the end of the AGB. In all cases, evidence for axisymmetry in the dust density is seen, suggesting that the presence of an axisymmetric outflow may be a ubiquitous phenomenon of the AGB to post-AGB transition. We use the polarized flux images to classify the objects into detached shell, bipolar and unresolved targets. Modelling based on a simple axisymmetric shell geometry supports the contention that post-AGB objects fall into one of two classes that differ in the amount of dust in the circumstellar environment: the detached shells correspond to stars with an optically thin expanding circumstellar envelope (CSE) whereas the bipolar and unresolved targets have optically thick dust structures, probably in the form of discs, which remain bound to the star, rather than partaking in the expansion of the AGB CSE. It is suggested that this bifurcation in morphology is rooted in the presence or absence of a binary companion, which determines whether or not a disc forms. Because the detached shell objects also appear axisymmetric, an additional mechanism for generating the axisymmetry, such as a magnetically shaped outflow, is needed if they do indeed have single star progenitors.

We present 10 and 20 micron images of IRAS 19500-1709 taken with the mid-infrared camera, OSCIR, mounted on the Gemini North Telescope. An extended circumstellar envelope is detected, with the N band image indicating an elongation in a NE-SW direction. We use a dust radiation transport code to fit the spectral energy distribution from UV to sub-mm wavelengths, with a detached dust shell model. A good fit is achieved using dust composed of amorphous carbon, silicon carbide and magnesium sulphide. We derive estimates for the inner and outer radius, density and mass of the dust in the shell. The inner radius is not resolved in our OSCIR imaging, giving an upper limit of 0.4 arcsec. With this constraint, we conclude that IRAS 19500-1709 must be at least 4 kpc away in order to have the minimum luminosity consistent with a post-AGB status., 5 pages, 2 figures, accepted for publication in MNRAS

We present the third in a series of results from our programme of the detection and measurement of magnetic fields in protoplanetary nebulae (PPN), using full-polarization MERLIN observations of OH masers. These are the first maps of the OH 1612- and 1667-MHz masing emission from IRAS 20406+2953. We have identified a Zeeman pair in the 1612-MHz data; this result heralds the second magnetic field strength measured in-a PPN. We show that the field, of strength -3.1 mG, is sufficiently strong to be shaping the outflowing mass from the star. By considering the spatial distribution of the masers and the structure of the linear polarization data, we suggest a field configuration that is toroidal. The observed change in polarization position angle between the peak red- and blueshifted components of the maser features, if attributed to Faraday rotation within the circumstellar envelope, gives an electron density of ∼1 cm -3 . We show that this is sufficient to freeze the field into the outflowing wind.

We report the diminution of the 1667-MHz OH maser in the post-asymptotic giant branch star IRAS 17436 + 5003, by a factor of greater than or similar to 17 over a period of less than or similar to 12 yr, from observations with MERLIN. This circumstellar maser was detected by Likkel in 1987, at the 13sigma level of her observations with the Green Bank Telescope. We discuss a number of possible reasons for this phenomenon and conclude that it is most likely due to turbulence arising from interacting stellar winds.

We present mid-infrared (IR) images of HD 161796 (IRAS 17436+5003), taken with the OSCIR imager on the Gemini North Telescope, that resolve for the first time the thermal emission structure of the dust shell around this post-asymptotic giant branch (AGB) star. As well as a basic axisymmetric structure, the observations show deviations from axisymmetry in the dust density and a twist in the symmetry axis. Modelling of the mid-IR images and of the spectral energy distribution from ultraviolet to submillimetre wavelengths reproduces all of the axisymmetric features with an equator-to-pole density contrast of 6: 1 and an inclination of the symmetry axis of 10° to the plane of the sky. We find that a model incorporating small (0.01μm) grains and a steep (α a - 6 ) power-law size distribution can successfully account for the thermal emission and for the observed degrees of near-IR polarization. Assuming a distance of 1.2 kpc to HD 161796, the stellar luminosity is 3.4 x 10 3 L O . and the mass of the shell is ∼0.7 M O .. This is consistent with a star of initial mass between 1 and 2 M O . that has undergone an intensive (2.2 x 10 - 4 M O . yr - 1 ) phase of mass loss lasting about 3000 yr at the end of the AGB. A current stellar mass of 0.56 M O ., as indicated by the luminosity, suggests that HD 161796 is a few hundred years into its post-AGB evolution and will take about 5000 yr to evolve from its present temperature of 7500 K to become the central star of an extended elliptical planetary nebula.

‘The definitive version is available at www.blackwell-synergy.com '. Copyright Royal Astronomical Society. DOI: 10.1046/j.1365-8711.2003.06071.x [Full text of this article is not available in the UHRA]

‘The definitive version is available at www.blackwell-synergy.com '. Copyright Royal Astronomical Society. DOI: 10.1046/j.1365-8711.2002.05550.x [Full text of this article is not available in the UHRA]

‘The definitive version is available at www.blackwell-synergy.com '. Copyright Royal Astronautical Society. DOI: 10.1046/j.1365-8711.2001.04886.x [Full text of this article is not available in the UHRA]

We have used the technique of spectro-astrometry to study the milli-arcsecond scale structure of the emission lines in the T Tauri star RU Lupi. The wings of the H-alpha emission are found to be displaced from the star towards the south-west (blue wing) and north-east (red wing) with angular scales of 20-30 milli-arcsecs. This structure is consistent with a bipolar outflow from the star. From a study of the variability of the intensity and position spectra we argue that a combination of magnetically-driven bipolar outflow and accreting gas contribute to the H-alpha emission. On the other hand, the [OI] and [SII] emission are displaced from the star to the south-west but at much larger distances than the H-alpha, hundreds of milli-arcsecs for the high-velocity component (HVC) and down to 30 milli-arcsecs for the low-velocity components (LVC). The presence of both red-shifted and blue-shifted outflows in H-alpha but only a blue-shifted outflow in the forbidden lines can be explained if the disc obscures the red-shifted forbidden line outflow, but a disc gap with outer radius 3-4 au allows the red-shifted H-alpha to be seen. This gap could be induced by an unseen companion., Comment: accepted for publication in MNRAS

We use ground-based imaging polarimetry to detect and image the dusty circumstellar envelopes of a sample of proto-planetary nebulae (PPNe) at near-infrared wavelengths. We detect extended (up to 9 arcsec diameter) circumstellar envelopes around 15 out of 16 sources with a range of morphologies including bipolars and shells. The distribution of scattered light in combination with its polarization (up to 40 per cent) provides unambiguous evidence for axisymmetry in 14 objects showing this to be a common trait of PPNe. We suggest that the range of observed envelope morphologies results from the development of an axisymmetric dust distribution during the superwind phase at the end of the AGB. We identify shells seen in polarized light with scattering from these superwind dust distributions which allows us to provide constraints on the duration of the superwind phase. In one object (IRAS 19475+3119) the circumstellar envelope has a two-armed spiral structure which we suggest results from the interaction of the mass losing star with a binary companion., 25 pages (two column format) and 16 figures. Accepted by MNRAS

ABSTRA C T Large degrees of circular polarization at near-infrared wavelengths have been reported in the OMC1 star-forming region. This discovery, in combination with compelling evidence for the existence of non-spherical aligned grains in star formation regions, has prompted us to investigate scattering from spheroidal particles as a possible mechanism for the production of large circular polarization in reflection nebulae. We use a dipole calculation to model the small particle limit and a T-matrix code to treat arbitrarily sized particles. We find that size distributions of perfectly aligned spheroids, with only modest 2:1 axis ratios, are capable of producing circular polarization of up to 50 per cent when scattering unpolarized incident light. This is the case even for dielectric materials, such as ‘astronomical silicate’, as long as sufficient large particles are included in the size distribution. We consider the effects of particle alignment and find that spinning oblate spheroids should be much more efficient circular polarizers than equivalent prolate spheroids.

We present the first imaging circular polarimetry of the Orion Molecular Cloud, OMC-1. The observations, taken in the J, H, Kn and nbL bands, reveal a complex pattern of circular polarization. Globally, there is a background circular polarization of the order of ±2 per cent in the Kn band, conforming to the typical quadrupolar patterns that have been observed in other outflow sources. Overlying this pattern are regions of relatively high degrees of circular polarization to the east and west of the source IRc2, with degrees as high as +17 per cent in the Kn band, the highest circular polarization yet measured for any young stellar object. No circular polarization is seen in the J band, indicating that the circular polarization detected at longer wavelengths originates from within OMC-1 and not from scattering off the foreground ionization front associated with the M42 nebula. We demonstrate a correlation between these patches of high circular polarization and regions of enhanced linear polarization, and argue that these observations are best explained using a model that incorporates scattering of radiation off oblate grains, which have been aligned by the local magnetic field. Modelling of the ellipticity (the ratio of circular to linear polarization) suggests that the grains are composed of silicate and/or organic refractory material, and that grains larger than are typically found in the interstellar medium are needed. The lower, background, circular polarization is produced by scattering off randomly oriented grains in the outflow cavities, the grain alignment being destroyed by the passage of shocks. We put forward a morphological model for OMC-1 which has the regions of high polarization separate from, but near to, the main outflow region. Those regions exhibiting high polarization must somehow have a direct view of the illuminating source of the nebula. Implications of this work to the origins of life are briefly discussed.

We present broad-band, near-infrared (IHKn) imaging linear polarimetry of the young stellar object GSS 30. The overall polarization pattern is centrosymmetric about the illuminating source, IRS 1. The model by Clark & McCall is used to derive the wavelength dependence of the degrees of polarization of the scattered radiation in the nebula. The results suggest that the axis of the nebula is inclined at an angle of - 25°-30° to the plane of the sky, with the northern lobe towards us. The grain size distribution is best fitted by grains covering the range 0.005 to 0.35 ~m. However, the model cannot reproduce the observed polarization pattern across the nebula, which is seen to decrease towards its edge. A polarization disc, i.e. a band of aligned polarization vectors, is seen close to the source. This pattern breaks down to the east of the source where the polarization pattern reverts back to a centro symmetric one. We speculate that a binary system could disrupt the density gradient across the circumstellar disc such that photons can easily escape in this direction and are then scattered (singly) towards us. To the west of the source the pattern of the polarization disc remains intact. The degrees of polarization, both in the line of sight to the source and along the disc, are higher at I and H than they are at Kn. We propose that the wavelength dependence of the polarization here may be produced by a combination of scattering and dichroism, with the grains aligned by a magnetic field parallel to the plane of the disc.

We present linear and circular imaging polarimetry observations of the Chamaeleon Infrared Nebula, a bipolar reflection nebula in the Chamaeleon I dark cloud, at near infrared (JHKn) wavelengths. The detection of both high degrees of linear polarisation and a significant degree of circular polarisation in the extended nebulosity allows us to comment on the scattering geometry and the range of particle sizes present.

Some evolved stars in the pre-planetary nebula phase produce highly-collimated molecular outflows that resemble the accretion-driven jets and outflows from pre-main sequence stars. We show that IRAS 16342-3814 (the Water Fountain Nebula) is such an object and present K-band integral field spectroscopy revealing a fast (> 150 km/s) bipolar H2 outflow. The H2 emission is shock excited and may arise in fast-moving clumps, accelerated by the previously observed precessing jet. The total luminosity in H2 is 0.37 L$_{\odot}$ which is comparable with that of accretion-powered outflows from Class 0 protostars. We also detect CO overtone bandhead emission in the scattered continuum, indicating hot molecular gas close to the centre, a feature also observed in a number of protostars with active jets. It seems likely that the jet and outflow in IRAS 16342-3814 are powered by accretion onto a binary companion.

In a companion work (Paper I) we detected a large population of highly variable Young Stellar Objects (YSOs) in the Vista Variables in the Via Lactea (VVV) survey, typically with class I or flat spectrum spectral energy distributions and diverse light curve types. Here we present infrared spectra (0.9--2.5 $\mu$m) of 37 of these variables, many of them observed in a bright state. The spectra confirm that 15/18 sources with eruptive light curves have signatures of a high accretion rate, either showing EXor-like emission features ($\Delta$v=2 CO, Br$\gamma$) and/or FUor-like features ($\Delta$v=2 CO and H$_{2}$O strongly in absorption). Similar features were seen in some long term periodic YSOs and faders but not in dippers or short-term variables. The sample includes some dusty Mira variables (typically distinguished by smooth Mira-like light curves), 2 cataclysmic variables and a carbon star. In total we have added 19 new objects to the broad class of eruptive variable YSOs with episodic accretion. Eruptive variable YSOs in our sample that were observed at bright states show higher accretion luminosities than the rest of the sample. Most of the eruptive variables differ from the established FUor and EXor subclasses, showing intermediate outburst durations and a mixture of their spectroscopic characteristics. This is in line with a small number of other recent discoveries. Since these previously atypical objects are now the majority amongst embedded members of the class, we propose a new classification for them as MNors. This term (pronounced emnor) follows V1647 Ori, the illuminating star of McNeil's Nebula., Comment: Accepted for publication in MNRAS, 71 pages, 47 figures