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We demonstrate structure functions, long-standing tools in extra-galactic astronomy, which have been recently applied to studies of young stellar objects. They can characterise the variability in time-series data in a way that doesn’t rely on periodicity. We use structure functions to investigate the light curves of Class II YSOs in the star forming region NGC 2264., {"references":["Sergison, D. et al. (2020), Monthly Notices of the Royal Astronomical Society, Volume 491, Issue 4, p.5035-5055","Venuti, L. et al. (2021), The Astronomical Journal, Volume 162, Issue 3, id.101, 27 pp","Lakeland, B. & Naylor, T. (2022) Monthly Notices of the Royal Astronomical Society, Volume 514, Issue 2, pp.2736-2755"]}

We present a description of A dual-Beam pOlarimetric Robotic Aperture for the Sun (ABORAS), to serve as a Solar input with a dedicated Stokes V polarimeter for the HARPS3 high-resolution spectrograph. ABORAS has three main science drivers: trying to understand the physics behind stellar variability, tracking the long-term stability of HARPS3, and serve as a benchmark for Earth-sized exoplanet detection with HARPS3 by injecting an Earth RV signal into the data. By design, ABORAS will (together with the HARPS3 instrument) be able to measure 10cm/s variations in RV of the integrated Solar disk and detect integrated magnetic field levels at sub 1 Gauss level through circularly polarized light., 8 pages, 5 figures, SPIE Proceedings pre-print, draft version 2

We present an i-band photometric study of over 800 young stellar objects in the OB association Cep OB3b, which samples time-scales from one minute to 10 yr. Using structure functions we show that on all time-scales (τ) there is a monotonic decrease in variability from Class I to Class II through the transition disc (TD) systems to Class III, i.e. the more evolved systems are less variable. The Class Is show an approximately power-law increase (τ0.8) in variability from time-scales of a few minutes to 10 yr. The Class II, TDs, and Class III systems show a qualitatively different behaviour with most showing a power-law increase in variability up to a time-scale corresponding to the rotational period of the star, with little additional variability beyond that time-scale. However, about a third of the Class IIs shows lower overall variability, but their variability is still increasing at 10 yr. This behaviour can be explained if all Class IIs have two primary components to their variability. The first is an underlying roughly power-law variability spectrum, which evidence from the infrared suggests is driven by accretion rate changes. The second component is approximately sinusoidal and results from the rotation of the star. We suggest that the systems with dominant longer time-scale variability have a smaller rotational modulation either because they are seen at low inclinations or have more complex magnetic field geometries. We derive a new way of calculating structure functions for large simulated data sets (the ‘fast structure function’), based on fast Fourier transforms.

The overwhelming majority of objects visible to LSST lie within the Galactic Plane. Though many previous surveys have avoided this region for fear of stellar crowding, LSST's spatial resolution combined with its state-of-the-art Difference Image Analysis mean that it can conduct a high cadence survey of most of the Galaxy for the first time. Here we outline the many areas of science that would greatly benefit from an LSST survey that included the Galactic Plane, Magellanic Clouds and Bulge at a cadence of 2-3 d. Particular highlights include measuring the mass spectrum of black holes, and mapping the population of exoplanets in the Galaxy in relation to variations in star forming environments. But the same survey data will provide a goldmine for a wide range of science, and we explore possible survey strategies which maximize the scientific return for a number of fields including young stellar objects, cataclysmic variables and Neptune Trojans., Comment: White Paper submitted in response to the 2018 call for LSST cadence proposals

We have developed a new method to detect starspots on the surface of the secondary star in cataclysmic variables. We demonstrate that it is a good method, by deducing the host star spectral type, the temperature and percentage coverage of spots, of two U Gem type dwarf novae; SS Cyg and V426 Oph. We support this detection through examining two known spotted stars. This is the first detection of starspots on the cool secondary star in cataclysmic variables and it supports magnetic braking as a method by which such systems evolve.

An introduction is given to the fields of X-ray and cataclysmic binaries, low mass X-ray binaries (LMXBs) and globular clusters. New observations of the W Vir star AC5 (=V86) are used show that it is probably the source of Hα emission previous authors have found in core of the globular cluster M15. The first phase resolved optical spectroscopy of AC211, the optical counterpart of the X-ray source in M15, are presented, and its binary period discovered to be 9.l±0.5 hours. A re-analysis of archive ultraviolet (UV) spectra of M15, shows spectral features which are attributed to AC211. These observations are combined with those of other authors, to prove AC211 is probably an "accretion disc corona" (ADC) source. After reviewing the superoutbursts of the SU UMa class of dwarf novae, X-ray, UV, optical and infrared observations of the SU UMa star OY Car are used to show that during superoutburst there is extensive vertical structure in its accretion disc, similar to that in the ADC and "dipping" LMXBs. Archive UV data from the 1978 outburst of WZ Sge shows that it had similar vertical structure. UV observations presented of EX Hya during a bright outburst may have the same explanation. From the OY Car data, a temperature and area for the region which produces the "superhump" light are derived, of 8 OOOK and -1020cm2, respectively. It is found that during OY Car's superoutburst, the size of the 0-C variations of the eclipse timings are significantly smaller than was previously thought, and that it has an extended X-ray source whose size is comparable to the binary separation. The results are discussed with respect to models of the superhump phenomena in SU UMa stars, and possible causes of vertical disc structure in X-ray and cataclysmic binaries.

This thesis develops a theory of international social closure to examine (i) the politics of membership in status groups – or, clubs – in international society and (ii) the persistence of clubs in international society. This thesis offers new concepts to improve the English School’s understanding of international society, its expansion, and its reproduction. In so doing it also addresses limitations and gaps in the IR status literature and the global governance and diplomacy literatures concerned with clubs and networks. This thesis analyses strategies of exclusion, entry, and incorporation used by actors to deny, attempt, or grant inclusion into clubs as well as the institutional contexts underpinning those clubs. Specifically, this research undertakes a study of instances of exclusion, entry, and incorporation in the context of three clubs: the Family of Civilised Nations, the Great Powers club, and G-summitry. In the first two cases, this research relies primarily on secondary sources while in the case of G-summitry it presents original empirical research gathered through archival research, interviews, and ethnographic participant observation. This thesis presents four main conclusions about the operation of closure: (i) the logics of different closure games are defined by overarching normative institutions of international society; (ii) despite a collectivist closure rule, closure in international society is predominantly individualistic; (iii) actors seeking entry tend to employ deferential entry strategies that reproduce a stratified status quo order; and (iv) incorporation promotes stratification along both functional and cultural lines. This thesis also draws three specific conclusions that run counter to much current scholarship: (i) contemporary international society is neither more open nor less hierarchical than nineteenth century international society; (ii) hierarchy is reproduced to a large degree by entry and incorporation strategies rather than exclusion strategies; and (iii) closure does not run along a ‘west versus the rest’ fault line.

In our Galaxy, star formation occurs in a variety of environments, with a large fraction of stars formed in clusters hosting massive stars. OB stars have an important feedback on the evolution of protoplanetary disks around nearby young stars and likely on the process of planet formation occurring in them. The nearby massive association Cygnus OB2 is an outstanding laboratory to study this feedback. It is the closest massive association to our Sun, and hosts hundreds of massive stars and thousands of low mass members. In this paper, we analyze the spatial variation of the disk fraction in Cygnus OB2 and we study its correlation with the local values of Far and Extreme ultraviolet radiation fields and the local stellar surface density. We present definitive evidence that disks are more rapidly dissipated in the regions of the association characterized by intense local UV field and large stellar density. In particular, the FUV radiation dominates disks dissipation timescales in the proximity (i.e. within 0.5 pc) of the O stars. In the rest of the association, EUV photons potentially induce a significant mass loss from the irradiated disks across the entire association, but the efficiency of this process is reduced at increasing distances from the massive stars due to absorption by the intervening intracluster material. We find that disk dissipation due to close stellar encounters is negligible in Cygnus OB2, and likely to have affected 1% or fewer of the stellar population. Disk dissipation is instead dominated by photoevaporation. We also compare our results to what has been found in other young clusters with different massive populations, concluding that massive associations like Cygnus OB2 are potentially hostile to protoplanetary disks, but that the environments where disks can safely evolve in planetary systems are likely quite common in our Galaxy., Accepted for publication in ApJS as part of the special issue on the Chandra Cygnus OB2 Legacy Project

The young massive OB association Cygnus OB2, in the Cygnus X complex, is the closest (1400 pc) star forming region to the Sun hosting thousands of young low mass stars and up to 1000 OB stars, among which are some of the most massive stars known in our Galaxy. This region holds great importance for several fields of modern astrophysics, such as the study of the physical properties of massive and young low-mass stars and the feedback provided by massive stars on star and planet formation process. Cygnus OB2 has been recently observed with Chandra/ACIS-I as part of the 1.08Msec Chandra Cygnus OB2 Legacy Project. This survey detected 7924 X-ray sources in a square degree area centered on Cyg OB2. Since a proper classification and study of the observed X-ray sources also requires the analysis of their optical and infrared counterparts, we combined a large and deep set of optical and infrared catalogs available for this region with our new X-ray catalog. In this paper we describe the matching procedure and present the combined catalog containing 5703 sources. We also briefly discuss the nature of the X-ray sources with optical and infrared counterparts using their position in the color-magnitude and color-color diagrams., Comment: Matched catalog can be provided by the authors; Accepted for publication by ApJ

Archival data on permanent superhump systems are compiled to test the thermal stability of their accretion discs. We find that their discs are almost certainly thermally stable as expected. This result confirms Osaki's suggestion (1996) that permanent superhump systems form a new subclass of cataclysmic variables (CVs), with relatively short orbital periods and high mass transfer rates. We note that if the high accretion rates estimated in permanent superhump systems represent their mean secular values, then their mass transfer rates cannot be explained by gravitational radiation, therefore, either magnetic braking should be extrapolated to systems below the period gap or they must have mass transfer cycles. Alternatively, a new mechanism that removes angular momentum from CVs below the gap should be invoked. We suggest applying the nova cycle scenarios offered for systems above the period gap to the short orbital period CVs. Permanent superhumps have been observed in the two non-magnetic ex-novae with binary periods below the gap. Their post-nova magnitudes are brighter than their pre-outburst values. In one case (V1974 Cyg) it has been demonstrated that the pre-nova should have been a regular SU UMa system. Thus it is the first nova whose accretion disc was observed to change its thermal stability. If the superhumps in this system indicate persistent high mass transfer rates rather than a temporary change induced by irradiation from the hot post-nova white dwarf, it is the first direct evidence for mass transfer cycles in CVs. The proposed cycles are driven by the nova eruption., 7 pages, 2 eps. figures, Latex, accepted for publication in MNRAS

In this Letter, we analyse the distributions of stellar ages in Giant Molecular Clouds (GMCs) in spiral arms, inter-arm spurs, and at large galactic radii, where the spiral arms are relatively weak. We use the results of numerical simulations of galaxies, which follow the evolution of GMCs and include star particles where star formation events occur. We find that GMCs in spiral arms tend to have predominantly young (< 10 Myr) stars. By contrast, clouds which are the remainders of spiral arm GMAs that have been sheared into inter-arm GMCs, contain fewer young (< 10 Myr) stars, and more ~20 Myr stars. We also show that clouds which form in the absence of spiral arms, due to local gravitational and thermal instabilities, contain preferentially young stars. We propose the age distributions of stars in GMCs will be a useful diagnostic to test different cloud evolution scenarios, the origin of spiral arms, and the success of numerical models of galactic star formation. We discuss the implications of our results in the context of Galactic and extragalactic molecular clouds., 5 pages, 2 figures, accepted for publication in MNRAS Letters

We present a critical assessment of commonly used pre-main-sequence isochrones by comparing their predictions to a set of well-calibrated colour-magnitude diagrams of the Pleiades in the wavelength range 0.4 to 2.5 microns. Our analysis shows that for temperatures less than 4000 K the models systematically overestimate the flux by a factor two at 0.5 microns, though this decreases with wavelength, becoming negligible at 2.2 microns. In optical colours this will result in the ages for stars younger than 10 Myr being underestimated by factors between two and three. We show that using observations of standard stars to transform the data into a standard system can introduce significant errors in the positioning of pre-main-sequences in colour-magnitude diagrams. Therefore we have compared the models to the data in the natural photometric system in which the observations were taken. Thus we have constructed and tested a model of the system responses for the Wide-Field Camera on the Isaac Newton Telescope. As a benchmark test for the development of pre-main-sequence models we provide both our system responses and the Pleiades sequence., Comment: 15 pages, 12 figures, 7 tables, accepted for publication in MNRAS. All tables are available online at the Cluster Collaboration homepage http://www.astro.ex.ac.uk/people/timn/Catalogues/

Accepted: 1994-01-14, 資料番号: SA1001960000

The wide luminosity dispersion seen for stars at a given effective temperature in the H-R diagrams of young clusters and star forming regions is often interpreted as due to significant (~10 Myr) spreads in stellar contraction age. In the scenario where most stars are born with circumstellar discs, and that disc signatures decay monotonically (on average) over timescales of only a few Myr, then any such age spread should lead to clear differences in the age distributions of stars with and without discs. We have investigated large samples of stars in the Orion Nebula Cluster (ONC) using three methods to diagnose disc presence from infrared measurements. We find no significant difference in the mean ages or age distributions of stars with and without discs, consistent with expectations for a coeval population. Using a simple quantitative model we show that any real age spread must be smaller than the median disc lifetime. For a log-normal age distribution, there is an upper limit of, To appear in MNRAS, 13 pages

Context. The new VISual and Infrared Telescope for Astronomy (VISTA) has started operations. Over its first five years it will be collecting data for six public surveys, one of which is the near-infrared YJK(s) VISTA survey of the Magellanic Clouds system (VMC). This survey comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud, the Magellanic Bridge connecting the two galaxies and two fields in the Magellanic Stream. Aims. This paper provides an overview of the VMC survey strategy and presents first science results. The main goals of the VMC survey are the determination of the spatially-resolved star-formation history and the three-dimensional structure of the Magellanic system. The VMC survey is therefore designed to reach stars as faint as the oldest main sequence turn-off point and to constrain the mean magnitude of pulsating variables such as RR Lyrae stars and Cepheids. This paper focuses on observations of VMC fields in the LMC obtained between November 2009 and March 2010. These observations correspond to a completeness of 7% of the planned LMC fields. Methods. The VMC data are comprised of multi-epoch observations which are executed following specific time constraints. The data were reduced using the VISTA Data Flow System pipeline with source catalogues, including astrometric and photometric corrections, produced and made available via the VISTA Science Archive. The VMC data will be released to the astronomical community following the European Southern Observatorys Public Survey policy. The analysis of the data shows that the sensitivity in each wave band agrees with expectations. Uncertainties and completeness of the data are also derived. Results. The first science results, aimed at assessing the scientific quality of the VMC data, include an overview of the distribution of stars in colour-magnitude and colour-colour diagrams, the detection of planetary nebulae and stellar clusters, and the K-s band light-curves of variable stars. Conclusions. The VMC survey represents a tremendous improvement, in spatial resolution and sensitivity, on previous panoramic observations of the Magellanic system in the near-infrared, providing a powerful complement to deep observations at other wavelengths.

We present a photometric study of I-band variability in the young association Cepheus OB3b. The study is sensitive to periodic variability on timescales of less than a day, to more than 20 days. After rejection of contaminating objects using V, I, R and narrowband H-alpha photometry, we find 475 objects with measured rotation periods, which are very likely pre-main-sequence members of the Cep OB3b star forming region. We revise the distance and age to Cep OB3b, putting it on the self-consistent age and distance ladder of Mayne & Naylor (2008). This yields a distance modulus of 8.8 +/- 0.2 mags, corresponding to a distance of 580 +/- 60 pc, and an age of 4-5Myrs. The rotation period distribution confirms the general picture of rotational evolution in young stars, exhibiting both the correlation between accretion (determined in this case through narrowband H-alpha photometry) and rotation expected from disc locking, and the dependence of rotation upon mass that is seen in other star forming regions. However, this mass dependence is much weaker in our data than found in other studies. Comparison to the similarly aged NGC 2362 shows that the low-mass stars in Cep OB3b are rotating much more slowly. This points to a possible link between star forming environment and rotation properties. Such a link would call into question models of stellar angular momentum evolution, which assume that the rotational period distributions of young clusters and associations can be assembled into an evolutionary sequence, thus ignoring environmental effects., accepted for publication in MNRAS

It is thought that the first generations of massive stars in the Universe were an important, and quite possibly dominant, source of the ultra-violet radiation that reionized the hydrogen gas in the intergalactic medium (IGM); a state in which it has remained to the present day. Measurements of cosmic microwave background anisotropies suggest that this phase-change largely took place in the redshift range z=10.8 +/- 1.4, while observations of quasars and Lyman-alpha galaxies have shown that the process was essentially completed by z=6. However, the detailed history of reionization, and characteristics of the stars and proto-galaxies that drove it, remain unknown. Further progress in understanding requires direct observations of the sources of ultra-violet radiation in the era of reionization, and mapping the evolution of the neutral hydrogen fraction through time. The detection of galaxies at such redshifts is highly challenging, due to their intrinsic faintness and high luminosity distance, whilst bright quasars appear to be rare beyond z~7. Here we report the discovery of a gamma-ray burst, GRB 090423, at redshift z=8.26 -0.08 +0.07. This is well beyond the redshift of the most distant spectroscopically confirmed galaxy (z=6.96) and quasar (z=6.43). It establishes that massive stars were being produced, and dying as GRBs, ~625 million years after the Big Bang. In addition, the accurate position of the burst pinpoints the location of the most distant galaxy known to date. Larger samples of GRBs beyond z~7 will constrain the evolving rate of star formation in the early universe, while rapid spectroscopy of their afterglows will allow direct exploration of the progress of reionization with cosmic time., Comment: Submitted to Nature

Proceedings of the Cambridge Antiquarian Society, 4 (1), 3-6

We have used RCIC CCD photometry from the Isaac Newton telescope and intermediate-resolution spectroscopy from the Gemini North telescope to identify and characterize low-mass (0.15 < M/M⊙ < 1.3) pre-main-sequence stars in the young open cluster NGC 2169. Isochrone fitting to the high- and low-mass populations yields an intrinsic distance modulus of 10.13+0.06−0.09 mag and a model-dependent age of 9 ± 2 Myr. Compared to the nearby, kinematically defined groups of a similar age, NGC 2169 has a large low-mass population which potentially offers a more precise statistical investigation of several aspects of star formation and early stellar evolution. By modelling the distribution of low-mass stars in the IC versus RC−IC diagram, we find that any age spread among cluster members has a Gaussian full width at half-maximum (FWHM) ≤ 2.5 Myr. A young age and a small age spread (

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We have selected pre-main-sequence stars in 12 groups of notional ages ranging from 1 Myr to 35 Myrs, using heterogeneous membership criteria. Using these members we have constructed empirical isochrones in V, V-I colour magnitude diagrams (CMDs). This allows us to identify clearly the gap between the radiative main sequence and the convective pre-main-sequence (the R-C gap). We follow the evolution of this gap with age and show that it can be a useful age indicator for groups less than ~15 Myrs old. We also observe a reduction in absolute spreads about the sequences with age. Finally the empirical isochrones allow us to place the groups in order of age, independently of theory. The youngest groups can be collated into three sets of similar ages. The youngest set is the ONC, NGC6530 and IC5146 (nominally 1 Myrs); next Cep OB3b, NGC2362, Lambda Ori and NGC2264 (nominally 3 Myrs); and finally Sigma Ori and IC348 (nominally 4-5 Myrs). This suggests Cep OB3b is younger than previously thought, and IC348 older. For IC348 the stellar rotation rate distribution and fraction of stars with discs imply a younger age than we derive. We suggest this is because of the absence of O-stars in this cluster, whose winds and/or ionising radiation may be an important factor in the removal of discs in other clusters., Comment: 24 pages, 35 figures. Accepted to MNRAS. Now the figures display correctly

We have investigated the role of photometric variability in causing the apparent age spreads observed in the colour-magnitude diagrams of OB associations. We have found that the combination of binarity, photometric uncertainty and variability on timescales of a few years is not sufficient to explain the observed spread in either of the OB associations we have studied. Such effects can account for about half the observed spread in the sigma Orionis subgroup and about 1/20 of the observed spread in Cep OB3b. This rules out variability caused by stellar rotation and rotation of structures within inner accretion discs as the source of the majority of the the apparent age spreads. We also find that the variability tends to move objects parallel to isochrones in V/V-i' CMDs, and thus has little influence on apparent age spreads. We conclude that the remaining unexplained spread either reflects a true spread in the ages of the PMS objects or arises as a result of longer term variability associated with changes in accretion flow., Comment: 10 pages, 12 figures. High resolution version with colour is available at http://www.astro.ex.ac.uk/people/bgb/research/ . MNRAS accepted

The globular cluster M15 was observed on three occasions with the High Resolution Camera on board Chandra in 2001 in order to investigate the X-ray source population in the cluster centre. After subtraction of the two bright central sources, four faint sources were identified within 50 arcsec of the core. One of these sources is probably the planetary nebula, K648, making this the first positive detection of X-rays from a planetary nebula inside a globular cluster. Another two are identified with UV variables (one previously known), which we suggest are cataclysmic variables (CVs). The nature of the fourth source is more difficult to ascertain, and we discuss whether it is possibly a quiescent soft X-ray transient (qSXT) or also a CV., 9 pages, 6 figures, accepted for publication in MNRAS. Original figures can be obtained from http://www.astro.helsinki.fi/~diana/M15.html

We present HST UV observations of the high-inclination low mass X-ray binary AC211 (X2127+119), which is located in the globular cluster M15 (NGC 7078). We have discovered a CIV P Cygni profile in this system, which confirms the existence of an outflow from AC211. The outflow velocity as measured from the P Cygni profile is 1500km/s. We calculate that the mass lost through this wind is too small to support a large period derivative as favoured by Homer & Charles (1998). Using new X-ray observations we have revised the ephemeris for AC211 and we find no evidence in support of a period derivative. The UV spectrum exhibits several absorption features due to O, Si and C. The very strong HeII line at 1640A is not seen to modulate strongly with orbital phase, suggesting its origin lies in the outer parts of the system. In contrast, the eclipse of the UV continuum is short compared with the X-ray and optical eclipses., Accepted for Astronomy and Astrophysics. 9 pages and 6 figures

We present optical spectroscopy of 71 photometric candidate low-mass members of the cluster associated with Sigma Orionis. Thirty-five of these are found to pass the lithium test and hence are confirmed as true cluster members, covering a mass range of, To appear in the 12th Cambridge Workshop on Cool Stars Stellar Systems and the Sun

Re-examination of extensive photometric data of TV Col reveals evidence for a permanent positive superhump. Its period (6.4 h) is 16 percent longer than the orbital period and obeys the well known relation between superhump period excess and binary period. At 5.5-h, TV Col has an orbital period longer than any known superhumping cataclysmic variable and, therefore, a mass ratio which might be outside the range at which superhumps can occur according to the current theory. We suggest several solutions for this problem., 5 pages, 2 eps. figures, Latex, proceedings of `Evolution of Binary and Multiple Star Systems', a Meeting in Celebration of Peter Eggleton's 60th Birthday, Bormio, Italy, ASP Conference Series, eds. Ph. Podsiadlowski et al., ASP, San Francisco

We take a critical look at the lithium depletion boundary (LDB) technique that has recently been used to derive the ages of open clusters. We identify the sources of experimental and systematic error and show that the probable errors are larger by approximately a factor two than presently claimed in the literature. We then use the Pleiades LDB age and photometry in combination with evolutionary models to define empirical colour-T_eff relations that can be applied to younger clusters. We find that these relationships DO NOT produce model isochrones that match the younger cluster data. We propose that this is due either to systematic problems in the evolutionary models or an age (gravity) sensitivity in the colour-T_eff relation which is not present in published atmospheric models., 6 pages, to appear in - From Darkness to Light, ASP Conference Series, eds. T. Montmerle and Ph. Andre

We suggest new evolutionary scenarios for non-magnetic short orbital period CVs. The first model is the analogy of the `hibernation scenario' or the `modern hibernation scenario'. The second one is an extension of Mukai and Naylor (1995) ideas. All models imply a tight connection between permanent superhump systems and classical novae. We highlight the significance of the observed evolution of V1974 Cyg, which might pose a major problem to Mukai and Naylor concept., 2 pages, Latex file, 1 .sty file, to appear in "Cataclysmic Variables: a 60th Birthday Symposium in Honour of Brian Warner", held in Oxforf, 12-16/4/99, eds. P. Charles, A. King, D. O'Donoghue, New Astronomy Reviews. also available at: ftp://ftp.astro.keele.ac.uk/pub/preprints/Oxford.html

A method, based on the disc instability model, for testing the thermal stability of Cataclysmic Variables (CVs), is presented. It is shown that the border line between thermal stability and instability is crossed during some nova outbursts and decays, however it is not clear whether this is the general behaviour. We suggest two new evolutionary scenarios for short orbital period CVs. One of them is the analogy for the 'modified hibernation scenario' and the other is an extension of the ideas of Mukai and Naylor (1993) for long orbital period CVs. We conclude that the observations have not favoured one of the two models. Finally, we speculate the existence of a new type of nova - an AM CVn like nova., Comment: 6 pages, Latex, 3 style files, to be published in the proceedings of ''Disk Instabilities in Close Binary Systems'', Kyoto, 27-30/11/98, eds. Mineshige S., Wheeker C., Universal Academy Press

The Gaia-ESO Public Spectroscopic Survey has begun and will obtain high quality spectroscopy of some 100000 Milky Way stars, in the field and in open clusters, down to magnitude 19, systematically covering all the major components of the Milky Way. This survey will provide the first homogeneous overview of the distributions of kinematics and chemical element abundances in the Galaxy. The motivation, organisation and implementation of the Gaia-ESO Survey are described, emphasising the complementarity with the ESA Gaia mission. Spectra from the very first observing run of the survey are presented.

An introduction is given to the fields of X-ray and cataclysmic binaries, low mass X-ray binaries (LMXBs) and globular clusters. New observations of the W Vir star AC5 (=V86) are used show that it is probably the source of Hα emission previous authors have found in core of the globular cluster M15. The first phase resolved optical spectroscopy of AC211, the optical counterpart of the X-ray source in M15, are presented, and its binary period discovered to be 9.l±0.5 hours. A re-analysis of archive ultraviolet (UV) spectra of M15, shows spectral features which are attributed to AC211. These observations are combined with those of other authors, to prove AC211 is probably an "accretion disc corona" (ADC) source. After reviewing the superoutbursts of the SU UMa class of dwarf novae, X-ray, UV, optical and infrared observations of the SU UMa star OY Car are used to show that during superoutburst there is extensive vertical structure in its accretion disc, similar to that in the ADC and "dipping" LMXBs. Archive UV data from the 1978 outburst of WZ Sge shows that it had similar vertical structure. UV observations presented of EX Hya during a bright outburst may have the same explanation. From the OY Car data, a temperature and area for the region which produces the "superhump" light are derived, of 8 OOOK and -1020cm2, respectively. It is found that during OY Car's superoutburst, the size of the 0-C variations of the eclipse timings are significantly smaller than was previously thought, and that it has an extended X-ray source whose size is comparable to the binary separation. The results are discussed with respect to models of the superhump phenomena in SU UMa stars, and possible causes of vertical disc structure in X-ray and cataclysmic binaries.

We present results from a two week multi-longitude photometric campaign on TV Col held in 2001 January. The data confirm the presence of a permanent positive superhump found in re-examination of extensive archive photometric data of TV Col. The 6.3-h period is 15 per cent longer than the orbital period and obeys the well known relation between superhump period excess and binary period. At 5.5-h, TV Col has an orbital period longer than any known superhumping cataclysmic variable and, therefore, a mass ratio which might be outside the range at which superhumps can occur according to the current theory. We suggest several solutions for this problem., Comment: 8 pages, 1 Latex file, 7 eps figures, MNRAS, accepted

We propose a public IR variability survey, named \Vista Variables in the Vía Láctea" (V V V ), of the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high. This would take 1920 hours, covering ~ 109 point sources within an area of 520 sq deg, including 33 known globular clusters and ~ 350 open clusters. The final products will be a deep IR atlas in 5 passbands and a catalogue of ~ 106 variable point sources. These will produce a 3-D map of the surveyed region (unlike single-epoch surveys that only give 2-D maps) using well-understood primary distance indicators such as RR Lyrae stars. It will yield important information on the ages of the populations. The observations will be combined with data from MACHO, OGLE, EROS, VST, SPITZER, HST, CHANDRA, INTEGRAL, and ALMA for a complete understanding of the variable sources in the inner Milky Way. Several important implications for the history of the Milky Way, for globular cluster evolution, for the population census of the bulge and center, and for pulsation theory would follow from this survey.

We propose a public IR variability survey, named "Vista Variables in the Vía Láctea" (V V V ), of the Milky Way bulge and an adjacent section of the mid-plane where star formation activity is high. This would take 1920 hours, covering ̃ 109 point sources within an area of 520 sq deg, including 33 known globular clusters and ̃ 350 open clusters. The final products will be a deep IR atlas in 5 passbands and a catalogue of ̃ 106 variable point sources. These will produce a 3-D map of the surveyed region (unlike single-epoch surveys that only give 2-D maps) using well-understood primary distance indicators such as RR Lyrae stars. It will yield important information on the ages of the populations. The observations will be combined with data from MACHO, OGLE, EROS, VST, SPITZER, HST, CHANDRA, INTEGRAL, and ALMA for a complete understanding of the variable sources in the inner Milky Way. Several important implications for the history of the Milky Way, for globular cluster evolution, for the population census of the bulge and center, and for pulsation theory would follow from this survey.