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WEAVE, the new wide-field, massively multiplexed spectroscopic survey facility for the William Herschel Telescope, will see first light in late 2022. WEAVE comprises a new 2-degree field-of-view prime-focus corrector system, a nearly 1000-multiplex fibre positioner, 20 individually deployable 'mini' integral field units (IFUs), and a single large IFU. These fibre systems feed a dual-beam spectrograph covering the wavelength range 366$-$959\,nm at $R\sim5000$, or two shorter ranges at $R\sim20\,000$. After summarising the design and implementation of WEAVE and its data systems, we present the organisation, science drivers and design of a five- to seven-year programme of eight individual surveys to: (i) study our Galaxy's origins by completing Gaia's phase-space information, providing metallicities to its limiting magnitude for $\sim$3 million stars and detailed abundances for $\sim1.5$ million brighter field and open-cluster stars; (ii) survey $\sim0.4$ million Galactic-plane OBA stars, young stellar objects and nearby gas to understand the evolution of young stars and their environments; (iii) perform an extensive spectral survey of white dwarfs; (iv) survey $\sim400$ neutral-hydrogen-selected galaxies with the IFUs; (v) study properties and kinematics of stellar populations and ionised gas in $z1$ million spectra of LOFAR-selected radio sources; (viii) trace structures using intergalactic/circumgalactic gas at $z>2$. Finally, we describe the WEAVE Operational Rehearsals using the WEAVE Simulator., 41 pages, 27 figures, accepted for publication by MNRAS

Globular clusters (GCs) are dense, gravitationally bound systems of thousands to millions of stars. They are preferentially associated with the oldest components of galaxies, and measurements of their composition can therefore provide insight into the build-up of the chemical elements in galaxies in the early Universe. We report a massive GC in the Andromeda Galaxy (M31) that is extremely depleted in heavy elements. Its iron abundance is about 800 times lower than that of the Sun, and about three times lower than in the most iron-poor GCs previously known. It is also strongly depleted in magnesium. These measurements challenge the notion of a metallicity floor for GCs and theoretical expectations that massive GCs could not have formed at such low metallicities., Comment: Accepted for publication in Science. For supplementary materials, see under ancillary files

The Javalambre Photometric Local Universe Survey (J-PLUS) provides wide field-of-view images in 12 narrow, intermediate and broad-band filters optimized for stellar photometry. Here we have applied J-PLUS data for the first time for the study of Galactic GCs using science verification data obtained for the very metal-poor GC M\,15. Our J-PLUS data provide low-resolution spectral energy distributions covering the near-UV to the near-IR, allowing us to search for MPs based on pseudo-spectral fitting diagnostics. J-PLUS CMDs are found to be particularly useful to search for splits in the sequences formed by the upper red giant branch (RGB) and asymptotic giant branch (AGB) stars. We interpret these split sequences as evidence for the presence of MPs. This demonstrates that the J-PLUS survey will have sufficient spatial coverage and spectral resolution to perform a large statistical study of GCs through multi-band photometry in the coming years., Comment: 11 pages, 11 figures. Accepted for publication @ A&A

We recently found the globular cluster (GC) EXT8 in M31 to have an extremely low metallicity of [Fe/H]=-2.91+/-0.04 using high-resolution spectroscopy. Here we present a colour-magnitude diagram (CMD) for EXT8, obtained with the Wide Field Camera 3 on board the Hubble Space Telescope. Compared with the CMDs of metal-poor Galactic GCs, we find that the upper red giant branch (RGB) of EXT8 is about 0.03 mag bluer in F606W-F814W and slightly steeper, as expected from the low spectroscopic metallicity. The observed colour spread on the upper RGB is consistent with being caused entirely by the measurement uncertainties, and we place an upper limit of sigma(F606W-F814W)=0.015 mag on any intrinsic colour spread. The corresponding metallicity spread can be up to sigma([Fe/H])=0.2 dex or >0.7 dex, depending on the isochrone library adopted. The horizontal branch (HB) is located mostly on the blue side of the instability strip and has a tail extending to at least M(F606W)=+3, as in the Galactic GC M15. We identify two candidate RR Lyrae variables and several UV-luminous post-HB/post AGB star candidates, including one very bright (M(F300X)=-3.2) source near the centre of EXT8. The surface brightness of EXT8 out to a radius of 25 arcsec is well fitted by a Wilson-type profile with an ellipticity of epsilon=0.20, a semi-major axis core radius of 0.25", and a central surface brightness of 15.2 mag per square arcsec in the F606W band, with no evidence of extra-tidal structure. Overall, EXT8 has properties consistent with it being a "normal", but very metal-poor GC, and its combination of relatively high mass and very low metallicity thus remains challenging to explain in the context of GC formation theories operating within the hierarchical galaxy assembly paradigm., Accepted for publication in Astronomy & Astrophysics

Recent work has shown that the properties of multiple populations within massive stellar clusters (i.e., in the extent of their abundance variations as well as the fraction of stars that show the anomalous chemistry) depend on the mass as well as the age of the host cluster. Such correlations are largely unexpected in current models for the formation of multiple populations and hence provide essential insight into their origin. Here we extend or previous study into the presence or absence of multiple populations using integrated light spectroscopy of the $\sim600$~Myr, massive ($\sim10^7 - 10^8$~\msun) clusters, W3 and W30, in the galactic merger remnant, NGC 7252. Due to the extreme mass of both clusters, the expectation is that they should host rather extreme abundance spreads, manifested through, e.g., high mean [Na/Fe] abundances. However, we do not find evidence for a strong [Na/Fe] enhancement, with the observations being consistent with the solar value. This suggests that age is playing a key role, or alternatively that multiple populations only manifest below a certain stellar mass, as the integrated light at all ages above $\sim100$~Myr is dominated by stars near or above the main sequence turn-off., Comment: 7 pages, 7 figures, accepted for publication in MNRAS

We present optical photometric and spectroscopic observations of the likely stellar counterpart to the unassociated \emph{Fermi}-Large Area Telescope (LAT) $\gamma$-ray source 2FGL J0846.0+2820, selected for study based on positional coincidences of optical variables with unassociated LAT sources. Using optical spectroscopy from the SOAR telescope, we have identified a late-G giant in an eccentric ($e$ = 0.06) 8.133 day orbit with an invisible primary. Modeling the spectroscopy and photometry together lead us to infer a heavy neutron star primary of $\sim 2 M_{\odot}$ and a partially stripped giant secondary of $\sim 0.8 M_{\odot}$. H$\alpha$ emission is observed in some of the spectra, perhaps consistent with the presence of a faint accretion disk. We find the $\gamma$-ray flux of 2FGL J0846.0+2820 dropped substantially in mid-2009, accompanied by an increased variation in the optical brightness, and since then it has not been detected by \emph{Fermi}. The long period and giant secondary are reminiscent of the $\gamma$-ray bright binary 1FGL J1417.7--4407, which hosts a millisecond pulsar apparently in the final stages of the pulsar recycling process. The discovery of 2FGL J0846.0+2820 suggests the identification of a new subclass of millisecond pulsar binaries that are the likely progenitors of typical field millisecond pulsars., Comment: 12 pages, 8 figures, 3 tables. Accepted for publication in ApJ

The presence of star-to-star light-element abundance variations (a.k.a. multiple populations, MPs) appears to be ubiquitous within old and massive clusters in the Milky Way and all studied nearby galaxies. Most previous studies have focussed on resolved images or spectroscopy of individual stars, although there has been significant effort in the past few years to look for multiple population signatures in integrated light spectroscopy. If proven feasible, integrated light studies offer a potential way to vastly open parameter space, as clusters out to tens of Mpc can be studied. We use the NaD lines in the integrated spectra of two clusters with similar ages ($2-3$ Gyr) but very different masses, NGC 1978 ($\sim3\times10^5$ Msun) in the LMC and G114 ($1.7\times10^7$ Msun) in NGC 1316. For NGC 1978, our findings agree with resolved studies of individual stars which did not find evidence for Na spreads. However, for G114, we find clear evidence for the presence of multiple populations. The fact that the same anomalous abundance patterns are found in both the intermediate age and ancient GCs lends further support to the notion that young massive clusters are effectively the same as the ancient globular clusters, only separated in age., MNRAS letters, in press (5 pages + appendix)

Stellar populations are powerful tools for investigating the evolution of extragalactic environments. We present the first UV integrated-light spectroscopic observations for 15 young star clusters in the starburst M83 with a special focus on metallicity measurements. The data were obtained with the Cosmic Origins Spectrograph (COS) onboard the Hubble Space Telescope. We analyse the data applying an abundance technique previously used to study an optical set of star clusters. We estimate a central metallicity of [Z] = $+$0.20 $\pm$ 0.15 dex in agreement with those obtained through independent methods, i.e. $J$-band and blue supergiants. We estimate a UV metallicity gradient of $-$0.041 $\pm$ 0.022 dex kpc$^{-1}$ consistent with the optical metallicity gradient of $-$0.040 $\pm$ 0.032 dex kpc$^{-1}$ for $R/R_{25}, Comment: 18 pages, 7 figures, Accepted for Publication in ApJ

We report the confirmation of an old, metal-poor globular cluster in the nearby dwarf irregular galaxy Sextans A, the first globular cluster known in this galaxy. The cluster, which we designate as Sextans A-GC1, lies some 4.4 arcminutes ($\sim1.8$ kpc) to the SW of the galaxy centre and clearly resolves into stars in sub-arcsecond seeing ground-based imaging.We measure an integrated magnitude $V=18.04$, corresponding to an absolute magnitude, $M_{V,0} = -7.85$. This gives an inferred mass $M\sim$1.6$\times10^5~M\odot$, assuming a Kroupa IMF. An integrated spectrum of Sextans A-GC1 reveals a heliocentric radial velocity $v_{\rm helio}=305\pm15$~ km/s, consistent with the systemic velocity of Sextans A. The location of candidate red giant branch stars in the cluster, and stellar population analyses of the cluster's integrated optical spectrum, suggests a metallicity [Fe/H] $\sim$--2.4, and an age $\sim9$ Gyr. We measure a half light radius, $R_h = 7.6\pm0.2$ pc. Normalising to the galaxy integrated magnitude, we obtain a $V$-band specific frequency, $S_N=2.1$. We compile a sample of 1,928 GCs in 28 galaxies with spectroscopic metallicities and find that the low metallicity of Sextans A-GC1 is close to a "metallicity floor" at [Fe/H] $\sim-2.5$ seen in these globular cluster systems which include the Milky Way, M31, M87 and the Large Magellanic Cloud. This metallicity floor appears to hold across 6 dex in host galaxy stellar mass and is seen in galaxies with and without accreted GC subpopulations., 8 pages, 7 figures, 2 tables, accepted for publication in MNRAS after minor revision

We perform a detailed abundance analysis on integrated-light spectra of 20 globular clusters (GCs) in the early-type galaxy NGC 5128 (Centaurus A). The GCs were observed with X-Shooter on the VLT. The cluster sample spans a metallicity range of $-1.92 < $ [Fe/H] $< -0.13$ dex. Using theoretical isochrones we compute synthetic integrated-light spectra and iterate the individual abundances until the best fit to the observations is obtained. We measured abundances of Mg, Ca, and Ti, and find a slightly higher enhancement in NGC 5128 GCs with metallicities [Fe/H] < $-$0.75 dex, of the order of $\sim$0.1 dex, than in the average values observed in the MW for GCs of the same metallicity. If this $\alpha$-enhancement in the metal-poor GCs in NGC 5128 is genuine, it could hint at a chemical enrichment history different than that experienced by the MW. We also measure Na abundances in 9 out of 20 GCs. We find evidence for intra-cluster abundance variations in 6 of these clusters where we see enhanced [Na/Fe] > $+$0.25 dex. We obtain the first abundance measurements of Cr, Mn, and Ni for a sample of the GC population in NGC 5128 and find consistency with the overall trends observed in the MW, with a slight enhancement ($, Comment: 31 pages, 11 Figures, MNRAS accepted

In previous papers, we introduced our method for measuring chemical abundances from integrated-light spectra of globular clusters and applied it to a variety of extragalactic star clusters. Here we extend our analysis technique to the infrared. We simultaneously analyse an optical spectrum of the massive globular cluster G280 in M31, obtained with the HIRES spectrograph on the Keck I telescope, and an H-band spectrum obtained with NIRSPEC on Keck II. We discuss the sensitivity of our results to various modifications of the input assumptions, such as different line lists and isochrones and the possible presence of a metallicity spread in G280. When using the most recent version of the Kurucz line list, we measure iron abundances of [Fe/H]=-0.68+/-0.02 from the optical spectrum and [Fe/H]=-0.60+/-0.07 from the infrared spectrum. These values agree well with previous spectroscopic determinations of the metallicity of G280. While the small difference between the optical and infrared measurements is insignificant given the uncertainties, it is also consistent with a metallicity spread similar to that observed in massive GCs such as Omega Cen and G1, and also hinted at by the colour-magnitude diagram of G280. The optical and infrared spectra both indicate an alpha-enhancement of about 0.3-0.4 dex relative to solar-scaled abundances, as typically also observed in Milky Way GCs. It appears that our integrated-light analysis technique also performs well in the H-band. However, complications due to the presence of molecular bands and telluric contamination are more severe in the infrared, and accurate modelling of the coolest giants is more critical., Accepted for publication in Astronomy & Astrophysics

We discuss some of the key open questions regarding the formation and evolution of globular clusters (GCs) during galaxy formation and assembly within a cosmological framework. The current state-of-the-art for both observations and simulations is described, and we briefly mention directions for future research. The oldest GCs have ages $\ge$ 12.5 Gyr and formed around the time of reionisation. Resolved colour-magnitude diagrams of Milky Way GCs and direct imaging of lensed proto-GCs at z $\sim$ 6 with JWST promise further insight. Globular clusters are known to host multiple populations of stars with variations in their chemical abundances. Recently, such multiple populations have been detected in $\sim$2 Gyr old compact, massive star clusters. This suggests a common, single pathway for the formation of GCs at high and low redshift. The shape of the initial mass function for GCs remains unknown, however for massive galaxies a power-law mass function is favoured. Significant progress has been made recently modelling GC formation in the context of galaxy formation, with success in reproducing many of the observed GC-galaxy scaling relations., Comment: 28 pages, accepted for publication in the Proceedings of the Royal Society A journal. Version 2 with updated references

We present integrated-light spectra of 8 Young Massive Clusters (YMCs) in the metal-rich spiral galaxy NGC 5236 (M 83). The observations were taken with the X-Shooter spectrograph on the ESO Very Large Telescope. Through the use of theoretical isochrones and synthetic integrated-light (IL) spectra we derive metallicities and study the radial metallicity gradient observed through these young populations. For the inner regions of the galaxy we observe a relatively shallow metallicity gradient of $-$0.37 $\pm$0.29 dex R$_{25}^{-1}$, agreeing with chemical evolution models with an absence of infall material and a relatively low mass loss due to winds in the inner parts of the disk. We estimate a central metallicity of [$Z$] = $+$0.17 $\pm$ 0.12 dex, finding excellent agreement with that obtained via other methods (e.g. blue supergiants and J-band). We infer a metallicity of 12+log(O/H) = 8.75 $\pm$ 0.08 dex at R/R$_{25}$ = 0.4, which fits the stellar mass-metallicity relation (MZR) compilation of blue supergiants and IL studies., 13 pages, 10 figures, MNRAS accepted

We test the performance of our analysis technique for integrated-light spectra by applying it to seven well-studied Galactic GCs that span a wide range of metallicities. Integrated-light spectra were obtained by scanning the slit of the UVES spectrograph on the ESO Very Large Telescope across the half-light diameters of the clusters. We modelled the spectra using resolved HST colour-magnitude diagrams (CMDs), as well as theoretical isochrones, in combination with standard stellar atmosphere and spectral synthesis codes. The abundances of Fe, Na, Mg, Ca, Ti, Cr, and Ba were compared with literature data for individual stars in the clusters. The typical differences between iron abundances derived from our integrated-light spectra and those compiled from the literature are less than 0.1 dex. A larger difference is found for one cluster (NGC 6752), and is most likely caused primarily by stochastic fluctuations in the numbers of bright red giants within the scanned area. As expected, the alpha-elements (Ca, Ti) are enhanced by about 0.3 dex compared to the Solar-scaled composition, while the [Cr/Fe] ratios are close to Solar. When using up-to-date line lists, our [Mg/Fe] ratios also agree well with literature data. Our [Na/Fe] ratios are, on average, 0.08-0.14 dex lower than average values quoted in the literature, and our [Ba/Fe] ratios may be overestimated by 0.20-0.35 dex at the lowest metallicities. We find that analyses based on theoretical isochrones give very similar results to those based on resolved CMDs. Overall, the agreement between our integrated-light abundance measurements and the literature data is satisfactory. Refinements of the modelling procedure, such as corrections for stellar evolutionary and non-LTE effects, might further reduce some of the remaining offsets., Comment: 35 pages, 16 figures, accepted for A&A

Intraoperative fluorescent cholangiography is a novel non-invasive imaging technique to visualise the extrahepatic biliary tract during laparoscopic cholecystectomy. It has been proven feasible, fast and cost effective. Never-theless, there is only sparse data on the capacity of fluorescent cholangiography to visualise the biliary anatomy.Based on a non-inferiority design, patients with complicated gallstone disease are randomised to either -intraoperative conventional X-ray cholangiography (reference group, n = 60) or intraoperative fluorescent cholangiography (n = 60). The primary outcome is visualisation of the junction between the cystic duct, the common hepatic duct and the common bile duct.The present study may show that fluorescent cholangiography is as valid for visualisation of important structures of the extrahepatic biliary tract as conventional X-ray cholangiography. This may lead to the introduction of online imaging of the extrahepatic tract during dissection of the gallbladder during cholecystectomy.none.This study was registered with clinicaltrials.gov (No. NCT02344654), with the National Committee on Health Research Ethics (Reg. no. H-15000817) and with the Danish Data Protection Agency (Reg no. AHH- 2015-005).

Background Correct mediastinal staging is a cornerstone in the treatment of patients with non-small cell lung cancer. A large range of methods is available for this purpose, making the process of adequate staging complex. The objective of this study was to describe faults and benefits of positron emission tomography (PET)-CT in multimodality mediastinal staging. Methods A randomised clinical trial was conducted including patients with a verified diagnosis of non-small cell lung cancer, who were considered operable. Patients were assigned to staging with PET-CT (PET-CT group) followed by invasive staging (mediastinoscopy and/or endoscopic ultrasound with fine needle aspiration (EUS-FNA)) or invasive staging without prior PET-CT (conventional work up (CWU) group). Mediastinal involvement (dichotomising N stage into N0–1 versus N2–3) was described according to CT, PET-CT, mediastinoscopy, EUS-FNA and consensus (based on all available information), and compared with the final N stage as verified by thoracotomy or a conclusive invasive diagnostic procedure. Results A total of 189 patients were recruited, 98 in the PET-CT group and 91 in the CWU group. In an intention-to-treat analysis the overall accuracy of the consensus N stage was not significantly higher in the PET-CT group than in the CWU group (90% (95% confidence interval 82% to 95%) vs 85% (95% CI 77% to 91%)). Excluding the patients in whom PET-CT was not performed (n=14) the difference was significant (95% (95% CI 88% to 98%) vs 85% (95% CI 77% to 91%), p=0.034). This was mainly based on a higher sensitivity of the staging approach including PET-CT. Conclusion An approach to lung cancer staging with PET-CT improves discrimination between N0–1 and N2–3. In those without enlarged lymph nodes and a PET-negative mediastinum the patient may proceed directly to surgery. However, enlarged lymph nodes on CT needs confirmation independent of PET findings and a positive finding on PET-CT needs confirmation before a decision on surgery is made. Clinical trial number NCT00867412.

We present new abundance measurements for eleven GCs in the Local Group galaxies NGC 147, NGC 6822, and Messier 33. These are combined with previously published observations of four GCs in the Fornax and WLM galaxies. The abundances were determined from analysis of integrated-light spectra, obtained with HIRES on the Keck I telescope and with UVES on the VLT. We find that the clusters with [Fe/H]-1.5, the GCs in M33 are also alpha-enhanced, while the GCs that belong to dwarfs (NGC 6822 SC7 and Fornax 4) have closer to Solar-scaled alpha-element abundances, thus mimicking the abundance trends observed in field stars in nearby dwarf galaxies. The abundance patterns in SC7 are remarkably similar to those in the Galactic GC Ruprecht 106, including significantly sub-solar [Na/Fe] and [Ni/Fe] ratios. In NGC 147, the GCs with [Fe/H], Comment: Accepted for publication in A&A. Updated Table 5 with metallicities for Hodge II and SD7 determined from continuum shape fitting (Sharina & Davoust 2009). Added comparison with M33 GC metallicities from Beasley et al. (2015)

We present new H-band echelle spectra, obtained with the NIRSPEC spectrograph at Keck II, for the massive star cluster "B" in the nearby dwarf irregular galaxy NGC 1569. From spectral synthesis and equivalent width measurements we obtain abundances and abundance patterns. We derive an Fe abundance of [Fe/H]=-0.63+/-0.08, a super-solar [alpha/Fe] abundance ratio of +0.31+/-0.09, and an O abundance of [O/H]=-0.29+/-0.07. We also measure a low 12C/13C = 5+/-1 isotopic ratio. Using archival imaging from the Advanced Camera for Surveys on board HST, we construct a colour-magnitude diagram (CMD) for the cluster in which we identify about 60 red supergiant (RSG) stars, consistent with the strong RSG features seen in the H-band spectrum. The mean effective temperature of these RSGs, derived from their observed colours and weighted by their estimated H-band luminosities, is 3790 K, in excellent agreement with our spectroscopic estimate of Teff = 3800+/-200 K. From the CMD we derive an age of 15-25 Myr, slightly older than previous estimates based on integrated broad-band colours. We derive a radial velocity of -78+/-3 km/s and a velocity dispersion of 9.6+/-0.3 km/s. In combination with an estimate of the half-light radius of 0.20"+/-0.05" from the HST data, this leads to a dynamical mass of (4.4+/-1.1)E5 Msun. The dynamical mass agrees very well with the mass predicted by simple stellar population models for a cluster of this age and luminosity, assuming a normal stellar IMF. The cluster core radius appears smaller at longer wavelengths, as has previously been found in other extragalactic young star clusters.

We present radial stellar population parameters for a subsample of 12 galaxies from the 36 isolated early-type galaxies of Reda et al. Using new long-slit spectra, central values and radial gradients for the stellar age, metallicity [Z/H] and alpha-element abundance [E/Fe] are measured. Similarly, the central stellar population parameters are derived for a further 5 isolated early-type galaxies using their Lick indices from the literature. On average, the seventeen isolated galaxies have mean central [Z/H]o and [E/Fe]o of 0.29+/-0.03 and 0.17+/-0.03 respectively and span a wide range of ages from 1.7 to 15 Gyrs. We find that isolated galaxies follow similar scaling relations between central stellar population parameters and galaxy velocity dispersion to their counterparts in high density environments. However, we note a tendency for isolated galaxies to have slightly younger ages, higher [Z/H] and lower [E/Fe]. Such properties are qualitatively consistent with the expectation of an extended star formation history for galaxies in lower density environments. Generally we measure constant age and [E/Fe] radial gradients. We find that the age gradients anti-correlate with the central galaxy age. Metallicity gradients range from near zero to strongly negative. For our high mass galaxies metallicity gradients are shallower with increasing mass. Such behaviour is not predicted in dissipational collapse models but might be expected in multiple mergers. The metallicity gradients correlate with the central age and metallicity, as well as to the age gradients. In conclusion, our stellar population data for isolated galaxies are more compatible with an extended merger/accretion history than early dissipative collapse., The paper contains 8 figures and 5 tables. Accepted for publication in the MNRAS

We present a sample of 11 M31 Cepheids in stellar clusters, derived from the overlap of the Panchromatic Hubble Andromeda Treasury (PHAT) cluster catalog and the Pan-STARRS1 (PS1) disk Cepheid catalog. After identifying the PS1 Cepheids in the HST catalog, we calibrate the PS1 mean magnitudes using the higher resolution HST photometry, revealing up to 1 magnitude offsets due to crowding effects in the ground-based catalog. We measure ages of the clusters by performing single stellar population fits to their color-magnitude diagrams (CMDs) excluding their Cepheids. From these cluster age measurements, we derive an empirical period-age relation which agrees well with the existing literature values. By confirming this relation for M31 Cepheids, we justify its application in high-precision pointwise age estimation across M31., 14 pages, 16 figures, accepted by ApJ

We introduce a method to relate a possible truncation of the star cluster mass function at the high mass end to the shape of the cluster luminosity function (LF). We compare the observed LFs of five galaxies containing young star clusters with synthetic cluster population models with varying initial conditions. The LF of the SMC, the LMC and NGC 5236 are characterized by a power-law behavior NdL~L^-a dL, with a mean exponent of = 2.0 +/- 0.2. This can be explained by a cluster population formed with a constant cluster formation rate, in which the maximum cluster mass per logarithmic age bin is determined by the size-of-sample effect and therefore increases with log(age/yr). The LFs of NGC 6946 and M51 are better described by a double power-law distribution or a Schechter function. When a cluster population has a mass function that is truncated below the limit given by the size-of-sample effect, the total LF shows a bend at the magnitude of the maximum mass, with the age of the oldest cluster in the population, typically a few Gyr due to disruption. For NGC 6946 and M51 this implies a maximum mass of M_max = 5*10^5 M_sun. Faint-ward of the bend the LF has the same slope as the underlying initial cluster mass function and bright-ward of the bend it is steeper. This behavior can be well explained by our population model. We compare our results with the only other galaxy for which a bend in the LF has been observed, the ``Antennae'' galaxies (NGC 4038/4039). There the bend occurs brighter than in NGC 6946 and M51, corresponding to a maximum cluster mass of M_max = 2*10^6 M_sun (abridged)., Comment: 18 pages, 17 figures, accepted for publication in Astronomy & Astrophysics

High signal-to-noise, low-resolution spectra have been obtained for 22 globular clusters (GCs) in NGC 4365. Some of these were selected as probable representatives of an intermediate-age (2-5 Gyr), extremely metal-rich GC subpopulation. The presence of such a subpopulation had been inferred from the unusual optical and near-IR color distributions of GCs in this otherwise typical Virgo elliptical galaxy. However, ages derived from Lick indices are consistent with uniformly old mean ages for all GCs in our sample. The metallicities of the clusters show some evidence for a trimodal distribution. The most metal-poor and metal-rich peaks are consistent with the values expected for an elliptical galaxy of this luminosity, but there appears to be an additional, intermediate-metallicity peak lying between them. New Hubble Space Telescope photometry is consistent with this result. A plausible scenario is that in earlier data these three peaks merged into a single broad distribution. Our results suggest that it is difficult to identify intermediate-age GC subpopulations solely with photometry, even when both optical and near-infrared colors are used., Comment: 30 pages, including 11 figures. AJ in press

Trans-esophageal endoscopic ultrasound-guided fine needle aspiration biopsy (EUS-FNA) has proven to be a safe and minimally invasive tissue-sampling method which can be used to obtain a cytological diagnosis from mediastinal lesions. The aims of EUS-FNA in the mediastinum are either to diagnose a lesion of unknown origin, to stage mediastinal lymph nodes in lung cancer patients or to diagnose other diseases involving lymph nodes of the mediastinum. In patients with non-small cell lung cancer (NSCLC), surgery may be regarded as futile in up to 45% of patients operated, apparently because the stage of the disease is more advanced than expected preoperatively. This, combined with a stage-dependent multimodality treatment, underlines the importance of exact staging of the disease. Conventional imaging and tissue sampling methods all have variable sensitivities. Twenty-two studies concerning EUS-FNA and mediastinal staging of lung cancer have been published with a total number of 1245 patients. The reported sensitivity for mediastinal malignancy range from 0.61–1.00 (median 0.90), and with specificities of 0.71–1.00 (median 1.00). The majority of the studies are retrospective and present the results of EUS-FNA performed in lung cancer patients selected by computer tomography (CT). Recent data suggests that EUS-FNA in addition can diagnose advanced mediastinal disease in 22–42% of NSCLC patients with normal sized lymph nodes (

We present spectroscopy for globular clusters (GCs) in the elliptical galaxy NGC 4365, obtained with the LRIS spectrograph on the Keck I telescope. Previous studies have shown that the optical color distribution of GCs in NGC 4365 lacks the bimodal structure that is common in globular cluster systems, showing only a single broad peak. Measurements of Balmer line indices (Hbeta, Hgamma and Hdelta) on the GC spectra support recent suggestions by Puzia et al., based on optical and near-infrared photometry, that some of the clusters in NGC 4365 are intermediate-age (2-5 Gyrs) and metal-rich (-0.4, Comment: 19 pages, including 6 figures and 3 tables. Accepted for publication in ApJ

Using high-dispersion spectra from the HIRES echelle spectrograph on the Keck I telescope, we measure velocity dispersions for 4 globular clusters in M33. Combining the velocity dispersions with integrated photometry and structural parameters derived from King-Michie model fits to WFPC2 images, we obtain mass-to-light ratios for the clusters. The mean value is M/LV = 1.53 +/- 0.18, very similar to the M/LV of Milky Way and M31 globular clusters. The M33 clusters also fit very well onto the fundamental plane and binding energy - luminosity relations derived for Milky Way GCs. Dynamically and structurally, the four M33 clusters studied here appear virtually identical to Milky Way and M31 GCs., Comment: 25 pages, including 7 figures and 4 tables. Accepted for AJ, Nov 2002

We analyze high signal-to-noise spectra for 14 globular clusters (GCs) in the Sombrero galaxy, NGC 4594 = M104, obtained with the LRIS spectrograph on the Keck I telescope. We find generally good agreement between spectroscopic metallicities and previous photometric metallicities based on V-I colors. Further, we use measurements of various Balmer line indices on co-added spectra of metal-poor and metal-rich GCs to estimate ages for the GC subpopulations and find ages of 10-15 Gyr, with preferred ages around 11-12 Gyr and no detectable differences between the metal-rich and metal-poor subpopulations. However, because of model and measurement uncertainties, age differences of a few (2-3) Gyrs cannot be be ruled out. We also measure alpha-to-iron abundance ratios from Mg and TiO features and find enhancements on the order of +0.4 dex relative to the Sun, similar to the alpha/Fe abundance ratios observed in other old stellar populations. Finally, we combined our sample with radial velocities for 34 GCs from Bridges et al. 1997 and obtain virial and projected masses for the Sombrero of M(Vir) = 8.1+/-1.8 x 10^11 M(sun) and M(P) = 5.3+/-1.0 x 10^11 Msun within 17 kpc, respectively. Using 12 clusters within the central 4.5 kpc, the corresponding numbers are M(Vir) = 2.1+/-1.1 x 10^11 Msun and M(P) = 2.0+/-1.3 x 10^11 Msun., Comment: 24 pages, including 9 figures and 3 tables. Accepted for publication in AJ

We present Keck/LRIS spectra for 11 old globular clusters in the S0-type galaxy NGC 1023 and 2 young blue clusters in the nearby companion NGC 1023A. Analysis of the spectra of 7 old clusters with sufficient S/N shows generally good agreement between spectroscopic and previous photometric metallicity estimates, but the integrated colors of two clusters are too blue for their spectroscopic metallicities. Although the cluster ages are not well constrained, they are most likely similar to those of Milky Way globular clusters and certainly older than about 5 Gyr. The brightest GC in the sample shows enhanced cyanogen, possibly indicating an abundance anomaly similar to that observed in some M31 globular clusters. For the two blue clusters in NGC 1023A we estimate ages between 125 and 500 Myr, based on their strong Balmer lines. The total masses are about 80000 Msun and 60000 Msun for a Miller-Scalo IMF and Z=0.004, making these objects similar to the young populous clusters in the LMC. It is suggested that the two young clusters might have formed during a period of enhanced star formation activity in NGC 1023A, stimulated by a close encounter with NGC 1023., 32 pages, including 7 figures and 6 tables. Accepted for publication in AJ

Background: A study was undertaken to evaluate the clinical impact of endoscopic ultrasound guided fine needle aspiration biopsy (EUS-FNA) in patients with mediastinal masses suspected of malignancy. Methods: From April 1993 to December 1999, 84 patients were referred for EUS-FNA. In all patients CT scanning had shown a lesion of the mediastinum suspected of malignancy located adjacent to the oesophagus. In order to evaluate the clinical impact of EUS-FNA, the history of each patient up to referral for EUS-FNA was reviewed. A board of thoracic specialists was asked to decide the further course of the patient if EUS-FNA had not been available, and this diagnostic strategy was compared with the actual clinical course after EUS-FNA. Results: For the 79 patients in whom sufficient verification was obtained, EUS-FNA had a sensitivity of 92%, specificity of 100%, PPV of 100%, NPV of 80%, and an accuracy of 94% for cancer of the mediastinum. In 18 of 37 patients (49%) a thoracotomy/thoracoscopy was avoided as a result of EUS-FNA, and in 28 of 41 patients (68%) a mediastinoscopy was avoided. The direct result of the cytological diagnosis obtained by EUS-FNA was that a final diagnosis of small cell lung cancer was made in eight patients resulting in referral for chemotherapy, and in another three patients with benign disease specific treatment could be initiated (sarcoidosis, mediastinal abscess, and leiomyoma of the oesophagus). Conclusions: EUS-FNA is a safe and sensitive minimally invasive method for evaluating patients with a solid lesion of the mediastinum suspected by CT scanning. EUS-FNA has a significant impact on patient management and should be considered for diagnosing the spread of cancer to the mediastinum in patients with lung cancer considered for surgery, as well as for the primary diagnosis of solid lesions located in the mediastinum adjacent to the oesophagus.

Populations of young star clusters show significant differences even among “normal” disk galaxies. In this contribution I discuss how properties of young cluster systems are related to those of their host galaxies, based on a recent study of clusters in a sample of 22 nearby spiral galaxies. Luminous young clusters similar to the “super” star clusters observed in starbursts and mergers exist in several of these galaxies, and it is found that the luminosity of the brightest star cluster as well as the specific luminosity of the cluster systems both correlate well with the host galaxy star formation rate. When considering star clusters in different environments the traditional distinction between “open”, “massive” and “globular” clusters breaks down, underscoring the need for a universal physical description of cluster formation.

Intraoperative fluorescent cholangiography (IFC) with concomitant fluorescent angiography was recently developed for non-invasive identification of the anatomy during laparoscopic cholecystectomy. The objective of this study was to assess the time required for routine-use of IFC and to evaluate the success rate of the procedures.A total of 35 patients scheduled for laparoscopic cholecystectomy and operated by the same surgeon were consecutively enrolled. A standardised protocol with IFC including angiography was performed during laparoscopic cholecystectomy. Intraoperative time and exposure of predefined anatomical structures were recorded.The median time used for IFC was 2.6 minutes (range: 1.5-11.4 minutes) corresponding to a median of 6.2% (range: 3.0-15.2%) of the operation time. The junction between the cystic duct, the common bile duct and the common hepatic duct was identified by IFC in all patients. In 29 of the 35 patients (83%; 95% confidence interval: 71-96%), the cystic artery was visualised by fluorescent angiography. No adverse effects or complications were recorded.Routine-use of IFC with fluorescent angiography during laparoscopic cholecystectomy is feasible and associated with an acceptable time expenditure and a satisfactory success-rate.Not relevant.The Regional Ethics Committee approved the study (J. No. H-3-2013-FSP45). The study is registered with clinicaltrials.gov (ID: NCT02136095).

We use measurements of nitrogen abundances in red giants to search for multiple stellar populations in the four most metal-poor globular clusters (GCs) in the Fornax dwarf spheroidal galaxy (Fornax 1, 2, 3, and 5). New imaging in the F343N filter, obtained with the Wide Field Camera 3 on the Hubble Space Telescope, is combined with archival F555W and F814W observations to determine the strength of the NH band near 3370 AA. After accounting for observational errors, the spread in the F343N-F555W colors of red giants in the Fornax GCs is similar to that in M15 and corresponds to an abundance range of Delta([N/Fe])=2 dex, as observed also in several Galactic GCs. The spread in F555W-F814W is, instead, fully accounted for by observational errors. The stars with the reddest F343N-F555W colors (indicative of N-enhanced composition) have more centrally concentrated radial distributions in all four clusters, although the difference is not highly statistically significant within any individual cluster. From double-Gaussian fits to the color distributions we find roughly equal numbers of "N-normal" and "N-enhanced" stars (formally about 40% N-normal stars in Fornax 1, 3, and 5 and 60% in Fornax 2). We conclude that GC formation, in particular regarding the processes responsible for the origin of multiple stellar populations, appears to have operated similarly in the Milky Way and in the Fornax dSph. Combined with the high ratio of metal-poor GCs to field stars in the Fornax dSph, this places an important constraint on scenarios for the origin of multiple stellar populations in GCs., Comment: 16 pages, 7 figures, accepted for publication in ApJ

We determine the metallicities for globular clusters (GCs) in the WLM and IKN dwarf galaxies, using VLT/UVES and Keck/ESI spectroscopy. For the WLM GC we also measure detailed abundance ratios for a number of light, alpha, Fe-peak and n-capture elements. We find low metallicities of [Fe/H]=-2.0 and -2.1 for the WLM GC and the GC IKN-5, respectively. We estimate that 17%-31% of the metal-poor stars in WLM belong to the GC, and IKN-5 may even contain a similar number of metal-poor stars as the whole of the IKN dwarf itself. These high ratios of metal-poor GCs to field stars are in tension with GC formation scenarios that require GCs to have lost a very large fraction of their initial mass. The GCs in the WLM and IKN dwarf galaxies resemble those in the Fornax dSph by being significantly more metal-poor than a typical halo GC in the Milky Way and other large galaxies. They are also substantially more metal-poor than the bulk of the field stars in their parent galaxies. The overall abundance patterns in the WLM GC are similar to those observed for GCs in the Fornax dSph: [Ca/Fe] and [Ti/Fe] are super-Solar at about +0.3 dex, while [Mg/Fe] is less elevated than [Ca/Fe] and [Ti/Fe]. The [Na/Fe] ratio is similar to the averaged [Na/Fe] ratios in Milky Way GCs, but higher than those of Milky Way halo stars. Fe-peak (Mn, Sc, Cr) and heavy elements (Ba, Y, La) generally follow the trends seen in the Milky Way halo. The relatively high Na abundance in the WLM GC suggests that the [Na/O] anti-correlation is present in this cluster., 15 pages, 12 figures. Accepted for publication in A&A. Minor corrections by language editor taken into account

The structure of a very bright (MV = -10.9) globular cluster in NGC 1023 is analyzed on two sets of images taken with the Hubble Space Telescope. From careful modeling of King profile fits to the cluster image, a core radius of 0.55+/-0.1 pc, effective radius 3.7+/-0.3 pc and a central V-band surface brightness of 12.9+/-0.5 mag / square arcsec are derived. This makes the cluster much more compact than Omega Cen, but very similar to the brightest globular cluster in M31, G1 = Mayall II. The cluster in NGC 1023 appears to be very highly flattened with an ellipticity of about 0.37, even higher than for Omega Cen and G1, and similar to the most flattened clusters in the Large Magellanic Cloud., Comment: 14 pages, 3 figures, 1 table. Accepted for AJ, Oct 2001

OBJECTIVE Our aim was to chart the short-term results of the first 75 of our patients who had undergone first-time aortic valve replacement (AVR) with stentless xenografts. DESIGN Our study included a complete follow-up (mean/max. 1.5/3.7 years) of the first 75 patients (42 males, 33 females; mean age 74, range 61-84 years) who underwent a first AVR with stentless xenografts. RESULTS Forty-three percent of patients were in functional class II and 57% in classes III-IV preoperatively. Coronary artery bypass grafting (CABG) was performed in 33 patients. Early mortality (< or = 30 days) was 6.7%, with no significant relation to CABG or age. Crude survival was 81% (95% confidence interval, CI: 71-91 %) at 3 years. Using a multivariate analysis, we identified a low left ventricular ejection fraction as a predictor of early and late mortality. Late survival (early mortality excluded) was comparable with the survival of a matched Danish background population. There were six embolic events (all cerebral: 3 minor, 1 major, 2 fatal), while two patients underwent redo-AVR because of either endocarditis (fatal) or aortic regurgitation caused by malaligned commissures. There were no other valve-related complications. Cumulative freedom was 89% (95% CI: 79-99%) for embolism and 86% (95% CI: 76-96 %) for all complications at 3 years. At the end of the study, 64% of the survivors were in functional class I, 34% were in class II and 2% in class III. CONCLUSIONS Considering the age composition of our patients, and compared with international results, our early mortality rates were acceptable. The absence of late excess mortality compared with the background population and the functional status at end-of-study may indicate the potential haemodynamic advantages of stentless aortic valves, at least in the short term.

To elucidate the mechanisms responsible for the development of anti-estrogen resistance, we have cloned and established 3 stable ICI-182,780-resistant sub-lines, MCF-7/182R-1, MCF-7/182R-6 and MCF-7/182R-7 from the estrogen-receptor(ER)-positive and estrogen-responsive human breast-cancer MCF-7 cell line by long-term treatment with 10(-7) M ICI 182,780. The ICI-182,780-resistant MCF-7 sub-lines express ER, but compared with MCF-7 cells the level is significantly lower in all 3 sub-lines. In the MCF-7 cell line we find that ER expression is regulated by estrogen and anti-estrogens at the transcriptional and post-transcriptional level. This is in contrast to the ICI-182,780-resistant sub-lines, in which we find very little hormonal effects on the ER mRNA expression level. The resistant sub-lines also deviate from parent characteristics by the complete lack of expression of progesterone receptor even when grown in the presence of estradiol. All 3 resistant sub-lines have a lower basal expression of cathepsin-D mRNA comparable with the lower ER expression, but, in contrast, they have higher basal expression of the pS2 mRNA than the parent MCF-7 cell line. Although there are different basal expression levels of the pS2 and cathepsin-D genes, the resistant sub-lines behave like the parent MCF-7 cell line with respect to the hormonal regulation of both genes. The estrogen receptors in the resistant sub-lines have also maintained wild-type characteristics with respect to estrogen and anti-estrogen regulation of the estrogen-regulated proteins procathepsin D, alpha1-antitrypsin and a 42-kDa protein. The resistant cells require estrogen for growth in athymic nude mice. Our results clearly demonstrate that the ER in the resistant sub-lines have a normal function for most parameters investigated, supporting our earlier observation that only wild-type ER protein is expressed in these cells. The few observed differences in ER function between the parent MCF-7 cell line and the resistant sub-lines are not likely to be responsible for the ICI-182,780-resistant phenotype.

RESUMO: O correcto estadiamento do cancro do pulmão é fundamental, não só na determinação do prognóstico mas também na orientação terapêutica.A avaliação da extensão tumoral ao mediastino, por invasão directa ou metastática ganglionar, é um dos passos deste estadiamento. A TAC torácica é falível na detecção de metástases ganglionares, sendo o exame anatomopatológico mais fidedigno. Das várias técnicas de punção e biópsia, o método transbrônquico tornou-se uma rotina em diversos centros, sendo contudo a sua sensibilidade variável (técnica cega).Os autores descrevem um novo método de diagnóstico de lesões sólidas, incluindo gânglios mediastínicos e hilares através de ecografia endoscópica transbrônquica com biópsia aspirativa guiada em tempo real.Onze doentes com idade média de 58 anos foram submetidos a esta técnica: 3 com o diagnóstico de cancro do pulmão e suspeita de metástases ganglionares mediastínicas; 4 com suspeita de recorrência de tumor com metástases ganglionares; 3 com metástases ganglionares mediastínicas e hilares de etiologia desconhecida e um com suspeita de metastização ganglionar de cancro da mama. Todos os doentes tinham previamente efectuado broncofibroscopia que foi inconclusiva.O broncofibroscópio (BFC) ecográfico utilizado foi um protótipo criado pela Olympus, com uma sonda endoscópica na extremidade distal e com um grau de penetração em profundidade de 5 cm e um ângulo de varredura de 50º. Os doentes realizaram o exame sob anestesia geral, com introdução do BFC através de um tubo orotraqueal.A endoscopia foi efectuada em contacto directo com a parede brônquica e, ao localizar a lesão, a agulha de aspiração era introduzida através do canal de trabalho com visualização endoscópica directa da inserção e da biópsia.Quize lesões com dimensões de 7 a 80 mm foram puncionadas, sem registo de complicações, identificandose células malignas em 13 e células benignas em 2 lesões. Com base nestes achados, 8 doentes foram submetidos a quimioterapia, 1 submetido a pneumectomia, 1 a mastectomia e 1 a toracotomia exploradora que revelou carcinoma do esófago inoperável.O novo protótipo de BFC utilizado, além de manter um melhor estadiamento T e N do tumor, consegue em simultâneo realizar endoscopia e biópsia ou punção aspirativa. Com esta técnica conseguiuse o diagnóstico em todos os casos, sempre com repercussão na opção terapêutica e sem necessidade de recorrer a exames mais invasivos. O objectivo deste estudo foi exactamente verificar se este método é exequível, o que foi cumprido, tendo como futura intenção realizálo com anestesia local, para o diagnóstico de lesões sólidas adjacentes aos brônquios e traqueia e estadiamento ganglionar. Os autores referem a necessidade de uma experiência mais alargada e de estudos comparativos com a punção aspirativa transbrônquica convencional e a mediastinoscopia. COMENTÁRIO: A TAC torácica detecta algumas situações que afastam a hipótese de cirurgia curativa no cancro do pulmão, nomeadamente a invasão da artéria pulmonar ou da parede do ventrículo esquerdo, mas não é muito sensível na detecção de pequenas metástases ganglionares que podem tornar o doente inóperavel. A tomografia emissora de positrões (PET) é mais sensível na detecção de metástases, contudo também possui limitações, apresentando 25% de falsos positivos a nível ganglionar mediastínico e 31% nas lesões à distância. A necessidade de obtenção de tecido ganglionar é pois relevante para o diagnóstico, estadiamento e decisão terapêutica.O diagnóstico e estadiamento do cancro do pulmão pode ser difícil de obter por broncofibroscopia. A mediastinoscopia é o exame mais utilizado na obtenção de tecido ganglionar do mediastino, sendo porém um exame invasivo e não isento de riscos. Deste modo, um exame minimamente invasivo na obtenção de biópsias, como a aspiração com agulha transbrônquica (TBNA), tem vindo a ganhar importância, particularmente quando associada a ecografia endoscópica para localização mais precisa das lesões. A TBNA em conjugação com o escovado endobrônquico, o lavado e as biópsias por fórceps, aumenta significativamente o diagnóstico do tumor. A endoscopia endobrônquica só nos últimos anos tem despertado o interesse como meio de localização de lesões sólidas adjacentes à árvore brônquica e gânglios mediastínicos e hilares.Apesar destas vantagens, da sensibilidade e do baixo número de complicações, a TBNA ainda é uma técnica pouco utilizada. Por exemplo, nos Estados Unidos apenas 11,8% dos broncologistas a utilizam no diagnóstico de lesões malignas, sendo portanto necessário um maior investimento e treino nesta área. Este estudo, no fundo, vem reforçar os bons resultados obtidos através da biópsia transbrônquica, especialmente se guiada por ecografia endoscópica, revelando a experiência com um novo protótipo de broncofibroscópio que acopla ecografia e permite visualizar ao vivo as biópsias, não existindo para já nenhum aparelho deste tipo disponível comercialmente. Palavras chave: ecografia endoscópica transbrônquica, biópsia transbrônquica guiada

We use the Panchromatic Hubble Andromeda Treasury (PHAT) survey dataset to perform spatially resolved measurements of star cluster formation efficiency ($\Gamma$), the fraction of stellar mass formed in long-lived star clusters. We use robust star formation history and cluster parameter constraints, obtained through color-magnitude diagram analysis of resolved stellar populations, to study Andromeda's cluster and field populations over the last $\sim$300 Myr. We measure $\Gamma$ of 4-8% for young, 10-100 Myr old populations in M31. We find that cluster formation efficiency varies systematically across the M31 disk, consistent with variations in mid-plane pressure. These $\Gamma$ measurements expand the range of well-studied galactic environments, providing precise constraints in an HI-dominated, low intensity star formation environment. Spatially resolved results from M31 are broadly consistent with previous trends observed on galaxy-integrated scales, where $\Gamma$ increases with increasing star formation rate surface density ($\Sigma_{\mathrm{SFR}}$). However, we can explain observed scatter in the relation and attain better agreement between observations and theoretical models if we account for environmental variations in gas depletion time ($\tau_{\mathrm{dep}}$) when modeling $\Gamma$, accounting for the qualitative shift in star formation behavior when transitioning from a H$_2$-dominated to a HI-dominated interstellar medium. We also demonstrate that $\Gamma$ measurements in high $\Sigma_{\mathrm{SFR}}$ starburst systems are well-explained by $\tau_{\mathrm{dep}}$-dependent fiducial $\Gamma$ models., Comment: 26 pages, 13 figures, Accepted by ApJ

As part of the Panchromatic Hubble Andromeda Treasury (PHAT) multi-cycle program, we observed a 12' \times 6.5' area of the bulge of M31 with the WFC3/UVIS filters F275W and F336W. From these data we have assembled a sample of \sim4000 UV-bright, old stars, vastly larger than previously available. We use updated Padova stellar evolutionary tracks to classify these hot stars into three classes: Post-AGB stars (P-AGB), Post-Early AGB (PE-AGB) stars and AGB-manqu\'e stars. P-AGB stars are the end result of the asymptotic giant branch (AGB) phase and are expected in a wide range of stellar populations, whereas PE-AGB and AGB-manqu\'e (together referred to as the hot post-horizontal branch; HP-HB) stars are the result of insufficient envelope masses to allow a full AGB phase, and are expected to be particularly prominent at high helium or {\alpha} abundances when the mass loss on the RGB is high. Our data support previous claims that most UV-bright sources in the bulge are likely hot (extreme) horizontal branch stars (EHB) and their progeny. We construct the first radial profiles of these stellar populations, and show that they are highly centrally concentrated, even more so than the integrated UV or optical light. However, we find that this UV-bright population does not dominate the total UV luminosity at any radius, as we are detecting only the progeny of the EHB stars that are the likely source of the UVX. We calculate that only a few percent of MS stars in the central bulge can have gone through the HP-HB phase and that this percentage decreases strongly with distance from the center. We also find that the surface density of hot UV-bright stars has the same radial variation as that of low-mass X-ray binaries. We discuss age, metallicity, and abundance variations as possible explanations for the observed radial variation in the UV-bright population., Comment: Accepted for publication in ApJ

Aims: We describe our newly developed approach to detailed abundance analysis from integrated-light high-dispersion spectra of star clusters. As a pilot project, we measure abundances of several elements for three globular clusters (GCs) in the Fornax dSph, using VLT/UVES spectra. Methods: We divide the cluster colour-magnitude diagrams into about 100 bins and compute synthetic spectra for each bin. The individual model spectra are co-added and the abundances are iteratively adjusted until the best match to the observed spectra is achieved. Results: We find [Fe/H] = -2.3, -1.4 and -2.1 for Fornax 3, 4 and 5, with +/-0.1 dex uncertainties. Fornax 3 and 5 are thus similar in metallicity to the most metal-poor Milky Way GCs and fall near the extreme metal-poor end of the field star metallicity distribution in Fornax. The [alpha/Fe] ratios, as traced by Ca and Ti, are enhanced with respect to the Solar composition at the level of about +0.25 dex for Fornax 3 and 5, and possibly slightly less (about +0.12 dex) for Fornax 4. For all three clusters the [Mg/Fe] ratio is significantly less elevated than [Ca/Fe] and [Ti/Fe], possibly an effect of the abundance anomalies that are well-known in Galactic GCs. We thus confirm that Mg may be a poor proxy for the overall alpha-element abundances for GCs. The abundance patterns of heavy elements (Y, Ba and Eu) indicate a dominant contribution to nucleosynthesis from the r-process in all three clusters, with a mean [Ba/Eu]=-0.7, suggesting rapid formation of the GCs. Conclusions: Combining our results with literature data for Fornax 1 and 2, four of the five Fornax GCs fall in the range -2.5, Comment: 18 pages, accepted for publication in A&A

Recently, high-dispersion spectroscopy has demonstrated conclusively that four of the five globular clusters (GCs) in the Fornax dwarf spheroidal galaxy are very metal-poor with [Fe/H], Comment: 4 pages, 2 figures, accepted for A&A Letters

The Panchromatic Hubble Andromeda Treasury (PHAT) survey is an on-going Hubble Space Telescope (HST) multi-cycle program to obtain high spatial resolution imaging of one-third of the M31 disk at ultraviolet through near-infrared wavelengths. In this paper, we present the first installment of the PHAT stellar cluster catalog. When completed, the PHAT cluster catalog will be among the largest and most comprehensive surveys of resolved star clusters in any galaxy. The exquisite spatial resolution achieved with HST has allowed us to identify hundreds of new clusters that were previously inaccessible with existing ground-based surveys. We identify 601 clusters in the Year 1 sample, representing more than a factor of four increase over previous catalogs within the current survey area (390 arcmin^2). This work presents results derived from the first \sim25% of the survey data; we estimate that the final sample will include \sim2500 clusters. For the Year 1 objects, we present a catalog with positions, radii, and six-band integrated photometry. Along with a general characterization of the cluster luminosities and colors, we discuss the cluster luminosity function, the cluster size distributions, and highlight a number of individually interesting clusters found in the Year 1 search., 26 pages, 22 figures, Accepted by ApJ

The apparent age and mass of a stellar cluster can be strongly affected by stochastic sampling of the stellar initial mass function, when inferred from the integrated color of low mass clusters (less than ~10^4 solar masses). We use simulated star clusters to show that these effects are minimized when the brightest, rapidly evolving stars in a cluster can be resolved, and the light of the fainter, more numerous unresolved stars can be analyzed separately. When comparing the light from the less luminous cluster members to models of unresolved light, more accurate age estimates can be obtained than when analyzing the integrated light from the entire cluster under the assumption that the initial mass function is fully populated. We show the success of this technique first using simulated clusters, and then with a stellar cluster in M31. This method represents one way of accounting for the discrete, stochastic sampling of the stellar initial mass function in less massive clusters and can be leveraged in studies of clusters throughout the Local Group and other nearby galaxies., Comment: 11 pages, 8 figures, accepted for publication in ApJ

Using new (Cycle 9) HST / WFPC2 data, we have studied a peculiar star forming region in the nearby Sc-type spiral NGC 6946. The region has a bubble-like shape and a diameter of about 600 pc. Near the centre is an extremely luminous young globular cluster with MV = −13.2 mag. The cluster has a compact core with a core radius of about 1.3 pc but is surrounded by an extended halo with a power-law luminosity profile similar to that observed for young LMC clusters. From Keck / HIRES high-dispersion spectroscopy we measure a velocity dispersion of 10 km s−1, leading to a dynamical mass estimate of about 1.7 × 106 solar masses. The dynamical mass estimate is comparable to the expectation from population synthesis modelling under the assumption of a Salpeter IMF extending down to 0.1 M⊙.

With HST, colour–magnitude diagrams (CMDs) can be obtained for young star clusters well beyond the Local Group. Such data can help constrain cluster ages and metallicities, and also provide a reference against which intermediate- and high mass stellar models can be compared. Here, CMDs are presented for two massive (>105 M⊙) clusters and compared with Padua and Geneva isochrones. The problem of the ratio of blue to red supergiants is also addressed.