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SECCO 1 is an extremely dark, low-mass (M★ ≈ 105 Mʘ), star-forming stellar system lying in the low-velocity cloud (LVC) substructure of the Virgo cluster of galaxies, and hosting several HII regions. Here, we review our knowledge of this remarkable system, and present the results of (a) additional analysis of our panoramic spectroscopic observations with MUSE, (b) the combined analysis of Hubble Space Telescope and MUSE data, and (c) new narrowband observations obtained with OSIRIS@GTC to search for additional HII regions in the surroundings of the system. We provide new evidence supporting an age as young as ≤4Myr for the stars that are currently ionizing the gas in SECCO 1. We identify only one new promising candidate HII region possibly associated with SECCO 1, thus confirming the extreme isolation of the system.We also identify three additional candidate pressure-supported dark clouds in Virgo among the targets of the SECCO survey. Various possible hypotheses for the nature and origin of SECCO 1 are considered and discussed, also with the help of dedicated hydrodynamical simulations showing that a hydrogen cloud with the characteristics of SECCO 1 can likely survive for ≥1 Gyr while travelling within the LVC Intra Cluster Medium. [ABSTRACT FROM AUTHOR]

Recent photometric analyses of the colour-magnitude diagrams of young massive clusters (YMCs) have found evidence for splitting in the main sequence and extended main-sequence turn-offs, both of which have been suggested to be caused by stellar rotation. Comparison of the observed main-sequence splitting with models has led various authors to suggest a rather extreme stellar rotation distribution, with a minority (10-30 per cent) of stars with low rotational velocities and the remainder (70-90 per cent) of stars rotating near the critical rotation (i.e. near break-up). We test this hypothesis by searching for Be stars within two YMCs in the Large Magellanic Cloud (NGC 1850 and NGC 1856), which are thought to be critically rotating stars with decretion discs that are (partially) ionized by their host stars. In both clusters, we detect large populations of Be stars at the main-sequence turn-off (~30-60?per?cent of stars), which supports previous suggestions of large populations of rapidly rotating stars within massive clusters. [ABSTRACT FROM AUTHOR]

We present the results of VLT-MUSE (Very Large Telescope-Multi Unit Spectroscopic Explorer) integral field spectroscopy of SECCO 1, a faint, star-forming stellar system recently discovered as the stellar counterpart of an ultracompact high-velocity cloud (HVC 274.68+74.0), very likely residing within a substructure of the Virgo cluster of galaxies. We have obtained the radial velocity of a total of 38 individual compact sources identified as HII regions in the main and secondary bodies of the system, and derived the metallicity for 18 of them. We provide the first direct demonstration that the two stellar bodies of SECCO 1 are physically associated and that their velocities match the HI velocities. The metallicity is quite uniform over the whole system, with a dispersion lower than the uncertainty on individual metallicity estimates. The mean abundance, <12 + log(O/H)> = 8.44, is much higher than the typical values for local dwarf galaxies of similar stellar mass. This strongly suggests that the SECCO 1 stars were born from a pre-enriched gas cloud, possibly stripped from a larger galaxy. Using archival Hubble Space Telescope (HST) images, we derive a total stellar mass of ⋍1.6 × 105M⊙ for SECCO 1, confirming that it has a very high HI-to-stellar mass ratio for a dwarf galaxy, MHI/M* ~ 100. The star formation rate, derived from the Ha flux, is a factor of more than 10 higher than in typical dwarf galaxies of similar luminosity. [ABSTRACT FROM AUTHOR]

We present an imaging survey that searches for the stellar counterparts of recently discovered ultra-compact high-velocity H?i clouds (UCHVC). It has been proposed that these clouds are candidate mini-haloes in the Local Group and its surroundings within a distance range of 0.25-2.0 Mpc. Using the Large Binocular Telescope we obtained wide-field (≃ 23' × 23') g- and r-band images of the twenty-five most promising and most compact clouds amongst the fifty-nine that have been identified. Careful visual inspection of all the images does not reveal any stellar counterpart that even slightly resembles Leo P, the only local dwarf galaxy that was found as a counterpart to a previously detected high-velocity cloud. Only a possible distant (D > 3.0 Mpc) counterpart to HVC274.68+74.70-123 has been identified in our images. The point source photometry in the central 17.3' × 7.7' chips reaches r ≤ 26.5 and is expected to contain most of the stellar counterparts to the UCHVCs. However, no obvious stellar over-density is detected in any of our fields, in marked contrast to our comparison Leo P field, in which the dwarf galaxy is detected at a >30σ-significance level. Only HVC352.45+59.06+263 may be associated with a weak over-density, whose nature cannot be ascertained with our data. Sensitivity tests show that our survey would have detected any dwarf galaxy dominated by an old stellar population, with an integrated absolute magnitude of MV ≤ - 8.0 and a half-light radius of rh ≤ 300 pc that lies within 1.5 Mpc of us, thereby confirming that it is unlikely that the observed UCHVCs are associated with the stellar counterparts typical of known Local Group dwarf galaxies. [ABSTRACT FROM AUTHOR]

We present a study of the kinematics of the remote globular cluster NGC 5694 based on GIRAFFE@VLT medium-resolution spectra. A sample of 165 individual stars selected to lie on the red giant branch in the cluster colour-magnitude diagram was considered. Using radial velocity and metallicity from Calcium triplet, we were able to select 83 bona fide cluster members. The addition of six previously known members leads to a total sample of 89 cluster giants with typical uncertainties ≤1.0?km?s-1 in their radial velocity estimates. The sample covers a wide range of projected distances from the cluster centre, from ~0.2 arcmin to 6.5 arcmin ≃ 23 half-light radii (rh). We find only very weak rotation, as typical of metal-poor globular clusters. The velocity dispersion gently declines from a central value of σ = 6.1 km s-1 to σ ≃ 2.5 km s-1 at ~2 arcmin ≃ 7.1rh, then it remains flat out to the next (and last) measured point of the dispersion profile, at ~4 arcmin ≃ 14.0rh, at odds with the predictions of isotropic King models. We show that both isotropic single-mass non-collisional models and multimass anisotropic models can reproduce the observed surface brightness and velocity dispersion profiles. [ABSTRACT FROM AUTHOR]

ABSTRACT We report on the discovery of an extended stellar halo surrounding the distant Galactic globular cluster NGC 5694, based on new deep ( V≃ 24.5) wide-field (24 × 20 arcmin2) photometry acquired with the VIMOS at the VLT. Stars with colour and magnitude consistent with the main sequence of the cluster are clearly identified out to r≃ 9 arcmin (≃93 pc) from the cluster centre, much beyond the tidal radius of the King model that best fits the inner profile ( rt= 3.15 arcmin). We do not find a clear end of the structure within our field. The overall observed profile cannot be properly fitted with either a King model, an Elson et al. model or a Wilson model; however, it is very smooth and does not show any sign of the break near the tidal radius that is typically observed in stellar systems with tidal tails. The density map we derived does not show evidence of tidal tails, within the considered field. The extra-tidal component contains ≃ 3.5 per cent of the cluster light (mass) and has a surface density profile falling as ∼ r−3.2. The possible origin of the detected structure is discussed, as a clear-cut conclusion cannot be reached with the available data. [ABSTRACT FROM AUTHOR]

We present the results of a survey of radial velocities over a wide region extending from out to 80 arcmin (∼1.5 tidal radii) within the massive star cluster ω Centauri (ω Cen). The survey was performed with , to study the velocity dispersion profile in the outer regions of this stellar system. We derived accurate radial velocities for a sample of 2557 newly observed stars, identifying 318 bona fide cluster red giants. Merging our data with those provided by our previous survey, we assembled a final homogeneous sample of 946 cluster members that allowed us to trace the velocity dispersion profile from the centre out to arcmin. The velocity dispersion appears to decrease monotonically over this range, from a central value of down to a minimum value of . The observed surface brightness profile, rotation curve, velocity dispersion profile and ellipticity profile are simultaneously well reproduced by a simple dynamical model in which mass follows light, within the classical Newtonian theory of gravitation. The comparison with an N-body model of the evolution of a system mimicking ω Cen during the last 10 orbits into the Galactic potential suggests that (i) the rotation of stars lying in the inner arcmin of the clusters is not due to the effects of the tidal field of the Milky Way, as hypothesized by other authors and (ii) the overall observational scenario is still compatible with the possibility that the outer regions of the cluster are subject to some tidal stirring. [ABSTRACT FROM AUTHOR]

The aim of this work was to detect and typify human papillomaviruses (HPV) in oral squamous cell carcinoma (OSCC) in a Venezuelan population. Eighteen tissue samples were obtained from biopsies, formalin-fixed, and paraffin-embedded; 16 were diagnosed as SCC. We isolated DNA from paraffin-embedded tissue; two to three sections of 5 μm were obtained and resuspended in digestion buffer and proteinase K. Five microliters of the aqueous phase was used for polymerase chain reaction (PCR). The PCR for HPV amplification was carried out with consensus primers for L1 region (MY09 and MY11) and β-globin gene was used as internal control. The viral types were determined by molecular hybridization with a mix of probes for high/intermediate and low HPV oncogenic risk types. The HPV-DNA was detected in 50% (eight of 16) of the SCC cases. Of these HPV-DNA-positive samples, 68% were histopathologically diagnosed as moderately differentiated SCC. The most common anatomical location was the alveolar ridge mucosa. All positive biopsies contained high oncogenic HPV types. We observed a high prevalence of HPV infection of high oncogenic potential types in patients with SCC in our studied group. The moderately differentiated SCCs were more associated to HPV infection. These differences could be influenced by nutritional, environmental and genetical factors in our population but further studies should be carried out to determine these aspects. [ABSTRACT FROM AUTHOR]

The polymerase chain reaction (PCR) was applied to the detection of human papillomavirus (HPV) infection in biopsies taken from clinically normal oral mucosa of 20 subjects and clinical lesions of 40 patients. PCR for HPV-DNA amplification was performed using consensus primers MYO9/MYO11 and subsequent typing for HPV of high and low oncogenic risk HPV types were identified by restriction enzyme analysis (restriction fragment length polymorphism, RFLP). The HPV viral genome was present in 55% (22/40) of the oral benign lesions (OBL) and in 10% (2/20) of the control samples. In the PCR+ OBL, we observed 90.9% of low oncogenic risk types (HPV-6 -13 and -32) and 9.1% of the samples had a mixed infection with low and high oncogenic types (HPV-6 and -16). In the control samples, we observed one patient with HPV-6 and another with HPV-6 and -16 in the same sample. All of the eight focal epithelial hyperplasia cases were positive for low risk HPV types (88% HPV-13 and 12.5% HPV-32). In conclusion, this study demonstrates a high incidence of HPV in oral benign lesions from Venezuelan patients. [ABSTRACT FROM AUTHOR]

It has recently been suggested that the peculiar cluster Pal 1 is associated to the Canis Major dwarf galaxy, which existence is still at the center of a debate. Our first measurement of the cluster's chemical abundance ratios allows us to examine this association and to advance further in the clarification of Pal 1 possible origin. [ABSTRACT FROM AUTHOR]

We present deep B,V,I photometry of three wide fields within the core of the Sagittarius dwarf spheroidal galaxy (Sgr dSph). We provide accurate templates for some well identified sequences of the CMD of the galaxy (Blue HB, Red HB, etc.) as tools to recognize portion of the tidal Stream detected by various surveys, to compare the stellar populations in the main body of Sgr and in its Stream, and to derive accurate distances to Stream stars. [ABSTRACT FROM PUBLISHER]

We report on the detection of a population of Red Clump (RC) stars probably associated with the recently discovered stellar system Boötes III. The RC is identified as a 3σ peak in the luminosity function (LF) of colour-selected stars extracted from the Sloan Digital Sky Survey data base. The peak is consistently detected in the and z LFs at the expected luminosity of a typical RC at the distance of Boötes III. Moreover, the stars around the LF peak show a maximum of surface density nearly coincident with the reported centre of the system. Assuming that the detected feature is the genuine RC of Boötes III, we find that the system has the horizontal branch morphology typical of old and metal-poor dwarf spheroidals, it has an integrated magnitude and an ellipticity , quite typical of the recently identified new class of very faint dwarf galaxies. [ABSTRACT FROM AUTHOR]