A massive association around the obscured open cluster RSGC3

Context. Four clusters of red supergiants have been discovered in a region of the Milky Way close to base of the Scutum-Crux Arm and the tip of the Long Bar. Population synthesis models indicate that they must be very massive to harbour so many supergiants. If the clusters are physically connected, this Scutum Complex would be the largest and most massive star-forming region ever identified in the Milky Way. Aims. The spatial extent of one of these clusters, RSGC3, has not been investigated. In this paper we explore the possibility that a population of red supergiants could be located in its vicinity. Methods. We utilised 2MASS JHKS photometry to identify candidate obscured luminous red stars in the vicinity of RSGC3. We observed a sample of candidates with the TWIN spectrograph on the 3.5-m telescope at Calar Alto, obtaining intermediate-resolution spectroscopy in the 8000−9000 Å range. We re-evaluated a number of classification criteria proposed in the literature for this spectral range and found that we could use our spectra to derive spectral types and luminosity classes. Results. We measured the radial velocity of five members of RSGC3, finding velocities similar to the average for members of Stephenson 2. Among the candidates observed outside the cluster, our spectra revealed eight M-type supergiants at distances <18′ from the centre of RSGC3, distributed in two clumps. The southern clump is most likely another cluster of red supergiants, with reddening and age identical to RSGC3. From 2MASS photometry, we identified four likely supergiant members of the cluster in addition to the five spectroscopically observed. The northern clump may be a small cluster with similar parameters. Photometric analysis of the area around RSGC3 suggests the presence of a large (>30) population of red supergiants with similar colours. Conclusions. Our data suggest that the massive cluster RSGC3 is surrounded by an extended association, which may be very massive ( ≳ 105 M⊙). We also show that supergiants in the Scutum Complex may be characterised via a combination of 2MASS photometry and intermediate-to-high-resolution spectroscopy in the Z band.

A new survey of cool supergiants in the Magellanic Clouds

Aims. In this study we conduct a pilot program aimed at the red supergiant population of the Magellanic Clouds. We intend to extend the current known sample to the unexplored low end of the brightness distribution of these stars, building a more representative dataset with which to extrapolate their behaviour to other Galactic and extra-galactic environments. Methods. We select candidates using only near infrared photometry, and with medium resolution multi-object spectroscopy, we perform spectral classification and derive their line-of-sight velocities, confirming the nature of the candidates and their membership in the clouds. Results. Around two hundred new red supergiants have been detected, hinting at a yet to be observed large population. Using near- and mid-infrared photometry we study the brightness distribution of these stars, the onset of mass-loss, and the effect of dust in their atmospheres. Based on this sample, new a priori classification criteria are investigated, combining mid- and near-infrared photometry to improve the observational efficiency of similar programs to this.

Does the scientific evidence support the advertising claims made for products containing Lactobacillus casei and Bifidobacterium lactis? A systematic review

Background To analyse the scientific evidence that exists for the advertising claims made for two products containing Lactobacillus casei and Bifidobacterium lactis and to conduct a comparison between the published literature and what is presented in the corporate website. Methods Systematic review, using Medline through Pubmed and Embase. We included human clinical trials that exclusively measured the effect of Lactobacillus casei or Bifidobacterium lactis on a healthy population, and where the objective was related to the health claims made for certain products in advertising. We assessed the levels of evidence and the strength of the recommendation according to the classification criteria established by the Oxford Centre for Evidence Based Medicine (CEBM). We also assessed the outcomes of the studies published on the website that did not appear in the search. Results Of the 440 articles identified, 16 met the inclusion criteria. Only four (25%) of these presented a level of evidence of 1b and a recommendation grade of A, all corresponding to studies on product containing Bifidobacterium lactis, and only 12 of the 16 studies were published on the corporate website (47). Conclusions There is insufficient scientific evidence to support the health claims made for these products, especially in the case of product containing Lactobacillus casei.