The morphology of HII regions around young star clusters provides insight into the timescales and physical processes that clear a cluster's natal gas. We study ~700 young clusters (<10Myr) in three ...nearby spiral galaxies (NGC 7793, NGC 4395, and NGC 1313) using Hubble Space Telescope (HST) imaging from LEGUS (Legacy ExtraGalactic Ultraviolet Survey). Clusters are classified by their H\(\alpha\) morphology (concentrated, partially exposed, no-emission) and whether they have neighboring clusters (which could affect the clearing timescales). Through visual inspection of the HST images, and analysis of ages, reddenings, and stellar masses from spectral energy distributions fitting, together with the (U-B), (V-I) colors, we find: 1) the median ages indicate a progression from concentrated (~3 Myr), to partially exposed (~4 Myr), to no H\(\alpha\) emission (>5Myr), consistent with the expected temporal evolution of HII regions and previous results. However, 2) similarities in the age distributions for clusters with concentrated and partially exposed H\(\alpha\) morphologies imply a short timescale for gas clearing (<1Myr). 3) our cluster sample's median mass is ~1000 M, and a significant fraction (~20%) contain one or more bright red sources (presumably supergiants), which can mimic reddening effects. Finally, 4) the median E(B-V) values for clusters with concentrated H\(\alpha\) and those without H\(\alpha\) emission appear to be more similar than expected (~0.18 vs. ~0.14, respectively), but when accounting for stochastic effects, clusters without H\(\alpha\) emission are less reddened. To mitigate stochastic effects, we experiment with synthesizing more massive clusters by stacking fluxes of clusters within each H\(\alpha\) morphological class. Composite isolated clusters also reveal a color and age progression for H\(\alpha\) morphological classes, consistent with analysis of the individual clusters.
We used near-infrared data obtained with the Wide Field Camera 3 on the Hubble Space Telescope to identify objects having the colors of brown dwarfs (BDs) in the field of the massive galactic cluster ...NGC 3603. These are identified through a combination of narrow- and medium-band filters which span the J and H bands and are particularly sensitive to the presence of the 1.3-1.5 Delta *mm H2O molecular band unique to BDs. We provide a calibration of the relationship between effective temperature and color for both field stars and BDs. This photometric method provides effective temperatures for BDs to an accuracy of ?350 K relative to spectroscopic techniques. This accuracy is shown to be not significantly affected by either stellar surface gravity or uncertainties in the interstellar extinction. We identify nine objects having effective temperatures between 1700 and 2200 K, typical of BDs, observed J-band magnitudes in the range 19.5-21.5, and that are strongly clustered toward the luminous core of NGC 3603. However, if these are located at the distance of the cluster, they are far too luminous to be normal BDs. We argue that it is unlikely that these objects are either artifacts of our data set, normal field BDs/M-type giants, or extragalactic contaminants and, therefore, might represent a new class of stars having the effective temperatures of BDs but with luminosities of more massive stars. We explore the interesting scenario in which these objects would be normal stars that have recently tidally ingested a hot Jupiter, the remnants of which are providing a short-lived extended photosphere to the central star. In this case, we would expect them to show the signature of fast rotation.
The effectiveness of BCG in preventing disease progression in patients with superficial bladder cancer is evaluated. Long-term follow-up of high-risk patients treated in a previously reported ...randomized control trial of intravesical plus percutaneous BCG shows that progression occurred in 41/43 (95%) of control and 23/43 (53%) of BCG-treated patients. Muscle invasive and/or metastatic disease occurred with equal frequency in the two groups, but was significantly delayed by BCG treatment (P = .012). Cystectomies were required in 18/43 (42%) control and 11/43 (26%) BCG-treated patients. Median time to cystectomy was 8 months for control v 24 months for BCG-treated patients. Based on initial treatment, survival was improved by BCG therapy (P = .032) (median follow-up 6 years). These results suggest that in high-risk patients intravesical BCG can delay disease progression, prolong the period of bladder preservation, and increase overall survival.
This paper presents distributions of topological observables in inclusive three- and four-jet events produced in pp collisions at a centre-of-mass energy of 7
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with a data sample collected by the CMS experiment corresponding to a luminosity of 5.1
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. The distributions are corrected for detector effects, and compared with several event generators based on two- and multi-parton matrix elements at leading order. Among the considered calculations,
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interfaced with
pythia6
displays the overall best agreement with
data.
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