22 research outputs found
GEOS RR Lyr survey: FM Del is indeed a cepheid
Though FM Del has been considered as a RR Lyr star by Preston et al. in 1959
(following discovery by Huth, 1957), Huth (1960) eventually changed his mind by
showing that it is in fact a cepheid of W Vir type of period of 3.95452 days.
Various authors since then have considered it as a cepheid indeed, with the
exception of Wils et al. (2006) who list this star in their RR Lyr catalog with
a period of 0.79688 days. On this basis, FM Del was added to Tarot RR Lyr
program. We present here these observations which confirm the cepheid type.Comment: Published in the GEOS circulars (Groupe Europeen d'Observations
Stellaires, http://geos.upv.es/
The star RR Lyr and the Cepheid variables in the era of the space photometry revolution
The long-term behaviours of the pulsation and Blazhko periods of RR Lyr are
investigated by means of Kepler and ground-based observations. The difficulties
in detecting additional modes in the Cepheids monitored with CoRoT are
discussed.Comment: Conference Proceedings - CoRoT3-KASC7 The Space Photometry
Revolution, Toulouse, France, July 6-11 2014. Paper on CoRoT Cepheids
submitted to MNRA
The zCOSMOS 10k-Bright Spectroscopic Sample
We present spectroscopic redshifts of a large sample of galaxies with I_(AB) < 22.5 in the COSMOS field, measured from spectra of 10,644 objects that have been obtained in the first two years of observations in the zCOSMOS-bright redshift survey. These include a statistically complete subset of 10,109 objects. The average accuracy of individual redshifts is 110 km s^(–1), independent of redshift. The reliability of individual redshifts is described by a Confidence Class that has been empirically calibrated through repeat spectroscopic observations of over 600 galaxies. There is very good agreement between spectroscopic and photometric redshifts for the most secure Confidence Classes. For the less secure Confidence Classes, there is a good correspondence between the fraction of objects with a consistent photometric redshift and the spectroscopic repeatability, suggesting that the photometric redshifts can be used to indicate which of the less secure spectroscopic redshifts are likely right and which are probably wrong, and to give an indication of the nature of objects for which we failed to determine a redshift. Using this approach, we can construct a spectroscopic sample that is 99% reliable and which is 88% complete in the sample as a whole, and 95% complete in the redshift range 0.5 < z < 0.8. The luminosity and mass completeness levels of the zCOSMOS-bright sample of galaxies is also discussed
Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
We explore the inter-relationships between mass, star-formation rate and
environment in the SDSS, zCOSMOS and other surveys. The differential effects of
mass and environment are completely separable to z ~ 1, indicating that two
distinct processes are operating, "mass-quenching" and "environment-quenching".
Environment-quenching, at fixed over-density, evidently does not change with
epoch to z ~ 1, suggesting that it occurs as large-scale structure develops in
the Universe. The observed constancy of the mass-function shape for
star-forming galaxies, demands that the mass-quenching of galaxies around and
above M*, must be proportional to their star-formation rates at all z < 2. We
postulate that this simple mass-quenching law also holds over a much broader
range of stellar mass and epoch. These two simple quenching processes, plus
some additional quenching due to merging, then naturally produce (a) a
quasi-static Schechter mass function for star-forming galaxies with a value of
M* that is set by the proportionality between the star-formation and
mass-quenching rates, (b) a double Schechter function for passive galaxies with
two components: the dominant one is produced by mass-quenching and has exactly
the same M* as the star-forming galaxies but an alpha shallower by +1, while
the other is produced by environment effects and has the same M* and alpha as
the star-forming galaxies, and is larger in high density environments.
Subsequent merging of quenched galaxies modifies these predictions somewhat in
the denser environments, slightly increasing M* and making alpha more negative.
All of these detailed quantitative relationships between the Schechter
parameters are indeed seen in the SDSS, lending strong support to our simple
empirically-based model. The model naturally produces for passive galaxies the
"anti-hierarchical" run of mean ages and alpha-element abundances with mass.Comment: 66 pages, 19 figures, 1 movie, accepted for publication in ApJ. The
movie is also available at
http://www.exp-astro.phys.ethz.ch/zCOSMOS/MF_simulation_d1_d4.mo
Cleaved CD31 as a target for in vivo molecular imaging of inflammation
International audienceAbstract There is a need for new targets to specifically localize inflammatory foci, usable in a wide range of organs. Here, we hypothesized that the cleaved molecular form of CD31 is a suitable target for molecular imaging of inflammation. We evaluated a bioconjugate of D-P8RI, a synthetic peptide that binds all cells with cleaved CD31, in an experimental rat model of sterile acute inflammation. Male Wistar rats were injected with turpentine oil into the gastrocnemius muscle two days before 99m Tc-HYNIC-D-P8RI (or its analogue with L-Proline) SPECT/CT or [ 18 F]FDG PET/MRI. Biodistribution, stability study, histology, imaging and autoradiography of 99m Tc-HYNIC-D-P8RI were further performed. Biodistribution studies revealed rapid elimination of 99m Tc-HYNIC-D-P8RI through renal excretion with almost no uptake from most organs and excellent in vitro and in vivo stability were observed. SPECT/CT imaging showed a significant higher 99m Tc-HYNIC-D-P8RI uptake compared with its analogue with L-Proline (negative control) and no significant difference compared with [ 18 F]FDG (positive control). Moreover, autoradiography and histology revealed a co-localization between 99m Tc-HYNIC-D-P8RI uptake and inflammatory cell infiltration. 99m Tc-HYNIC-D-P8RI constitutes a new tool for the detection and localization of inflammatory sites. Our work suggests that targeting cleaved CD31 is an attractive strategy for the specific in vivo imaging of inflammatory processes