A catalog of known Galactic K-M stars of class I, candidate RSGs, in Gaia DR2

We investigate individual distances and luminosities of a sample of 889 nearby candidate red supergiants with reliable parallaxes (plx/plxerr > 4 and RUWE < 2.7) from Gaia DR2. The sample was extracted from the historical compilation of spectroscopically derived spectral types by Skiff (2014), and consists of K-M stars that are listed with class I at least once. The sample includes well-known red supergiants from Humphreys (1978), Elias et al. (1985), Jura and Kleinmann (1990), and Levesque et al. (2005). Infrared and optical measurements from the 2MASS, CIO, MSX, WISE, MIPSGAL, GLIMPSE, and NOMAD catalogs allow us to estimate the stellar bolometric magnitudes. We analyze the stars in the luminosity versus effective temperature plane and confirm that 43 sources are highly-probably red supergiants with Mbol<-7.1 mag. 43% of the sample is made of stars with masses > 7 Msun. Another 30% of the sample consists of giant stars.Comment: 14 pages, 7 Figures, accepted by ApJ. See https://somethingaboutrsgstars.wordpress.com/ or http://staff.ustc.edu.cn/~messine

Measurements of vacuum magnetic birefringence using permanent dipole magnets: the PVLAS experiment

The PVLAS collaboration is presently assembling a new apparatus (at the INFN section of Ferrara, Italy) to detect vacuum magnetic birefringence (VMB). VMB is related to the structure of the QED vacuum and is predicted by the Euler-Heisenberg-Weisskopf effective Lagrangian. It can be detected by measuring the ellipticity acquired by a linearly polarised light beam propagating through a strong magnetic field. Using the very same optical technique it is also possible to search for hypothetical low-mass particles interacting with two photons, such as axion-like (ALP) or millicharged particles (MCP). Here we report results of a scaled-down test setup and describe the new PVLAS apparatus. This latter one is in construction and is based on a high-sensitivity ellipsometer with a high-finesse Fabry-Perot cavity ($>4\times 10^5$) and two 0.8 m long 2.5 T rotating permanent dipole magnets. Measurements with the test setup have improved by a factor 2 the previous upper bound on the parameter $A_e$, which determines the strength of the nonlinear terms in the QED Lagrangian: $A_e^{\rm (PVLAS)} < 3.3 \times 10^{-21}$ T$^{-2}$ 95% c.l. Furthermore, new laboratory limits have been put on the inverse coupling constant of ALPs to two photons and confirmation of previous limits on the fractional charge of millicharged particles is given

Evaluation of equilibrium moisture content in ligno-cellulosic residues of olive culture

The use of ligno-cellulosic residuals from agriculture as means for renewable energy production is well known; nonetheless significant problems still exist on development of bioenergy value chains. Moisture content and hygroscopicity are among these problems. Higher moisture content of the biomass means lower calorific value and higher perishability, hence storage difficulties. For this reason it is important to evaluate how the moisture content of the material varies while it is stored and how the calorific value of the feedstock is affected by it. The purpose of this study is to determine the variation of moisture content and its influence on lower calorific value (LCV) of four types of solid residual biomass: oven dried chipped olive tree trimmings, milled olive pomace; oven dried olive tree trimmings and fresh olive tree trimmings. Moisture content of the samples is calculated by means of thermogravimetric analysis (TGA) according to standard CEN/TS 14774-2:2004, while the LCVs are calculated by means of a calorimeter, following standard UNI EN 14918:2010. All the biomass samples were left to reach equilibrium moisture content (EMC) in a temperature and humidity controlled environment. Two different phases were analyzed with respect to moisture uptake rates: 1) fast moisture uptake rate phase (first four hours of exposure) and 2) slow moisture uptake rate, (the days following the first four hours of exposure). Samples experiencing fast moisture uptake rate, during the first four hours of exposure, were kept in a monitored ambient at T=22 \ub1 1oC and RH=59 \ub1 2%, while samples exposed to slow moisture uptake rate were kept in a climatic chamber at three different set of temperature and humidity controlled environment simulating the climatic conditions in different periods of the year in Enna province: 10oC - 80% RH (winter), 15oC - 70% RH (spring/autumn) and 20oC - 55% RH, (summer). The results obtained show that the olive pruning chips (0.425 mm to 1.00 mm and 1.00 mm to 2.00 mm particle size ranges) stored in a heap in a controlled climatic chamber require approximately 20 days to reach EMC. Depending on the particle size range EMCs reach the values of 6.2 and 7.5% by weight in the "summer" condition, 14.3% and 16.9% in "spring/autumn" condition, 24.1% and 28.2% in "winter" condition. Moisture is absorbed gradually over time and results show that in the first four hours, the dry sample exposed to ambient condition (T=22 \ub1 1 oC and RH=59 \ub1 2%) reaches a moisture content between 0.75 and 0.96% of its weight; the LCV at equilibrium is evaluated between 18, 576 J\u2022odg-1 and 18, 793 J\u2022odg-1, the higher value related to the bigger particle size range examined. Pomace heap under the same experimental set up and time period, reaches an equilibrium moisture content of 8.5% and 9.7% (summer conditions), 19.2% and 22.0% (spring/autumn condition) and between 30.9% and 34.1% (winter condition). Olive pomace accumulates moisture relatively faster than olive trimmings as dry sample recovers about 1.61% to 1.97% of moisture in the first four hours of exposure. The LCV at equilibrium is determined between 20, 145 J\u2022odg-1 and 20, 436 J\u2022odg-1. Pruning dried samples reach an EMC equal to 6.1% in approximately 25 days, with a LCV equal to18, 921 J\u2022odg-1 \ub1 1.9%. Heaps of fresh prunings reach an EMC of 8.2% in approximately 20 days; LCV of the feedstock is 19, 356 J\u2022odg-1\ub1 1.6%.\ua92006-2014 Asian Research Publishing Network (ARPN). All rights reserved

The PVLAS experiment: measuring vacuum magnetic birefringence and dichroism with a birefringent Fabry-Perot cavity

Vacuum magnetic birefringence was predicted long time ago and is still lacking a direct experimental confirmation. Several experimental efforts are striving to reach this goal, and the sequence of results promises a success in the next few years. This measurement generally is accompanied by the search for hypothetical light particles that couple to two photons. The PVLAS experiment employs a sensitive polarimeter based on a high finesse Fabry-Perot cavity. In this paper we report on the latest experimental results of this experiment. The data are analysed taking into account the intrinsic birefringence of the dielectric mirrors of the cavity. Besides the limit on the vacuum magnetic birefringence, the measurements also allow the model-independent exclusion of new regions in the parameter space of axion-like and milli-charged particles. In particular, these last limits hold also for all types of neutrinos, resulting in a laboratory limit on their charge

New PVLAS model independent limit for the axion coupling to γγ\gamma\gamma for axion masses above 1meV

During 2014 the PVLAS experiment has started data taking with a new apparatus installed at the INFN Section of Ferrara, Italy. The main target of the experiment is the observation of magnetic birefringence of vacuum. According to QED, the ellipticity generated by the magnetic birefringence of vacuum in the experimental apparatus is expected to be $\psi^{\rm(QED)} \approx 5\times10^{-11}$. No ellipticity signal is present so far with a noise floor $\psi^{\rm(noise)} \approx 2.5\times10^{-9}$ after 210 hours of data taking. The resulting ellipticity limit provides the best model independent upper limit on the coupling of axions to $\gamma\gamma$ for axion masses above $10^{-3}$eV

Measurement of the Cotton Mouton effect of water vapour

In this paper we report on a measurement of the Cotton Mouton effect of water vapour. Measurement performed at room temperature ($T=301$ K) with a wavelength of 1064 nm gave the value $\Delta n_u = (6.67 \pm 0.45) \cdot 10^{-15}$ for the unit magnetic birefringence (1 T magnetic field and atmospheric pressure)

First results from the new PVLAS apparatus: a new limit on vacuum magnetic birefringence

Several groups are carrying out experiments to observe and measure vacuum magnetic birefringence, predicted by Quantum Electrodynamics (QED). We have started running the new PVLAS apparatus installed in Ferrara, Italy, and have measured a noise floor value for the unitary field magnetic birefringence of vacuum $\Delta n_u^{\rm (vac)}= (4\pm 20) \times 10^{-23}$ T$^{-2}$ (the error represents a 1$\sigma$ deviation). This measurement is compatible with zero and hence represents a new limit on vacuum magnetic birefringence deriving from non linear electrodynamics. This result reduces to a factor 50 the gap to be overcome to measure for the first time the value of $\Delta n_u^{\rm (vac,QED)}$ predicted by QED: $\Delta n_u^{\rm (vac,QED)}= 4\times 10^{-24}$ ~T$^{-2}$. These birefringence measurements also yield improved model-independent bounds on the coupling constant of axion-like particles to two photons, for masses greater than 1 meV, along with a factor two improvement of the fractional charge limit on millicharged particles (fermions and scalars), including neutrinos

An experimental apparatus for measuring the Casimir effect at large distances

An experimental set-up for the measurement of the Casimir effect at separations larger than a few microns is presented. The apparatus is based on a mechanical resonator and uses a homodyne detection technique to sense the Casimir force in the plane-parallel configuration. First measurements in the 3-10 micrometer range show an unexpected large force probably due to patch effects.Comment: Proceedings of the workshop On the 60 Years on Casimir Effec

Hunter-gatherer mobility and territories in the dunefields of center Argentina

The distribution of certain rocks in the landscape allows us to reconstruct diverse aspects of past hunter-gatherer behavior. In this work, we evaluate the mobility patterns employed by these groups and the presence or absence of boundaries in the Aeolian system of the center of Argentina. To accomplish this objective, we consider two types of evidence: 1) raw material frequencies and distributions in three areas of this Aeolian System and 2) presence and frequency of knapping stones from Tandilia sources. We construct a fall-off curve that is based on the relationship between the frequency of an item and the distance to the source of supply. The characteristics of each area yielded the human groups that inhabited delineate different modes of exploitation of the rocks. The fall-off curve documents a steep drop-off between 300 and 350 km from the Tandilia source and the spatial analysis indicates that within this distance the source probably represents the threshold of direct access to the quarries. Tandilia stone-tools seem to systematically supply a relatively wide area of the Central Pampean Dunefields of the Pampa grasslands, through varied processes, but they arrive at very low frequencies over great distances. The presence of Tandilia rocks in the Western Pampean Dunefields and Western Pampas Sand Mantles and Dunefields indicates social interaction between human groups that shared some common technological knowledge. The presence of stones in the Central Pampean Dunefields coming from the xerophytic woodland of the Dry Pampas can be related with contacts and exchanges among the hunter-gatherer group that occupied different territories

The Global sphere reconstruction (GSR) - Demonstrating an independent implementation of the astrometric core solution for Gaia

Context. The Gaia ESA mission will estimate the astrometric and physical data of more than one billion objects, providing the largest and most precise catalog of absolute astrometry in the history of Astronomy. The core of this process, the so-called global sphere reconstruction, is represented by the reduction of a subset of these objects which will be used to define the celestial reference frame. As the Hipparcos mission showed, and as is inherent to all kinds of absolute measurements, possible errors in the data reduction can hardly be identified from the catalog, thus potentially introducing systematic errors in all derived work. Aims. Following up on the lessons learned from Hipparcos, our aim is thus to develop an independent sphere reconstruction method that contributes to guarantee the quality of the astrometric results without fully reproducing the main processing chain. Methods. Indeed, given the unfeasibility of a complete replica of the data reduction pipeline, an astrometric verification unit (AVU) was instituted by the Gaia Data Processing and Analysis Consortium (DPAC). One of its jobs is to implement and operate an independent global sphere reconstruction (GSR), parallel to the baseline one (AGIS, namely Astrometric Global Iterative Solution) but limited to the primary stars and for validation purposes, to compare the two results, and to report on any significant differences. Results. Tests performed on simulated data show that GSR is able to reproduce at the sub-$\mu$as level the results of the AGIS demonstration run presented in Lindegren et al. (2012). Conclusions. Further development is ongoing to improve on the treatment of real data and on the software modules that compare the AGIS and GSR solutions to identify possible discrepancies above the tolerance level set by the accuracy of the Gaia catalog.Comment: Accepted for publication on Astronomy & Astrophysic