Building the cosmic distance scale: from Hipparcos to Gaia

Hipparcos, the first ever experiment of global astrometry, was launched by ESA in 1989 and its results published in 1997 (Perryman et al., Astron. Astrophys. 323, L49, 1997; Perryman & ESA (eds), The Hipparcos and Tycho catalogues, ESA SP-1200, 1997). A new reduction was later performed using an improved satellite attitude reconstruction leading to an improved accuracy for stars brighter than 9th magnitude (van Leeuwen & Fantino, Astron. Astrophys. 439, 791, 2005; van Leeuwen, Astron. Astrophys. 474, 653, 2007). The Hipparcos Catalogue provided an extended dataset of very accurate astrometric data (positions, trigonometric parallaxes and proper motions), enlarging by two orders of magnitude the quantity and quality of distance determinations and luminosity calibrations. The availability of more than 20000 stars with a trigonometric parallax known to better than 10% opened the way to a drastic revision of our 3-D knowledge of the solar neighbourhood and to a renewal of the calibration of many distance indicators and age estimations. The prospects opened by Gaia, the next ESA cornerstone, planned for launch in June 2013 (Perryman et al., Astron. Astrophys. 369, 339, 2001), are still much more dramatic: a billion objects with systematic and quasi simultaneous astrometric, spectrophotometric and spectroscopic observations, about 150 million stars with expected distances to better than 10%, all over the Galaxy. All stellar distance indicators, in very large numbers, will be directly measured, providing a direct calibration of their luminosity and making possible detailed studies of the impacts of various effects linked to chemical element abundances, age or cluster membership. With the help of simulations of the data expected from Gaia, obtained from the mission simulator developed by DPAC, we will illustrate what Gaia can provide with some selected examples.Comment: 16 pages, 16 figures, Conference "The Fundamental Cosmic Distance scale: State of the Art and the Gaia perspective, 3-6 May 2011, INAF, Osservatorio Astronomico di Capodimonte, Naples. Accepted for publication in Astrophysics & Space Scienc

The Arctic

peer reviewe

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Not AvailableBACKGROUND Protein hydrolysate powder was prepared from non‐penaeid shrimp (Acetes indicus) by enzymatic hydrolysis using Alcalase enzyme. Extraction conditions such as pH (6.5, 7.5 and 8.5), enzyme to substrate ratio and temperature were optimized against the degree of hydrolysis using response surface methodology. RESULTS Protein hydrolysate comprised of 740 g per kilogram protein, 150 g per kilogram ash and 90 g per kilogram fat contents. The amino acid score showed superior attributes with 56% essential amino acids. Furthermore, the functional properties of spray‐dried protein hydrolysates were evaluated. Protein solubility was found to be the 90.20% at pH 2 and 96.92% at pH 12. Emulsifying properties were found to vary with the concentration of protein hydrolysates and the highest emulsifying capacity and emulsion stability were found at a concentration of 20 mg per millilitre. The highest and the lowest foaming capacity were observed at pH 6 and pH 10 with a concentration of 20 mg per millilitre. The water holding capacity of protein hydrolysate was found to increase with concentration, with a value of 5.4 mL per gram at a concentration of 20 mg per millilitre. CONCLUSION The results of the present study indicate that the use of A. indicus for the production of protein hydrolysate has good functional properties and nutritional value, rendering it suitable for broad industrial food applications.Not Availabl

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Not AvailableThe natural biopolymer, chitin is a structural polysaccharide synthesized by numerous living organisms, which has gained great interest due to its versatile biological activities and distinctive physicochemical properties. In spite of the general occurrence of chitin, so far, the major sources are crab and shrimp shells from marine processing wastes. However, the conventional methods of chitin extraction make use of extremely harsh chemicals such as acids and bases at high temperatures for long durations resulting in final inconsistent physicochemical properties in the final product and environmental pollution. Therefore, a much needed alternative eco-friendly approach would be the use of low-cost commercial enzymes such as papain/pepsin for deproteinization of shell wastes. In the present study, protein hydrolysate was produced through enzymatic hydrolysis of paste shrimp (Acetes spp.) which forms a major group of bycatch in Maharashtra and Gujarat Coasts and the residual shell was utilized for bio-extraction of chitin. This facilitates the complete utilization of Acetes spp. for the production of peptides and chitin, both of which act as bioactive molecules. The extraction conditions, viz., enzyme/substrate ratio (E/S), temperature and time were optimized using Response Surface Methodology for attaining maximum degree of deproteinization. For papain and pepsin hydrolysis, the degree of deproteinization was 96.5% and 89.5% respectively while the optimum extraction conditions obtained for papain were: pH-7.0, E/S (%)-2.1 and temperature-52p C and those for pepsin were: pH-3.1, E/S (%)-1.5 and temperature-37p C. These results suggest that enzymatic deproteinization of the shell residue obtained following protein hydrolysate extraction, could be a prominent eco-friendly strategy to produce chitin.Not Availabl

Analysis of a marine phototrophic biofilm by confocal laser scanning microscopy using the new image quantification software PHLIP

Applied Science

First discoveries and localizations of Fast Radio Bursts with MeerTRAP: real-time, commensal MeerKAT survey

International audienceWe report on the discovery and localization of fast radio bursts (FRBs) from the MeerTRAP project, a commensal fast radio transient-detection programme at MeerKAT in South Africa. Our hybrid approach combines a coherent search with an average field-of-view (FoV) of 0.4 |$\rm deg^{2}$| with an incoherent search utilizing a FoV of ∼1.27 |$\rm deg^{2}$| (both at 1284 MHz). Here, we present results on the first three FRBs: FRB 20200413A (DM = 1990.05 pc cm^−3), FRB 20200915A (DM = 740.65 pc cm^−3), and FRB 20201123A (DM = 433.55 pc cm^−3). FRB 20200413A was discovered only in the incoherent beam. FRB 20200915A (also discovered only in the incoherent beam) shows speckled emission in the dynamic spectrum, which cannot be explained by interstellar scintillation in our Galaxy or plasma lensing, and might be intrinsic to the source. FRB 20201123A shows a faint post-cursor burst of about 200 ms after the main burst and warrants further follow-up to confirm whether it is a repeating FRB. FRB 20201123A also exhibits significant temporal broadening, consistent with scattering, by a turbulent medium. The broadening exceeds from what is predicted for the medium along the sightline through our Galaxy. We associate this scattering with the turbulent medium in the environment of the FRB in the host galaxy. Within the approximately 1 arcmin localization region of FRB 20201123A, we identify one luminous galaxy (r ≈ 15.67; J173438.35-504550.4) that dominates the posterior probability for a host association. The galaxy’s measured properties are consistent with other FRB hosts with secure associations