scholarly journals Distances of Stars by mean of the Phase-lag Method

2017 ◽  
Vol 13 (S336) ◽  
pp. 381-384
Author(s):  
Sandra Etoka ◽  
Dieter Engels ◽  
Eric Gérard ◽  
Anita M. S. Richards
Keyword(s):  
Monitoring Program ◽  
High Sensitivity ◽  
Mass Range ◽  
Asymptotic Giant Branch ◽  
Circumstellar Envelope ◽  
Phase Lag ◽  
Agb Stars ◽  
The Galaxy ◽  
Term Monitoring

AbstractVariable OH/IR stars are Asymptotic Giant Branch (AGB) stars with an optically thick circumstellar envelope that emit strong OH 1612 MHz emission. They are commonly observed throughout the Galaxy but also in the LMC and SMC. Hence, the precise inference of the distances of these stars will ultimately result in better constraints on their mass range in different metallicity environments. Through a multi-year long-term monitoring program at the Nancay Radio telescope (NRT) and a complementary high-sensitivity mapping campaign at the eMERLIN and JVLA to measure precisely the angular diameter of the envelopes, we have been re-exploring distance determination through the phase-lag method for a sample of stars, in order to refine the poorly-constrained distances of some and infer the currently unknown distances of others. We present here an update of this project.

scholarly journals VLBI monitoring of Mira variables with VERA

2007 ◽  
Vol 3 (S242) ◽  
pp. 326-327
Author(s):  
A. Nakagawa ◽  
T. Omodaka ◽  
K. M. Shibata ◽  
T. Kurayama ◽  
H. Imai ◽  
...  
Keyword(s):  
Monitoring Program ◽  
Asymptotic Giant Branch ◽  
Agb Stars ◽  
Current Analysis ◽  
Mira Variables ◽  
Vlbi Observations ◽  
The Galaxy ◽  
Absolute Magnitudes ◽  
Infrared Monitoring ◽  
Good Coverage

AbstractWe have started a VLBI monitoring program for Asymptotic Giant Branch (AGB) stars at 22 and 43 GHz as part of a project of the VLBI Exploration of Radio Astrometry (VERA) for precisely obtaining the period-luminosity (PL) relation of Galactic Mira variables. Using accurate distances measured with VERA, we reveal PL relation in the Galaxy based on the absolute magnitudes of the sources. We selected the sources for VLBI monitoring so that they have a good coverage of various pulsation periods. Photometry in the infrared J, H, and K bands for over 600 AGB stars has also started since 2003 with the 1m telescope of Kagoshima University to obtain the pulsation periods and magnitudes. Current analysis of the phase referencing VLBI observations of S Crt shows that the parallax of 2.3±0.2 milliarcsec (mas) corresponds to a distance of 435+41−35 pc. From the infrared monitoring data, pulsation periods and magnitudes in K band for 248 sources were obtained.

Distribution and Abundance of Odonata Species Across Massachusetts: Results of a Long-term Monitoring Program

2016 ◽  
Vol 23 (4) ◽  
pp. 501-524 ◽  
Author(s):  
Robert Buchsbaum ◽  
Christopher W. Leahy ◽  
Taber Allison
Keyword(s):  
Monitoring Program ◽  
Long Term Monitoring ◽  
Term Monitoring

Development and Assembly of a MEMS Based High-Sensitivity Relative Gravimeter for Multi-Pixel Imaging Applications 

2021 ◽  
Author(s):  
Karl Toland ◽  
Abhinav Prasad ◽  
Andreas Noack ◽  
Kristian Anastasiou ◽  
Richard Middlemiss ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Cost Effective ◽  
Mount Etna ◽  
Earth Tides ◽  
Gravity Measurements ◽  
Stepper Motors ◽  
Long Term Monitoring ◽  
The Stability ◽  
Term Monitoring

<p>The manufacture and production of a high-sensitivity cost-effective gravimeter has the potential to change the methodology and efficiency of gravity measurements. Currently, the most common method to conduct a survey is by using a single gravimeter, usually costing tens of thousands of Dollars, with measurements taken at multiple locations to obtain the required data. The availability of a cost-effective gravimeter however would allow the user to install multiple gravimeters, at the same cost of a single gravimeter, to increase the efficiency of surveys and long-term monitoring.  </p><p> </p><p>Since the previous reporting on a low-drift relative MEMS gravimeter for multi-pixel imaging applications (Prasad, A. et al, EGU2020-18528), significant progress has been made in the development and assembly of the previously reported system. Field prototypes have been manufactured and undergone significant testing to investigate the stability and robustness of the system in preparation for the deployment of multiple devices as part of the gravity imager on Mount Etna. The device, known as Wee-g, has several key features which makes it an attractive prospect in the field of gravimetry. Examples of these features are that the Wee-g is small and portable with the ability to connect to the device remotely, can be powered through a mains connected power supply, or through portable batteries, weighs under 4kg, has a low power consumption during normal use of 5W, correct for tilt through manual adjustments or remotely through integrated stepper motors with a total tilt correction range of 5 degrees, the ability to read out tilt of the device through an inclinometer for either alignment or long term monitoring and numerous temperature sensors and heater servos to control the temperature of the MEMS to <1mK.</p><p> </p><p>This presentation aims to report on the progress that has been achieved in the development and manufacturing of the prototype devices, various testing of the devices under various laboratory conditions (such as the measurements of the Earth tides, and a relative measurement of gravity at various floor levels), as well as additional applications that are to be explored in 2021. </p>

Census of the Brown Hare (Lepus europaeus) at Leveste, Municipality of Gehrden, Germany

2013 ◽  
pp. 168-171
Author(s):  
Gabor von Bethlenfalvy ◽  
Julia Hindersin ◽  
Egbert Strauß
Keyword(s):  
Arable Land ◽  
Monitoring Program ◽  
Lepus Europaeus ◽  
Brown Hare ◽  
Lower Saxony ◽  
Long Term Monitoring ◽  
Term Monitoring

The case study used spotlight strip census routes to estimate Brown Hare numbers in a 793 ha hunting district. The habitats, dominated by intensively farmed arable land were also mapped. This is part of a Germany-wide long-term monitoring program of game populations which is carried out by hunters and was initiated by the German Hunters’ Association and the Hunters’ Association of Lower Saxony in 2001.

scholarly journals Two practical approaches to monitoring the zooplanktonic community at Lago Grande do Curuai, Pará, Brazil

2015 ◽  
Vol 45 (3) ◽  
pp. 293-298 ◽  
Author(s):  
Leonardo Fernandes GOMES ◽  
Ludgero Cardoso Galli VIEIRA ◽  
Marie Paule BONNET
Keyword(s):  
Spatial Distribution ◽  
Monitoring Program ◽  
Zooplankton Community ◽  
Species Level ◽  
Genus Level ◽  
Time Costs ◽  
Financial Costs ◽  
Long Term Monitoring ◽  
Term Monitoring

The use of substitute groups in biomonitoring programs has been proposed to minimize the high financial costs and time for samples processing. The objectives of this study were to evaluate the correlation between (i) the spatial distribution among the major zooplankton groups (cladocerans, copepods, rotifers, and testaceans protozoa), (ii) the data of density and presence/absence of species, and (iii) the data of species, genera, and families from samples collected in the Lago Grande do Curuai, Pará, Brazil. A total of 55 sample of the zooplanktonic community was collected, with 28 samples obtained in March and 27 in September, 2013. The agreement between the different sets of data was assessed using Mantel and Procrustes tests. Our results indicated high correlations between genus level and species level and high correlations between presence/absence of species and abundance, regardless of the seasonal period. These results suggest that zooplankton community could be incorporated in a long-term monitoring program at relatively low financial and time costs.

Differential Surface Plasmon Resonance Sensor for the Detection of Chemicals and Biochemicals

2013 ◽  
Vol 543 ◽  
pp. 310-313 ◽  
Author(s):  
Carmelo Fallauto ◽  
Guido Perrone ◽  
Alberto Vallan
Keyword(s):  
Surface Plasmon Resonance ◽  
Surface Plasmon ◽  
Plasmon Resonance ◽  
High Sensitivity ◽  
Practical Implementation ◽  
Resonance Sensor ◽  
Order Of Magnitude ◽  
Long Term Monitoring ◽  
Term Monitoring

Surface plasmon resonance is one the most common optical sensing techniques for the detection of chemicals and biochemicals, although still mainly confined to lab applications. Typically, these sensors are made by a thin gold layer deposited on a glass prism or on an optical fiber similar to those used in telecom applications. Key advantages of this technique are the possibility to specifically detect different chemicals through functionalization of the metal surface and the high sensitivity, although the latter may turn into a weakness in long term monitoring applications due to cross-sensitivity to parasitic effects. To overcome this limitation the paper proposes a novel sensor implementation with a cascaded double sensing area, particularly suited for long term monitoring of pollutant since one sensing area is actually used to detect the desired molecules, while the other for compensating drifts due to fluctuations, misalignments and temperature variations. The paper addresses mainly the prism-based implementation, but the proposed configuration is suited also for an all-fiber approach. Examples of practical implementation of the proposed techniques are given, evidencing an accuracy improvement of more than an order of magnitude.

Millimetre Observations of Evolved Stars

1996 ◽  
Vol 13 (2) ◽  
pp. 185-186
Author(s):  
Jessica M. Chapman
Keyword(s):  
Mass Loss ◽  
Stellar Atmosphere ◽  
Asymptotic Giant Branch ◽  
High Mass ◽  
Circumstellar Envelope ◽  
Agb Stars ◽  
Circumstellar Envelopes ◽  
Evolved Stars ◽  
High Mass Loss ◽  
Transfer Momentum

Radio emission at centimetre and millimetre wavelengths provides a powerful tool for studying the circumstellar envelopes of evolved stars. These include stars on the asymptotic giant branch (AGB), post-AGB stars and a small number of massive M-type supergiant stars. The AGB stars and M-type supergiants are characterised by extremely high mass-loss rates. The mass loss in such an evolved star is driven by radiation pressure acting on grains which form in the outer stellar atmosphere. The grains are accelerated outwards and transfer momentum to the gas through grain–gas collisions. The outflowing dust and gas thus form an expanding circumstellar envelope through which matter flows from the star to the interstellar medium, at a typical velocity of 15 km s−1. For a recent review of circumstellar mass loss see Chapman, Habing & Killeen (1995).

scholarly journals On the Mass and Metallicity Distributions of the Parent AGB Stars of O-Rich Presolar Stardust Grains

2009 ◽  
Vol 26 (3) ◽  
pp. 271-277 ◽  
Author(s):  
Larry R. Nittler
Keyword(s):  
Molecular Clouds ◽  
Asymptotic Giant Branch ◽  
Agb Stars ◽  
Isotopic Data ◽  
Intermediate Mass ◽  
Presolar Grains ◽  
Model Predictions ◽  
The Galaxy ◽  
Low Metallicity ◽  
The Masses

AbstractPresolar grains in meteorites formed in a sample of Asymptotic Giant Branch (AGB) stars that ended their lives within ≈1 Gyr of the origin of the Solar System 4.6 Gyr ago. The O-isotopic compositions of presolar O-rich stardust reflect the masses and metallicities of their parent stars. We present simple Monte Carlo simulations of the parent AGB stars of presolar grains. Comparison of model predictions with the grain data allow some broad conclusions to be drawn: (1) Presolar O-rich grains formed in AGB stars of mass ∼1.15–2.2 M⊙. The upper-mass cutoff reflects dredge-up of C in more massive AGB stars, leading to C-rich dust rather than O-rich, but the lack of grains from intermediate-mass AGB stars (>4 M⊙) is a major puzzle; (2) The grain O-isotopic data are reproduced well if the Galaxy in presolar times was assumed to have a moderate age-metallicity relationship, but with significant metallicity scatter for stars born at the same time; (3) The Sun appears to have a moderately low metallicity for its age and/or unusual 17O/16O and 18O/16O ratios for its metallicity; and (4) The Solar 17O/18O ratio, while unusual relative to present-day molecular clouds and protostars, was not atypical for the presolar disk and does not require self-pollution of the protosolar molecular cloud by supernova ejecta.

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