scholarly journals Surface properties of icy transneptunian objects from the second ESO large program

2009 ◽  
Vol 5 (S263) ◽  
pp. 186-191
Author(s):  
Francesca E. DeMeo ◽  
Maria Antonietta Barucci ◽  
Alvaro Alvarez-Candal ◽  
Catherine de Bergh ◽  
Sonia Fornasier ◽  
...  
Keyword(s):  
Solar System ◽  
Surface Properties ◽  
New Technology ◽  
Outer Solar System ◽  
Large Telescope ◽  
Very Large Telescope ◽  
Large Program ◽  
Transneptunian Objects ◽  
Photometric Color

AbstractAn analysis is well underway for the data from the second Large Program (PI M. A. Barucci) dedicated to investigating the surface properties of Centaurs and Transneptunian objects through spectroscopic, photometric color, lightcurve, and polarimetric observations using the European Southern Observatory (ESO) Very Large Telescope (VLT) and New Technology Telescope (NTT). 45 objects were observed between 2006 and 2008, allowing a broad characterization of at least the largest and brightest objects among this population. In this report, we summarize all our findings, but focus on the analysis of the presence of ices such as methane, ethane, nitrogen, ammonia hydrate, methanol, and particularly H2O which is so abundant throughout the outer solar system.

scholarly journals From Passive Support Systems to the NTT Active Support

1984 ◽  
Vol 79 ◽  
pp. 23-40
Author(s):  
R.N. Wilson ◽  
F. Franza ◽  
L. Noethe
Keyword(s):  
Support System ◽  
Support Systems ◽  
New Technology ◽  
Study Phase ◽  
Large Telescope ◽  
Basic Principles ◽  
Very Large Telescope ◽  
Primary Support

ESO has two telescope projects: the NTT (New Technology Telescope) with 3.5 m aperture and the VLT (Very Large Telescope) with 16 m equivalent aperture. The former is already in the engineering phase and should be completed in 1987; the latter is still in the study phase and will be described at this conference by our colleague, D. Enard.This paper is concerned with the primary support system of the NTT. The basic principles and layout of this support have already been described in the literature 1,2,3).

scholarly journals Are the Dyson rings around pulsars detectable?

2017 ◽  
Vol 17 (2) ◽  
pp. 112-115 ◽  
Author(s):  
Z. Osmanov
Keyword(s):  
Neutron Star ◽  
Solar System ◽  
Spherical Shell ◽  
Angular Resolution ◽  
Wide Field ◽  
Large Telescope ◽  
Very Large Telescope ◽  
Freeman Dyson ◽  
Infrared Survey

AbstractIn the previous paper ring (Osmanov 2016) (henceforth Paper-I) we have extended the idea of Freeman Dyson and have shown that a supercivilization has to use ring-like megastructures around pulsars instead of a spherical shell. In this work we reexamine the same problem in the observational context and we show that facilities of modern infrared (IR) telescopes (Very Large Telescope Interferometer and Wide-field Infrared Survey Explorer (WISE)) might efficiently monitor the nearby zone of the solar system and search for the IR Dyson-rings up to distances of the order of 0.2 kpc, corresponding to the current highest achievable angular resolution, 0.001 mas. In this case the total number of pulsars in the observationally reachable area is about 64 ± 21. We show that pulsars from the distance of the order of ~ 1 kpc are still visible for WISE as point-like sources but in order to confirm that the object is the neutron star, one has to use the ultraviolet telescopes, which at this moment cannot provide enough sensitivity.

scholarly journals Unusual polarimetric properties for interstellar comet 2I/Borisov

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
S. Bagnulo ◽  
A. Cellino ◽  
L. Kolokolova ◽  
R. Nežič ◽  
T. Santana-Ros ◽  
...  
Keyword(s):  
Solar System ◽  
Physical Characteristics ◽  
Dust Particles ◽  
The Sun ◽  
Large Telescope ◽  
European Southern Observatory ◽  
Long Period ◽  
Very Large Telescope ◽  
Cometary Activity

AbstractSo far, only two interstellar objects have been observed within our Solar System. While the first one, 1I/‘Oumuamua, had asteroidal characteristics, the second one, 2I/Borisov, showed clear evidence of cometary activity. We performed polarimetric observations of comet 2I/Borisov using the European Southern Observatory Very Large Telescope to derive the physical characteristics of its coma dust particles. Here we show that the polarization of 2I/Borisov is higher than what is typically measured for Solar System comets. This feature distinguishes 2I/Borisov from dynamically evolved objects such as Jupiter-family and all short- and long-period comets in our Solar System. The only object with similar polarimetric properties as 2I/Borisov is comet C/1995 O1 (Hale-Bopp), an object that is believed to have approached the Sun only once before its apparition in 1997. Unlike Hale-Bopp and many other comets, though, comet 2I/Borisov shows a polarimetrically homogeneous coma, suggesting that it is an even more pristine object.

scholarly journals Detection and characterization of two VLM binaries: LP 1033-31 and LP 877-72

2020 ◽  
Vol 498 (1) ◽  
pp. 737-749
Author(s):  
Subhajeet Karmakar ◽  
A S Rajpurohit ◽  
F Allard ◽  
D Homeier
Keyword(s):  
Adaptive Optics ◽  
Spectral Type ◽  
Near Infrared ◽  
Binding Energies ◽  
Secondary Component ◽  
Large Telescope ◽  
Very Large Telescope ◽  
Adaptive Optics Imaging ◽  
M Dwarf

ABSTRACT Using the high-resolution near-infrared adaptive optics imaging from the NaCo instrument at the Very Large Telescope, we report the discovery of a new binary companion to the M-dwarf LP 1033-31 and also confirm the binarity of LP 877-72. We have characterized both the stellar systems and estimated the properties of their individual components. We have found that LP 1033-31 AB with the spectral type of M4.5+M4.5 has a projected separation of 6.7 ± 1.3 AU. Whereas with the spectral type of M1+M4, the projected separation of LP 877-72 AB is estimated to be 45.8 ± 0.3 AU. The binary companions of LP 1033-31 AB are found to have similar masses, radii, effective temperatures, and log g with the estimated values of 0.20 ± 0.04 $\rm {M}_{\odot }$, 0.22 ± 0.03 $\rm {R}_{\odot }$, and 3200 K, 5.06 ± 0.04. However, the primary of LP 877-72 AB is found to be twice as massive as the secondary with the derived mass of 0.520 ± 0.006 $\rm {M}_{\odot }$. The radius and log g for the primary of LP 877-72 AB are found to be 1.8 and 0.95 times that of the secondary component with the estimated values of 0.492 ± 0.011 $\rm {R}_{\odot }$ and 4.768 ± 0.005, respectively. With an effective temperature of 3750 ± 15 K, the primary of LP 877-72 AB is also estimated to be ∼400 K hotter than the secondary component. We have also estimated the orbital period of LP 1033-31 and LP 877-72 to be ∼28 and ∼349 yr, respectively. The binding energies for both systems are found to be >1043 erg, which signifies that both systems are stable.

scholarly journals Characterization of the ground layer of turbulence at Paranal using a robotic SLODAR system

2019 ◽  
Vol 492 (1) ◽  
pp. 934-949
Author(s):  
T Butterley ◽  
R W Wilson ◽  
M Sarazin ◽  
C M Dubbeldam ◽  
J Osborn ◽  
...  
Keyword(s):  
Vertical Profile ◽  
Ground Level ◽  
Ground Layer ◽  
Weak Turbulence ◽  
Large Telescope ◽  
Active Optics ◽  
Very Large Telescope ◽  
Statistical Results ◽  
Good Agreement

ABSTRACT We describe the implementation of a robotic SLODAR instrument at the Cerro Paranal observatory. The instrument measures the vertical profile of the optical atmospheric turbulence strength, in 8 resolution elements, to a maximum altitude ranging between 100 and 500 m. We present statistical results of measurements of the turbulence profile on a total of 875 nights between 2014 and 2018. The vertical profile of the ground layer of turbulence is very varied, but in the median case most of the turbulence strength in the ground layer is concentrated within the first 50 m altitude, with relatively weak turbulence at higher altitudes up to 500 m. We find good agreement between measurements of the seeing angle from the SLODAR and from the Paranal DIMM seeing monitor, and also for seeing values extracted from the Shack–Hartmann active optics sensor of Very Large Telescope (VLT) Unit Telescope 1 (UT1), adjusting for the height of each instrument above ground level. The SLODAR data suggest that a median improvement in the seeing angle from 0.689 to 0.481 arcsec at wavelength 500 nm would be obtained by fully correcting the ground-layer turbulence between the height of the UTs (taken as 10 m) and altitude 500 m.

scholarly journals Characterization of the Zonal Wind Flow in the Upper Atmosphere of Titan with the VLT

2005 ◽  
Vol 13 ◽  
pp. 897-897
Author(s):  
Régis Courtin ◽  
David Luz ◽  
Daniel Gautier ◽  
Thierry Appourchaux ◽  
Jean-Pierre Lebreton ◽  
...  
Keyword(s):  
High Resolution ◽  
Zonal Wind ◽  
Upper Atmosphere ◽  
Wind Flow ◽  
Large Telescope ◽  
Spectroscopic Observations ◽  
Very Large Telescope

AbstractWe report on recent efforts to characterize the zonal wind flow in the upper atmosphere of Titan from high resolution spectroscopic observations with the Very Large Telescope.

scholarly journals Astrometric and photometric accuracies in high contrast imaging: The SPHERE speckle calibration tool (SpeCal)

2018 ◽  
Vol 615 ◽  
pp. A92 ◽  
Author(s):  
R. Galicher ◽  
A. Boccaletti ◽  
D. Mesa ◽  
P. Delorme ◽  
R. Gratton ◽  
...  
Keyword(s):  
Circumstellar Disks ◽  
Observation Time ◽  
High Contrast ◽  
Large Telescope ◽  
Contrast Imaging ◽  
High Contrast Imaging ◽  
Very Large Telescope ◽  
User Friendly ◽  
Calibration Tool

Context. The consortium of the Spectro-Polarimetric High-contrast Exoplanet REsearch installed at the Very Large Telescope (SPHERE/VLT) has been operating its guaranteed observation time (260 nights over five years) since February 2015. The main part of this time (200 nights) is dedicated to the detection and characterization of young and giant exoplanets on wide orbits. Aims. The large amount of data must be uniformly processed so that accurate and homogeneous measurements of photometry and astrometry can be obtained for any source in the field. Methods. To complement the European Southern Observatory pipeline, the SPHERE consortium developed a dedicated piece of software to process the data. First, the software corrects for instrumental artifacts. Then, it uses the speckle calibration tool (SpeCal) to minimize the stellar light halo that prevents us from detecting faint sources like exoplanets or circumstellar disks. SpeCal is meant to extract the astrometry and photometry of detected point-like sources (exoplanets, brown dwarfs, or background sources). SpeCal was intensively tested to ensure the consistency of all reduced images (cADI, Loci, TLoci, PCA, and others) for any SPHERE observing strategy (ADI, SDI, ASDI as well as the accuracy of the astrometry and photometry of detected point-like sources. Results. SpeCal is robust, user friendly, and efficient at detecting and characterizing point-like sources in high contrast images. It is used to process all SPHERE data systematically, and its outputs have been used for most of the SPHERE consortium papers to date. SpeCal is also a useful framework to compare different algorithms using various sets of data (different observing modes and conditions). Finally, our tests show that the extracted astrometry and photometry are accurate and not biased.

Characterization of RF Sputtered ZnO Piezoelectric Films Using Transmission Electron Microscope

1975 ◽  
Vol 33 ◽  
pp. 86-87
Author(s):  
Kemining W. Yeh ◽  
Richard S. Muller ◽  
Wei-Kuo Wu ◽  
Jack Washburn
Keyword(s):  
Integrated Circuit ◽  
Acoustic Waves ◽  
New Technology ◽  
Surface Acoustic Waves ◽  
Electromechanical Properties ◽  
Leading Role ◽  
Saw Devices ◽  
Transmission Electron ◽  
High Degree

Considerable and continuing interest has been shown in the thin film transducer fabrication for surface acoustic waves (SAW) in the past few years. Due to the high degree of miniaturization, compatibility with silicon integrated circuit technology, simplicity and ease of design, this new technology has played an important role in the design of new devices for communications and signal processing. Among the commonly used piezoelectric thin films, ZnO generally yields superior electromechanical properties and is expected to play a leading role in the development of SAW devices.

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