Fabrication of Rod-Connected Diamond Structures at Optical Wavelengths by Micromanipulation

2006 ◽  
Author(s):  
Kanna Aoki ◽  
Satoshi Iwamoto ◽  
Yasuhiko Arakawa
Keyword(s):  
Optical Wavelengths

scholarly journals Variability of young stellar objects in the star-forming region Pelican Nebula

2019 ◽  
Vol 627 ◽  
pp. A135 ◽  
Author(s):  
A. Bhardwaj ◽  
N. Panwar ◽  
G. J. Herczeg ◽  
W. P. Chen ◽  
H. P. Singh
Keyword(s):  
Main Sequence ◽  
T Tauri Stars ◽  
Young Stellar Objects ◽  
Spectral Energy ◽  
Physical Parameters ◽  
Main Sequence Stars ◽  
Stellar Objects ◽  
Star Forming ◽  
T Tauri ◽  
Optical Wavelengths

Context. Pre-main-sequence variability characteristics can be used to probe the physical processes leading to the formation and initial evolution of both stars and planets. Aims. The photometric variability of pre-main-sequence stars is studied at optical wavelengths to explore star–disk interactions, accretion, spots, and other physical mechanisms associated with young stellar objects. Methods. We observed a field of 16′ × 16′ in the star-forming region Pelican Nebula (IC 5070) at BVRI wavelengths for 90 nights spread over one year in 2012−2013. More than 250 epochs in the VRI bands are used to identify and classify variables up to V ∼ 21 mag. Their physical association with the cluster IC 5070 is established based on the parallaxes and proper motions from the Gaia second data release (DR2). Multiwavelength photometric data are used to estimate physical parameters based on the isochrone fitting and spectral energy distributions. Results. We present a catalog of optical time-series photometry with periods, mean magnitudes, and classifications for 95 variable stars including 67 pre-main-sequence variables towards star-forming region IC 5070. The pre-main-sequence variables are further classified as candidate classical T Tauri and weak-line T Tauri stars based on their light curve variations and the locations on the color-color and color-magnitude diagrams using optical and infrared data together with Gaia DR2 astrometry. Classical T Tauri stars display variability amplitudes up to three times the maximum fluctuation in disk-free weak-line T Tauri stars, which show strong periodic variations. Short-term variability is missed in our photometry within single nights. Several classical T Tauri stars display long-lasting (≥10 days) single or multiple fading and brightening events of up to two magnitudes at optical wavelengths. The typical mass and age of the pre-main-sequence variables from the isochrone fitting and spectral energy distributions are estimated to be ≤1 M⊙ and ∼2 Myr, respectively. We do not find any correlation between the optical amplitudes or periods with the physical parameters (mass and age) of pre-main-sequence stars. Conclusions. The low-mass pre-main-sequence stars in the Pelican Nebula region display distinct variability and color trends and nearly 30% of the variables exhibit strong periodic signatures attributed to cold spot modulations. In the case of accretion bursts and extinction events, the average amplitudes are larger than one magnitude at optical wavelengths. These optical magnitude fluctuations are stable on a timescale of one year.

scholarly journals NGC 7679: an anomalous, composite Seyfert 1 galaxy whose X-ray luminous AGN vanishes at optical wavelengths

2006 ◽  
Vol 447 (2) ◽  
pp. 441-451 ◽  
Author(s):  
L. M. Buson ◽  
M. Cappellari ◽  
E. M. Corsini ◽  
E. V. Held ◽  
J. Lim ◽  
...  
Keyword(s):  
X Ray ◽  
Optical Wavelengths

25-m telescope for optical wavelengths

1993 ◽  
Author(s):  
Arne L. Ardeberg ◽  
Torben Andersen ◽  
Mette Owner-Petersen ◽  
Tapio K. Korhonen
Keyword(s):  
Optical Wavelengths

3-Dimensional Photonic Crystals at Optical Wavelengths

1998 ◽  
Vol 07 (02) ◽  
pp. 181-200 ◽  
Author(s):  
S. G. Romanov
Keyword(s):  
Photonic Crystals ◽  
Band Gap ◽  
Photonic Band Gap ◽  
Stop Band ◽  
High Refractive Index ◽  
3 Dimensional ◽  
Optical Wavelength ◽  
Photonic Band Gap Materials ◽  
Optical Wavelengths ◽  
Photonic Band

Different experimental strategies towards the 3-dimensional photonic crystals operating at optical wavelength are classified. The detailed discussion is devoted to the recent progress in photonic crystals fabricated by template method — the photonic band gap materials on the base of opal. The control of photonic properties of opal-based gratings is achieved through impregnating the opal with high refractive index semiconductors and dielectrics. Experimental study demonstrated the dependence of the stop band behaviour upon the type of impregnation (complete or partial) and showed a way for approaching complete photonic band gap. The photoluminescence from opal- semiconductor gratings revealed suppression of spontaneous emission in the gap region with following enhancement of the emission efficiency at the low-energy edge of the gap.

scholarly journals The Breakthrough Listen search for intelligent life: Wide-bandwidth digital instrumentation for the CSIRO Parkes 64-m telescope

2018 ◽  
Vol 35 ◽  
Author(s):  
Danny C. Price ◽  
David H. E. MacMahon ◽  
Matt Lebofsky ◽  
Steve Croft ◽  
David DeBoer ◽  
...  
Keyword(s):  
New South ◽  
Recording System ◽  
Ultra Wideband ◽  
Digital Data ◽  
Single Beam ◽  
Digital Instrumentation ◽  
South Wales ◽  
Optical Wavelengths ◽  
Performance Results ◽  
Beam Mode

AbstractBreakthrough Listen is a 10-yr initiative to search for signatures of technologies created by extraterrestrial civilisations at radio and optical wavelengths. Here, we detail the digital data recording system deployed for Breakthrough Listen observations at the 64-m aperture CSIRO Parkes Telescope in New South Wales, Australia. The recording system currently implements two modes: a dual-polarisation, 1.125-GHz bandwidth mode for single-beam observations, and a 26-input, 308-MHz bandwidth mode for the 21-cm multibeam receiver. The system is also designed to support a 3-GHz single-beam mode for the forthcoming Parkes ultra-wideband feed. In this paper, we present details of the system architecture, provide an overview of hardware and software, and present initial performance results.

Metamaterial Window Glass for Adaptable Energy Efficiency

2013 ◽  
Author(s):  
Alex Heltzel ◽  
Tyler Mann ◽  
John R. Howell
Keyword(s):  
Energy Efficiency ◽  
Computational Analysis ◽  
Near Infrared ◽  
Window Glass ◽  
Sustainable Construction ◽  
Nanometer Scale ◽  
Glass Technology ◽  
Optical Wavelengths ◽  
Window Design ◽  
Difference Time

A computational analysis of a metamaterial (MTM) window design is presented for the purpose of increasing the energy efficiency of buildings in seasonal or cold climates. Commercial low-emissivity windows use nanometer-scale Ag films to reflect infrared energy, while retaining most transmission of optical wavelengths for functionality. An opportunity exists to further increase efficiency through a variable emissivity implementation of Ag thin-film structures. 3-D finite-difference time-domain simulations predict nonlinear absorption of near-infrared energy, providing the means to capture a substantial portion of solar energy during cold periods. The effect of various configuration parameters is quantified, with prediction of the net sustainability advantage. MTM window glass technology can be realized as a modification to current, commercial low-emissivity windows through the application of nanomanufactured films, creating the opportunity for both new and after-market sustainable construction.

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