scholarly journals The effect of surface gravity on line-depth ratios in the wavelength range 0.97–1.32 µm

2020 ◽  
Vol 494 (2) ◽  
pp. 1724-1734
Author(s):  
Mingjie Jian ◽  
Daisuke Taniguchi ◽  
Noriyuki Matsunaga ◽  
Naoto Kobayashi ◽  
Yuji Ikeda ◽  
...  
Keyword(s):  
Spectral Lines ◽  
Surface Gravity ◽  
Line Pair ◽  
On Line ◽  
Optical Wavelengths ◽  
The Difference ◽  
Band Spectra ◽  
Parameter Ranges ◽  
Line Depth ◽  
Effect Of Surface

ABSTRACT A line-depth ratio (LDR) of two spectral lines with different excitation potentials is expected to be correlated with the effective temperature (Teff). It is possible to determine Teff of a star with a precision of tens of Kelvin if dozens or hundreds of tight LDR–Teff relations can be used. Most of the previous studies on the LDR method were limited to optical wavelengths, but Taniguchi and collaborators reported 81 LDR relations in the YJ band, 0.97–1.32 µm, in 2018. However, with their sample of only 10 giants, it was impossible to account for the effects of surface gravity and metallicity on the LDRs well. Here, we investigate the gravity effect based on YJ-band spectra of 63 stars including dwarfs, giants, and supergiants observed with the WINERED spectrograph. We found that some LDR–Teff relations show clear offsets between the sequence of dwarfs and those of giants/supergiants. The difference between the ionization potentials of the elements considered in each line pair and the corresponding difference in the depths can, at least partly, explain the dependency of the LDR on the surface gravity. In order to expand the stellar parameter ranges that the LDR method can cover with high precision, we obtained new sets of LDR–Teff relations for solar-metal G0–K4 dwarfs and F7–K5 supergiants, respectively. The typical precision that can be achieved with our relations is 10–30 K for both dwarfs and supergiants.

scholarly journals RASSINE: Interactive tool for normalising stellar spectra

2020 ◽  
Vol 640 ◽  
pp. A42 ◽  
Author(s):  
M. Cretignier ◽  
J. Francfort ◽  
X. Dumusque ◽  
R. Allart ◽  
F. Pepe
Keyword(s):  
Spectral Lines ◽  
Parameter Determination ◽  
Polynomial Fitting ◽  
Stellar Spectra ◽  
Photon Noise ◽  
Graphical Feedback ◽  
Noise Limit ◽  
On Line ◽  
Band Absorption ◽  
Line Depth

Aims. We provide an open-source code allowing an easy, intuitive, and robust normalisation of spectra. Methods. We developed RASSINE, a Python code for normalising merged 1D spectra through the concepts of convex hulls. The code uses six parameters that can be easily fine-tuned. The code also provides a complete user-friendly interactive interface, including graphical feedback, that helps the user to choose the parameters as easily as possible. To facilitate the normalisation even further, RASSINE can provide a first guess for the parameters that are derived directly from the merged 1D spectrum based on previously performed calibrations. Results. For HARPS spectra of the Sun that were obtained with the HELIOS solar telescope, a continuum accuracy of 0.20% on line depth can be reached after normalisation with RASSINE. This is three times better than with the commonly used method of polynomial fitting. For HARPS spectra of α Cen B, a continuum accuracy of 2.0% is reached. This rather poor accuracy is mainly due to molecular band absorption and the high density of spectral lines in the bluest part of the merged 1D spectrum. When wavelengths shorter than 4500 Å are excluded, the continuum accuracy improves by up to 1.2%. The line-depth precision on individual spectrum normalisation is estimated to be ∼0.15%, which can be reduced to the photon-noise limit (0.10%) when a time series of spectra is given as input for RASSINE. Conclusions. With a continuum accuracy higher than the polynomial fitting method and a line-depth precision compatible with photon noise, RASSINE is a tool that can find applications in numerous cases, for example stellar parameter determination, transmission spectroscopy of exoplanet atmospheres, or activity-sensitive line detection.

scholarly journals The metallicity effect on line-depth ratios in APOGEE H-band spectra

2019 ◽  
Vol 485 (1) ◽  
pp. 1310-1319 ◽  
Author(s):  
Mingjie Jian ◽  
Noriyuki Matsunaga ◽  
Kei Fukue
Keyword(s):  
On Line ◽  
Band Spectra ◽  
Line Depth

scholarly journals Atomic physics and solar polarimetry

2017 ◽  
Vol 95 (9) ◽  
pp. 847-854 ◽  
Author(s):  
P.G. Judge
Keyword(s):  
Adaptive Optics ◽  
Atomic Physics ◽  
Solar Physics ◽  
Polarized Light ◽  
Initial Study ◽  
Spectral Lines ◽  
Calibration Data ◽  
Science Data ◽  
On Line ◽  
Singly Charged

Major outstanding problems in solar physics relate to solar magnetism. Spectropolarimetry offers the best, and sometimes only, method of obtaining accurate measurements of the Sun’s magnetic field. New 1.5–2 m class telescopes with adaptive optics have come on line, and the Daniel K. Inouye 4 m Solar Telescope (DKIST) will begin observing in 2019. The calibration of polarized light entering such a large and polarizing ground-based telescope represents difficult challenges. This paper explores how special polarization properties of particular atomic transitions may provide calibration data, augmenting or even avoiding time-consuming calibration observations, as well as science data. This initial study concludes that solar spectral lines exist with special polarization properties, allowing the telescope calibration to be determined. The Sun’s visible and infrared spectrum is dominated by lines of neutral atoms and singly charged ions of iron and other complex atoms. Both solar and atomic physics should jointly benefit from telescopic advances, as observers explore regimes of broader wavelength ranges, and higher spatial resolutions and polarimetric sensitivities, than they have reached in the past. Further work is in progress to identify particular transitions of practical use to aid in calibrations.

scholarly journals The formation of strip-like vortex motion by surface gravity waves

2021 ◽  
Vol 2056 (1) ◽  
pp. 012033
Author(s):  
A V Poplevin ◽  
S V Filatov ◽  
A A Levchenko
Keyword(s):  
Gravity Waves ◽  
Wave Vector ◽  
Water Surface ◽  
Vortex Flow ◽  
Vortex Motion ◽  
Surface Contamination ◽  
Surface Gravity ◽  
Surface Gravity Waves ◽  
Measured Dependence ◽  
Effect Of Surface

Abstract We studied experimentally the generation of vortex flow by non-collinear gravity waves with a frequency of 2.34 Hz. The vortices formed on the water surface have the form of stripes, the width L=π/(2k sin θ) of which is determined by the wave vector k and the angle between them, and the length is determined by the size of the system. We demonstrate that the measured dependence Ω(t) can be described within the recently developed model that considers the Eulerian contribution to the generated vortex flow and the effect of surface contamination.

scholarly journals Prototype Mesin Pengantar Barang Otomatis Menggunakan Load Cell Berbasis Robot Line Follower

2018 ◽  
Vol 10 (1) ◽  
pp. 23-29
Author(s):  
Dwi Budi Susilo ◽  
Hari Wibawanto ◽  
Anggraini Mulwinda
Keyword(s):  
Load Cell ◽  
Load Testing ◽  
White Line ◽  
Photo Diode ◽  
Testing Data ◽  
Data Output ◽  
On Line ◽  
The Difference ◽  
Development Methods ◽  
Prototype Design

Overloaded condition in the product porter like hand pallet, hand stacker, forclift, and etc, can causes damage and terrible accident in the machine operator. This research aim to build a prototype of porter machine that can prevent overloaded condition through the reading of load cell and photo diode sensor to guide the line follower direction. Research and development methods are used with the systematic writing are background of study and problems, prototype design and validation, testing, taking and analysis of the data. Output of the research is a prototype of porter machine using load cell sensor based on line follower robot. The Result of the load cell reading is compared to SF-400 weigher, and found the difference amount 0.117%. The load testing data of automatic moving trigger is 1 gram until 2999 gram. The Overload condition warning is active while the load is more than 3000 gram. The data reading of the photo diode on the black line is running succesfully, however on the white line with orange color is found some error.

On-Line Fuzzy Logic Temperature Control of a Concentric-Tubes Heat Exchanger Facility

2006 ◽  
Author(s):  
Claudia Ruiz-Mercado ◽  
Arturo Pacheco-Vega ◽  
Kevin Peters
Keyword(s):  
Heat Exchanger ◽  
Temperature Control ◽  
Fuzzy Controller ◽  
Fuzzy Rule ◽  
Outlet Temperature ◽  
Single Input Single Output ◽  
Single Output ◽  
On Line ◽  
The Difference ◽  
Two Stages

We develop a fuzzy rule based controller to perform on-line temperature control of a concentric-tubes heat exchanger facility. The rules were derived from dynamical values of the mass flow rates and fluid temperatures in the heat exchanger. The controller was embedded in a closed-loop single-input single-output system to control the outlet temperature of the cold fluid. The controller was constructed in two stages, the difference between them being the amount of information provided to the controller. To validate the fuzzy controller two sets of tests were carried out for maintaining a constant value of the outlet temperature under different perturbations. Results from this analysis demonstrate that the fuzzy-based controller is able to achieve control of the system, and that the information about the system provided to it is important in terms of accuracy and efficiency.

scholarly journals Using the infrared iron lines to probe solar subsurface convection

2019 ◽  
Vol 630 ◽  
pp. A133 ◽  
Author(s):  
I. Milić ◽  
H. N. Smitha ◽  
A. Lagg
Keyword(s):  
Three Dimensional ◽  
Spectral Lines ◽  
Stray Light ◽  
Line Pair ◽  
Solar Photosphere ◽  
Solar Convection ◽  
Diagnostic Potential ◽  
Optimal Node ◽  
Zero Response ◽  
Magnetohydrodynamic Simulation

Context. Studying the properties of solar convection using high-resolution spectropolarimetry began in the early 1990s with the focus on observations in the visible wavelength regions. Its extension to the infrared (IR) remains largely unexplored. Aims. The IR iron lines around 15 600 Å, most commonly known for their high magnetic sensitivity, also have a non-zero response to line-of-sight (LOS) velocity below log(τ) = 0.0. In this paper we explore the possibility of using these lines to measure subsurface convective velocities. Methods. By assuming a snapshot of a three-dimensional magnetohydrodynamic simulation to represent the quiet Sun, we investigate how well the iron IR lines can reproduce the LOS velocity in the cube and to what depth. We use the recently developed spectropolarimetric inversion code SNAPI and discuss the optimal node placements for the retrieval of reliable results from these spectral lines. Results. We find that the IR iron lines can measure the convective velocities down to log(τ) = 0.5, below the photosphere, not only at the original resolution of the cube, but also when degraded with a reasonable spectral and spatial PSF and stray light. Instead, the commonly used Fe I 6300 Å line pair performs significantly worse. Conclusions. Our investigation reveals that the IR iron lines can probe the subsurface convection in the solar photosphere. This paper is a first step towards exploiting this diagnostic potential.

scholarly journals Identification of barriers to co-create on-line: the perspectives of customers and companies

2018 ◽  
Vol 12 (4) ◽  
pp. 452-471 ◽  
Author(s):  
Maryna Chepurna ◽  
Josep Rialp Criado
Keyword(s):  
Rank Correlation ◽  
Point Of View ◽  
The Internet ◽  
Structured Interviews ◽  
Conceptual Information ◽  
Content Type ◽  
Spearman’S Rank Correlation ◽  
Internet Users ◽  
On Line ◽  
The Difference

Purpose Value co-creation is an important topic of interest in marketing domain for the past decade. Co-creation via the internet has received a particular attention in the literature (O’Hern and Rindfleisch, 2010). Although there have been substantive number of studies of what motivates customers to participate in value co-creation in the internet-based platforms, there is a lack of research of what the deterrents are that may prevent customers from contributing their ideas online. This research was undertaken to define the deterrents from the customers and companies’ point of view. Furthermore, the difference, if exists, between the users’ and marketing professionals’ ranking of the inhibitors to co-creation online is also studied. Design/methodology/approach This exploratory qualitative research is based on 20 in-depth semi-structured interviews with customers and 20 in-depth semi-structured interviews with marketing specialists from different companies. Spearman’s rank correlation is applied to explore the relationship between the internet users’ and marketers’ responses. Findings There are nine constraining factors. The results show that although there is a repetition of the mentioned constraining factors indicated by the both groups of the interviewees, the ranking of the barriers is distinctive. Research Implications New conceptual information is received on what restrains customers from co-creation from both customers’ and companies’ point of view. Practical Implications This paper explains the potential problems to be confronted when launching a co-creation project in the internet-based platforms and offers managers a preliminary guide to comprehension of the users’ deterrents rating. Originality The paper that defines deterrents to co-creation online.

scholarly journals Average Variations of Photospheric FeI and FeII Line Parameters as Function of the Magnetic Filling Factor

1990 ◽  
Vol 138 ◽  
pp. 41-46
Author(s):  
P.N. Brandt ◽  
M. Steinegger
Keyword(s):  
Filling Factor ◽  
Line Strength ◽  
Blue Shift ◽  
Disk Center ◽  
Flux Tubes ◽  
On Line ◽  
Fourier Transform Spectra ◽  
Similar Depth ◽  
Line Depth ◽  
The Continuum

A series of 17 Fourier transform spectra taken at the McMath telescope near disk center in regions of different magnetic field strengths were analyzed. Applying a multi-variate regression analysis magnetic filling factors 0 < α ≥ 0.11 were determined. With α increasing from 0 to 0.11, line bisectors averaged over groups of lines of similar depth are found to show a blue shift decreasing from 0.35 km s–1 to nearly 0.1 km s–1, when referred to the MgI line λ5172.7å. The bisectors of FeII lines exhibit smaller blue shifts than FeI lines. The increase of bisector red shift near the continuum with increasing α, found earlier by Brandt and Solanki (1987), was confirmed and is tentatively interpreted as a manifestation of downdrafts in the vicinity of flux tubes (Deinzer et al., 1984).A significant increase of line width (typically between 3 and 8%, depending on line strength) and a decrease of line depth is found with increasing filling factor. For strong lines the equivalent width W shows no variation or a slight increase, while for the weaker lines a reduction of W between a few % and > 10% is found.

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