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In this paper we study the feasibility of inferring the magnetic field from polarized multi-line spectra using two methods: The pseudo line approach and The PCA-ZDI approach. We use multi-line techniques, meaning that all the lines of a…

Solar and Stellar Astrophysics · Physics 2015-05-14 J. C. Ramirez Velez , M. Semel , M. Stift , M. J. Martinez Gonzalez , P. Petit , N. Dunstone

Our main objective is to develop a denoising strategy to increase the signal to noise ratio of individual spectral lines of stellar spectropolarimetric observations. We use a multivariate statistics technique called Principal Component…

PolarBase is an evolving data base that contains all stellar data collected with the ESPaDOnS and NARVAL high-resolution spectropolarimeters, in their reduced form, as soon as they become public. As of early 2014, observations of 2,000…

Solar and Stellar Astrophysics · Physics 2016-03-09 P. Petit , T. Louge , S. Théado , F. Paletou , N. Manset , J. Morin , S. C. Marsden , S. V. Jeffers

Designed at the Crimean Astrophysical Observatory the SL-method of stellar magnetic field measurement is based on the calculation of the distance between the centers of gravity of the left and right circularly polarized components of the…

Solar and Stellar Astrophysics · Physics 2019-10-04 S. Plachinda , D. Shulyak , N. Pankov

This work addresses a procedure to estimate fundamental stellar parameters such as T eff , logg, [Fe/H], and v sin i using a dimensionality reduction technique called Principal Component Analysis (PCA), applied to a large database of…

Solar and Stellar Astrophysics · Physics 2015-08-18 W. Farah , M. Gebran , F. Paletou , R. Blomme

The luminosity changes of most types of variable stars are correlated in the different wavelengths, and these correlations may be exploited for several purposes: for variability detection, for distinction of microvariability from noise, for…

Instrumentation and Methods for Astrophysics · Physics 2015-05-28 Maria Süveges , Paul Bartholdi , Andrew Becker , Zeljko Ivezic , Mathias Beck , Laurent Eyer

Insights on stellar surface large-scale magnetic field topologies are usually drawn by applying Zeeman-Doppler-Imaging (ZDI) to the observed spectropolarimetric time series. However, ZDI requires experience for reliable results to be…

Solar and Stellar Astrophysics · Physics 2022-06-02 L. T. Lehmann , J. -F. Donati

Principal Component Analysis (PCA) is a well-known multivariate technique used to decorrelate a set of vectors. PCA has been extensively applied in the past to the classification of stellar and galaxy spectra. Here we apply PCA to the…

Astrophysics · Physics 2007-05-23 I. Ferreras , B. Rogers , O. Lahav , .

Context. Stellar activity and instrumental signals are the main limitations to the detection of Earth-like planets using the radial velocity (RV) technique. Recent studies show that the key to mitigating those perturbing effects might…

Instrumentation and Methods for Astrophysics · Physics 2022-03-14 M. Cretignier , X. Dumusque , F. Pepe

An empirical method of modeling the stellar spectrum of galaxies is proposed, based on two successive applications of Principal Component Analysis (PCA). PCA is first applied to the newly available stellar library STELIB, supplemented by…

Astrophysics · Physics 2009-11-10 Cheng Li , Ting-Gui Wang , Hong-Yan Zhou , Xiao-Bo Dong , Fu-Zhen Cheng

We investigate the application of 2-dimensional Principal Component Analysis (2D PCA) to the problem of removal of polarization fringes from spectro-polarimetric data sets. We show how the transformation of the PCA basis through a series of…

Instrumentation and Methods for Astrophysics · Physics 2018-11-09 Roberto Casini , Wenxian Li

We describe a simple technique for the acceleration of spectro-polarimetric inversions based on principal component analysis (PCA) of Stokes profiles. This technique involves the indexing of the database models based on the sign of the…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 R. Casini , A. Asensio Ramos , B. W. Lites , A. Lopez Ariste

We present a novel analysis method for measurements of polarization transferred in $A(\vec{e},e'\vec{N})$ experiments, which can be applied to other kinds of polarization measurements as well. In this method the polarization transfer…

Nuclear Theory · Physics 2018-08-15 D. Izraeli , I. Mardor , E. O. Cohen , M. Duer , T. Y. Izraeli , I. Korover , J. Lichtenstadt , E. Piasetzky

We have developed a web tool to perform Principal Component Analysis (PCA, Murtagh & Heck 1987; Kendall 1980) onto spectral data. The method is especially designed to perform spectral classification of galaxies from a sample of input…

Astrophysics of Galaxies · Physics 2009-09-22 Mauricio Ortiz , Gaspar Galaz

Principal component analysis (PCA) is widely used for feature extraction and dimensionality reduction, with documented merits in diverse tasks involving high-dimensional data. Standard PCA copes with one dataset at a time, but it is…

Machine Learning · Computer Science 2019-01-30 Jia Chen , Gang Wang , Georgios B. Giannakis

We present two diagnostic methods based on ideas of Principal Component Analysis and demonstrate their efficiency for sophisticated processing of multicolour photometric observations of variable objects.

Astrophysics · Physics 2015-06-24 Zdenek Mikulasek

Data reconciliation (DR) and Principal Component Analysis (PCA) are two popular data analysis techniques in process industries. Data reconciliation is used to obtain accurate and consistent estimates of variables and parameters from…

Machine Learning · Computer Science 2015-05-05 Shankar Narasimhan , Nirav Bhatt

In order to get a significant Zeeman signature in the polarised spectra of a magnetic star, we usually 'add' the contributions of numerous spectral lines; the ultimate goal is to recover the spectropolarimetric prints of the magnetic field…

Solar and Stellar Astrophysics · Physics 2015-05-13 M. Semel , J. C. Ramirez Velez , M. J. Martinez Gonzalez , A. Asensio Ramos , M. J. Stift , A. Lopez Ariste , F. Leone

Due to the continuous developments in polarimetric instrumentation, which will become even more dramatic in the near future with the availability of new generation solar telescopes, we are now severely confronted with a variety of new…

Solar and Stellar Astrophysics · Physics 2011-03-29 Luca Belluzzi

Stacking polarized radio emission in SKA surveys provides statistical information on large samples that is not accessible otherwise due to limitations in sensitivity, source statistics in small fields, and averaging over frequency…

Instrumentation and Methods for Astrophysics · Physics 2015-01-05 J. M. Stil , B. W. Keller
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