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Magnetic fields are important for stellar photospheres and magnetospheres, influencing photospheric physics and sculpting stellar winds. Observations of stellar magnetic fields are typically made in the visible, although infrared…

Solar and Stellar Astrophysics · Physics 2022-12-21 C. P. Folsom , R. Ignace , C. Erba , R. Casini , T. del Pino Alemán , K. Gayley , K. Hobbs , R. Manso Sainz , C. Neiner , V. Petit , M. E. Shultz , G. A. Wade

A variety of interstellar complex organic molecules (COMs) have been detected in various physical conditions. However, in the protostellar and protoplanetary environments, their complex kinematics make line profiles blend each other and the…

Astrophysics of Galaxies · Physics 2023-09-19 Hyeong-Sik Yun , Jeong-Eun Lee

Principal component analysis (PCA) is an important tool in exploring data. The conventional approach to PCA leads to a solution which favours the structures with large variances. This is sensitive to outliers and could obfuscate interesting…

Methodology · Statistics 2015-06-16 A. A. Akinduko , A. N. Gorban

Principal Component Analysis (PCA) is a commonly used tool for dimension reduction in analyzing high dimensional data; Multilinear Principal Component Analysis (MPCA) has the potential to serve the similar function for analyzing tensor…

Statistics Theory · Mathematics 2011-04-29 Hung Hung , Pei-Shien Wu , I-Ping Tu , Su-Yun Huang

(Abridged) We apply Principal Component Analysis (PCA) to a sample of early-type galaxies from the Sloan Digital Sky Survey (SDSS) in order to infer differences in their star formation histories. Out of the first few principal components…

Stars with radiative envelopes, specifically the upper main sequence chemically peculiar (Ap) stars, were among the first objects outside our solar system for which surface magnetic fields have been detected. Currently magnetic Ap stars…

Solar and Stellar Astrophysics · Physics 2015-06-17 O. Kochukhov

Magnetic fields in cool stars are ubiquitous but can still be challenging to characterize due to their complexity and relatively low strength. The polarization signature amplitudes are proportional to the field strength, and current studies…

Solar and Stellar Astrophysics · Physics 2014-08-19 L. Rosén , O. Kochukhov , G. A. Wade

We aim to characterise the magnetic field of the eclipsing binary CU Cnc. The determination of magnetic field parameters of this target enables comparisons with both observations of similar stars and theoretical predictions of the magnetic…

Solar and Stellar Astrophysics · Physics 2024-02-02 A. Hahlin , O. Kochukhov , A. D. Rains , J. Morin , G. Hussain , L. Hebb , K. Stassun

Principal Component analysis (PCA) is a useful statistical technique that is commonly used for multivariate analysis of correlated variables. It is usually applied as a dimension reduction method: the top principal components (PCs)…

Aims: The goal of this study is to perform numerical tests of Zeeman Doppler Imaging (ZDI) to asses whether correct reconstruction of magnetic fields is at all possible without taking temperature into account for stars in which magnetic and…

Solar and Stellar Astrophysics · Physics 2012-11-13 Lisa Rosén , Oleg Kochukhov

Principal Component Analysis (PCA) is an efficient tool to optimize the multiparameter tests of general relativity (GR) where one tests for simultaneous deviations in multiple post-Newtonian (PN) phasing coefficients by introducing…

General Relativity and Quantum Cosmology · Physics 2022-08-17 Sayantani Datta , M. Saleem , K. G. Arun , B. S. Sathyaprakash

Multiline techniques assuming similar line profiles have become a standard tool in stellar astronomy for increasing the signal-to-noise ratio (SNR) of spectropolarimetric measurements. However, due to the widely-used weak field…

Solar and Stellar Astrophysics · Physics 2010-03-29 C. Sennhauser , S. V. Berdyugina

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

The concept of quantum correlation matrix for observables leads to the application of the PCA (Principal Component Analysis) also for quantum system in Hilbert space. It is shown that, in the case of a 2x2 spin system where the observables…

Quantum Physics · Physics 2017-01-12 Renzo Mosetti

The advancement in the field of data science especially in machine learning along with vast databases of variable star projects like the Optical Gravitational Lensing Experiment (OGLE) encourages researchers to analyse as well as classify…

Solar and Stellar Astrophysics · Physics 2022-01-24 Suman Paul , Tanuka Chattopadhyay

Principal component analysis (PCA) is recognised as a quintessential data analysis technique when it comes to describing linear relationships between the features of a dataset. However, the well-known sensitivity of PCA to non-Gaussian…

Machine Learning · Statistics 2019-10-28 Jean P. Chereau , Bruno Scalzo Dees , Danilo P. Mandic

Principal component analysis (PCA) is a widely used dimension reduction tool in the analysis of many kind of high-dimensional data. It is used in signal processing, mechanical engineering, psychometrics, and other fields under different…

Methodology · Statistics 2014-01-15 Ngoc Mai Tran , Maria Osipenko , Wolfgang Karl Haerdle

ZDI studies have shown that the magnetic fields of T Tauri stars can be significantly more complex than a simple dipole and can vary markedly between sources. We collect and summarize the magnetic field topology information obtained to date…

Solar and Stellar Astrophysics · Physics 2015-06-05 S. G. Gregory , J. -F. Donati , J. Morin , G. A. J. Hussain , N. J. Mayne , L. A. Hillenbrand , M. Jardine

The general context of this study concerns the post-processing of multiline spectropolarimetric observations of stars, and in particular these numerical analysis techniques aiming at the detection and the characterization of polarized…

Instrumentation and Methods for Astrophysics · Physics 2015-06-05 Frederic Paletou

We demonstrate the use of a variant of Principal Component Analysis (PCA) for discrimination problems in astronomy. This variant of PCA is shown to provide the best linear discrimination between data classes. As a test case, we present the…

Astrophysics · Physics 2009-10-30 Rodrigo Ibata , Michael Irwin
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