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We investigate the variety in quasar UV spectra (1020-1600A) with emphasis on the weak emission lines in the Ly alpha forest region using principal component analysis (PCA). This paper is a continuation of Suzuki et al. (2005, Paper I), but…

Astrophysics · Physics 2007-05-23 Nao Suzuki

We describe a scheme to extract linearly supporting (LSU) features from stellar spectra to automatically estimate the atmospheric parameters $T_{eff}$, log$~g$, and [Fe/H]. "Linearly supporting" means that the atmospheric parameters can be…

Solar and Stellar Astrophysics · Physics 2019-03-20 Xiangru Li , Yu Lu , Georges Comte , Ali Luo , Yongheng Zhao , Yongjun Wang

Sky subtraction is the key technique in data reduction of multi-fiber spectra. Knowledge of the related instrument character is necessary to determine the method adopted in sky subtraction. In this study, we described the sky subtraction…

Instrumentation and Methods for Astrophysics · Physics 2017-09-20 Zhong-Rui Bai , Hao-Tong Zhang , Hai-Long Yuan , Guang-Wei Li , Jian-Jun Chen , Ya-Juan Lei , Hui-Qin Yang , Yi-Qiao Dong , Gang Wang , Yong-Heng Zhao

Thanks to the execution of extensive spectroscopic surveys that have covered large fractions of the sky down to magnitudes as faint as $i \approx 19$, it has been possible to identify several narrow-line Seyfert 1 galaxies (NLS1s) and to…

Astrophysics of Galaxies · Physics 2018-09-10 G. La Mura , D. Bastieri , M. Berton , S. Chen , S. Ciroi , E. Congiu , V. Cracco , J. -H. Fan , P. Rafanelli

Optical spectra of galaxies and quasars from large cosmological surveys are used to measure redshifts and infer distances. They are also rich with information on the intrinsic properties of these astronomical objects. However, their…

Line segment detection is a fundamental low-level task in computer vision, and improvements in this task can impact more advanced methods that depend on it. Most new methods developed for line segment detection are based on Convolutional…

Computer Vision and Pattern Recognition · Computer Science 2024-11-21 Sebastian Janampa , Marios Pattichis

With the aim of building a data-set of spectral properties of well studied early-type galaxies showing emission lines, we present intermediate resolution spectra of 50 galaxies in the nearby Universe. The sample, which covers several of the…

Astrophysics · Physics 2009-11-10 R. Rampazzo , F. Annibali , A. Bressan , M. Longhetti , F. Padoan , W. W. Zeilinger

Hot subdwarf stars are core He burning stars located at the blue end of the horizontal branch, also known as the extreme horizontal branch. The properties of hot subdwarf stars are important for our understanding of the stellar…

Instrumentation and Methods for Astrophysics · Physics 2020-01-08 Yude Bu , Jingjing Zeng , Zhenxin Lei

How can we discover objects we did not know existed within the large datasets that now abound in astronomy? We present an outlier detection algorithm that we developed, based on an unsupervised Random Forest. We test the algorithm on more…

Astrophysics of Galaxies · Physics 2017-01-11 Dalya Baron , Dovi Poznanski

DIBs are ubiquitous in stellar spectra. Traditionally, they have been studied through their extraction from hot stars, because of their smooth continuum. In an era where there are several going-on or planned massive Galactic surveys using…

Astrophysics of Galaxies · Physics 2017-03-08 A. Monreal-Ibero , R. Lallement

The WFC3 Infrared Spectroscopic Parallel Survey (WISP) uses the Hubble Space Telescope (HST) infrared grism capabilities to obtain slitless spectra of thousands of galaxies over a wide redshift range including the peak of star formation…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 H. Atek , B. Siana , C. Scarlata , M. Malkan , P. McCarthy , H. Teplitz , A. Henry , J. Colbert , C. Bridge , A. J. Bunker , A. Dressler , R. Fosbury , N. P. Hathi , C. Martin , N. R. Ross , H. Shim

Due to the ever-expanding volume of observed spectroscopic data from surveys such as SDSS and LAMOST, it has become important to apply artificial intelligence (AI) techniques for analysing stellar spectra to solve spectral classification…

Solar and Stellar Astrophysics · Physics 2020-01-08 Kaushal Sharma , Ajit Kembhavi , Aniruddha Kembhavi , T. Sivarani , Sheelu Abraham , Kaustubh Vaghmare

We present an overview of the Velocity Coordinate Spectrum (VCS), a new technique for studying astrophysical turbulence that utilizes the line-of-sight statistics of Doppler-broadened spectral lines. We consider the retrieval of turbulence…

Astrophysics of Galaxies · Physics 2009-02-03 D. Pogosyan , A. Lazarian

Using data mining techniques applied on emission line characteristics of Be stars spectra we attempted to find new Be stars candidates in SDSS SEGUE survey. The mid-resolution spectra of confirmed Be stars obtained from VO-compatible…

Instrumentation and Methods for Astrophysics · Physics 2011-12-14 Petr Škoda , Jaroslav Vážný

We discuss a method for detecting the emission from high redshift galaxies by cross correlating flux fluctuations from multiple spectral lines. If one can fit and subtract away the continuum emission with a smooth function of frequency, the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Eli Visbal , Abraham Loeb

We present a detection scheme for diffusing wave spectroscopy (DWS) based on a two cell geometry that allows efficient ensemble averaging. This is achieved by putting a fast rotating diffuser in the optical path between laser and sample. We…

Soft Condensed Matter · Physics 2009-11-11 P. Zakharov , F. Cardinaux , F. Scheffold

Modern spectroscopic surveys produce large spectroscopic databases, generally with sizes well beyond the scope of manual investigation. The need arises, therefore, for an automated line detection method with objective indicators for…

Instrumentation and Methods for Astrophysics · Physics 2015-01-27 Sungryong Hong , Arjun Dey , Moire K. M. Prescott

We present new observations from Z-Spec, a broadband 185-305 GHz spectrometer, of five sub-millimeter bright lensed sources selected from the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) science demonstration phase (SDP)…

Adaptive sampling results in dramatic improvements in the recovery of sparse signals in white Gaussian noise. A sequential adaptive sampling-and-refinement procedure called Distilled Sensing (DS) is proposed and analyzed. DS is a form of…

Statistics Theory · Mathematics 2010-05-31 Jarvis Haupt , Rui Castro , Robert Nowak