The fainter the better: Cataclysmic variable stars from the Sloan Digital Sky Survey

AbstractThe orbital period is one of the most accessible observables of a cataclysmic variable. It has been a concern for many years that the orbital period distribution of the known systems does not match that predicted by evolutionary theory. The sample of objects discovered by the Sloan Digital Sky Survey has changed this: it shows the long-expected predominance of short-period objects termed the ‘period spike’. The minimum period remains in conflict with theory, suggesting that the angular momentum loss mechanisms are stronger than predicted.

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Chasing down variable stars from a decade-long dataset

Proceedings of the Wisconsin Space Conference ◽

10.17307/wsc.v1i1.310 ◽

2020 ◽

Vol 1 (1) ◽

Author(s):

Nikki Giti Noughani ◽

Ralf Kotulla

Keyword(s):

Brightness Temperature ◽

Stellar Evolution ◽

Time Domain ◽

Variable Stars ◽

Sloan Digital Sky Survey ◽

Sky Survey

Finding and characterizing variable stars is at the heart of a relatively modern branch of astronomy named time-domain astrophysics. Variable Stars are ordinary stars that change in brightness on widely varying degrees. Characterizing the details of how this brightness fluctuates and on what timescales, as well as the star's average properties (mean brightness, temperature, etc.), is greatly important to understanding the process of stellar evolution. For this project, we use data over ten years from the 0.5 meter Sloan Digital Sky Survey telescope. We will develop tools that can identify several variable stars, estimate their variability periods and timescales, and determine the shape of their brightness variations over this time.

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Eleven New DA White Dwarf Variable Stars from the Sloan Digital Sky Survey

The Astrophysical Journal ◽

10.1086/429885 ◽

2005 ◽

Vol 625 (2) ◽

pp. 966-972 ◽

Cited By ~ 53

Author(s):

F. Mullally ◽

S. E. Thompson ◽

B. G. Castanheira ◽

D. E. Winget ◽

S. O. Kepler ◽

...

Keyword(s):

White Dwarf ◽

Variable Stars ◽

Sloan Digital Sky Survey ◽

Sky Survey

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Investigating the Sloan Digital Sky Survey Cataclysmic Variable SDSS J132723.39+652854.2

Publications of the Astronomical Society of the Pacific ◽

10.1086/377013 ◽

2003 ◽

Vol 115 (811) ◽

pp. 1118-1123 ◽

Cited By ~ 5

Author(s):

Michael A. Wolfe ◽

Paula Szkody ◽

Oliver J. Fraser ◽

Lee Homer ◽

Sam Skinner ◽

...

Keyword(s):

Sloan Digital Sky Survey ◽

Cataclysmic Variable ◽

Sky Survey

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Revised and Updated Catalogue of the First Byurakan Survey Late-Type Stars. 2nd Edition

Communications of the Byurakan Astrophysical Observatory ◽

10.52526/25792776-2018.2.2-262 ◽

2018 ◽

pp. 262-267

Author(s):

K. S. Gigoyan ◽

A. M. Mickaelian ◽

G. R. Kostandyan

Keyword(s):

Variable Stars ◽

Sloan Digital Sky Survey ◽

Asymptotic Giant Branch ◽

Wide Field ◽

Late Type ◽

Byurakan Survey ◽

First Byurakan Survey ◽

Sky Survey ◽

Search And Selection ◽

Low Dispersion

Eighteen lists of late-type stars (LTSs) have been published between 1990 and 2016. These LTSs have been found in the low-dispersion spectroscopic plates of the First Byurakan Survey (FBS). The systematic search and selection was carried out on a surface _16000 deg2 on almost the whole area of the FBS. As a result, \Revised And Updated Catalogue Of The First Byurakan Survey Of Late-Type Stars" was generated (LTSs, _rst version). Since 2007, all FBS low-resolution spectral plates are digitized, and Digitized First Byurakan Survey (DFBS) database and second catalog of objects has been assembled. All DFBS spectral plates are analysed with the help of standard image analysis softwares (FITSView and SAO Image ds9) and numerous of comparatively faint LTSs were discovered. We present the 2nd version of the FBS catalogue of LTSs with new data. We have made cross-correlation with the Digitized First Byurakan Survey (DFBS), the United State Naval Observatory-B1.0 Catalogue, the Two Micron All-Sky Survey (2MASS), the Wide-Field Infrared Survey Explorer (new version-ALLWISE) catalogue, the Infrared Astronomical Satellite Point Source Catalogue/Faint Source Catalogue, the AKARI catalogue, the ROSAT Bright Source Catalogue/Faint Source Catalogue, the General Catalogue of Variable Stars, Sloan Digital Sky Survey (SDSS) photometric catalogue. We have added updated IMBAD data for the objects. For numerous of the new detected objects we present accurate Digitized Sky Survey 2 positions, approximate spectral subtypes refined from the DFBS low-dispersion spectra, luminosity classes estimated from 2MASS colours, and available proper motions for 1471 FBS LTSs. 2nd Version of the Revised and Updated Catalogue lists a large number of completely new objects, which promise to extend very significantly the census of M giants, faint N-type Asymptotic Giant Branch (AGB) carbon stars, CH {type carbon giants at high Galactic latitudes, also M dwarfs in the vicinity of the Sun up to 16.0-17.0 mag. in visual. We present also some important data from the Gaia DR2 data base for FBS LTSs. Some supplementary spectra obtained with the Byurakan Observatory 2.6 m telescope and LAMOST telescope are shown.

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Cataclysmic Variable Star Spectra Data Mining Engineering in SDSS Archive

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.740.633 ◽

2015 ◽

Vol 740 ◽

pp. 633-638

Author(s):

Wen Yu Wang ◽

Xin Jun Wang ◽

Wei Wang ◽

Jing Chang Pan

Keyword(s):

Data Mining ◽

Principal Component ◽

Feature Space ◽

Variable Stars ◽

Support Vector ◽

Cataclysmic Variable ◽

Data Mining Technique ◽

Efficient Manner ◽

Sky Survey ◽

Binary Evolution

We present an automatic method to identify cataclysmic variable stars (CVs) in the ninth data release of the Sloan digital sky survey (SDSS). The data mining technique is employed and the massive spectra are identified quickly and efficiently. The high dimensional spectra are mapped to feature space constructed by the principal component analysis (PCA), and dimensionality reduction is carried out accordingly. Massive SDSS spectra are classified by the support vector machine (SVM) and most of the non-candidates are excluded. The final greatly reduced candidates can be identified manually and easily. Experiments show that this data mining method can find CVs from the SDSS database in an effective and efficient manner. In addition, this method is also applicable to mining other special celestial objects in sky survey telescope data. We report the identification of a new CV with spectra. The newly found CV enriches the CVs spectral library and will be useful to the research of binary evolution models.

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Intrinsic Characteristics of Quasars Redshifts

JOURNAL OF ADVANCES IN PHYSICS ◽

10.24297/jap.v4i3.2020 ◽

2014 ◽

Vol 4 (3) ◽

pp. 655-661

Author(s):

Waleed Elsanhoury

Keyword(s):

Absolute Magnitude ◽

Sloan Digital Sky Survey ◽

Strong Correlations ◽

Sky Survey

Using Sloan Digital Sky Survey SDSS catalog, some intrinsic characteristics of Quasars (10,000 points) are developed of these are the strong correlations between redshifts and other parameters, e.g. combined magnitude, luminosity, and absolute magnitude .Moreover ,the Karlsson peak of our sample is also computed.

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SuperWASP variable stars: classifying light curves using citizen science

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab140 ◽

2021 ◽

Vol 502 (1) ◽

pp. 1299-1311

Author(s):

Heidi B Thiemann ◽

Andrew J Norton ◽

Hugh J Dickinson ◽

Adam McMaster ◽

Ulrich C Kolb

Keyword(s):

Variable Stars ◽

Eclipsing Binaries ◽

Light Curves ◽

Data Set ◽

Resultant Data ◽

Sky Survey ◽

Short Period ◽

Contact Binaries ◽

Analysis Of Results

ABSTRACT We present the first analysis of results from the SuperWASP variable stars Zooniverse project, which is aiming to classify 1.6 million phase-folded light curves of candidate stellar variables observed by the SuperWASP all sky survey with periods detected in the SuperWASP periodicity catalogue. The resultant data set currently contains >1 million classifications corresponding to >500 000 object–period combinations, provided by citizen–scientist volunteers. Volunteer-classified light curves have ∼89 per cent accuracy for detached and semidetached eclipsing binaries, but only ∼9 per cent accuracy for rotationally modulated variables, based on known objects. We demonstrate that this Zooniverse project will be valuable for both population studies of individual variable types and the identification of stellar variables for follow-up. We present preliminary findings on various unique and extreme variables in this analysis, including long-period contact binaries and binaries near the short-period cut-off, and we identify 301 previously unknown binaries and pulsators. We are now in the process of developing a web portal to enable other researchers to access the outputs of the SuperWASP variable stars project.

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Characterizing the abundance, properties, and kinematics of the cool circumgalactic medium of galaxies in absorption with SDSS DR16

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab871 ◽

2021 ◽

Vol 504 (1) ◽

pp. 65-88

Author(s):

Abhijeet Anand ◽

Dylan Nelson ◽

Guinevere Kauffmann

Keyword(s):

Formation Rate ◽

Sloan Digital Sky Survey ◽

Gas Absorption ◽

Dark Matter Halo ◽

Star Forming ◽

Sky Survey ◽

Optical Continuum ◽

Circumgalactic Medium ◽

Emission Line Galaxies ◽

Red Galaxies

ABSTRACT In order to study the circumgalactic medium (CGM) of galaxies we develop an automated pipeline to estimate the optical continuum of quasars and detect intervening metal absorption line systems with a matched kernel convolution technique and adaptive S/N criteria. We process ∼ one million quasars in the latest Data Release 16 (DR16) of the Sloan Digital Sky Survey (SDSS) and compile a large sample of ∼ 160 000 Mg ii absorbers, together with ∼ 70 000 Fe ii systems, in the redshift range 0.35 < zabs < 2.3. Combining these with the SDSS DR16 spectroscopy of ∼1.1 million luminous red galaxies (LRGs) and ∼200 000 emission line galaxies (ELGs), we investigate the nature of cold gas absorption at 0.5 < z < 1. These large samples allow us to characterize the scale dependence of Mg ii with greater accuracy than in previous work. We find that there is a strong enhancement of Mg ii absorption within ∼50 kpc of ELGs, and the covering fraction within 0.5rvir of ELGs is 2–5 times higher than for LRGs. Beyond 50 kpc, there is a sharp decline in Mg ii for both kinds of galaxies, indicating a transition to the regime where the CGM is tightly linked with the dark matter halo. The Mg ii-covering fraction correlates strongly with stellar mass for LRGs, but weakly for ELGs, where covering fractions increase with star formation rate. Our analysis implies that cool circumgalactic gas has a different physical origin for star-forming versus quiescent galaxies.

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The Quest for Relics: Massive compact galaxies in the local Universe

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002045 ◽

2019 ◽

Vol 15 (S359) ◽

pp. 441-443

Author(s):

F. S. Lohmann ◽

A. Schnorr-Müller ◽

M. Trevisan ◽

R. Riffel ◽

N. Mallmann ◽

...

Keyword(s):

High Redshift ◽

Control Sample ◽

Sloan Digital Sky Survey ◽

Integral Field Spectroscopy ◽

Sky Survey ◽

Size Evolution ◽

Compact Galaxies ◽

Minor Mergers ◽

Significant Size ◽

Integral Field

AbstractObservations at high redshift reveal that a population of massive, quiescent galaxies (called red nuggets) already existed 10 Gyr ago. These objects undergo a significant size evolution over time, likely due to minor mergers. In this work we present an analysis of local massive compact galaxies to assess if their properties are consistent with what is expected for unevolved red nuggets (relic galaxies). Using integral field spectroscopy (IFS) data from the MaNGA survey from the Sloan Digital Sky Survey (SDSS), we characterized the kinematics and properties of stellar populations of massive compact galaxies, and find that these objects exhibit, on average, a higher rotational support than a control sample of average sized early-type galaxies. This is in agreement with a scenario in which these objects have a quiet accretion history, rendering them candidates for relic galaxies.

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