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Randomly oriented flattened spheroids have been used to describe a broad range of astrophysical phenomena. Here we use this geometric approach to derive equations representing lines of sight through quasar absorption clouds to constrain…

Cosmology and Nongalactic Astrophysics · Physics 2022-12-06 John K. Webb

Recently, it has been noticed that the discrepancies in the integrated colour indices (CIs) between star clusters and models are mostly due to the projection of bright stars in the apertures. In order to reduce this problem, the method of…

Astrophysics of Galaxies · Physics 2025-06-12 Karolis Daugevičius , Eimantas Kriščiūnas , Erikas Cicėnas , Rima Stonkutė , Vladas Vansevičius

We present a $\approx 11.5$ year adaptive optics (AO) study of stellar variability and search for eclipsing binaries in the central $\sim 0.4$ pc ($\sim 10''$) of the Milky Way nuclear star cluster. We measure the photometry of 563 stars…

The gravitational action of the smooth energy-matter components filling in the universe can affect the orbit of a planetary system. Changes are related to the acceleration of the cosmological scale size R. In a universe with significant…

Astrophysics · Physics 2008-11-26 M. Sereno , Ph. Jetzer

According to most literature sources, the amplitude of the pulsational variability observed in gamma Doradus stars does not exceed 0.1 mag in Johnson V. We have analyzed fifteen high-amplitude gamma Doradus stars with photometric…

Solar and Stellar Astrophysics · Physics 2020-10-22 Ernst Paunzen , Klaus Bernhard , Stefan Huemmerich , Franz-Josef Hambsch , Christopher Lloyd , Sebastian Otero

STAR is a large acceptance spectrometer capable of precision measurements of a wide variety of strange particles. We discuss the STAR detector, its configuration during the first two years of RHIC operation, and its initial performance for…

Nuclear Experiment · Physics 2008-11-26 P. G. Jones , P. M. Jacobs , the STAR Collaboration

Modified theories of gravity have received a renewed interest due to their ability to account for the cosmic acceleration. In order to satisfy the solar system tests of gravity, these theories need to include a screening mechanism that…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-15 Jeremy Sakstein , Bhuvnesh Jain , Vinu Vikram

The varying speed of light (VSL) theory is controversial. It succeeds in explaining some cosmological problems, but on the other hand it is excluded by mainstream physics because it will shake the foundation of physics. In the present…

General Relativity and Quantum Cosmology · Physics 2014-10-08 Jing-Zhao Qi , Ming-Jian Zhang , Wen-Biao Liu

Proteins appear to be the most dramatic natural example of self-organized network criticality (SONC), a concept that explains many otherwise apparently exponentially unlikely phenomena. Adaptive plasticity is a term which has become much…

Soft Condensed Matter · Physics 2011-01-18 J. C. Phillips

Stars accrete near invisible hydrogen dominated agglomerates. This population, the `dark matter,' effects the nature of stars. Measurements show plasma streams impacting Earth, planets, Sun and stars. This mass-energy source contradicts…

Astrophysics · Physics 2007-05-23 Maurice Dubin , Robert K. Soberman

We present preliminary results of the first near-infrared variability study of the Arches cluster, using adaptive optics data from NIRI/Gemini and NACO/VLT. The goal is to discover eclipsing binaries in this young (2.5 $\pm$ 0.5 Myr),…

Solar and Stellar Astrophysics · Physics 2011-08-24 K. Markakis , A. Z. Bonanos , G. Pietrzynski , L. Macri , K. Z. Stanek

The strength and vertical distribution of atmospheric turbulence is a key factor determining the performance of optical and infrared telescopes, with and without adaptive optics. Yet, this remains challenging to measure. We describe a new…

Instrumentation and Methods for Astrophysics · Physics 2019-10-11 Paul Hickson , Bin Ma , Zhaohui Shang , Suijian Xue

In previous work we identified six Sun-like stars observed by Kepler with exceptionally clear asteroseismic signatures of rotation. Here, we show that five of these stars exhibit surface variability suitable for measuring rotation. In order…

Solar and Stellar Astrophysics · Physics 2015-10-07 M. B. Nielsen , H. Schunker , L. Gizon , W. H. Ball

To detect brown dwarfs in the dark galactic halo through gravitational lensing, experiments follow the luminosity of millions of stars to observe a few lensing events par year. The luminosity of a star too faint to be continuously followed…

Astrophysics · Physics 2007-05-23 Alain Bouquet

Variable stars have a unique part to play in Galactic astronomy. Among the most important of these variables are the Cepheids (types I and II), the RR Lyraes and the Miras (O- and C-rich). The current status of the basic calibration of…

Astrophysics of Galaxies · Physics 2015-06-17 Michael W. Feast , Patricia A. Whitelock

The adaptive optics system at the 3.6 m AEOS telescope was used to measure the astrometry and differential magnitude in I-band of 56 binary stars in 2002. The astrometric measurements will be of use for future orbital determination, and the…

Solar and Stellar Astrophysics · Physics 2015-05-20 Lewis C. Roberts,

We provide a status report on the determination of stellar ages from asteroseismology for stars of various masses and evolutionary stages. The ability to deduce the ages of stars with a relative precision of typically 10 to 20% is a unique…

Solar and Stellar Astrophysics · Physics 2015-08-06 Conny Aerts

The Kepler space telescope has revolutionised our knowledge about exoplanets and stars and is continuing to do so in the K2 mission. The exquisite photometric precision, together with the long, uninterrupted observations opened up a new way…

Solar and Stellar Astrophysics · Physics 2016-10-10 László Molnár , Róbert Szabó , Emese Plachy

MAVIS (the MCAO-Assisted Visible Imager and Spectrograph), planned for the VLT Adaptive Optics Facility, represents an innovative step in Multi-Conjugate Adaptive Optics (MCAO) systems, particularly in its operation at visible wavelengths…

The modelling of massive star evolution is a complex task, and is very sensitive to the way physical processes (such as convection, rotation, mass loss, etc.) are included in stellar evolution code. Moreover, the very high observed fraction…

Solar and Stellar Astrophysics · Physics 2016-12-19 Cyril Georgy , Raphael Hirschi , Sylvia Ekström