Search Publications
Quasi-periodic Oscillation of a Coronal Bright Point
Tian, Hui; Banerjee, Dipankar; Samanta, Tanmoy
Coronal bright points (BPs) are small-scale luminous features seen in the solar corona. Quasi-periodic brightenings are frequently observed in the BPs and are generally linked with underlying magnetic flux changes. We study the dynamics of a BP seen in the coronal hole using the Atmospheric Imaging Assembly images, the Helioseismic and Magnetic Im…
On Extreme-ultraviolet Helium Line Intensity Enhancement Factors on the Sun
Curdt, W.; Fludra, A.; Lanzafame, A. C. +3 more
Helium lines in the solar EUV spectrum provide useful diagnostics of the solar atmosphere plasma. Helium is one of the few elements that exhibits strong emission lines formed in the lower transition region, and it is the second most abundant element in the Sun. However, the analysis of helium lines is complicated by their optical thickness and the…
Nonlinear MHD Waves in a Prominence Foot
Schmieder, B.; Ofman, L.; Kucera, T. +1 more
We study nonlinear waves in a prominence foot using a 2.5D MHD model motivated by recent high-resolution observations with Hinode/Solar Optical Telescope in Ca ii emission of a prominence on 2012 October 10 showing highly dynamic small-scale motions in the prominence material. Observations of Hα intensities and of Doppler shifts show similar propa…
A Method for the Estimation of p-Mode Parameters from Averaged Solar Oscillation Power Spectra
Kosovichev, A. G.; Scherrer, P. H.; Larson, T. P. +3 more
A new fitting methodology is presented that is equally well suited for the estimation of low-, medium-, and high-degree mode parameters from m-averaged solar oscillation power spectra of widely differing spectral resolution. This method, which we call the “Windowed, MuLTiple-Peak, averaged-spectrum” or WMLTP Method, constructs a theoretical profil…
Solar Radius Variations: An Inquisitive Wavelength Dependence
Kilcik, Ali; Kosovichev, Alexander; Rozelot, Jean Pierre
Recent solar radius determinations from space observations of Mercury and Venus transits have been made by different teams in 2003, 2006, 2012, and 2014. Seemingly the results are not consistent: the authors interpreted the discrepancies as caused by the different methods of analysis. However, looking at the wavelength dependence and adding other …
Magnetic Flux Conservation in the Heliosheath Including Solar Cycle Variations of Magnetic Field Intensity
Tóth, G.; Richardson, J. D.; Opher, M. +2 more
In the heliosheath (HS), Voyager 2 has observed a flow with constant radial velocity and magnetic flux conservation. Voyager 1, however, has observed a decrease in the flow’s radial velocity and an order of magnitude decrease in magnetic flux. We investigate the role of the 11 yr solar cycle variation of the magnetic field strength on the magnetic…
Core Shapes and Orientations of Core-Sérsic Galaxies
Graham, Alister W.; Dullo, Bililign T.
The inner and outer shapes and orientations of core-Sérsic galaxies may hold important clues to their formation and evolution. We have therefore measured the central and outer ellipticities and position angles for a sample of 24 core-Sérsic galaxies using archival Hubble Space Telescope (HST) images and data. By selecting galaxies with core-Sérsic…
Does the Variation of Solar Intra-network Horizontal Field Follow Sunspot Cycle?
Wang, J. X.; Jin, C. L.
The ubiquitousness of the solar inter-network horizontal magnetic field has been revealed by space-borne observations with high spatial resolution and polarization sensitivity. However, no consensus has been achieved on the origin of the horizontal field among solar physicists. For a better understanding, in this study, we analyze the cyclic varia…
Finding η Car Analogs in Nearby Galaxies Using Spitzer. II. Identification of An Emerging Class of Extragalactic Self-Obscured Stars
Kochanek, C. S.; Stanek, K. Z.; Khan, Rubab +1 more
Understanding the late-stage evolution of the most massive stars such as η Carinae is challenging because no true analogs of η Car have been clearly identified in the Milky Way or other galaxies. In Khan et al., we utilized Spitzer IRAC images of 7 nearby (lsim 4 Mpc) galaxies to search for such analogs, and found 34 candidates with flat or red mi…
Magnetospheric Accretion in Close Pre-main-sequence Binaries
Herczeg, Gregory J.; Ardila, David R.; Mathieu, Robert D. +2 more
The transfer of matter between a circumbinary disk and a young binary system remains poorly understood, obscuring the interpretation of accretion indicators. To explore the behavior of these indicators in multiple systems, we have performed the first systematic time-domain study of young binaries in the ultraviolet. We obtained far- and near-ultra…