Search Publications
Neon and Oxygen Abundances and Abundance Ratio in the Solar Corona
Landi, E.; Testa, P.
In this work we determine the Ne/O abundance ratio from Solar and Heliospheric Observatory (SOHO)/Solar Ultraviolet Measurement of Emitted Radiation (SUMER) off-disk observations of quiescent streamers over the 1996-2008 period. We find that the Ne/O ratio is approximately constant over solar cycle 23 from 1996 to 2005, at a value of 0.099 ± 0.017…
Hubble Space Telescope Proper Motions along the Sagittarius Stream. I. Observations and Results for Stars in Four Fields
Anderson, Jay; Law, David R.; van der Marel, Roeland P. +5 more
We present a multi-epoch Hubble Space Telescope (HST) study of stellar proper motions (PMs) for four fields spanning 200° along the Sagittarius (Sgr) stream: one trailing arm field, one field near the Sgr dwarf spheroidal tidal radius, and two leading arm fields. We determine absolute PMs of dozens of individual stars per field, using established …
On Flare Predictability Based on Sunspot Group Evolution
Erdélyi, R.; Korsós, M. B.; Ludmány, A. +1 more
The forecast method introduced by Korsós et al. is generalized from the horizontal magnetic gradient (GM), defined between two opposite polarity spots, to all spots within an appropriately defined region close to the magnetic neutral line of an active region. This novel approach is not limited to searching for the largest GM …
Suzaku Observations of γ-Ray Bright Radio Galaxies: Origin of the X-Ray Emission and Broadband Modeling
Fukazawa, Yasushi; Itoh, Ryosuke; Stawarz, Łukasz +3 more
We performed a systematic X-ray study of eight nearby γ-ray bright radio galaxies with Suzaku in order to understand the origins of their X-ray emissions. The Suzaku spectra for five of those have been presented previously, while the remaining three (M87, PKS 0625-354, and 3C 78) are presented here for the first time. Based on the Fe-K line streng…
Measuring Infrared Surface Brightness Fluctuation Distances with HST WFC3: Calibration and Advice
Blakeslee, John P.; Jensen, Joseph B.; Cantiello, Michele +5 more
We present new calibrations of the near-infrared (near-IR) surface brightness fluctuation (SBF) distance method for the F110W ({J}110) and F160W ({H}160) bandpasses of the Wide Field Camera 3 Infrared Channel (WFC3/IR) on the Hubble Space Telescope. The calibrations are based on data for 16 early-type galaxies in the Virgo an…
Predictions for Ultra-deep Radio Counts of Star-forming Galaxies
Cai, Zhen-Yi; Lapi, Andrea; Negrello, Mattia +6 more
We have worked outty predictions for the radio counts of star-forming galaxies down to nJy levels, along with redshift distributions down to the detection limits of the phase 1 Square Kilometer Array MID telescope (SKA1-MID) and of its precursors. Such predictions were obtained by coupling epoch-dependent star formation rate (SFR) functions with r…
Parallel Evolution of Quasi-separatrix Layers and Active Region Upflows
Pick, M.; Mandrini, C. H.; van Driel-Gesztelyi, L. +6 more
Persistent plasma upflows were observed with Hinode’s EUV Imaging Spectrometer (EIS) at the edges of active region (AR) 10978 as it crossed the solar disk. We analyze the evolution of the photospheric magnetic and velocity fields of the AR, model its coronal magnetic field, and compute the location of magnetic null-points and quasi-sepratrix layer…
Using Multiple-viewpoint Observations to Determine the Interaction of Three Coronal Mass Ejections Observed on 2012 March 5
Vourlidas, Angelos; Colaninno, Robin C.
We examine the interaction of three coronal mass ejections (CMEs) that took place on 2012 March 5 at heights less than 20 R ⊙ in the corona. We used a forward fitting model to reconstruct the three-dimensional trajectories and kinematics of the CMEs and determine their interaction in the observations from three viewpoints: Solar and Hel…
On the Viability of the PAH Model as an Explanation of the Unidentified Infrared Emission Features
Zhang, Yong; Kwok, Sun
Polycyclic aromatic hydrocarbon (PAH) molecules are widely considered the preferred candidate for the carrier of the unidentified infrared emission bands observed in the interstellar medium and circumstellar envelopes. In this paper, we report the results of fitting a variety of non-PAH spectra (silicates, hydrogenated amorphous carbon, coal, and …
The M31 Near-infrared Period-Luminosity Relation and its Non-linearity for δ Cep Variables with 0.5 <= log (P) <= 1.7
Lee, Chien-Hsiu; Bender, Ralf; Seitz, Stella +7 more
We present the largest M31 near-infrared (F110W (close to J band), F160W (H band)) Cepheid sample so far. The sample consists of 371 Cepheids with photometry obtained from the Hubble Space Telescope PHAT program. The sample of 319 fundamental mode Cepheids, 16 first overtone Cepheids, and 36 type II Cepheids was identified using the median absolut…