Search Publications
What can We Learn about Solar Coronal Mass Ejections, Coronal Dimmings, and Extreme-ultraviolet Jets through Spectroscopic Observations?
He, Jiansen; Wang, Xin; McIntosh, Scott W. +2 more
Solar eruptions, particularly coronal mass ejections (CMEs) and extreme-ultraviolet (EUV) jets, have rarely been investigated with spectroscopic observations. We analyze several data sets obtained by the EUV Imaging Spectrometer on board Hinode and find various types of flows during CMEs and jet eruptions. CME-induced dimming regions are found to …
Supermassive Black Holes, Pseudobulges, and the Narrow-line Seyfert 1 Galaxies
Peterson, Bradley M.; Mathur, Smita; Grupe, Dirk +1 more
We present Hubble Space Telescope Advanced Camera for Surveys (ACS) observations of 10 galaxies that host narrow-line Seyfert 1 (NLS1) nuclei, believed to contain relatively smaller mass black holes accreting at high Eddington ratios. We deconvolve each ACS image into a nuclear point source (AGN), a bulge, and a disk, and fitted the bulge with a S…
Mid- and Far-infrared Properties of a Complete Sample of Local Active Galactic Nuclei
Nakagawa, Takao; Oyabu, Shinki; Gandhi, Poshak +4 more
We investigate the mid- (MIR) to far-infrared (FIR) properties of a nearly complete sample of local active galactic nuclei (AGNs) detected in the Swift/Burst Alert Telescope (BAT) all-sky hard X-ray (14-195 keV) survey, based on the cross correlation with the AKARI infrared survey catalogs complemented by those with Infrared Astronomical Satellite…
Hα Equivalent Widths from the 3D-HST Survey: Evolution with Redshift and Dependence on Stellar Mass
Schmidt, Kasper B.; Franx, Marijn; van Dokkum, Pieter +12 more
We investigate the evolution of the Hα equivalent width, EW(Hα), with redshift and its dependence on stellar mass, using the first data from the 3D-HST survey, a large spectroscopic Treasury program with the Hubble Space Telescope Wide Field Camera 3. Combining our Hα measurements of 854 galaxies at 0.8 < z < 1.5 with those of ground-based s…
A Far-ultraviolet Atlas of Low-resolution Hubble Space Telescope Spectra of T Tauri Stars
Herczeg, Gregory J.; Valenti, Jeff A.; Brown, Alexander +6 more
We present a far-ultraviolet (FUV) spectral atlas consisting of spectra of 91 pre-main-sequence stars. Most stars in this sample were observed with the Space Telescope Imaging Spectrograph and Advanced Camera for Surveys on the Hubble Space Telescope (HST). A few archival spectra from the International Ultraviolet Explorer and the Goddard High Res…
Can Dust Emission be Used to Estimate the Mass of the Interstellar Medium in Galaxies—A Pilot Project with the Herschel Reference Survey
Gear, Walter; Wilson, Christine D.; De Looze, Ilse +23 more
The standard method for estimating the mass of the interstellar medium (ISM) in a galaxy is to use the 21 cm line to trace the atomic gas and the CO 1-0 line to trace the molecular gas. In this paper, we investigate the alternative technique of using the continuum dust emission to estimate the mass of gas in all phases of the ISM. Using Herschel o…
The Role of Streamers in the Deflection of Coronal Mass Ejections: Comparison between STEREO Three-dimensional Reconstructions and Numerical Simulations
Mierla, M.; Poedts, S.; Bemporad, A. +3 more
On 2009 September 21, a filament eruption and the associated coronal mass ejection (CME) were observed by the Solar Terrestrial Relations Observatory (STEREO) spacecraft. The CME originated from the southern hemisphere and showed a deflection of about 15° toward the heliospheric current sheet (HCS) during the propagation in the COR1 field of view.…
Separation of Two Contributions to the High Energy Emission of Cygnus X-1: Polarization Measurements with INTEGRAL SPI
Clark, D. J.; Jourdain, E.; Roques, J. P. +1 more
Operational since 2002 on board the INTEGRAL observatory, the SPI spectrometer can be used to perform polarization measurements in the hard X-ray/softγ-ray domain (~130 keV-8 MeV). However, this phenomenon is complex to measure at high energy and requires high fluxes. Cyg X-1 appears to be the best candidate amongst the X-ray binaries since it is …
New Insight into Short-wavelength Solar Wind Fluctuations from Vlasov Theory
Belmont, G.; Sahraoui, F.; Goldstein, M. L.
The nature of solar wind (SW) turbulence below the proton gyroscale is a topic that is being investigated extensively nowadays, both theoretically and observationally. Although recent observations gave evidence of the dominance of kinetic Alfvén waves (KAWs) at sub-ion scales with ω < ωci, other studies suggest that the KAW mode cann…
Calibrating 100 Years of Polar Faculae Measurements: Implications for the Evolution of the Heliospheric Magnetic Field
DeLuca, Edward E.; Zhang, Jie; Muñoz-Jaramillo, Andrés +1 more
Although the Sun's polar magnetic fields are thought to provide important clues for understanding the 11 year sunspot cycle, including the observed variations of its amplitude and period, the current database of high-quality polar field measurements spans relatively few sunspot cycles. In this paper, we address this deficiency by consolidating Mou…