Search Publications
Small Magnetic Loops Connecting the Quiet Surface and the Hot Outer Atmosphere of the Sun
Bellot Rubio, L. R.; Asensio Ramos, A.; Martínez González, M. J. +1 more
Sunspots are the most spectacular manifestation of solar magnetism, yet 99% of the solar surface remains "quiet" at any time of the solar cycle. The quiet sun is not void of magnetic fields, though; they are organized at smaller spatial scales and evolve relatively fast, which makes them difficult to detect. Thus, although extensive quiet Sun magn…
Fibrillar Chromospheric Spicule-like Counterparts to an Extreme-ultraviolet and Soft X-ray Blowout Coronal Jet
Harra, Louise K.; Moore, Ronald L.; Sterling, Alphonse C.
We observe an erupting jet feature in a solar polar coronal hole, using data from Hinode/Solar Optical Telescope (SOT), Extreme Ultraviolet Imaging Spectrometer (EIS), and X-Ray Telescope (XRT), with supplemental data from STEREO/EUVI. From extreme-ultraviolet (EUV) and soft X-ray (SXR) images we identify the erupting feature as a blowout coronal …
Suzaku Observation of GRS 1915+105: Evolution of Accretion Disk Structure during Limit-cycle Oscillation
Yamaoka, K.; Done, C.; Fukazawa, Y. +9 more
We present results from the Suzaku observation of the microquasar GRS 1915+105 performed during the 2005 October multiwavelength campaign. The data include both stable state (class χ) and limit-cycle oscillation (class θ). Correct interstellar absorption as well as effects of dust scattering are fully taken into account in the spectral analysis. T…
The ACS Fornax Cluster Survey. IX. The Color-Magnitude Relation of Globular Cluster Systems
Jordán, Andrés; Mieske, Steffen; Infante, Leopoldo +8 more
We investigate the color-magnitude relation for globular clusters (GCs)—the so-called blue tilt—detected in the Advanced Camera for Surveys (ACS) Fornax Cluster Survey and using the combined sample of GCs from the ACS Fornax and Virgo Cluster Surveys. We find a tilt of γ z ≡ d(g - z)/dz = -0.0257 ± 0.0050 for the full GC sample of the …
Statistical Distribution of Size and Lifetime of Bright Points Observed with the New Solar Telescope
Kilcik, Ali; Yurchyshyn, Vasyl; Abramenko, Valentyna +1 more
We present results of 2 hr non-interrupted observations of solar granulation obtained under excellent seeing conditions with the largest aperture ground-based solar telescope—the New Solar Telescope (NST)—of Big Bear Solar Observatory. Observations were performed with adaptive optics correction using a broadband TiO filter in the 705.7 nm spectral…
Long-Term Optical Continuum Color Variability of Nearby Active Galactic Nuclei
Minezaki, Takeo; Yoshii, Yuzuru; Enya, Keigo +8 more
We examine whether the spectral energy distribution of optical continuum emission of active galactic nuclei (AGNs) changes during flux variation, based on accurate and frequent monitoring observations of 11 nearby Seyfert galaxies and QSOs carried out in the B, V, and I bands for seven years by the MAGNUM telescope. The multi-epoch flux data in an…
The Lick AGN Monitoring Project: Alternate Routes to a Broad-line Region Radius
Treu, Tommaso; Filippenko, Alexei V.; Barth, Aaron J. +8 more
It is now possible to estimate black hole (BH) masses across cosmic time, using broad emission lines in active galaxies. This technique informs our views of how galaxies and their central BHs coevolve. Unfortunately, there are many outstanding uncertainties associated with these "virial" mass estimates. One of these comes from using the accretion …
A Multi-wavelength Study of the Nature of Type 1.8/1.9 Seyfert Galaxies
Turner, T. J.; Kraemer, S. B.; Crenshaw, D. M. +4 more
We focus on determining the underlying physical cause of a Seyfert galaxy's appearance as type 1.8 or 1.9. Are these "intermediate" Seyfert types typical Seyfert 1 nuclei with reddened broad-line regions? Or are they objects with intrinsically weak continua and broad emission lines? We compare measurements of the optical reddening of the narrow an…
Galaxies Probing Galaxies: Cool Halo Gas from a z = 0.47 Post-Starburst Galaxy
Weiner, Benjamin J.; Prochaska, J. Xavier; Koo, David C. +2 more
We study the cool gas around a galaxy at z = 0.4729 using Keck/LRIS spectroscopy of a bright (B = 21.7) background galaxy at z = 0.6942 at a transverse distance of 16.5h -1 70 kpc. The background galaxy spectrum reveals strong Fe II, Mg II, Mg I, and Ca II absorption at the redshift of the foreground galaxy, with an Mg II λ27…
The WFC3 Galactic Bulge Treasury Program: Metallicity Estimates for the Stellar Population and Exoplanet Hosts
Ferguson, Henry C.; Brown, Thomas M.; Casertano, Stefano +14 more
We present new UV-to-IR stellar photometry of four low-extinction windows in the Galactic bulge, obtained with the Wide Field Camera 3 on the Hubble Space Telescope (HST). Using our five bandpasses, we have defined reddening-free photometric indices sensitive to stellar effective temperature and metallicity. We find that the bulge populations rese…