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The Star-forming Torus and Stellar Dynamical Black Hole Mass in the Seyfert 1 Nucleus of NGC 3227
Genzel, R.; Tacconi, L. J.; Sternberg, A. +7 more
We report R~4300 VLT SINFONI adaptive optics integral field K-band spectroscopy of the nucleus of the Seyfert 1 galaxy NGC 3227 at a spatial resolution of 0.085" (7 pc). We present the morphologies and kinematics of emission lines and absorption features and give the first derivation of a black hole mass in a Seyfert 1 nucleus from stellar dynamic…
A Survey of Kiloparsec-Scale Radio Outflows in Radio-Quiet Active Galactic Nuclei
Baum, Stefi A.; O'Dea, Christopher P.; Gallimore, Jack F. +2 more
Seyfert galaxies commonly host compact jets spanning 10-100 pc scales, but larger structures are resolved out in long-baseline aperture synthesis surveys. Previous, targeted studies showed that kiloparsec-scale radio structures (KSRs) may be a common feature of Seyfert and LINER galaxies, and the origin of KSRs may be starbursts or active galactic…
Massive-Star Supernovae as Major Dust Factories
Gordon, Karl D.; Kennicutt, Robert C.; Panagia, Nino +15 more
We present late-time optical and mid-infrared observations of the Type II supernova 2003gd in the galaxy NGC 628. Mid-infrared excesses consistent with cooling dust in the ejecta are observed 499 to 678 days after outburst and are accompanied by increasing optical extinction and growing asymmetries in the emission-line profiles. Radiative-transfer…
Solar activity variations of the ionospheric peak electron density
Liu, Libo; Wan, Weixing; Ning, Baiqi +2 more
The daily averaged Solar EUV Monitor (SEM)/Solar Heliospheric Observatory (SOHO) EUV measurements, solar proxies, and foF2 data at 20 ionosonde stations in the east Asia/Australia sector are collected to investigate the solar activity dependences of the ionospheric peak electron density (NmF2). The intensities of solar EUV from the SEM/SOHO measur…
Ultraviolet spectroscopy of the extended solar corona
Kohl, John L.; Noci, Giancarlo; Cranmer, Steven R. +1 more
The first observations of ultraviolet spectral line profiles and intensities from the extended solar corona (i.e., more than 1.5 solar radii from Sun-center) were obtained on 13 April 1979 when a rocket-borne ultraviolet coronagraph spectrometer of the Harvard-Smithsonian Center for Astrophysics made direct measurements of proton kinetic temperatu…
Different Power-Law Indices in the Frequency Distributions of Flares with and without Coronal Mass Ejections
Howard, R. A.; Gopalswamy, N.; Yashiro, S. +1 more
We investigated the frequency distributions of flares with and without coronal mass ejections (CMEs) as a function of flare parameters (peak flux, fluence, and duration of soft X-ray flares). We used CMEs observed by the Large Angle and Spectrometric Coronagraph (LASCO) on board the Solar and Heliospheric Observatory (SOHO) mission and soft X-ray …
Unveiling Supergiant Fast X-Ray Transient Sources with INTEGRAL
Hill, A. B.; Bird, A. J.; Ubertini, P. +9 more
Supergiant high-mass X-ray binaries (SGXBs) are believed to be rare objects, as stars in the supergiant phase have a very short lifetime and to date only about a dozen of them have been discovered. They are known to be persistent and bright X-ray sources. INTEGRAL is changing this classical picture, as its observations are revealing the presence o…
Titan's methane cycle
Atreya, Sushil K.; Ferri, Francesca; Niemann, Hasso B. +5 more
Methane is key to sustaining Titan's thick nitrogen atmosphere. However, methane is destroyed and converted to heavier hydrocarbons irreversibly on a relatively short timescale of approximately 10-100 million years. Without the warming provided by CH 4-generated hydrocarbon hazes in the stratosphere and the pressure induced opacity in t…
Origin of the Galactic ridge X-ray emission
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +2 more
We analyze a map of the Galactic ridge X-ray emission (GRXE) constructed in the 3-20 keV energy band from RXTE/PCA scan and slew observations. We show that the GRXE intensity follows the Galactic near-infrared surface brightness closely and thus traces the Galactic stellar mass distribution. The GRXE consists of two spatial components that can be …
The colours of the Sun
Flynn, Chris; Holmberg, Johan; Portinari, Laura
We compile a sample of Sun-like stars with accurate effective temperatures, metallicities and colours (from the ultraviolet to the near-infrared). A crucial improvement is that the effective temperature scale of the stars has recently been established as both accurate and precise through direct measurement of angular diameters obtained with stella…