Navegação Ciências Exatas e da Terra por Assunto "Accretion, accretion disks"
Resultados 1-12 de 12
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DB white dwarfs in the Sloan Digital Sky Survey data release 10 and 12
(2015) [Artigo de periódico]Aims. White dwarfs with helium-dominated atmospheres (spectral types DO, DB) comprise approximately 20% of all white dwarfs. There are fewer studies than of their hydrogen-rich counterparts (DA) and thus several questions ... -
Discovery of a new AM CVn system with the Kepler satellite
(2011) [Artigo de periódico]We report the discovery of a new AM CVn system on the basis of broadband photometry obtained with the Kepler satellite supplemented by ground-based optical spectroscopy. Initially retained on Kepler target lists as a ... -
Double-peaked profiles : ubiquitous signatures of disks in the broad emission lines of active galactic nuclei
(2017) [Artigo de periódico]Broad (10,000 km s−1), double-peaked emission-line profiles of Balmer lines emitted by active galactic nuclei (AGN) are thought to originate in the outer parts of an accretion disk surrounding a nuclear supermassive black ... -
Elliptical accretion disks in active galactc nuclei
(1995) [Artigo de periódico]We present a calculation of the profiles of emission lines originating in a relativistic, eccentric disk, and show examples of the resulting model profiles. Our calculations are motivated by the fact that in about one ... -
Evidence for a precessing accretion disk in the nucleus of NGC 1097
(1997) [Artigo de periódico]We present new spectroscopic observations of the LINER (and now Seyfert 1) nucleus of NGC 1097, and discuss the evolution of its broad, double-peaked Balmer lines. When originally discovered in 1991, the red peak of the ... -
Evidence of a starburst within 9 parsecs of the active nucleus of NGC 1097
(2005) [Artigo de periódico]We report evidence of a recent burst of star formation located within 9 pc of the active nucleus of NGC 1097. The observational signatures of the starburst include UV absorption lines and continuum emission from young stars ... -
Evolution of the nuclear accretion disk emission in NGC 1097 : getting closer to the black hole
(2003) [Artigo de periódico]We study the evolution of the broad, double-peaked H emission-line profile of the LINER/Seyfert 1 nucleus of NGC 1097, using 24 spectra obtained over a time span of 11 years—from 1991 November through 2002 October. While ... -
Long-term profile variability in active galactic nucleus with double-peaked Balmer emission lines
(2010) [Artigo de periódico]An increasing number of active galactic nuclei (AGNs) exhibit broad, double-peaked Balmer emission lines, which represent some of the best evidence for the existence of relatively large-scale accretion disks in AGNs. A set ... -
Radiatively inefficient accretion flow in the nucleus of NGC 1097
(2006) [Artigo de periódico]We present a model for the accretion flow around the supermassive black hole in the LINER nucleus of NGC 1097 that fits the optical to X-ray spectral energy distribution (SED). The X-ray segment of the SED is based on ... -
Short timescale monitoring of the X-ray, UV, and broad double-pead emission line of the nucleus of 1097
(2015) [Artigo de periódico]Recent studies have suggested that the short-timescale (<~ 7 days) variability of the broad (∼10,000 km s-ˡ) doublepeaked Hα profile of the LINER nucleus of NGC 1097 could be driven by a variable X-ray emission from a ... -
Short timescale variations of the Hα double-peaked profile of the nucleus of NGC 1097
(2012) [Artigo de periódico]The broad (FWHM ∼ 10,000 km s-ˡ) double-peaked Hα profile from the LINER/Seyfert 1 nucleus of NGC 1097 was discovered in 1991 and monitored for the following 11 years. The profile showed variations attributed to the rotation ... -
The unusual helium variable AM Canum Venaticorum
(1995) [Artigo de periódico]The unusual variable star AM CVn has puzzled astronomers for over 40 years. This object, both a photometric and spectroscopic variable, is believed to contain a pair of hydrogen-deficient white dwarfs of extreme mass ratio, ...