Download or read book Infrared Fine structure Line Emission from the Galactic Center written by John Howard Lacy and published by . This book was released on 1979 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Far infrared Fine structure Line Studies of Galactic Nebulae written by Gary Joel Melnick and published by . This book was released on 1981 with total page 334 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Photoionization Modeling of Infrared Fine Structure Lines in Luminous Galaxies with Central Dust Bounded Nebulae written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Far-infrared spectroscopy of a small sample of IR-bright galaxies taken with the Infrared Space Observatory Long Wavelength Spectrometer has revealed a dramatic progression extending from strong fine-structure line emission from photoionized and photodissociated gas in the starburst galaxy Arp 299 to faint [C II]158 micrometers line emission and absorption in lines of OH, H2O, CH, and [O I] in the ultraluminous galaxy Arp 220. The progression to weaker emission lines is accompanied by lower excitation and does not appear to be due to far-infrared extinction or density effects. Although aging of short duration starbursts with a relatively small range in age might explain much of the sequence, the spectra of Arp 220 and other ultraluminous galaxies may be more reasonably explained by high ionization parameter, dust-bounded nebulae. To test this hypothesis, we ran photoionization models of mid- and far-infrared lines for power law (index -1.5) and starburst cases with moderate (500 cm(exp -3)) and high (10(exp 5) cm(exp -3)) densities. Indeed, we find that for dust-bounded nebulae and photonization by a power law source, the relative emission line strengths and the high-to-low ionization infrared line ratios decrease with ionization parameter. For starburst ionization sources and dust-bounded nebulae, the [N III] 57 micron/[N II] 122 micron line ratio is found to drop with ionization parameter.
Download or read book Mid Infrared Fine Structure Line Ratios in Active Galactic Nuclei Observed with the Spitzer IRS Evidence for Extinction by the Torus written by and published by . This book was released on 2007 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: We present the first systematic investigation of the [Ne v] (14 micron/24 micron) and [S III] (18 micron/33 micron) infrared line flux ratios, traditionally used to estimate the density of the ionized gas, in a sample of 41 type 1 and type 2 active galactic nuclei (AGNs) observed with the Infrared Spectrograph on board Spitzer. The majority of galaxies with both [Ne v] lines detected have observed [Ne v] line flux ratios consistent with or below the theoretical low-density limit, based on calculations using currently available collision strengths and ignoring absorption and stimulated emission. We find that type 2 AGNs have lower line flux ratios than type 1 AGNs and that all of the galaxies with line flux ratios below the low-density limit are type 2 AGNs. We argue that differential infrared extinction to the [Ne v] emitting region due to dust in the obscuring torus is responsible for the ratios below the low-density limit and we suggest that the ratio may be a tracer of the inclination angle of the torus to our line of sight. Because the temperature of the gas, the amount of extinction, and the effect of absorption and stimulated emission on the line ratios are all unknown, we are not able to determine the electron densities associated with the [Ne v] line flux ratios for the objects in our sample. We also find that the [S III] emission from the galaxies in our sample is extended and originates primarily in star-forming regions. Since the emission from low-ionization species is extended, any analysis using line flux ratios from such species obtained from slits of different sizes is invalid for most nearby galaxies.
Download or read book Far infrared Line Emission from the Galaxy written by Gordon John Stacey and published by . This book was released on 1985 with total page 464 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1991 with total page 1460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book A Fabry Perot for Airborne Infrared Astronomy and the SiII Emission from the Galactic Center written by Paul Hamilton Graf and published by . This book was released on 1988 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rocket Infrared Multicolor Observations of the Interplanetary Medium H II Regions and the Galactic Center Region written by Baruch Thomas Soifer and published by . This book was released on 1972 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Galactic Supermassive Black Hole written by Fulvio Melia and published by Princeton University Press. This book was released on 2020-12-08 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Here, one of the world's leading astrophysicists provides the first comprehensive and logically structured overview of the many ideas and discoveries pertaining to the supermassive black hole at the galactic center known as Sagittarius A*. By far the closest galactic nucleus in the universe, Sagittarius A* alone can provide us with a realistic expectation of learning about the physics of strong gravitational fields, and the impact of such fields on the behavior of matter and radiation under severe physical conditions. Its proximity may even provide the opportunity to directly test one of general relativity's most enigmatic predictions--the existence of closed pockets of space-time hidden behind an event horizon. The plethora of research on Sagittarius A* since its discovery in 1974 has long seemed an interwoven pattern of loose threads. No one has successfully synthesized this growing body of work into a manageable, coherent book both for professional researchers and for students taking courses focusing on black holes and galactic nuclei--until now. With Fulvio Melia's The Galactic Supermassive Black Hole, readers finally have at their disposal a one-volume crucible of essential ideas, logically streamlined but with thorough references for those wishing to explore the various topics in greater depth.
Download or read book The Far Infrared Emission Line and Continuum Spectrum of the Seyfert Galaxy NGC 1068 written by and published by . This book was released on 2005 with total page 15 pages. Available in PDF, EPUB and Kindle. Book excerpt: We report on the analysis of the first complete far-infrared spectrum (43 197 m) of the Seyfert 2 galaxy NGC 1068 as observed with the> Long Wavelength Spectrometer (LWS) on board the Infrared Space Observatory (ISO). In addition to the seven expected ionic fine-structure emission lines, the OH rotational lines at 79, 119, and 163 m were all detected in emission, which is unique among galaxies with full LWS spectra, where the 119 m line, when detected, is always in absorption. The observed line intensities were modeled together with ISO> Short Wavelength Spectrometer (SWS) and optical and ultraviolet line intensities from the literature, considering two independent emission components: the active galactic nucleus (AGN) component and the starburst component in the circumnuclear ring of 3 kpc in size. Using the UV to mid-IR emission line spectrum to constrain the nuclear ionizing continuum, we have confirmed previous results: a canonical power-law ionizing spectrum is a poorer fit than one with a deep absorption trough, while the presence of a> big blue bump is ruled out. Based on the instantaneous starburst age of 5 Myr constrained by the Br equivalent width in the starburst ring, and starburst synthesis models of the mid- and far-infrared fine-structure line emission, a low-ionization parameter (U 10 3:5) and low densities (n 100 cm 3) are derived. Combining the AGN and starburst components, we succeeded in modeling the overall UV to far-IR atomic spectrum of NGC 1068, reproducing the line fluxes to within a factor of 2.0 on average with a standard deviation of 1.3, and the overall continuum as the sum of the contribution of the thermal dust emission in the ionized and neutral components. The OH 119 m emission indicates that the line is collisionally excited and arises in a warm and dense region.
Download or read book Proceedings of the Galactic Center Workshop 2002 Astronomische Nachrichten Supplementary Issue 1 2003 written by Angela Cotera and published by John Wiley & Sons. This book was released on 2008-09-26 with total page 653 pages. Available in PDF, EPUB and Kindle. Book excerpt: Our knowledge of the environment of the nucleus of our galaxy has been greatly enhanced, by more extensive and sensitive observations at radio and infrared wavelengths, the advent of high resolution x-ray imaging and spectroscopy, and considerable theoretical activity to understand the nucleus and its components, and their activity. The Galactic Center Workshop 2002 was organized to review recent research on the galactic center, including the latest state-of-the-art observations and important theoretical developments. The workshop covered phenomena on scales ranging from the central several hundred parsecs to the central parsec and within. Each topic was approached from both multi-wavelength observational and theoretical perspectives.
Download or read book Catalog of Infrared Observations Appendixes written by Daniel Y. Gezari and published by . This book was released on 1987 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Astrophysics Update 2 written by John Mason and published by Springer. This book was released on 2010-11-20 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Astrophysics Updates" is intended to serve the information needs of professional astronomers and postgraduate students about areas of astronomy, astrophysics and cosmology that are rich and active research spheres. Observational methods and the latest results of astronomical research are presented as well as their theoretical foundations and interrelations. The contributed commissioned articles are written by leading exponents in a format that will appeal to professional astronomers and astrophysicists who are interested in topics outside their own specific areas of research. This collection of timely reviews may also attract the interest of advanced amateur astronomers seeking scientifically rigorous coverage.
Download or read book The Large scale Characteristics of the Galaxy written by William Butler Burton and published by Springer Science & Business Media. This book was released on 1979-09 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt: At head of title: International Astronomical Union. Union astronomique internationale.
Download or read book Infrared Emission Lines in Planetary Nebulae written by and published by . This book was released on 1982 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book High Spatial Resolution written by Harri Michael Latvakoski and published by . This book was released on 1997 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1970 with total page 1054 pages. Available in PDF, EPUB and Kindle. Book excerpt:
