Smithsonian Astrophysical Observatory

About: Smithsonian Astrophysical Observatory is a facility organization based out in Cambridge, Massachusetts, United States. It is known for research contribution in the topics: Galaxy & Stars. The organization has 1665 authors who have published 3622 publications receiving 132183 citations. The organization is also known as: SAO.

Modeling the Interstellar Medium of Low Surface Brightness Galaxies: Constraining Internal Extinction, Disk Color Gradients, and Intrinsic Rotation Curve Shapes

Abstract: We use a combination of three-dimensional Monte Carlo radiative transfer techniques and multiwavelength (BRHK ,H a) imaging data to investigate the nature of the interstellar medium (ISM) in the edge-on, low surface brightness (LSB) galaxy UGC 7321. Using realistic models that incorporate multiple scattering eUects and clumping of the stars and the interstellar material, we explore the distribution and opacity of the interstellar material (gas]dust) and its eUects on the observed stellar disk luminosity pro—les, color gradients, and rotation curve shape. We —nd that UGC 7321 contains a small but nonnegligible dusty component to its ISM, yielding a B-band optical depth from disk edge to q6 e,B D 4.0 center. A signi—cant fraction (D50% ^ 10%) of the interstellar material in the innermost regions of UGC 7321 appears to be contained in a clumpy medium, indicating that LSB galaxies can support a modest, multiphase ISM structure. In spite of the clear presence of dust, we conclude that the large radial optical color gradients observed in UGC 7321 and other similar LSB spiral galaxies cannot be accounted for by dust and must result primarily from signi—cant stellar population and/or metallicity gradients. We show that realistic optical depth eUects will have little impact on the observed rotation curves of edge-on disk galaxies and cannot explain the linear, slowly rising rotation curves seen in some edge-on LSB spirals. Projection eUects create a far larger uncertainty in recovering the true underlying rotation curve shape of galaxies viewed at inclinations i Z 85i.

Smithsonian stratospheric far‐infrared spectrometer and data reduction system

Abstract: The Smithsonian far-infrared spectrometer (FIRS) is a remote sensing Fourier transform spectrometer that measures the mid- and far-infrared thermal emission spectrum of the stratosphere from balloon and aircraft platforms. The spectrometer has had nine successful balloon flights from 1987 to 1994, flying at float altitudes of 36 - 39 km and collecting 131 hours of midlatitude stratospheric limb spectra. The spectrometer also flew on a NASA CD-8 aircraft, as part of the second Airborne Arctic Stratospheric Expedition (AASE-2), collecting 140 hours of overhead spectra at latitudes ranging from the equator to the north pole. We present here a brief description of the instrument, a discussion of data reduction procedures, an estimation of both random and systematic errors, an outline of the procedure for retrieving mixing ratio profiles, and an explanation of the method of deriving temperature and pressure from the far- and mid-infrared spectra.

The role of SO2 in volcanism on Io

Abstract: Io and Earth are the only planetary bodies known to be volcanically active; the energetics of the eruptive plumes on Io have important structural implications and are closely linked with the presence of sulphur and SO2.

The Hinode X-Ray Telescope (XRT): Camera Design, Performance and Operations

Abstract: The X-ray Telescope (XRT) aboard the Hinode satellite is a grazing incidence X-ray imager equipped with a 2048×2048 CCD. The XRT has 1 arcsec pixels with a wide field of view of 34×34 arcmin. It is sensitive to plasmas with a wide temperature range from < 1 to 30 MK, allowing us to obtain TRACE-like low-temperature images as well as Yohkoh/SXT-like high-temperature images. The spacecraft Mission Data Processor (MDP) controls the XRT through sequence tables with versatile autonomous functions such as exposure control, region-of-interest tracking, flare detection, and flare location identification. Data are compressed either with DPCM or JPEG, depending on the purpose. This results in higher cadence and/or wider field of view for a given telemetry bandwidth. With a focus adjust mechanism, a higher resolution of Gaussian focus may be available on-axis. This paper follows the first instrument paper for the XRT (Golub et al., Solar Phys. 243, 63, 2007) and discusses the design and measured performance of the X-ray CCD camera for the XRT and its control system with the MDP.