Matthew A. Greenhouse

INFRARED FABRY-PEROT IMAGING OF M82 (Fe II) EMISSION. II. TRACING EXTRAGALACTIC SUPERNOVA REMNANTS

We report high spatial and spectral resolution [Fe II] 1.644 ?m Fabry-Perot imaging observations of M82. We present extinction-corrected [Fe II] images and discuss the nature of compact [Fe II] emission regions revealed by these new data. We conclude that these [Fe II] sources trace a population of supernova remnants in M82 that are substantially older than those revealed previously on 6 cm radiographs. In addition, we find that M82 contains a distributed [Fe II] emission component that is extended along the southern minor axis and that accounts for 90% of the galaxys [Fe II] luminosity. We interpret this extended emission as tracing disk material entrained in a super wind that has broken out of the galactic disk to the south. We find that the [Fe II]/Br? line ratio throughout M82 correlates with the age of the starburst as reflected by the color of the photospheric emission from the galaxys stars. This correlation suggests that the [Fe II] emission regions in M82 are colocated with a post-main-sequence stellar population. The engineering details of our Fabry-Perot imaging methodology are also discussed.

Near-infrared [Fe II] emission of M82 supernova remnants : implications for tracing the supernova content of galaxies

Near-infrared [Fe II] and Paβ spectra of two young supernova remnants and one H II region within the central 15 kpc of M 82 are reported. Comparison of these spectra reveal a [Fe II]/Paβ ratio similar to that observed in Galactic supernova remnants and H II regions, and show that the [Fe II] background emission in M 82 has local maxima at the position of the supernova remnants observed in the radio continuum.

The peculiar infrared temporal development of Nova Vulpeculae 1987 (QV Vulpeculae)

The paper reports 1.25-19.5-micron IR photometry and optical/IR spectroscopy of Nova QV Vul (1987) from November 1987 through September 1989. The measurements show that an optically thick carbon dust shell formed within 83 d of the outburst, and that the spectral signatures of four types of astrophysical grains appeared at various times during a 2-yr period following the eruption. Carbon, SiC, and hydrocarbons formed first; oxygen-rich silicates formed later. It is suggested that the carbon dust components formed in fast-moving polar flumes, and that the silicates formed in a slow-moving equatorial ring. Mass estimates from the IR photometry and optical spectroscopy confirm that grain condensation in both the slow and fast ejecta of QV Vul is consistent with constraints established by previous observations of other dusty novae. It is concluded that the condensible elements in these grains were present in approximately solar abundance.

The infrared coronal lines of recent novae

IR coronal line emissions are reported in the novae V1819 Cyg and V827 Her; high-resolution near-IR spectra of coronal line emission in the nova QU Vul have also been obtained, increasing the number of known IR coronal line novae from two to four. Each of the four is found to be characterized by approximately the same Si VI/Si VII line-intensity ratio, which indicates a common coronal-zone electron temperature of 300,000 K. The coronal-line novae are noted to possess a remarkably similar near-IR spectrum, suggesting that their coronal line emission will only occasionally be observed at optical wavelengths. 51 refs.

Microstructure technology for fabrication of metal-mesh grids

Motivated by the need for highly efficient far-IR Fabry-Perot étalons for airborne and space astronomy, we have developed a high-yield photolithographic technique for producing low-loss metal-mesh reflectors. We describe the production technique and report on the mesh flatness and uniformity. Optical measurements of meshes produced by this technique show that absorptivity of less than 1% with reflectivity of more than 98% was achieved at the longest wavelengths measured, which proved them to be significantly more efficient than commercially available meshes. This process can achieve wire widths that are less than the mesh thicknesses (typically 3 µm), which extends their applicability to wavelengths as short as ~ 20 µm without sacrificing mechanical strength for airborne and space-flight applications.

The Infrared Spectrum of the Optically Thin Dust Shell of V705 Cassiopeiae (Nova Cassiopeiae 1993)

We report 1.25 to 18 mm infrared photometry spectroscopy of the optically thin dust shell of V705 Cassiopeiae (Nova Cas 1993) between 330 and 418 days after the outburst. The measurements show that the dust shell, which had been optically thick until at least day2131, now shows the spectral signatures of optically thin astrophysical silicate grains at 10 and 20 mm and hydrocarbons at 3.2‐3.4 and 11.3 mm. The 1‐8 mm continuum which is due to carbon dust is still present, although it no longer has a blackbody spectral energy distribution. We estimate mass of silicate grains required to produce the observed visual extinction and conclude that the condensible elements in the silicate grains may be overabundant with respect to hydrogen. Subject headings: circumstellar matter—dust, extinction—infrared: stars —stars: individual (V705 Cassiopeiae)

Strong Fe II forbidden line emission from NGC 1275

The detection of a bright Fe II 12567-A forbidden line from the central regions of NGC 1275 is reported. The intensity of the Fe II 12567-A forbidden line relative to that of the other emission lines indicates the presence of a high abundance of iron in the gas phase, while the narrow width of the feature implies an origin outside the active nucleus. While a power-law continuum from the nucleus or from the cooling flows could excite the Fe II forbidden line emission, neither offers a likely mechanism for processing the circumnuclear dust grains in NGC 1275. This is not the case for shocks, which can also produce the low-ionization features characteristic of many of the off-nucleus emission line regions of NGC 1275.

Possibility of Infrared Coronal Line Laser Emission in Seyfert Nuclei

Energetic emitting regions in astronomical sources have traditionally been studied via x-ray, UV, and optical emission lines of highly ionized intermediate mass elements. Such lines are often referred to as “coronal lines” since the ions, when produced by collisional ionization, reach maximum abundance at electron temperatures of ~ 105 — 106 K typical of the sun’s upper atmosphere. However, optical and UV coronal lines are also observed in a wide variety of Galactic and extra- galactic sources including the Galactic interstellar medium [2], nova shells [3,4], supernova remnants [5, 6, 7], galaxies and QSOs [8, 9, 10].

Servicing and assembly: enabling the most ambitious future space observatories

The scientific measurement requirements of future major space astronomy missions are pushing the design limits that can be autonomously deployed JWST-style from even the largest plausible launch vehicles in the 2030s and beyond. In addition, to maximize the scientific return and make missions more cost-effective, they should be capable of being serviced and upgraded. This requirement was even codified by the US Congress in 2010 to ensure the best use of taxpayer investments in science. We need to advance technologies to support this new generation of space telescopes and utilize planned NASA assets to lower costs, reduce risks, and extend mission life of flagship-class science programs for astrophysics and other NASA science. These missions will be capable of searching very large numbers of extrasolar planets for evidence of life and will enable studies, in detail, of the structure of the first star-forming complexes in the earliest galaxies and the central engines in distant galaxies, and will be powerful tools for general astrophysics and solar system science. We will present and discuss current concepts for using astronauts and robots to service, upgrade, and eventually assemble space observatories and starshades designed to achieve major breakthroughs in our understanding of the cosmos. Notional telescopic missions and instruments (filled apertures, interferometers, evolvable systems, and starshades, among others) will be used to illustrate key characteristics of this approach and demonstrate the broad application such a deep-space facility would provide science missions. The goal of this effort is to understand how to use planned NASA human spaceflight assets and infrastructure, with minimal modification, to assemble, test, and service high-value science facilities. These deep space assets are currently being defined and now is the time to jointly develop requirements and capabilities that meet both science and human exploration objectives. The technical and engineering merits and challenges of in-space servicing and assembly will be discussed, including issues of launching telescopes and instruments in parts, assembly in space, and repair and replacement of instruments and systems. Possible future space infrastructure that may make on-orbit assembly and servicing feasible will also be discussed. Precursors and demonstration activities will be presented, as well as early candidate missions for in-space upgrade and servicing.

Development of transition edge sensors optimized for single-photon spectroscopy in the optical and near-infrared

The search for biosignatures in the atmospheres of exoplanets will be a key focus of future space telescopes that operate in the ultraviolet, visible, and near-infrared bands. Detection of biosignatures requires an instrument with moderate spectral resolving power (R ∼ 100) and a large bandwidth (∼ 400 nm – ∼ 1.8 μm). Additionally, biosignature detection is a photon-starved science; instruments designed for these measurements would ideally combine high optical efficiency with quantum-limited photon detectors (i.e., detectors that exhibit zero dark current). In this work, we report on our efforts to develop energy resolving transition edge sensor (TES)-based detectors designed for biosignature detection. TESs operated as microcalorimeters are compelling detectors for this application. Unlike semiconductor detectors, TESs eliminate the need for dispersive optics and are truly single photon detectors – fundamental TES noise yields uncertainty in the energies of detected photons, not in the number of detected photons. We introduce TESs designed for this application and discuss the path toward realizing a TES-based dispersionless spectrometer optimized for biosignature detection.