Garrett Jernigan

Transiting Exoplanet Survey Satellite (TESS)

The Transiting Exoplanet Survey Satellite (TESS ) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with IC (approximately less than) 13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the stars ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every four months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations.

Transiting Exoplanet Survey Satellite

Abstract. The Transiting Exoplanet Survey Satellite (TESS) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its 2-year mission, TESS will employ four wide-field optical charge-coupled device cameras to monitor at least 200,000 main-sequence dwarf stars with IC≈4−13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from 1 month to 1 year, depending mainly on the star’s ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10 to 100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every 4 months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations.

The transiting exoplanet survey satellite

The Transiting Exoplanet Survey Satellite (TESS ) will search the solar neighborhood for planets transiting bright stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with IC 13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending on the star’s ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10–100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every four months, inviting immediate Correspondence may be sent to George R. Ricker (grr@space.mit.edu). Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, edited by Howard A. MacEwen, Giovanni G. Fazio, Makenzie Lystrup, Proc. of SPIE Vol. 9904, 99042B ·

Quasi-periodic X-Ray Brightness Oscillations of GRO J1744–28

The newly discovered source GRO J1744-28 is remarkable in many respects. It is a low-mass X-ray binary system that shows 2.1 Hz coherent pulsations. It also produces type II X-ray bursts similar to those seen in the Rapid Burster. In this Letter we report results from a series of observations with the Rossi X-Ray Timing Explorer (RXTE) during which GRO J1744-28 showed quasi-periodic X-ray brightness oscillations (QPOs) at 20, 40, and 60 Hz. Their fractional rms amplitudes are 0.19%, 5.9%, and 0.42%, respectively. The QPO centroid frequency and its rms amplitude as a function of source brightness in the band of 2-60 keV indicate that these QPOs are of a different kind from the beat-frequency QPOs that have been observed among Z sources as well as X-ray pulsars. We discuss possible interpretations of these QPOs in the context of neutron star g-mode oscillations and photon bubble oscillations.

The mid-infrared radio correlation at high angular resolution : NGC 253

We present high angular resolution (1″.2), narrow-band (Δλ/λ=0.1) images of the nucleus of NGC 253 at three wavelengths in the mid-infrared (8.5, 10.0, and 12.5 μm). We find that most of the mid-IR flux in the nucleus of NGC 253 derives from a very small region ≤120 pc in diameter. Within this small region there are three spatially and spectrally distinct IR components: two bright compact sources, and a surrounding envelope of low-level, diffuse emission. The mid-IR and 6 cm radio are loosely correlated in position but not in brightness. The implication is that the mid-IR-radio correlation may begin to break down on small spatial scales relevant to individual star-forming regions and large individual sources

The environments of young stars : mid-infrared and molecular line imaging

Young late-type stars in massive-star-forming regions, though much fainter than their early-type neighbors, are detectable in brightened molecular line emission, IR continuum, and H 2 O maser emission. The stars are found deeply embedded in high-temperature, high-density gas and near newly formed massive stars. Because the time scales in massive-star-forming regions are so short, these lower mass stars must be in very early evolutionary stages relative to their much longer lifetimes

Subarcsecond mid-infrared imaging of the nuclei of the infrared bright galaxies NGC 1614 and NGC 7469

The first subarcsecond resolution mid-IR images of the nuclei of two galaxies from the IRAS bright sample, NGC 1614 and NGC 7469, are reported. These results show that the starburst galaxy NGC 1614 contains a double structure in the nuclear region. Most of the flux, 78% of 650 ± 50 mJy, is emitted in two unresolved regions of 0.6″ FWHM (190 pc at 64 Mpc) of nearly equal strength separated by 0.6″ (200 pc). Most of the remaining flux is derived from a small arm 1″ in length (310 pc). The Seyfert I galaxy NGC 7469 shows an elongated structure, 1.4″ × 0.7″ (450 × 220 pc at 66 Mpc)

Mid-infrared imaging of Markarian 231 and Arp 220

High angular resolution observations of Arp 220 and Mrk 231 provide images of the nuclei and show that the source of the strong mid-IR emission is confined to regions less than about 0.5 arcsec or 400 pc in diameter in Mrk 231 and less than 1.5 arcsec x 0.9 arcsec or 320 x 530 pc in Arp 220. If much of the far-IR emission also derives from such a small region, the implied radiation densities are quite high, equivalent to one O star per cu pc. Although in normal galaxies the near-IR traces an older population of evolved, cool stars, such high radiation densities in the IR bright galaxies suggest the possibility that the spatial correlation observed between the near-IR, mid-IR, and radio may hold because emission in all three bands is associated with hot interstellar gas and dust. 23 refs.

CHARACTERIZATION OF SOLID STATE ARRAY CAMERAS FOR THE MID-IR

We present a characterization of some processes affecting the performance of solid state array cameras designed for ground based astronomical imaging in the 8–13μm atmospheric window. Our discussion includes a novel model for electron-hole generationrecombination noise based on the probable pathlength of an electron in a photoconductor. We use the Berkeley mid-IR Array Camera as an example. For this camera, the results show that the total optical system composed of the camera, a 3m telescope, and the atmosphere has an efficiency of about 3%, a 1σ noise equivalent flux density of 25 mJy min−1/2arcsec−2 measured over a Δλ/λ=10% band width, and a noise equivalent expressed as the ambient temperature thermal black body noise of 23%.

Imaging and burst location with the EXIST high-energy telescope

The primary instrument of the proposed EXIST mission is a coded mask high energy telescope (the HET), that must have a wide field of view and extremely good sensitivity. In order to achieve the performance goals it will be crucial to minimize systematic errors so that even for very long total integration times the imaging performance is close to the statistical photon limit. There is also a requirement to be able to reconstruct images on-board in near real time in order to detect and localize gamma-ray bursts, as is currently being done by the BAT instrument on Swift. However for EXIST this must be done while the spacecraft is continuously scanning the sky. The scanning provides all-sky coverage and is also a key part of the strategy to reduce systematic errors. The on-board computational problem is made even more challenging for EXIST by the very large number of detector pixels (more than 107, compared with 32768 for BAT). The EXIST HET Imaging Technical Working Group has investigated and compared numerous alternative designs for the HET. The selected baseline concept meets all of the scientific requirements, while being compatible with spacecraft and launch constraints and with those imposed by the infra-red and soft X-ray telescopes that constitute the other key parts of the payload. The approach adopted depends on a unique coded mask with two spatial scales. Coarse elements in the mask are effective over the entire energy band of the instrument and are used to initially locate gamma-ray bursts. A finer mask component provides the good angular resolution needed to refine the burst position and reduces the cosmic X-ray background; it is optimized for operation at low energies and becomes transparent in the upper part of the energy band where an open fraction of 50% is optimal. Monte Carlo simulations and analytic analysis techniques have been used to demonstrate the capabilities of the proposed design and of the two-step burst localization procedure.