Browsing by Author "Silverstone, Murray D."

Now showing 1 - 7 of 7
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    Are debris disks and massive planets correlated?
    (IOP Publishing, 2007) Moro-Martin, Amaya; Carpenter, John M.; Meyer, Michael R.; Hillenbrand, Lynne A.; Malhotra, Renu; Hollenbach, David; Najita, Joan; Henning, Thomas; Kim, Jinyoung S.; Bouwman, Jeroen; Silverstone, Murray D.; Hines, Dean C.; Wolf, Sebastian; Pascucci, Ilaria; Mamajek, Eric E.; Lunine, Jonathan; Princeton University; California Institute of Technology; University of Arizona; National Aeronautics & Space Administration (NASA); NASA Ames Research Center; National Optical Astronomy Observatory; Max Planck Society; Harvard University; Smithsonian Astrophysical Observatory; Smithsonian Institution; University of Alabama Tuscaloosa
    Using data from the Spitzer Space Telescope Legacy Science Program Formation and Evolution of Planetary Systems (FEPS), we have searched for debris disks around nine FGK stars (2-10 Gyr), known from radial velocity ( RV) studies to have one or more massive planets. Only one of the sources, HD 38529, has excess emission above the stellar photosphere; at 70 mu m the signal-to-noise ratio in the excess is 4.7, while at lambda < 30 mu m there is no evidence of excess. The remaining sources show no excesses at any Spitzer wavelengths. Applying survival tests to the FEPS sample and the results for the FGK survey recently published in Bryden et al., we do not find a significant correlation between the frequency and properties of debris disks and the presence of close-in planets. We discuss possible reasons for the lack of a correlation.
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    Discovery of an 86 AU radius debris ring around HD 181327
    (IOP Publishing, 2006) Schneider, Glenn; Silverstone, Murray D.; Hines, Dean C.; Augereau, Jean-Charles; Pinte, Christophe; Menard, Francois; Krist, John; Clampin, Mark; Grady, Carol; Golimowski, David; Ardila, David; Henning, Thomas; Wolf, Sebastian; Rodmann, Jens; University of Arizona; National Aeronautics & Space Administration (NASA); NASA Goddard Space Flight Center; Eureka Scientific; Johns Hopkins University; Max Planck Society; University of Alabama Tuscaloosa
    HST NICMOS PSF-subtracted coronagraphic observations of HD 181327 have revealed the presence of a ringlike disk of circumstellar debris seen in 1.1 mu m light scattered by the disk grains, surrounded by a diffuse outer region of lower surface brightness. The annular disk appears to be inclined by 31.degrees 7 +/- 1.degrees 6 from face-on, with the disk major-axis P. A. at 107 degrees +/- 2 degrees. The total 1.1 mu m flux density of the light scattered by the disk (at 1."2 < r < 5."0) of 9.6 +/- 0.8 mJy is 0.17% +/- 0.015% of the starlight. Seventy percent of the light from the scattering grains appears to be confined in a 36 AU wide annulus centered on the peak of the radial surface brightness (SB) profile 86.3 +/- 3.9 AU from the star, well beyond the characteristic radius of thermal emission estimated from IRAS and Spitzer flux densities, assuming black-body grains (approximate to 22 AU). The 1.1 mu m light scattered by the ring (1) appears bilaterally symmetric, (2) exhibits directionally preferential scattering well represented by a Henyey-Greenstein scattering phase function with g(HG) = 0.30 +/- 0.03, and (3) has a median SB (over all azimuth angles) at the 86.3 AU radius of peak SB of 1.00 +/- 0.07 mJy arcsec(-2). No photocentric offset is seen in the ring relative to the position of the central star. A low SB diffuse halo is seen in the NICMOS image to a distance of similar to 4". Deeper 0.6 mu m Hubble Space Telescope (HST) ACS PSF-subtracted coronagraphic observations reveal a faint (V approximate to 21.5 mag arcsec(-2)) outer nebulosity at 4" < r < 9", asymmetrically brighter to the north of the star. We discuss models of the disk and properties of its grains, from which we infer a maximum vertical scale height of 4-8 AU at the 87.6 AU radius of maximum surface density, and a total maximum dust mass of collisionally replenished grains with minimum grain sizes of approximate to 1 mu m of approximate to 4M(Moon).
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    DISCOVERY OF AN INNER DISK COMPONENT AROUND HD 141569 A
    (IOP Publishing, 2016-02-20) Konishi, Mihoko; Grady, Carol A.; Schneider, Glenn; Shibai, Hiroshi; McElwain, Michael W.; Nesvold, Erika R.; Kuchner, Marc J.; Carson, Joseph; Debes, John. H.; Gaspar, Andras; Henning, Thomas K.; Hines, Dean C.; Hinz, Philip M.; Jang-Condell, Hannah; Moro-Martin, Amaya; Perrin, Marshall; Rodigas, Timothy J.; Serabyn, Eugene; Silverstone, Murray D.; Stark, Christopher C.; Tamura, Motohide; Weinberger, Alycia J.; Wisniewski, John. P.; Osaka University; Eureka Scientific; National Aeronautics & Space Administration (NASA); NASA Goddard Space Flight Center; University of Arizona; Carnegie Institution for Science; College of Charleston; Space Telescope Science Institute; Max Planck Society; University of Wyoming; California Institute of Technology; NASA Jet Propulsion Laboratory (JPL); University of Tokyo; University of Oklahoma System; University of Oklahoma - Norman; University of Alabama Tuscaloosa
    We report the discovery of a scattering component around the HD 141569 A circumstellar debris system, interior to the previously known inner ring. The discovered inner disk component, obtained in broadband optical light with Hubble Space Telescope/Space Telescope Imaging Spectrograph coronagraphy, was imaged with an inner working angle of 0 25, and can be traced from 0 ''.4 (similar to 46 AU) to 1 ''.0 (similar to 116 AU) after deprojection using i = 55 degrees. The inner disk component is seen to forward scatter in a manner similar to the previously known rings, has a pericenter offset of similar to 6 AU, and break points where the slope of the surface brightness changes. It also has a spiral arm trailing in the same sense as other spiral arms and arcs seen at larger stellocentric distances. The inner disk spatially overlaps with the previously reported warm gas disk seen in thermal emission. We detect no point sources within 2 ''(similar to 232 AU), in particular in the gap between the inner disk component and the inner ring. Our upper limit of 9 +/- 3 M-J is augmented by a new dynamical limit on single planetary mass bodies in the gap between the inner disk component and the inner ring of 1 M-J, which is broadly consistent with previous estimates.
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    THE FORMATION AND EVOLUTION OF PLANETARY SYSTEMS: DESCRIPTION OF THE SPITZER LEGACY SCIENCE DATABASE
    (IOP Publishing, 2008-12) Carpenter, John M.; Bouwman, Jeroen; Silverstone, Murray D.; Kim, Jinyoung Serena; Stauffer, John; Cohen, Martin; Hines, Dean C.; Meyer, Michael R.; Crockett, Nathan; California Institute of Technology; Max Planck Society; Eureka Scientific; University of Arizona; University of California System; University of California Berkeley; University of Michigan System; University of Michigan; University of Alabama Tuscaloosa
    We present the science database produced by the Formation and Evolution of Planetary Systems (FEPS) Spitzer Legacy program. Data reduction and validation procedures for the IRAC, MIPS, and IRS instruments are described in detail. We also derive stellar properties for the FEPS sample from available broadband photometry and spectral types, and present an algorithm to normalize Kurucz synthetic spectra to optical and near-infrared photometry. The final FEPS data products include IRAC and MIPS photometry for each star in the FEPS sample and calibrated IRS spectra.
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    FORMATION AND EVOLUTION OF PLANETARY SYSTEMS: PROPERTIES OF DEBRIS DUST AROUND SOLAR-TYPE STARS
    (IOP Publishing, 2009-03-05) Carpenter, John M.; Bouwman, Jeroen; Mamajek, Eric E.; Meyer, Michael R.; Hillenbrand, Lynne A.; Backman, Dana E.; Henning, Thomas; Hines, Dean C.; Hollenbach, David; Kim, Jinyoung Serena; Moro-Martin, Amaya; Pascucci, Ilaria; Silverstone, Murray D.; Stauffer, John R.; Wolf, Sebastian; California Institute of Technology; Max Planck Society; University of Arizona; Princeton University; Eureka Scientific; University of Alabama Tuscaloosa
    We present Spitzer photometric (IRAC and MIPS) and spectroscopic (IRS low resolution) observations for 314 stars in the Formation and Evolution of Planetary Systems Legacy program. These data are used to investigate the properties and evolution of circumstellar dust around solar-type stars spanning ages from approximately 3 Myr-3 Gyr. We identify 46 sources that exhibit excess infrared emission above the stellar photosphere at 24 mu m, and 21 sources with excesses at 70 mu m. Five sources with an infrared excess have characteristics of optically thick primordial disks, while the remaining sources have properties akin to debris systems. The fraction of systems exhibiting a 24 mu m excess greater than 10.2% above the photosphere is 15% for ages < 300 Myr and declines to 2.7% for older ages. The upper envelope to the 70 mu m fractional luminosity appears to decline over a similar age range. The characteristic temperature of the debris inferred from the IRS spectra range between 60 and 180 K, with evidence for the presence of cooler dust to account for the strength of the 70 mu m excess emission. No strong correlation is found between dust temperature and stellar age. Comparison of the observational data with disk models containing a power-law distribution of silicate grains suggests that the typical inner-disk radius is greater than or similar to 10 AU. Although the interpretation is not unique, the lack of excess emission shortward of 16 mu m and the relatively flat distribution of the 24 mu m excess for ages less than or similar to 300 Myr is consistent with steady-state collisional models.
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    The moth: an unusual circumstellar structure associated with HD 61005
    (IOP Publishing, 2007-11-21) Hines, Dean C.; Schneider, Glenn; Hollenbach, David; Mamajek, Eric E.; Hillenbrand, Lynne A.; Metchev, Stanimir A.; Meyer, Michael R.; Carpenter, John M.; Moro-Martin, Amaya; Silverstone, Murray D.; Kim, Jinyoung Serena; Henning, Thomas; Bouwman, Jeroen; Wolf, Sebastian; University of Arizona; National Aeronautics & Space Administration (NASA); NASA Ames Research Center; Harvard University; Smithsonian Astrophysical Observatory; Smithsonian Institution; California Institute of Technology; University of California System; University of California Los Angeles; Princeton University; Eureka Scientific; Max Planck Society; University of Alabama Tuscaloosa
    We present the discovery of an unusual spatially resolved circumstellar structure associated with the approximate to 90 Myr, nearby, G dwarf star HD 61005. Observations from the FEPS Spitzer Legacy Science survey reveal thermal emission in excess of expected stellar photospheric levels. Follow-up 0.1 '' resolution HST NICMOS coronagraphic images reveal scattered starlight <= 7 '' (similar to 240 AU) from the occulted star (1.1 mu m flux density = 18 +/- 3.3 mJy; and 0.77%+/- 0.16% starlight). The extremely high near-IR scattering fraction and IR excess luminosity f=L-IR/L-* approximate to 2x10(-3) suggests scattering particle sizes of order a <= 1.1 mu m/2 pi similar to 0.2 mu m comparable to the blowout size (a approximate to 0.3 mu m) due to radiation a pressure from the star. Dust-scattered starlight is traced inward to an instrumental limit of similar to 10 AU. The structure exhibits a strong asymmetry about its morphological major axis but is mirror-symmetric about its minor axis.
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    PROBING FOR EXOPLANETS HIDING IN DUSTY DEBRIS DISKS: DISK IMAGING, CHARACTERIZATION, AND EXPLORATION WITH HST/STIS MULTI-ROLL CORONAGRAPHY
    (IOP Publishing, 2014-10) Schneider, Glenn; Grady, Carol A.; Hines, Dean C.; Stark, Christopher C.; Debes, John H.; Carson, Joe; Kuchner, Marc J.; Perrin, Marshall D.; Weinberger, Alycia J.; Wisniewski, John P.; Silverstone, Murray D.; Jang-Condell, Hannah; Henning, Thomas; Woodgate, Bruce E.; Serabyn, Eugene; Moro-Martin, Amaya; Tamura, Motohide; Hinz, Phillip M.; Rodigas, Timothy J.; University of Arizona; Eureka Scientific; Space Telescope Science Institute; National Aeronautics & Space Administration (NASA); NASA Goddard Space Flight Center; College of Charleston; Carnegie Institution for Science; University of Oklahoma System; University of Oklahoma - Norman; University of Alabama Tuscaloosa; University of Wyoming; Max Planck Society; California Institute of Technology; NASA Jet Propulsion Laboratory (JPL); National Institutes of Natural Sciences (NINS) - Japan; National Astronomical Observatory of Japan (NAOJ); University of Tokyo
    Spatially resolved scattered-light images of circumstellar debris in exoplanetary systems constrain the physical properties and orbits of the dust particles in these systems. They also inform on co-orbiting (but unseen) planets, the systemic architectures, and forces perturbing the starlight-scattering circumstellar material. Using Hubble Space Telescope (HST)/Space Telescope Imaging Spectrograph (STIS) broadband optical coronagraphy, we have completed the observational phase of a program to study the spatial distribution of dust in a sample of 10 circumstellar debris systems and 1 "mature" protoplanetrary disk, all with HST pedigree, using point-spread-function-subtracted multi-roll coronagraphy. These observations probe stellocentric distances >= 5 AU for the nearest systems, and simultaneously resolve disk substructures well beyond corresponding to the giant planet and Kuiper Belt regions within our own solar system. They also disclose diffuse very low-surface-brightness dust at larger stellocentric distances. Herein we present new results inclusive of fainter disks such as HD 92945 (F-disk/F-star = 5 x 10(-5)), confirming, and better revealing, the existence of a narrow inner debris ring within a larger diffuse dust disk. Other disks with ring-like substructures and significant asymmetries and complex morphologies include HD 181327, for which we posit a spray of ejecta from a recent massive collision in an exo-Kuiper Belt; HD 61005, suggested to be interacting with the local interstellar medium; and HD 15115 and HD 32297, also discussed in the context of putative environmental interactions. These disks and HD 15745 suggest that debris system evolution cannot be treated in isolation. For AU Mic's edge-on disk, we find out-of-plane surface brightness asymmetries at >= 5 AU that may implicate the existence of one or more planetary perturbers. Time-resolved images of the MP Mus protoplanetary disk provide spatially resolved temporal variability in the disk illumination. These and other new images from our HST/STIS GO/12228 program enable direct inter-comparison of the architectures of these exoplanetary debris systems in the context of our own solar system.