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1

Wavefront Control for the Gemini Planet Imager.  

National Technical Information Service (NTIS)

The wavefront control strategy for the proposed Gemini Planet Imager, an extreme adaptive optics coronagraph for planet detection, is presented. Two key parts of this strategy are experimentally verified in a testbed at the Laboratory for Adaptive Optics,...

B. Macintosh D. Dillon J. P. Veran L. A. Poyneer S. Severson

2006-01-01

2

Vibration suppression for the Gemini Planet Imager  

NASA Astrophysics Data System (ADS)

The Gemini Planet Imager (GPi) is an instrument that will mount to either of two nominally identical Telescopes, Gemini North in Hawaii and Gemini South in Chile, to perform direct imaging and spectroscopy of extra-solar planets. This 2,000-kg instrument has stringent mass, center-of-gravity, flexure, and power constraints. The Flexure Sensitive Structure (FSS) supports the main opto-mechanical sub-systems of the GPi which work in series to process and analyse the telescope optical beam. The opto-mechanical sub-systems within the FSS are sensitive to mechanical vibrations, and passive damping strategies were considered to mitigate image jitter. Based on analysis with the system finite element model (FEM) of the GPi, an array of 1-kg tuned mass dampers (TMDs) was identified as an efficient approach to damp the first two FSS flexural modes which are the main sources of jitter. It is estimated that 5% of critical damping can be added to each of these modes with the addition of 23 kg of TMD mass. This estimate is based on installing TMD units on the FSS structural members. TMD mass can be reduced by nearly 50% if the units can be installed on the opto-mechanical sub-systems within the FSS with the highest modal displacements. This paper describes the structural design and vibration response of the FSS, modal test results, and plans for implementation of the TMDs. Modal measurements of the FSS structure were made to validate the FEM and to assess the viability of TMDs for reducing jitter. The test configuration differed from the operational one because some payloads were not present and the structure was mounted to a flexible base. However, this test was valuable for understanding the primary modes that will be addressed with the TMDs and measuring the effective mass of these modes.

Maly, Joseph R.; Erickson, Darren; Pargett, Timothy J.

2010-07-01

3

Wavefront control for the Gemini Planet Imager  

SciTech Connect

The wavefront control strategy for the proposed Gemini Planet Imager, an extreme adaptive optics coronagraph for planet detection, is presented. Two key parts of this strategy are experimentally verified in a testbed at the Laboratory for Adaptive Optics, which features a 32 x 32 MEMS device. Detailed analytic models and algorithms for Shack-Hartmann wavefront sensor alignment and calibration are presented. It is demonstrated that with these procedures, the spatially filtered WFS and the Fourier Transform reconstructor can be used to flatten to the MEMS to 1 nm RMS in the controllable band. Performance is further improved using the technique of modifying the reference slopes using a measurement of the static wavefront error in the science leg.

Poyneer, L A; Veran, J; Dillon, D; Severson, S; Macintosh, B

2006-04-14

4

The Gemini Planet Imager: integration and status  

NASA Astrophysics Data System (ADS)

The Gemini Planet Imager is a next-generation instrument for the direct detection and characterization of young warm exoplanets, designed to be an order of magnitude more sensitive than existing facilities. It combines a 1700-actuator adaptive optics system, an apodized-pupil Lyot coronagraph, a precision interferometric infrared wavefront sensor, and a integral field spectrograph. All hardware and software subsystems are now complete and undergoing integration and test at UC Santa Cruz. We will present test results on each subsystem and the results of end-to-end testing. In laboratory testing, GPI has achieved a raw contrast (without post-processing) of 10-6 5? at 0.4", and with multiwavelength speckle suppression, 2x10-7 at the same separation.

Macintosh, Bruce A.; Anthony, Andre; Atwood, Jennifer; Barriga, Nicolas; Bauman, Brian; Caputa, Kris; Chilcote, Jeffery; Dillon, Daren; Doyon, René; Dunn, Jennifer; Gavel, Donald T.; Galvez, Ramon; Goodsell, Stephen J.; Graham, James R.; Hartung, Markus; Isaacs, Joshua; Kerley, Dan; Konopacky, Quinn; Labrie, Kathleen; Larkin, James E.; Maire, Jerome; Marois, Christian; Millar-Blanchaer, Max; Nunez, Arturo; Oppenheimer, Ben R.; Palmer, David W.; Pazder, John; Perrin, Marshall; Poyneer, Lisa A.; Quirez, Carlos; Rantakyro, Frederik; Reshtov, Vlad; Saddlemyer, Leslie; Sadakuni, Naru; Savransky, Dmitry; Sivaramakrishnan, Anand; Smith, Malcolm; Soummer, Remi; Thomas, Sandrine; Wallace, J. Kent; Weiss, Jason; Wiktorowicz, Sloane

2012-09-01

5

Polarimetric performance of the Gemini Planet Imager  

NASA Astrophysics Data System (ADS)

We report on preliminary results from laboratory calibration of the Gemini Planet Imager (GPI) polarimetry mode. Utilizing a linear polarizer and a quarterwave plate in a telescope simulator testbed, we inject a set of 15 Stokes states into GPI that sample the Poincaré sphere. Calibration of the known and measured Stokes parameters allows us to determine the Mueller matrix of the instrument, from which we find that crosstalk from Stokes I to (Q,U) is < 1.5%. This is well within the acceptance test plan requirement that instrumental linear polarization be. However, instrumental circular polarization is 15%. Further testing is needed to identify the source of the significant circular polarization in the system to mitigate its effect on data quality. We find the instrument is sensitive enough to identify stress birefringence of the last lens in the telescope simulator testbed, and we measure it to have a retardance of 0.030 waves.

Wiktorowicz, Sloane J.; Millar-Blanchaer, Max; Perrin, Marshall D.; Graham, James R.; Thomas, Sandrine J.; Dillon, Daren; Fitzgerald, Michael P.; Maire, Jérôme; Macintosh, Bruce A.; Goodsell, Stephen J.

2012-09-01

6

Gemini Planet Imager: Preliminary Design Report  

SciTech Connect

For the first time in history, direct and indirect detection techniques have enabled the exploration of the environments of nearby stars on scales comparable to the size of our solar system. Precision Doppler measurements have led to the discovery of the first extrasolar planets, while high-contrast imaging has revealed new classes of objects including dusty circumstellar debris disks and brown dwarfs. The ability to recover spectrophotometry for a handful of transiting exoplanets through secondary-eclipse measurements has allowed us to begin to study exoplanets as individual entities rather than points on a mass/semi-major-axis diagram and led to new models of planetary atmospheres and interiors, even though such measurements are only available at low SNR and for a handful of planets that are automatically those most modified by their parent star. These discoveries have galvanized public interest in science and technology and have led to profound new insights into the formation and evolution of planetary systems, and they have set the stage for the next steps--direct detection and characterization of extrasolar Jovian planets with instruments such as the Gemini Planet Imager (GPI). As discussed in Volume 1, the ability to directly detect Jovian planets opens up new regions of extrasolar planet phase space that in turn will inform our understanding of the processes through which these systems form, while near-IR spectra will advance our understanding of planetary physics. Studies of circumstellar debris disks using GPI's polarimetric mode will trace the presence of otherwise-invisible low-mass planets and measure the build-up and destruction of planetesimals. To accomplish the science mission of GPI will require a dedicated instrument capable of achieving contrast of 10{sup -7} or more. This is vastly better than that delivered by existing astronomical AO systems. Currently achievable contrast, about 10{sup -5} at separations of 1 arc second or larger, is completely limited by quasi-static wave front errors, so that contrast does not improve with integration times longer than about 1 minute. Using the rotation of the Earth to distinguish companions from artifacts or multiwavelength imaging improves this somewhat, but GPI will still need to surpass the performance of existing systems by one to two orders of magnitude--an improvement comparable to the transition from photographic plates to CCDs. This may sound daunting, but other areas of optical science have achieved similar breakthroughs, for example, the transition to nanometer-quality optics for extreme ultraviolet lithography, the development of MEMS wave front control devices, and the ultra-high contrast demonstrated by JPL's High Contrast Imaging Test-bed. In astronomy, the Sloan Digital Sky Survey, long baseline radio interferometry, and multi-object spectrographs have led to improvements of similar or greater order of magnitude. GPI will be the first project to apply these revolutionary techniques to ground-based astronomy, with a systems engineering approach that studies the impact of every design decision on the key metric--final detectable planet contrast.

Macintosh, B

2007-05-10

7

The Gemini Planet Imager: From Science to Design to Construction  

SciTech Connect

The Gemini Planet Imager (GPI) is a facility instrument under construction for the 8-m Gemini South telescope. It combines a 1500 subaperture AO system using a MEMS deformable mirror, an apodized-pupil Lyot coronagraph, a high-accuracy IR interferometer calibration system, and a near-infrared integral field spectrograph to allow detection and characterization of self-luminous extrasolar planets at planet/star contrast ratios of 10{sup -7}. I will discuss the evolution from science requirements through modeling to the final detailed design, provide an overview of the subsystems and show models of the instrument's predicted performance.

Macintosh, B; Graham, J R; Palmer, D; Doyon, R; Dunn, J; Gavel, D; Larkin, J; Oppenheimer, B; Saddlemyer, L; Sivaramakrishnan, A; Wallace, J K; Bauman, B; Erickson, D; Marois, C; Poyneer, L; Soummer, R

2008-07-01

8

The Gemini Planet Imager Apodized Pupil Lyot Coronagraph  

NASA Astrophysics Data System (ADS)

The Gemini Planet Imager instrument is a multi-institution project which consists of an Extreme Adaptive Optics system, an Apodized Pupil Lyot Coronagraph, an Integral Field Unit and an active calibration system for speckle suppression. The AMNH group is designing and building the Apodized Pupil Lyot Coronagraph. This type of coronagraph is basically a classical Lyot coronagraph with an upstream pupil apodization, based on mathematical properties of the prolate spheroidal functions. An APLC produces a dramatic improvement over the classical Lyot coronagraph. We have identified appropriate technologies to manufacture the required components. We will present the current status of the design and laboratory infrared testing results.

Soummer, Remi; Sivaramakrishnan, A.; Oppenheimer, B. R.; Macintosh, B. A.; GPI Team

2006-12-01

9

Wavefront sensing and correction with the Gemini Planet Imager  

NASA Astrophysics Data System (ADS)

High-contrast imaging is a growing observational technique aimed at discovering and characterizing extrasolar planets. The Gemini Planet Imager (GPI) is designed to achieve contrast ratios of 10-6 - 10-7 and requires unprecedented wavefront correction and coronagraphic control of diffraction. G PI is a facility instrument now undergoing integration and testing and is scheduled for first light on the 8-m Gemini South telescope towards the end of 2012. In this paper, we focus on the wavefront sensing and correction aspects of the instrument. To measure the wavefront, GPI combines a Shack-Hartmann wavefront sensor and a high-accuracy infrared interferometric wavefront calibration system. The Shack-Hartmann wavefront sensor uses 1700 subapertures to precisely sample the wavefront at 1.5 kHz and features a spatial filter to prevent aliasing. The wavefront calibration system measures the slower temporal frequency errors as well as non-common path aberrations. The wavefront correction is performed using a two-stage adaptive optics system employing a 9x9 piezoelectric deformable mirror and a 43x43 actuators MEMS deformable mirror operating in a woofer-tweeter configuration. Finally, an image sharpening technique is used to further increase the contrast of the final image. In this paper, we describe the three wavefront sensing methods and how we combine their respective information to achieve the best possible contrast.

Thomas, S.; Poyneer, L.; Savransky, D.; Macintosh, B.; Hartung, M.; Dillon, D.; Gavel, D.; Dunn, Jennifer; Wallace, K.; Palmer, D.; De Rosa, Robert

2012-07-01

10

Test results for the Gemini Planet Imager data reduction pipeline  

NASA Astrophysics Data System (ADS)

The Gemini Planet Imager (GPI) is a new facility instrument for the Gemini Observatory designed to detect and characterize planets and debris disks orbiting nearby stars; its science camera is a near infrared integral field spectrograph. We have developed a data pipeline for this instrument, which will be made publicly available to the community. The GPI data reduction pipeline (DRP) incorporates all necessary image reduction and calibration steps for high contrast imaging in both the spectral and polarimetric modes, including datacube generation, wavelength solution, astrometric and photometric calibrations, and speckle suppression via ADI and SSDI algorithms. It is implemented in IDL as a flexible modular system, and includes both command line and graphical interface tools including a customized viewer for GPI datacubes. This GPI data reduction pipeline is currently working very well, and is in use daily processing data during the instrument’s ongoing integration and test period at UC Santa Cruz. Here we summarize the results from recent pipeline tests, and present reductions of instrument test data taken with GPI. We will continue to refine and improve these tools throughout the rest of GPI’s testing and commissioning, and they will be released to the community, including both IDL source code and compiled versions that can be used without an IDL license.

Maire, Jérôme; Perrin, Marshall D.; Doyon, René; Chilcote, Jeffrey; Larkin, James E.; Weiss, Jason L.; Marois, Christian; Konopacky, Quinn M.; Millar-Blanchaer, Maxwell; Graham, James R.; Dunn, Jennifer; Galicher, Raphael; Marchis, Franck; Wiktorowicz, Sloane J.; Labrie, Kathleen; Thomas, Sandrine J.; Goodsell, Stephen J.; Rantakyro, Fredrik T.; Palmer, David W.; Macintosh, Bruce A.

2012-09-01

11

Adaptive Optics for Direct Detection of Extrasolar Planets: The Gemini Planet Imager  

SciTech Connect

The direct detection of photons emitted or reflected by extrasolar planets, spatially resolved from their parent star, is a major frontier in the study of other solar systems. Direct detection will provide statistical information on planets in 5-50 AU orbits, inaccessible to current Doppler searches, and allow spectral characterization of radius, temperature, surface gravity, and perhaps composition. Achieving this will require new dedicated high-contrast instruments. One such system under construction is the Gemini Planet Imager (GPI.) This combines a high-order/high-speed adaptive optics system to control wavefront errors from the Earth's atmosphere, an advanced coronagraph to block diffraction, ultrasmooth optics, a precision infrared interferometer to measure and correct systematic errors, and a integral field spectrograph/polarimeter to image and characterize target planetary systems. We predict that GPI will be able to detect planets with brightness less than 10{sup -7} of their parent star, sufficient to observe warm self-luminous planets around a large population of targets.

Macintosh, B; Graham, J; Palmer, D; Doyon, R; Gavel, D; Larkin, J; Oppenheimer, B; Saddlemyer, L; Wallace, J K; Bauman, B; Erikson, D; Poyneer, L; Sivaramakrishnan, A; Soummer, R; Veran, J

2007-04-24

12

The optical alignment of the Gemini planet imager adaptive optics bench  

NASA Astrophysics Data System (ADS)

The Gemini Planet Imager (GPI) is a facility instrument under construction for the 8-m Gemini South telescope. This paper describes the methods used for optical alignment of the adaptive optics (AO) bench. The optical alignment of the off-axis paraboloid mirrors was done using a pre-alignment method utilizing a HeNe laser and alignment telescopes followed by a fine-tuning using a Shack-Hartmann wavefront sensor and a shear plate. A FARO arm measuring system was used to place the fiducials for the alignment. Using these methods the AO bench was aligned to 13nm RMS of wavefront error.

Pazder, John; Bauman, Brian; Dillon, Daren; Fletcher, Murray; Lacoursière, Jean; Reshetov, Vlad

2012-09-01

13

Status of the Integral Field Spectrograph for the Gemini Planet Imager  

NASA Astrophysics Data System (ADS)

We present the status of the construction, testing and characterization of the Integral Field Spectrograph (IFS) for the Gemini Planet Imager (GPI). GPI is a facility class instrument for the Gemini Observatory led by Bruce Macintosh at LLNL and involving eight institutions. The UCLA Infrared Lab is currently involved with the construction and testing of the IFS. The IFS design is similar to the OSIRIS instrument at Keck and utilizes an infrared transmissive lenslet array to sample a rectangular field of view. The IFS uses a Hawaii-2RG detector to produce a field of view greater than 2.8 x 2.8 arcseconds, with a spectral resolution in H band of R 45. A cryogenic Wollaston prism can be inserted into the reimaging optic path to produce two images of orthogonal polarization states. We present the most current results from in-lab system tests of performance and characterization.

Chilcote, Jeffrey K.; Larkin, J. E.; Doyon, R.; Fitzgerald, M. P.; Graham, J. R.; Macintosh, B. A.; Palmer, D. W.; Perrin, M. D.; Saddlemyer, L.

2011-09-01

14

The use of a high-order MEMS deformable mirror in the Gemini Planet Imager  

SciTech Connect

We briefly review the development history of the Gemini Planet Imager's 4K Boston Micromachines MEMS deformable mirror. We discuss essential calibration steps and algorithms to control the MEMS with nanometer precision, including voltage-phase calibration and influence function characterization. We discuss the integration of the MEMS into GPI's Adaptive Optics system at Lawrence Livermore and present experimental results of 1.5 kHz closed-loop control. We detail mitigation strategies in the coronagraph to reduce the impact of abnormal actuators on final image contrast.

Poyneer, L A; Bauman, B; Cornelissen, S; Jones, S; Macintosh, B; Palmer, D; Isaacs, J

2010-12-17

15

Performance of the integral field spectrograph for the Gemini Planet Imager  

NASA Astrophysics Data System (ADS)

We present performance results, from in-lab testing, of the Integral Field Spectrograph (IFS) for the Gemini Planet Imager (GPI). GPI is a facility class instrument for the Gemini Observatory with the primary goal of directly detecting young Jovian planets. The GPI IFS is based on concepts from the OSIRIS instrument at Keck and utilizes an infrared transmissive lenslet array to sample a rectangular 2.8 x 2.8 arcsecond field of view. The IFS provides low-resolution spectra across five bands between 1 and 2.5?m. Alternatively, the dispersing element can be replaced with a Wollaston prism to provide broadband polarimetry across the same five filter bands. The IFS construction was based at the University of California, Los Angeles in collaboration with the Université de Montr eal, Immervision and Lawrence Livermore National Laboratory. During its construction, we encountered an unusual noise source from microphonic pickup by the Hawaii-2RG detector. We describe this noise and how we eliminated it through vibration isolation. The IFS has passed its preship review and was shipped to University of California, Santa Cruz at the end of 2011 for integration with the remaining sub-systems of GPI. The IFS has been integrated with the rest of GPI and is delivering high quality spectral datacubes of GPI's coronagraphic field.

Chilcote, Jeffrey K.; Larkin, James E.; Maire, Jérôme; Perrin, Marshall D.; Fitzgerald, Michael P.; Doyon, René; Thibault, Simon; Bauman, Brian; Macintosh, Bruce A.; Graham, James R.; Saddlemyer, Les

2012-09-01

16

Flexure mount for a MEMS deformable mirror for the Gemini Planet Imager  

NASA Astrophysics Data System (ADS)

Small deformable mirrors (DMs) produced using microelectromechanical systems (MEMS) techniques have been used in thermally stable, bench-top laboratory environments. With advances in MEMS DM technology, a variety of field applications are becoming more common, such as the Gemini Planet Imager’s (GPI) adaptive optics system. Instruments at the Gemini Observatory operate in conditions where fluctuating ambient temperature, varying gravity orientations and humidity and dust can have a significant effect on DM performance. As such, it is crucial that the mechanical design of the MEMS DM mount be tailored to the environment. GPI’s approach has been to mount a 4096 actuator MEMS DM, developed by Boston Micromachines Corporation, using high performance optical mounting techniques rather than a typical laboratory set-up. Flexures are incorporated into the DM mount to reduce deformations on the optical surface due to thermal fluctuations. These flexures have also been sized to maintain alignment under varying gravity vector orientations. This paper is a follow-up to a previous paper which presented the preliminary design. The completed design of the opto-mechanical mounting scheme is discussed and results from finite element analysis are presented, including predicting the stability of the mirror surface in varying gravity vectors and thermal conditions.

Hill, Alexis; Cornelissen, Steven; Dillon, Daren; Lam, Charlie; Palmer, Dave; Saddlemyer, Les

2012-09-01

17

The Gemini NICI Planet-Finding Campaign: Combining Coronagraphy with Angular and Spectral Differencing imaging.  

NASA Astrophysics Data System (ADS)

The Gemini NICI Planet-Finding Campaign is the most ambitious ( 300 targets) direct extrasolar planet imaging campaign to date, achieving median contrasts of 12.5 and 15.0 magnitudes at 0.5 and 1.0'' respectively. Starting in December of 2008, we have been looking for both methane-bearing candidates and non-methane-bearing substellar companions around nearby stars chosen on the basis of youth, proximity, spectral type, etc. NICI (Near Infrared Coronagraphic Imager) is the combination of an 85 element adaptive optics system, a Lyot coronagraph, and a dual channel camera capable of simultaneous spectral difference imaging (SDI) on and off the 1.6um methane feature and angular difference imaging (ADI). We have developed a novel method of reducing the data which takes advantage of both SDI and ADI techniques. Speckles with long correlation times are removed by subtracting a static PSF, possible because of ADI. Short-lived speckles are removed by the subtracting the simultaneously imaged channel, possible because of SDI. Here, I present the data reduction techniques optimized for NICI, and compare among alternate techniques. We verify the contrasts achieved, and the photometric and astrometric accuracy by studying the recovery of simulated companions.

Wahhaj, Zahed; Liu, M. C.; Biller, B. A.; Nielsen, E. L.; Chun, M.; Close, L. M.; Ftaclas, C.; Hayward, T. L.; Toomey, D. W.; Gemini NICI Planet-Finding Campaign Team

2011-09-01

18

Calibrating IR optical densities for the Gemini Planet Imager extreme adaptive optics coronagraph apodizers  

NASA Astrophysics Data System (ADS)

High contrast imaging sometimes uses apodized masks in coronagraphs to suppress diffracted starlight from a bright source in order to observe its environs. Continuously graded opacity material and metallic half-tone dots are two possible apodizers fabrication techniques. In the latter approach if dot sizes are comparable to the wavelength of the light, surface plasmon effects can complicate the optical density (OD) vs. superficial dot density relation. OD can also be a complicated function of wavelength. We measured half-tone microdot screens' and continuous materials' transmissions. Our set-up replicated the f/ 64 optical configuration of the Gemini Planet Imager's Apodized Pupil Lyot Coronagraph pupil plane, where we plan to place our pupil plane masks. Our half-tone samples were fabricated with 2, 5, and 10 micron dot sizes, our continuous greyscale was High Energy Electron Beam Sensitive (HEBS) glass (Canyon Materials Inc.). We present optical density (OD) vs. wavelength curves for our half-tone and continuous greyscale samples 1.1 - 2.5 ?m wavelength range. Direct measurements of the beam intensity in the far field using a Fourier Transform Infrared Spectrograph on Beamline U4IR at Brookhaven National Laboratory's National Synchrotron Light Source (NSLS) provided transmission spectra of test patches and apodizers. We report the on-axis IR transmission spectra through screens composed of metallic dots that are comparable in size with the wavelength of the light used, over a range of optical densities. We also measured departures from simple theory describing the array of satellite spots created by thin periodic grids in the pupil of the system. Such spots are used for photometry and astrometry in coronagraphic situations. Our results pertain to both ground and space based coronagraphs that use spatially variable attenuation, typically in focal plane or pupil plane masks.

Sivaramakrishnan, Anand; Soummer, Rémi; Carr, G. Lawrence; Dorrer, Christophe; Bolognesi, Allen; Zimmerman, Neil; Oppenheimer, Ben R.; Roberts, Robin; Greenbaum, Alexandra

2009-08-01

19

DETECTABILITY OF EXOPLANETS IN THE {beta} PIC MOVING GROUP WITH THE GEMINI PLANET IMAGER  

SciTech Connect

We model the detectability of exoplanets around stars in the {beta} Pic Moving Group (BPMG) using the Gemini Planet Imager (GPI), a coronagraphic instrument designed to detect companions by imaging. Members of the BPMG are considered promising targets for exoplanet searches because of their youth ({approx}12 Myr) and proximity (median distance {approx}35 pc). We wrote a modeling procedure to generate hypothetical companions of given mass, age, eccentricity, and semi-major axis, and place them around BPMG members that fall within the V-band range of the GPI. We count companions lying within the GPI's field of view and H-band fluxes that have a host-companion flux ratio placing them within its sensitivity as possible detections. The fraction of companions that could be detected depends on their brightness at 12 Myr, and hence formation mechanism, and on their distribution of semi-major axes. We used brightness models for formation by disk instability and core-accretion. We considered the two extreme cases of the semi-major axis distribution-the log-normal distribution of the nearby F- and G-type stars and a power-law distribution indicated by the exoplanets detected by the radial velocity technique. We find that the GPI could detect exoplanets of all the F and G spectral type stars in the BPMG sample with a probability that depends on the brightness model and semi-major axis distribution. At spectral type K-M1, exoplanet detectability depends on brightness and hence distance of the host star. GPI will be able to detect the companions of M stars later than M1 only if they are closer than 10 pc. Of the four A stars in the BPMG sample, only one has a V-band brightness in the range of GPI; the others are too bright.

Kataria, Tiffany; Simon, Michal [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794 (United States)

2010-07-15

20

The Gemini Deep Planet Survey - GDPS  

SciTech Connect

We present the results of the Gemini Deep Planet Survey, a near-infrared adaptive optics search for giant planets and brown dwarfs around nearby young stars. The observations were obtained with the Altair adaptive optics system at the Gemini North telescope and angular differential imaging was used to suppress the speckle noise of the central star. Detection limits for the 85 stars observed are presented, along with a list of all faint point sources detected around them. Typically, the observations are sensitive to angular separations beyond 0.5-inch with 5{sigma} contrast sensitivities in magnitude difference at 1.6 {micro}m of 9.6 at 0.5-inch, 12.9 at 1-inch, 15 at 2-inch, and 16.6 at 5-inch. For the typical target of the survey, a 100 Myr old K0 star located 22 pc from the Sun, the observations are sensitive enough to detect planets more massive than 2 M{sub Jup} with a projected separation in the range 40-200 AU. Depending on the age, spectral type, and distance of the target stars, the minimum mass that could be detected with our observations can be {approx}1 M{sub Jup}. Second epoch observations of 48 stars with candidates (out of 54) have confirmed that all candidates are unrelated background stars. A detailed statistical analysis of the survey results, which provide upper limits on the fractions of stars with giant planet or low mass brown dwarf companions, is presented. Assuming a planet mass distribution dn/dm {proportional_to} m{sup -1.2} and a semi-major axis distribution dn/da {proportional_to} a{sup -1}, the upper limits on the fraction of stars with at least one planet of mass 0.5-13 M{sub Jup} are 0.29 for the range 10-25 AU, 0.13 for 25-50 AU, and 0.09 for 50-250 AU, with a 95% confidence level; this result is weakly dependent on the semi-major axis distribution power-law index. Without making any assumption on the mass and semi-major axis distributions, the fraction of stars with at least one brown dwarf companion having a semi-major axis in the range 25-200 AU is 0.018{sub -0.014}{sup +0.078}, with a 95% confidence level. The observations made as part of this survey have resolved the stars HD 14802, HD 135363, HD 160934, HD 166181, and HD 213845 into close binaries for the first time.

Lafreniere, D; Doyon, R; Marois, C; Nadeau, D; Oppenheimer, B R; Roche, P F; Rigaut, F; Graham, J R; Jayawardhana, R; Johnstone, D; Kalas, P G; Macintosh, B; Racine, R

2007-06-01

21

A Combined Very Large Telescope and Gemini Study of the Atmosphere of the Directly Imaged Planet, ? Pictoris b  

NASA Astrophysics Data System (ADS)

We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet ? Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While ? Pic b's near-IR colors mimic those of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects—i.e., ? And b and 1RXJ 1609B—match ? Pic b's JHKsL' photometry and its 3.1 ?m and 5 ?m photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large (~60 ?m) dust grains fail to reproduce the ? Pic b spectrum. However, models incorporating thick clouds similar to those found for HR 8799 bcde, but also with small (a few microns) modal particle sizes, yield fits consistent with the data within the uncertainties. Assuming solar abundance models, thick clouds, and small dust particles (langarang = 4 ?m), we derive atmosphere parameters of log (g) = 3.8 ± 0.2 and T eff = 1575-1650 K, an inferred mass of 7^{+4}_{-3} MJ , and a luminosity of log(L/L ?) ~–3.80 ± 0.02. The best-estimated planet radius, ?1.65 ± 0.06 RJ , is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if ? Pic b is younger than ?7 Myr, consistent with a late formation well after its host star's birth ~12^{+8}_{-4} Myr ago.

Currie, Thayne; Burrows, Adam; Madhusudhan, Nikku; Fukagawa, Misato; Girard, Julien H.; Dawson, Rebekah; Murray-Clay, Ruth; Kenyon, Scott; Kuchner, Marc; Matsumura, Soko; Jayawardhana, Ray; Chambers, John; Bromley, Ben

2013-10-01

22

The Gemini NICI Planet-Finding Campaign: the Frequency of Giant Planets Around Young A Stars  

NASA Astrophysics Data System (ADS)

The Gemini NICI Planet-Finding Campaign is a 3-year direct imaging survey for planets around over 200 young, nearby stars, using the Near Infrared Coronagraphic Imager at Gemini South, a specialized instrument for finding planets. We present here the results from the NICI Campaign's subsample of 69 A and B stars, which is the largest, deepest survey for planets around high mass stars conducted to date. In addition to our previously reported discovery that HD 1160 is a triple system made up of an A star, an M star, and an L-dwarf, the Campaign has found a tight binary brown dwarf around a nearby A star which will be useful for future dynamical mass measurements. We develop a new Bayesian approach to determining ages for A and B stars that yields more realistic age probability distributions for these stars. Monte Carlo simulations are used to determine the completeness of our observations to giant planets, and we find that, consistent with previous studies of solar-type stars, large- and medium-separation (>20 AU) giant planets are relatively rare around A and B stars. At 95% confidence, fewer than 10% of A stars can have a planet with the mass and separation of HR 8799 b.

Nielsen, Eric L.; Liu, M. C.; Wahhaj, Z.; Biller, B. A.; Hayward, T. L.; Close, L. M.; Chun, M. R.; Ftaclas, C.; Toomey, D. W.; Gemini NICI Planet-Finding Campaign Team

2013-01-01

23

The Gemini Planet-finding Campaign: The Frequency Of Giant Planets around Debris Disk Stars  

NASA Astrophysics Data System (ADS)

We have completed a high-contrast direct imaging survey for giant planets around 57 debris disk stars as part of the Gemini NICI Planet-Finding Campaign. We achieved median H-band contrasts of 12.4 mag at 0.''5 and 14.1 mag at 1'' separation. Follow-up observations of the 66 candidates with projected separation <500 AU show that all of them are background objects. To establish statistical constraints on the underlying giant planet population based on our imaging data, we have developed a new Bayesian formalism that incorporates (1) non-detections, (2) single-epoch candidates, (3) astrometric and (4) photometric information, and (5) the possibility of multiple planets per star to constrain the planet population. Our formalism allows us to include in our analysis the previously known ? Pictoris and the HR 8799 planets. Our results show at 95% confidence that <13% of debris disk stars have a >=5 M Jup planet beyond 80 AU, and <21% of debris disk stars have a >=3 M Jup planet outside of 40 AU, based on hot-start evolutionary models. We model the population of directly imaged planets as d 2 N/dMdavpropm ? a ?, where m is planet mass and a is orbital semi-major axis (with a maximum value of a max). We find that ? < -0.8 and/or ? > 1.7. Likewise, we find that ? < -0.8 and/or a max < 200 AU. For the case where the planet frequency rises sharply with mass (? > 1.7), this occurs because all the planets detected to date have masses above 5 M Jup, but planets of lower mass could easily have been detected by our search. If we ignore the ? Pic and HR 8799 planets (should they belong to a rare and distinct group), we find that <20% of debris disk stars have a >=3 M Jup planet beyond 10 AU, and ? < -0.8 and/or ? < -1.5. Likewise, ? < -0.8 and/or a max < 125 AU. Our Bayesian constraints are not strong enough to reveal any dependence of the planet frequency on stellar host mass. Studies of transition disks have suggested that about 20% of stars are undergoing planet formation; our non-detections at large separations show that planets with orbital separation >40 AU and planet masses >3 M Jup do not carve the central holes in these disks. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

Wahhaj, Zahed; Liu, Michael C.; Nielsen, Eric L.; Biller, Beth A.; Hayward, Thomas L.; Close, Laird M.; Males, Jared R.; Skemer, Andrew; Ftaclas, Christ; Chun, Mark; Thatte, Niranjan; Tecza, Matthias; Shkolnik, Evgenya L.; Kuchner, Marc; Reid, I. Neill; de Gouveia Dal Pino, Elisabete M.; Alencar, Silvia H. P.; Gregorio-Hetem, Jane; Boss, Alan; Lin, Douglas N. C.; Toomey, Douglas W.

2013-08-01

24

The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets around Young B and A Stars  

NASA Astrophysics Data System (ADS)

We have carried out high contrast imaging of 70 young, nearby B and A stars to search for brown dwarf and planetary companions as part of the Gemini NICI Planet-Finding Campaign. Our survey represents the largest, deepest survey for planets around high-mass stars (?1.5-2.5 M ?) conducted to date and includes the planet hosts ? Pic and Fomalhaut. We obtained follow-up astrometry of all candidate companions within 400 AU projected separation for stars in uncrowded fields and identified new low-mass companions to HD 1160 and HIP 79797. We have found that the previously known young brown dwarf companion to HIP 79797 is itself a tight (3 AU) binary, composed of brown dwarfs with masses 58^{+21}_{-20} M Jup and 55^{+20}_{-19} M Jup, making this system one of the rare substellar binaries in orbit around a star. Considering the contrast limits of our NICI data and the fact that we did not detect any planets, we use high-fidelity Monte Carlo simulations to show that fewer than 20% of 2 M ? stars can have giant planets greater than 4 M Jup between 59 and 460 AU at 95% confidence, and fewer than 10% of these stars can have a planet more massive than 10 M Jup between 38 and 650 AU. Overall, we find that large-separation giant planets are not common around B and A stars: fewer than 10% of B and A stars can have an analog to the HR 8799 b (7 M Jup, 68 AU) planet at 95% confidence. We also describe a new Bayesian technique for determining the ages of field B and A stars from photometry and theoretical isochrones. Our method produces more plausible ages for high-mass stars than previous age-dating techniques, which tend to underestimate stellar ages and their uncertainties.

Nielsen, Eric L.; Liu, Michael C.; Wahhaj, Zahed; Biller, Beth A.; Hayward, Thomas L.; Close, Laird M.; Males, Jared R.; Skemer, Andrew J.; Chun, Mark; Ftaclas, Christ; Alencar, Silvia H. P.; Artymowicz, Pawel; Boss, Alan; Clarke, Fraser; de Gouveia Dal Pino, Elisabete; Gregorio-Hetem, Jane; Hartung, Markus; Ida, Shigeru; Kuchner, Marc; Lin, Douglas N. C.; Reid, I. Neill; Shkolnik, Evgenya L.; Tecza, Matthias; Thatte, Niranjan; Toomey, Douglas W.

2013-10-01

25

Speckle Camera Imaging of the Planet Pluto  

NASA Astrophysics Data System (ADS)

We have obtained optical wavelength (692 nm and 880 nm) speckle imaging of the planet Pluto and its largest moon Charon. Using our DSSI speckle camera attached to the Gemini North 8 m telescope, we collected high resolution imaging with an angular resolution of ˜20 mas, a value at the Gemini-N telescope diffraction limit. We have produced for this binary system the first speckle reconstructed images, from which we can measure not only the orbital separation and position angle for Charon, but also the diameters of the two bodies. Our measurements of these parameters agree, within the uncertainties, with the current best values for Pluto and Charon. The Gemini-N speckle observations of Pluto are presented to illustrate the capabilities of our instrument and the robust production of high accuracy, high spatial resolution reconstructed images. We hope our results will suggest additional applications of high resolution speckle imaging for other objects within our solar system and beyond.

Howell, Steve B.; Horch, Elliott P.; Everett, Mark E.; Ciardi, David R.

2012-10-01

26

The Gemini/NICI Planet-Finding Campaign: The Frequency of Planets around Young Moving Group Stars  

NASA Astrophysics Data System (ADS)

We report results of a direct imaging survey for giant planets around 80 members of the ? Pic, TW Hya, Tucana-Horologium, AB Dor, and Hercules-Lyra moving groups, observed as part of the Gemini/NICI Planet-Finding Campaign. For this sample, we obtained median contrasts of ?H = 13.9 mag at 1'' in combined CH4 narrowband ADI+SDI mode and median contrasts of ?H = 15.1 mag at 2'' in H-band ADI mode. We found numerous (>70) candidate companions in our survey images. Some of these candidates were rejected as common-proper motion companions using archival data; we reobserved with Near-Infrared Coronagraphic Imager (NICI) all other candidates that lay within 400 AU of the star and were not in dense stellar fields. The vast majority of candidate companions were confirmed as background objects from archival observations and/or dedicated NICI Campaign followup. Four co-moving companions of brown dwarf or stellar mass were discovered in this moving group sample: PZ Tel B (36 ± 6 M Jup, 16.4 ± 1.0 AU), CD–35 2722B (31 ± 8 M Jup, 67 ± 4 AU), HD 12894B (0.46 ± 0.08 M ?, 15.7 ± 1.0 AU), and BD+07 1919C (0.20 ± 0.03 M ?, 12.5 ± 1.4 AU). From a Bayesian analysis of the achieved H band ADI and ASDI contrasts, using power-law models of planet distributions and hot-start evolutionary models, we restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-150 AU to <18% at a 95.4% confidence level using DUSTY models and to <6% at a 95.4% using COND models. Our results strongly constrain the frequency of planets within semi-major axes of 50 AU as well. We restrict the frequency of 1-20 M Jup companions at semi-major axes from 10-50 AU to <21% at a 95.4% confidence level using DUSTY models and to <7% at a 95.4% using COND models. This survey is the deepest search to date for giant planets around young moving group stars. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciência e Tecnologia (Brazil) and Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina).

Biller, Beth A.; Liu, Michael C.; Wahhaj, Zahed; Nielsen, Eric L.; Hayward, Thomas L.; Males, Jared R.; Skemer, Andrew; Close, Laird M.; Chun, Mark; Ftaclas, Christ; Clarke, Fraser; Thatte, Niranjan; Shkolnik, Evgenya L.; Reid, I. Neill; Hartung, Markus; Boss, Alan; Lin, Douglas; Alencar, Silvia H. P.; de Gouveia Dal Pino, Elisabete; Gregorio-Hetem, Jane; Toomey, Douglas

2013-11-01

27

The Gemini NICI Planet-Finding Campaign: The Frequency of Giant Planets Around Debris Disk Stars  

NASA Astrophysics Data System (ADS)

We have completed a high-contrast imaging survey for giant planets around 57 debris disk stars as part of the NICI Campaign. Debris disks are especially interesting environments to look for planets, as they already show signs of planetesimal production. Moreover, the systems with directly imaged planets within 120 AU of the primary, HR 8799, Beta Pic and Fomalhaut, all host debris disks. We achieved median contrasts of 12.4 mag at 0.5" and 14.1 mag at 1” and detected a total of 82 planet candidates around 26 stars. At the median age and distance of the sample (30 Myr and 45 pc), these correspond to mass sensitivities of 13 Mjup and 9 Mjup, according to Baraffe et al. (2003) models. Follow-up observations of 13 targets with 60 of the most promising candidates (projected separation < 500 AU), show that all of them are background objects. We develop a more general Bayesian formalism than previous studies, in order to use multiple detections in a single system, astrometric and photometric information, and non-detections to constrain the planet population. We find, at the 95% confidence level, that <24% (<24%) of debris disk stars have a planet with mass >9 (>4) Mjup outside of 8 (63) AU. Also, the average number of planets in a single system with mass >9 (>3) Mjup outside of 8 (63) AU is less than 0.28 (0.28). Interestingly, we set limits on the giant planet frequency at separations much smaller than the typical radial extents of the resolved debris disks 100 AU).

Wahhaj, Zahed; Liu, M. C.; Nielsen, E. L.; Biller, B. A.; Hayward, T. L.; Close, L. M.; Chun, M.; Ftaclas, C.; Toomey, D. W.; Gemini NICI Planet-Finding Campaign Team

2013-01-01

28

Direct imaging of multiple planets orbiting the star HR 8799  

SciTech Connect

Direct imaging of exoplanetary systems is a powerful technique that can reveal Jupiter-like planets in wide orbits, can enable detailed characterization of planetary atmospheres, and is a key step towards imaging Earth-like planets. Imaging detections are challenging due to the combined effect of small angular separation and large luminosity contrast between a planet and its host star. High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units. Multi-epoch data show counter-clockwise orbital motion for all three imaged planets. The low luminosity of the companions and the estimated age of the system imply planetary masses between 5 and 13 times that of Jupiter. This system resembles a scaled-up version of the outer portion of our Solar System.

Marois, C; Macintosh, B; Barman, T; Zuckerman, B; Song, I; Patience, J; Lafreniere, D; Doyon, R

2008-10-14

29

THE GEMINI NICI PLANET-FINDING CAMPAIGN: DISCOVERY OF A MULTIPLE SYSTEM ORBITING THE YOUNG A STAR HD 1160  

SciTech Connect

We report the discovery of two low-mass companions to the young A0V star HD 1160 at projected separations of 81 {+-} 5 AU (HD 1160 B) and 533 {+-} 25 AU (HD 1160 C) by the Gemini NICI Planet-Finding Campaign. Very Large Telescope images of the system taken over a decade for the purpose of using HD 1160 A as a photometric calibrator confirm that both companions are physically associated. By comparing the system to members of young moving groups and open clusters with well-established ages, we estimate an age of 50{sup +50}{sub -40} Myr for HD 1160 ABC. While the UVW motion of the system does not match any known moving group, the small magnitude of the space velocity is consistent with youth. Near-IR spectroscopy shows HD 1160 C to be an M3.5 {+-} 0.5 star with an estimated mass of 0.22{sup +0.03}{sub -0.04} M{sub Sun }, while NIR photometry of HD 1160 B suggests a brown dwarf with a mass of 33{sup +12}{sub -9} M{sub Jup}. The very small mass ratio (0.014) between the A and B components of the system is rare for A star binaries, and would represent a planetary-mass companion were HD 1160 A to be slightly less massive than the Sun.

Nielsen, Eric L.; Liu, Michael C.; Wahhaj, Zahed; Bowler, Brendan; Kraus, Adam; Chun, Mark; Ftaclas, Christ [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Biller, Beth A. [Max-Planck-Institut fuer Astronomie, Koenigstuhl 17, 69117 Heidelberg (Germany); Hayward, Thomas L. [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Boss, Alan [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, N.W., Washington, DC 20015 (United States); Shkolnik, Evgenya L. [Lowell Observatory, 1400 West Mars Road, Flagstaff, AZ 86001 (United States); Tecza, Matthias; Clarke, Fraser [Department of Astronomy, University of Oxford, DWB, Keble Road, Oxford OX1 3RH (United Kingdom); Close, Laird M.; Hartung, Markus; Males, Jared R.; Skemer, Andrew J. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Reid, I. Neill [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Alencar, Silvia H. P. [Departamento de Fisica, ICEx, Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil); Burrows, Adam [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); and others

2012-05-01

30

THE GEMINI NICI PLANET-FINDING CAMPAIGN: DISCOVERY OF A CLOSE SUBSTELLAR COMPANION TO THE YOUNG DEBRIS DISK STAR PZ Tel  

SciTech Connect

We report the discovery of a tight substellar companion to the young solar analog PZ Tel, a member of the {beta} Pic moving group observed with high-contrast adaptive optics imaging as part of the Gemini Near-Infrared Coronagraphic Imager Planet-Finding Campaign. The companion was detected at a projected separation of 16.4 {+-} 1.0 AU (0.''33 {+-} 0.''01) in 2009 April. Second-epoch observations in 2010 May demonstrate that the companion is physically associated and shows significant orbital motion. Monte Carlo modeling constrains the orbit of PZ Tel B to eccentricities >0.6. The near-IR colors of PZ Tel B indicate a spectral type of M7 {+-} 2 and thus this object will be a new benchmark companion for studies of ultracool, low-gravity photospheres. Adopting an age of 12{sup +8} {sub -4} Myr for the system, we estimate a mass of 36 {+-} 6 M {sub Jup} based on the Lyon/DUSTY evolutionary models. PZ Tel B is one of the few young substellar companions directly imaged at orbital separations similar to those of giant planets in our own solar system. Additionally, the primary star PZ Tel A shows a 70 {mu}m emission excess, evidence for a significant quantity of circumstellar dust that has not been disrupted by the orbital motion of the companion.

Biller, Beth A.; Liu, Michael C.; Wahhaj, Zahed; Dupuy, Trent J.; Ftaclas, Christ [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Nielsen, Eric L.; Close, Laird M.; Males, Jared; Skemer, Andrew [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Hayward, Thomas L.; Hartung, Markus [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Burrows, Adam [Department of Astrophysical Sciences, Peyton Hall, Princeton University, Princeton, NJ 08544 (United States); Chun, Mark [Institute for Astronomy, 640 North Aohoku Place, 209, Hilo, HI 96720-2700 (United States); Clarke, Fraser; Tecza, Matthias; Thatte, Niranjan [Department of Astronomy, University of Oxford, DWB, Keble Road, Oxford OX1 3RH (United Kingdom); Reid, I. Neill [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Shkolnik, Evgenya L. [Department of Terrestrial Magnetism, Carnegie Institution of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015 (United States); Alencar, Silvia H. P. [Departamento de Fisica-ICEx-Universidade Federal de Minas Gerais, Av. Antonio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil); Artymowicz, Pawel [University of Toronto at Scarborough, 1265 Military Trail, Toronto, Ontario M1C 1A4 (Canada)

2010-09-01

31

Maintenance and operation of the adaptive optics module for NICI, the high-contrast coronagraphic imager of GEMINI observatory  

NASA Astrophysics Data System (ADS)

NICI, the high-contrast coronagraphic imager of Gemini observatory, primarily dedicated to planet hunting has been offered to the astronomical community since end of 2008. We present our experiences in operating and maintaining NICI's 85 element curvature adaptive optics (AO) system. A detailed study of NICI AO telemetry data is also most relevant to prepare the arrival of next generation instruments. We summarize the behavior of interaction matrices, control matrices and error transfer functions under different operational conditions; a detailed understanding of the system helps monitoring and optimizing performance. Furthermore, we describe tuning (membrane mirror stroke/extra focal distance) for non-optimal seeing conditions as well as for niche applications of NICI such as observing small moons and asteroids. We compare on-sky measurements to theory or simulations.

Hartung, Markus; Hayward, Tom L.; Chun, M.; Kellerer, A.

2010-07-01

32

Beta Pictoris planet finally imaged?  

NASA Astrophysics Data System (ADS)

A team of French astronomers using ESO's Very Large Telescope have discovered an object located very close to the star Beta Pictoris, and which apparently lies inside its disc. With a projected distance from the star of only 8 times the Earth-Sun distance, this object is most likely the giant planet suspected from the peculiar shape of the disc and the previously observed infall of comets onto the star. It would then be the first image of a planet that is as close to its host star as Saturn is to the Sun. Sharpening Up Jupiter ESO PR Photo 42a/08 Beta Pictoris as seen in infrared light The hot star Beta Pictoris is one of the best-known examples of stars surrounded by a dusty 'debris' disc. Debris discs are composed of dust resulting from collisions among larger bodies like planetary embryos or asteroids. They are a bigger version of the zodiacal dust in our Solar System. Its disc was the first to be imaged -- as early as 1984 -- and remains the best-studied system. Earlier observations showed a warp of the disc, a secondary inclined disc and infalling comets onto the star. "These are indirect, but tell-tale signs that strongly suggest the presence of a massive planet lying between 5 and 10 times the mean Earth-Sun distance from its host star," says team leader Anne-Marie Lagrange. "However, probing the very inner region of the disc, so close to the glowing star, is a most challenging task." In 2003, the French team used the NAOS-CONICA instrument (or NACO [1]), mounted on one of the 8.2 m Unit Telescopes of ESO's Very Large Telescope (VLT), to benefit from both the high image quality provided by the Adaptive Optics system at infrared wavelengths and the good dynamics offered by the detector, in order to study the immediate surroundings of Beta Pictoris. Recently, a member of the team re-analysed the data in a different way to seek the trace of a companion to the star. Infrared wavelengths are indeed very well suited for such searches. "For this, the real challenge is to identify and subtract as accurately as possible the bright stellar halo," explains Lagrange. "We were able to achieve this after a precise and drastic selection of the best images recorded during our observations." The strategy proved very rewarding, as the astronomers were able to discern a feeble, point-like glow well inside the star's halo. To eliminate the possibility that this was an artefact and not a real object, a battery of tests was conducted and several members of the team, using three different methods, did the analysis independently, always with the same success. Moreover, the companion was also discovered in other data sets, further strengthening the team's conclusion: the companion is real. "Our observations point to the presence of a giant planet, about 8 times as massive as Jupiter and with a projected distance from its star of about 8 times the Earth-Sun distance, which is about the distance of Saturn in our Solar System [2]," says Lagrange. "We cannot yet rule out definitively, however, that the candidate companion could be a foreground or background object," cautions co-worker Gael Chauvin. "To eliminate this very small possibility, we will need to make new observations that confirm the nature of the discovery." The team also dug into the archives of the Hubble Space Telescope but couldn't see anything, "while most possible foreground or background objects would have been detected", remarks another team member, David Ehrenreich. The fact that the candidate companion lies in the plane of the disc also strongly implies that it is bound to the star and its proto-planetary disc. "Moreover, the candidate companion has exactly the mass and distance from its host star needed to explain all the disc's properties. This is clearly another nail in the coffin of the false alarm hypothesis," adds Lagrange. When confirmed, this candidate companion will be the closest planet from its star ever imaged. In particular, it will be located well inside the orbits of

2008-11-01

33

On the road to imaging extrasolar planets: Null results, other discoveries along the way, and signposts for the future  

NASA Astrophysics Data System (ADS)

I present my experiences designing, conducting, and analyzing the results from direct imaging surveys for extrasolar giant planets. Using the young, low-mass star AB Dor C, I show that models for low-mass stars and brown dwarfs at young ages are good representations of reality. I discuss the design of the Simultaneous Differential Imaging survey, and how Monte Carlo simulations of giant planet populations allow for the design of imaging surveys, including the choice of target list, that maximizes the expected yield of extrasolar planets. With the conclusion of the SDI survey, I examine how its null result for planets sets constraints on the allowable populations of long-period exoplanets, finding that fewer than 8% of sun-like stars can have planets more massive than 4M Jup between 20 and 100 AU, at 68% confidence. When I include null results from other direct imaging surveys, these constraints are further strengthened: at 68% confidence, fewer than 20% of sun-like stars can have planets more massive than 4M Jup , at orbital semi-major axes between 8.1 and 911 AU. Even when applying the mass scaling of Johnson et al. (2007), and the "cold start" planet luminosity models of Fortney et al. (2008), the results remain consistent: giant planets are rare at large separations around sun-like stars. I explain how these constraints and planet simulations were used to design the Gemini South NICI Planet-Finding Campaign survey and target list, in order to maximize the chance of NICI detecting a planet, and so giving the campaign the greatest ability to strongly constrain populations of extrasolar giant planets, even in the case of a null result. Finally, I discuss future directions for direct imaging planet searches, and the steps needed to move from existing surveys to a truly unified distribution of extrasolar planet populations.

Nielsen, Eric Ludwig

34

Direct imaging of extra-solar planets  

SciTech Connect

Direct imaging of extra-solar planets may be possible with the new generation of large ground-based telescopes equipped with state- of- the-art adaptive optics (AO) systems to compensate for the blurring effect of the Earth`s atmosphere. The first of these systems is scheduled to begin operation in 1998 on the 10 in Keck II telescope. In this paper, general formulas for high-contrast imaging with AO systems are presented and used to calculate the sensitivity of the Keck AO system. The results of these calculations show that the Keck AO system should achieve the sensitivity necessary to detect giant planets around several nearby bright stars.

Olivier, S.S.; Max, V.E.; Brase, J.M.; Caffano, C.J.; Gavel, D.T.; Macintosh, B.A.

1997-03-01

35

Gemini near-infrared imager on-instrument wavefront sensor gimbal tilt stage  

NASA Astrophysics Data System (ADS)

We present a high-resolution gimbal mirror mechanism which will perform the beam steering for the on-instrument wavefront sensor section of the Gemini near-IR imager. In turn, the wavefront sensor will generate correction signals for the tip-tilt and fast-focus secondary mirror. Preliminary testing of the current version of the gimbal assembly has revealed positive result when operated at room temperature, but demonstrated hysterisis problems at cryogenic temperatures. Described in this paper are the specifications, design and performance characteristics, and integration of the gimbal mechanism with the rest of the wavefront sensor system.

Thornton, Robert J.; Douglass, Jeffrey W.; Hodapp, Klaus-Werner; Young, Tony T.; Yamada, Hubert

1998-08-01

36

THE INNER ENVELOPE AND DISK OF L1527 REVEALED: GEMINI L'-BAND-SCATTERED LIGHT IMAGING  

SciTech Connect

We present high-resolution L'-band imaging of the inner scattered light structure of Class 0 protostar L1527 IRS (IRAS 04368+2557) taken with the Gemini North telescope. The central point-source-like feature seen in Spitzer Space Telescope IRAC images is resolved in the Gemini image into a compact bipolar structure with a narrow dark lane in the center. Two scattered light lobes are extended {approx}1.''8 (200 AU) perpendicular to the direction of the outflow and {approx}2.''5 (350 AU) along the outflow axis; the narrow dark lane between the scattered light lobes is {approx}0.''45 (60 AU) thick. The observations are consistent with our initial modeling of a bright inner cavity separated by a dark lane due to extinction along the line of sight of the central protostar by the disk. The bright, compact scattered light might be due to complex inner structure generated by the outflow, as suggested in our first paper, or it may more likely be the upper layers of the disk forming from infalling matter.

Tobin, John J.; Hartmann, Lee [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Loinard, Laurent, E-mail: jjtobin@umich.ed [Centro de Radioastronomia y Astrofisica, UNAM, Apartado Postal 3-72 (Xangari), 58089 Morelia, Michoacan (Mexico)

2010-10-10

37

Development of a 4096 Element MEMS Continuous Membrane Deformable Mirror for High Contrast Astronomical Imaging  

Microsoft Academic Search

Presented in this paper is the development of a 4096 element continuous membrane deformable mirror under development for the Gemini Planet Imaging instrument designed for extra solar planet detection. This deformable mirror will enable the next generation of adaptive optics (\\

S. A. Cornelissen; P. A. Bierden; T. G. Bifano

38

The Impact of Transiting Planet Science on the Next Generation of Direct-Imaging Planet Searches  

NASA Astrophysics Data System (ADS)

Within the next five years, a number of direct-imaging planet search instruments, like the VLT SPHERE instrument, will be coming online. To successfully carry out their programs, these instruments will rely heavily on a-priori information on planet composition, atmosphere, and evolution. Transiting planet surveys, while covering a different semi-major axis regime, have the potential to provide critical foundations for these next-generation surveys. For example, improved information on planetary evolutionary tracks may significantly impact the insights that can be drawn from direct-imaging statistical data. Other high-impact results from transiting planet science include information on mass-to-radius relationships as well as atmospheric absorption bands. The marriage of transiting planet and direct-imaging results may eventually give us the first complete picture of planet migration, multiplicity, and general evolution.

Carson, Joseph C.

2009-02-01

39

Gemini/GMOS imaging of globular clusters in the Virgo galaxy NGC 4649 (M60)  

NASA Astrophysics Data System (ADS)

We present Sloan g and i imaging from the Gemini Multi-object Spectrograph (GMOS) instrument on the Gemini North telescope for the globular cluster (GC) system around the Virgo galaxy NGC 4649 (M60). Our three pointings, taken in good seeing conditions, cover an area of about 90 square arcmin. We detect 2151 unresolved sources. Applying colour and magnitude selection criteria to this source list gives 995 candidate GCs. Our source list is greater than 90 per cent complete to a magnitude of i= 23.6, and has little contamination from background galaxies. We find fewer than half a dozen potential ultracompact dwarf galaxies around NGC 4649. Foreground extinction from the nearby spiral NGC 4647 is limited to be AV < 0.1. We confirm the bimodality in the GC colour distribution found by earlier work using Hubble Space Telescope/WFPC2 imaging. As is commonly seen in other galaxies, the red GCs are concentrated towards the centre of the galaxy, having a steeper number density profile than the blue GC subpopulation. The varying ratio of red-to-blue GCs with radius can largely explain the overall GC system colour gradient. The underlying galaxy starlight has a similar density profile slope and colour to the red GCs. This suggests a direct connection between the galaxy field stars and the red GC subpopulation. We estimate a total GC population of 3700 +/- 900, with the uncertainty dominated by the extrapolation to larger radii than observed. This total number corresponds to a specific frequency SN= 4.1 +/- 1.0. Future work will present properties derived from GMOS spectra of the NGC 4649 GCs.

Forbes, Duncan A.; Faifer, Favio Raúl; Forte, Juan Carlos; Bridges, Terry; Beasley, Michael A.; Gebhardt, Karl; Hanes, David A.; Sharples, Ray; Zepf, Stephen E.

2004-12-01

40

Gemini\\/GMOS imaging of globular cluster systems in five early-type galaxies  

Microsoft Academic Search

In this paper, we present deep high-quality photometry of globular cluster systems (GCSs) belonging to five early-type galaxies, covering a range of mass and environment. Photometric data were obtained with the Gemini North and Gemini South telescopes in the filter passbands g', r' and i'. The combination of these filters with good seeing conditions allows an excellent separation between globular

Favio R. Faifer; Juan C. Forte; Mark A. Norris; Terry Bridges; Duncan A. Forbes; Stephen E. Zepf; Mike Beasley; Karl Gebhardt; David A. Hanes; Ray M. Sharples

2011-01-01

41

Subaru and Gemini High Spatial Resolution Infrared 18 ?m Imaging Observations of Nearby Luminous Infrared Galaxies  

NASA Astrophysics Data System (ADS)

We present the results of a ground-based, high spatial resolution infrared 18 ?m imaging study of nearby luminous infrared galaxies (LIRGs), using the Subaru 8.2 m and Gemini-South 8.1 m telescopes. The diffraction-limited images routinely achieved with these telescopes in the Q band (17-23 ?m) allow us to investigate the detailed spatial distribution of infrared emission in these LIRGs. We then investigate whether the emission surface brightnesses are modest, as observed in starbursts, or are so high that luminous active galactic nuclei (AGNs; high emission surface brightness energy sources) are indicated. The sample consists of 18 luminous buried AGN candidates and starburst-classified LIRGs identified in earlier infrared spectroscopy. We find that the infrared 18 ?m emission from the buried AGN candidates is generally compact, and the estimated emission surface brightnesses are high, sometimes exceeding the maximum value observed in and theoretically predicted for a starburst phenomenon. The starburst-classified LIRGs usually display spatially extended 18 ?m emission and the estimated emission surface brightnesses are modest, within the range sustained by a starburst phenomenon. The general agreement between infrared spectroscopic and imaging energy diagnostic methods suggests that both are useful tools for understanding the hidden energy sources of the dusty LIRG population.

Imanishi, Masatoshi; Imase, Keisuke; Oi, Nagisa; Ichikawa, Kohei

2011-05-01

42

Stable flexure mounting of a MEMS deformable mirror for the GPI Planet Imager  

NASA Astrophysics Data System (ADS)

Small deformable mirrors (DMs) produced using microelectromechanical systems (MEMS) techniques have been used in thermally stable, bench-top laboratory environments. With advances in MEMS DM technology, a variety of field applications are becoming more common, such as the Gemini Planet Imager's (GPI) adaptive optics system. Instruments at the Gemini Observatory operate in conditions where fluctuating ambient temperature, varying gravity orientations and humidity and dust can have a significant affect on DM performance. As such, it is crucial that the mechanical design of the MEMS DM be tailored to the environment. GPI's approach has been to mount the MEMS DM using high performance optical mounting techniques rather than a typical laboratory set-up. This paper discusses the design of the opto-mechanical mounting scheme for a 4096 actuator MEMS DM, developed by Boston Micromachines Corporation for use in the GPI adaptive optics system. Flexures have been incorporated into the DM mount to reduce deformations on the optical surface due to thermal fluctuations. These flexures have also been sized to maintain alignment under varying gravity vector orientations. Finally, a system for environmentally sealing the mirror has been designed to prevent degradation due to humidity effects. A plan for testing the mechanical mount to ensure that it meets GPI's performance and environmental requirements is also presented.

Hill, Alexis; Erickson, Darren; Fitzsimmons, Joeleff; Bierden, Paul; Cornelissen, Steven; Palmer, Dave

2008-07-01

43

Study of Spin-Scan Imaging for Outer Planets Missions.  

National Technical Information Service (NTIS)

The constraints that are imposed on the Outer Planet Missions (OPM) imager design are of critical importance. Imager system modeling analyses define important parameters and systematic means for trade-offs applied to specific Jupiter orbiter missions. Pos...

E. E. Russell R. A. Chandos J. C. Kodak S. F. Pellicori M. G. Tomasko

1974-01-01

44

A UNIFORM ANALYSIS OF 118 STARS WITH HIGH-CONTRAST IMAGING: LONG-PERIOD EXTRASOLAR GIANT PLANETS ARE RARE AROUND SUN-LIKE STARS  

SciTech Connect

We expand on the results of Nielsen et al., using the null result for giant extrasolar planets around the 118 target stars from the Very Large Telescope (VLT) NACO H- and Ks-band planet search (conducted by Masciadri and collaborators in 2003 and 2004), the VLT and MMT Simultaneous Differential Imager survey, and the Gemini Deep Planet Survey to set constraints on the population of giant extrasolar planets. Our analysis is extended to include the planet luminosity models of Fortney et al., as well as the correlation between stellar mass and frequency of giant planets found by Johnson et al. Doubling the sample size of FGKM stars strengthens our conclusions: a model for extrasolar giant planets with power laws for mass and semimajor axis as given by Cumming et al. cannot, with 95% confidence, have planets beyond 65 AU, compared to the value of 94 AU reported by Nielsen et al., using the models of Baraffe et al. When the Johnson et al. correction for stellar mass (which gives fewer Jupiter-mass companions to M stars with respect to solar-type stars) is applied, however, this limit moves out to 82 AU. For the relatively new Fortney et al. models, which predict fainter planets across most of parameter space, these upper limits, with and without a correction for stellar mass, are 182 and 234 AU, respectively.

Nielsen, Eric L.; Close, Laird M., E-mail: enielsen@as.arizona.ed [Steward Observatory, University of Arizona, Tucson, AZ 85721 (United States)

2010-07-10

45

Images of a fourth planet orbiting HR 8799.  

PubMed

High-contrast near-infrared imaging of the nearby star HR 8799 has shown three giant planets. Such images were possible because of the wide orbits (>25?astronomical units, where 1?au is the Earth-Sun distance) and youth (<100?Myr) of the imaged planets, which are still hot and bright as they radiate away gravitational energy acquired during their formation. An important area of contention in the exoplanet community is whether outer planets (>10?au) more massive than Jupiter form by way of one-step gravitational instabilities or, rather, through a two-step process involving accretion of a core followed by accumulation of a massive outer envelope composed primarily of hydrogen and helium. Here we report the presence of a fourth planet, interior to and of about the same mass as the other three. The system, with this additional planet, represents a challenge for current planet formation models as none of them can explain the in situ formation of all four planets. With its four young giant planets and known cold/warm debris belts, the HR 8799 planetary system is a unique laboratory in which to study the formation and evolution of giant planets at wide (>10?au) separations. PMID:21150902

Marois, Christian; Zuckerman, B; Konopacky, Quinn M; Macintosh, Bruce; Barman, Travis

2010-12-08

46

Planet signatures in collisionally active debris discs: scattered light images  

NASA Astrophysics Data System (ADS)

Context. Planet perturbations have been often invoked as a potential explanation for many spatial structures that have been imaged in debris discs. So far this issue has been mostly investigated with pure N-body numerical models, which neglect the crucial effect collisions within the disc can have on the disc's response to dynamical perturbations. Aims: We numerically investigate how the coupled effect of collisions and radiation pressure can affect the formation and survival of radial and azimutal structures in a disc perturbed by a planet. We consider two different set-ups: a planet embedded within an extended disc and a planet exterior to an inner debris ring. One important issue we want to address is under which conditions a planet's signature can be observable in a collisionally active disc. Methods: We use our DyCoSS code, which is designed to investigate the structure of perturbed debris discs at dynamical and collisional steady-state, and derive synthetic images of the system in scattered light. The planet's mass and orbit, as well as the disc's collisional activity (parameterized by its average vertical optical depth ?0) are explored as free parameters. Results: We find that collisions always significantly damp planet-induced spatial structures. For the case of an embedded planet, the planet's signature, mostly a density gap around its radial position, should remain detectable in head-on images if Mplanet ? MSaturn. If the system is seen edge-on, however, inferring the presence of the planet is much more difficult, as only weak asymmetries remain in a collisionally active disc, although some planet-induced signatures might be observable under very favourable conditions. For the case of an inner ring and an external planet, planetary perturbations cannot prevent collision-produced small fragments from populating the regions beyond the ring. The radial luminosity profile exterior to the ring is in most cases close to the one it should have in the absence of the external planet. The most significant signature left by a Jovian planet on a circular orbit are precessing azimutal structures that can be used to indirectly infer its presence. For a planet on an eccentric orbit, we show that the ring becomes elliptic and that the well known pericentre glow effect is visible despite of collisions and radiation pressure, but that detecting such features in observed discs is not an unambiguous indicator of the presence of an outer planet. Movies are available in electronic form at http://www.aanda.org

Thebault, P.; Kral, Q.; Ertel, S.

2012-11-01

47

Project Gemini online digital archive  

NASA Astrophysics Data System (ADS)

An archive containing the first high-resolution digital scans of the original flight films from Project Gemini, the second U.S. human spaceflight program, was unveiled by the NASA Johnson Space Center and Arizona State University's (ASU) School of Earth and Space Exploration on 6 January. The archive includes images from 10 flights. Project Gemini, which ran from 1964 to 1966, followed Project Mercury and preceded the Apollo spacecraft. Mercury and Apollo imagery are also available through ASU. For more information, see http://tothemoon.ser.asu.edu/gallery/gemini and http://apollo.sese.asu.edu/index.html.

Showstack, Randy

2012-01-01

48

Planets  

NSDL National Science Digital Library

What planets are in our solar system? Today, we are going to learn about the eight planets in our solar system. While learning, we're going to try to answer the question: What planets are in our solar system? Use this Planet Organizer to fill in information about the solar system that you learn on your journey! First, we're going to find ...

Anderson, Ms.

2011-04-07

49

Planets  

NSDL National Science Digital Library

This radio broadcast discusses developments in the search for extraterrestrial planets. Topics include what causes a planet to form, and how they are detected. There is also speculation on the liklihood of an Earth-like planet being found and the basic requirements for extraterrestrial life. The broadcast is 42 minutes in length.

50

High Resolution Imaging of Kepler Exo-planet Target Stars  

NASA Astrophysics Data System (ADS)

The NASA Kepler mission will be launched in Feb. 2009 and begin science operations 1 month later. Kepler's main science focus is to identify earth-like exo-planets vis photometric transit detection. ``Hot Jupiters" will be found in the hundreds (using current ground- based statistics) but Earth-sized planets (up to 2.5 Earth radii) will be more difficult. A Earth-sized planet transiting a G2V star shows a drop in the light signal of only 10^-5. During the few hour event, many samples are obtained by the Kepler mission. These, as well as re- observation of 2 or more additional transits, will provide the basis for a candidate detection. To take the list of candidates and move them to probable or certain exo-planets, a decision tree of false positive elimination will occur. Kepler science team members have distributed the many false positive elimination tasks to a subset of the membership - this proposal is to explore and use high-resolution imaging from WIYN to search for faint background sources that may be eclipsing binaries masquerading as small planet transit events. We plan to use two types of high resolution imaging at WIYN - Speckle observations with the SPECKLE imager and high-speed, tip-tilt corrected video photometry with the OPTIC imager. Both provide high resolution images, each with some advantages and disadvantages.

Howell, Steve B.; Horch, Elliott

2008-08-01

51

Speckle Imaging of Kepler Exo-planet Transit Candidate Stars  

NASA Astrophysics Data System (ADS)

The NASA Kepler mission was successfully launched on 6 March 2009 and will begin science operations near 1 May. At the present time, commissioning tests are being performed and all spacecraft and science instruments are nominal. Kepler's main science focus is to discover Earth-like exo-planets via photometric transit detection. ``Hot Jupiters" will be found by the hundreds (using current ground-based statistics) but Earth-sized planets (up to 2.5 Earth radii) will be more difficult, yet are the holy grail of the mission. To take the list of candidate transiting planets found by Kepler and move them to probable or certain exo-planet detections, a decision tree of false positive elimination will occur. While earth-sized exo-planets can not currently be confirmed from the ground, many of the false positive eliminations steps can be performed. This proposal aims to obtain high resolution speckle imaging to 1) finish the characterization of ~500 comparison sample stars in the Kepler field of view prior to any transit information as a sample to place planet host stars in context with and to 2) observe Kepler exo-planet transit candidates in order to eliminate the largest false positive contributor in any transit search - background eclipsing binary stars or faint companion stars.

Howell, Steve B.; Horch, Elliott; Sherry, William

2009-08-01

52

eXtreme Adaptive Optics Planet Imager: Overview and status  

SciTech Connect

As adaptive optics (AO) matures, it becomes possible to envision AO systems oriented towards specific important scientific goals rather than general-purpose systems. One such goal for the next decade is the direct imaging detection of extrasolar planets. An 'extreme' adaptive optics (ExAO) system optimized for extrasolar planet detection will have very high actuator counts and rapid update rates - designed for observations of bright stars - and will require exquisite internal calibration at the nanometer level. In addition to extrasolar planet detection, such a system will be capable of characterizing dust disks around young or mature stars, outflows from evolved stars, and high Strehl ratio imaging even at visible wavelengths. The NSF Center for Adaptive Optics has carried out a detailed conceptual design study for such an instrument, dubbed the eXtreme Adaptive Optics Planet Imager or XAOPI. XAOPI is a 4096-actuator AO system, notionally for the Keck telescope, capable of achieving contrast ratios >10{sup 7} at angular separations of 0.2-1'. ExAO system performance analysis is quite different than conventional AO systems - the spatial and temporal frequency content of wavefront error sources is as critical as their magnitude. We present here an overview of the XAOPI project, and an error budget highlighting the key areas determining achievable contrast. The most challenging requirement is for residual static errors to be less than 2 nm over the controlled range of spatial frequencies. If this can be achieved, direct imaging of extrasolar planets will be feasible within this decade.

Macintosh, B A; Bauman, B; Evans, J W; Graham, J; Lockwood, C; Poyneer, L; Dillon, D; Gavel, D; Green, J; Lloyd, J; Makidon, R; Olivier, S; Palmer, D; Perrin, M; Severson, S; Sheinis, A; Sivaramakrishnan, A; Sommargren, G; Soumer, R; Troy, M; Wallace, K; Wishnow, E

2004-08-18

53

FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini  

NASA Astrophysics Data System (ADS)

We report on the design, on-sky performance, and status of the FLAMINGOS-2 instrument - the fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048x2048- pixel HAWAII-2 0.9-2.4 ?m detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6x2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi-Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3x1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On-Instrument WaveFront Sensor subsystems. We also present the on-sky performance measured during acceptance testing in 2009, as well as current status of the project and future plans.

Eikenberry, Stephen; Bandyopadhyay, Reba; Bennett, J. Greg; Bessoff, Aaron; Branch, Matt; Charcos, Miguel; Corley, Richard; Dewitt, Curtis; Eriksen, John-David; Elston, Richard; Frommeyer, Skip; Gonzalez, Anthony; Hanna, Kevin; Herlevich, Michael; Hon, David; Julian, Jeff; Julian, Roger; Lasso, Nestor; Marin-Franch, Antonio; Marti, Jose; Murphey, Charlie; Raines, S. N.; Rambold, William; Rashkind, David; Warner, Craig; Leckie, Brian; Gardhouse, W. R.; Fletcher, Murray; Hardy, Tim; Dunn, Jennifer; Wooff, Robert; Pazder, John

2012-09-01

54

FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini  

NASA Astrophysics Data System (ADS)

We report on the design and status of the FLAMINGOS-2 instrument - a fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048×2048-pixel HAWAII-2 0.9-2.4 ?m detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6×2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi- Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3×1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On- Instrument WaveFront Sensor subsystems. We also present the current status of the project, currently in final testing in mid-2006.

Eikenberry, Stephen; Elston, Richard; Raines, S. Nicholas; Julian, Jeff; Hanna, Kevin; Hon, David; Julian, Roger; Bandyopadhyay, R.; Bennett, J. Greg; Bessoff, Aaron; Branch, Matt; Corley, Richard; Eriksen, John-David; Frommeyer, Skip; Gonzalez, Anthony; Herlevich, Michael; Marin-Franch, Antonio; Marti, Jose; Murphey, Charlie; Rashkin, David; Warner, Craig; Leckie, Brian; Gardhouse, W. Rusty; Fletcher, Murray; Dunn, Jennifer; Wooff, Robert; Hardy, Tim

2006-07-01

55

FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini  

NASA Astrophysics Data System (ADS)

We report on the design and status of the FLAMINGOS-2 instrument - a fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048×2048-pixel HAWAII-2 0.9-2.4 ?m detector array. A slit/decker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6×2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi- Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3×1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On- Instrument WaveFront Sensor subsystems. We also present the current status of the project and future plans, including on-sky delivery planned for late 2008.

Eikenberry, Stephen; Elston, Richard; Raines, S. Nicholas; Julian, Jeff; Hanna, Kevin; Warner, Craig; Julian, Roger; Bandyopadhyay, Reba; Bennett, J. Greg; Bessoff, Aaron; Branch, Matt; Corley, Richard; Dewitt, Curtis; Eriksen, John-David; Frommeyer, Skip; Gonzalez, Anthony; Herlevich, Michael; Hon, David; Marin-Franch, Antonio; Marti, Jose; Murphey, Charlie; Rambold, William; Rashkin, David; Leckie, Brian; Gardhouse, W. Rusty; Fletcher, Murray; Hardy, Tim; Dunn, Jennifer; Wooff, Robert

2008-08-01

56

FLAMINGOS-2: the facility near-infrared wide-field imager and multi-object spectrograph for Gemini  

NASA Astrophysics Data System (ADS)

We report on the design and status of the FLAMINGOS-2 instrument - a fully-cryogenic facility near-infrared imager and multi-object spectrograph for the Gemini 8-meter telescopes. FLAMINGOS-2 has a refractive all-spherical optical system providing 0.18-arcsecond pixels and a 6.2-arcminute circular field-of-view on a 2048x2048-pixel HAWAII-2 0.9-2.4 mm detector array. A slit/Dekker wheel mechanism allows the selection of up to 9 multi-object laser-machined plates or 3 long slits for spectroscopy over a 6x2-arcminute field of view, and selectable grisms provide resolutions from ~1300 to ~3000 over the entire spectrograph bandpass. FLAMINGOS-2 is also compatible with the Gemini Multi-Conjugate Adaptive Optics system, providing multi-object spectroscopic capabilities over a 3x1-arcminute field with high spatial resolution (0.09-arcsec/pixel). We review the designs of optical, mechanical, electronics, software, and On-Instrument WaveFront Sensor subsystems. We also present the current status of the project, midway through its construction phase in June 2004.

Eikenberry, Stephen S.; Elston, Richard; Raines, S. Nicholas; Julian, Jeff; Corley, Richard J.; Hanna, Kevin; Hon, David; Julian, Roger; Rashkin, David; Leckie, Brian; Gardhouse, W. Rusty; Fletcher, Murray; Dunn, Jennifer; Wooff, Robert

2004-09-01

57

Mars Imaging Camera (MIC) on board PLANET-B  

Microsoft Academic Search

Mars Imaging Camera (MIC) on board PLANET-B, Japanese Mars mission, is a small, compact and lightweight imager. It features three-color linear CCD aligned with the spacecraft's spin axis and is designed to take two-dimensional images of Mars and its satellites using the spacecraft's spin.The total field of view (FOV) of the camera is 360 degree (around the spin axis) ×

Keiken Ninomiya; Tatsuaki Hashimoto; Akikom Nakamura; Tadashi Mukai; Masato Nakamura; Masahiro Ogasawara; Naoki Yoshizawa; Juro Ishida; Yasuhiko Mizushima; Hiroto Hosoda; Masayo Takano

1999-01-01

58

Integral Field Spectroscopy at Gemini  

NASA Astrophysics Data System (ADS)

Integral field units (IFUs) and spectrographs will be an important part of the instrument complement at both Gemini 8-meter telescopes. An especially powerful aspect of this will be the combination of IFUs with high spatial resolution adaptive optics systems. Adaptive optics will produce near diffraction-limited images with resolution approximately a factor of two better than the Hubble Space Telescope at 2 microns. Coupled with the light-gathering power of 8-meter telescopes, this combination will be well-suited for spatially resolved studies of intermediate and high redshift galaxies. IFUs employing both lenslet/fiber and image slicer technologies will give Gemini integral field capability at wavelengths from 0.4 microns to 5 microns. This presentation will review current and planned integral field capability at Gemini will give early results from the recently commissioned IFU for the Gemini Multi-Object Spectrograph (GMOS). This work is supported by the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil) and CONICET (Argentina).

Miller, B.

2001-12-01

59

Planets  

NSDL National Science Digital Library

The purpose of this project is to gather information and learn interesting facts about the planets in our solar sytem to complete a research project for Mrs. Hutchinson\\'s class. Begin by taking a quiz to measure your knowledge. Click this link for information and quiz. Quiz Next, you will choose two of the following sites and search for information on the planets in our solar system. Fill in the questions on your work sheet as you go to each site. Factmonster Planets Kids Astronomy 9 planets for kids Windows to the Universe Just for ...

Bhanks

2006-11-02

60

Characterization and testing of FLAMINGOS-2: the Gemini facility near-infrared multi-object spectrometer and wide-field imager  

NASA Astrophysics Data System (ADS)

FLAMINGOS-2 is a near-infrared wide-field imager and fully cryogenic multi-object spectrometer for Gemini Observatory being built by the University of Florida. FLAMINGOS-2 can simultaneously carry 9 custom cryogenic multi-object slit masks exchangeable without thermally cycling the entire instrument. Three selectable grisms provide resolving powers which are ~1300 to ~3000 over the entire spectrograph bandpass of 0.9-2.5 microns. We present and discuss characterization data for FLAMINGOS-2 including imaging throughput, image quality, spectral performance, and noise performance. After a lengthy integration process, we expect that FLAMINGOS-2 will be in the midst of commissioning at Gemini South by the fall of 2008.

Raines, Steven N.; Eikenberry, Stephen S.; Bandyopadhyay, Reba M.; Julian, Jeffrey A.; Hanna, Kevin T.; Warner, Craig D.; Julian, Roger E.; Bennett, J. Greg; DeWitt, Curtis N.; Frommeyer, Skip; Gonzalez, Anthony; Herlevich, Michael D.; Murphey, Charles

2008-08-01

61

SUBARU AND GEMINI HIGH SPATIAL RESOLUTION INFRARED 18 {mu}m IMAGING OBSERVATIONS OF NEARBY LUMINOUS INFRARED GALAXIES  

SciTech Connect

We present the results of a ground-based, high spatial resolution infrared 18 {mu}m imaging study of nearby luminous infrared galaxies (LIRGs), using the Subaru 8.2 m and Gemini-South 8.1 m telescopes. The diffraction-limited images routinely achieved with these telescopes in the Q band (17-23 {mu}m) allow us to investigate the detailed spatial distribution of infrared emission in these LIRGs. We then investigate whether the emission surface brightnesses are modest, as observed in starbursts, or are so high that luminous active galactic nuclei (AGNs; high emission surface brightness energy sources) are indicated. The sample consists of 18 luminous buried AGN candidates and starburst-classified LIRGs identified in earlier infrared spectroscopy. We find that the infrared 18 {mu}m emission from the buried AGN candidates is generally compact, and the estimated emission surface brightnesses are high, sometimes exceeding the maximum value observed in and theoretically predicted for a starburst phenomenon. The starburst-classified LIRGs usually display spatially extended 18 {mu}m emission and the estimated emission surface brightnesses are modest, within the range sustained by a starburst phenomenon. The general agreement between infrared spectroscopic and imaging energy diagnostic methods suggests that both are useful tools for understanding the hidden energy sources of the dusty LIRG population.

Imanishi, Masatoshi [Subaru Telescope, 650 North A'ohoku Place, Hilo, HI 96720 (United States); Imase, Keisuke; Oi, Nagisa [Department of Astronomy, School of Science, Graduate University for Advanced Studies (SOKENDAI), Mitaka, Tokyo 181-8588 (Japan); Ichikawa, Kohei, E-mail: masa.imanishi@nao.ac.jp [Department of Astronomy, Kyoto University, Kyoto 606-8502 (Japan)

2011-05-15

62

GEOMETRIC PROCESSING OF DIGITAL IMAGES OF THE PLANETS.  

USGS Publications Warehouse

New procedures and software have been developed for geometric transformations of images to support digital cartography of the planets. The procedures involve the correction of spacecraft camera orientation of each image with the use of ground control and the transformation of each image to a Sinusoidal Equal-Area map projection with an algorithm which allows the number of transformation calculations to vary as the distortion varies within the image. When the distortion is low in an area of an image, few transformation computations are required, and most pixels can be interpolated. When distortion is extreme, the location of each pixel is computed. Mosaics are made of these images and stored as digital databases.

Edwards, Kathleen

1987-01-01

63

Advancing the Gemini Observatory  

NASA Astrophysics Data System (ADS)

Gemini Science and User Meeting; San Francisco, California, 17-20 July 2012 More than 100 astronomers gathered in San Francisco to discuss results from the Gemini Observatory and to plan for its future. The Gemini Observatory consists of twin 8.1 meter diameter optical/infrared telescopes located on mountaintops in Hawai'i and Chile. Gemini was built and is operated by an international partnership that currently includes the United States, the United Kingdom, Canada, Chile, Australia, Brazil, and Argentina.

Hammel, Heidi B.; Levenson, Nancy A.

2012-11-01

64

MEMS-based extreme adaptive optics for planet detection  

SciTech Connect

The next major step in the study of extrasolar planets will be the direct detection, resolved from their parent star, of a significant sample of Jupiter-like extrasolar giant planets. Such detection will open up new parts of the extrasolar planet distribution and allow spectroscopic characterization of the planets themselves. Detecting Jovian planets at 5-50 AU scale orbiting nearby stars requires adaptive optics systems and coronagraphs an order of magnitude more powerful than those available today--the realm of ''Extreme'' adaptive optics. We present the basic requirements and design for such a system, the Gemini Planet Imager (GPI.) GPI will require a MEMS-based deformable mirror with good surface quality, 2-4 micron stroke (operated in tandem with a conventional low-order ''woofer'' mirror), and a fully-functional 48-actuator-diameter aperture.

Macintosh, B A; Graham, J R; Oppenheimer, B; Poyneer, L; Sivaramakrishnan, A; Veran, J

2005-11-18

65

Gemini world coordinates  

NASA Astrophysics Data System (ADS)

The Gemini World Coordinate Systems (WCS) facilities support various types of astrometric coordinates as well as instrument-specific quantities such as wavelengths or times. The astrometric facilities are based on the principle that, for sky-imaging applications, users are concerned only with (i) positions in the focal plane and (ii) celestial coordinates. All intermediate calculations, for example involving the position of the tip/tilt secondary mirror, the orientation of the instrument rotator, the selection of focal station, differential refraction and atmospheric dispersion, and field rotation effects caused by misalignments in the telescope mount, are encapsulated in the WCS transformation. We have implemented a library of C functions which support Gemini astrometric world coordinates. Most of them can be run off-line, and are applicable to other telescopes. More general WCS problems, involving data coordinates as well as astrometry, are treated by breaking the telescope, instrument and detector into a set of 'agents' each of which manages its own local transformations. The individual transformations can then be combined to provide the end-to-end transformations needed by data display and analysis facilities.

Wallace, Patrick T.

1998-05-01

66

Development of multi-spectral QWIPs for extrasolar planets imaging  

NASA Astrophysics Data System (ADS)

One of the most promising approaches for direct imaging of extrasolar planets is based on the next generation of extremely large ground-based telescopes and original differential observing techniques to overcome atmospheric fluctuations problems. One possibility is the use of phase-mask coronagraphy coupled with spectral differential imaging. Multispectral Quantum Well Infrared Photodetectors (QWIPs) are a promising technological solution that could answer the stringent requirements of this challenging topic. We present here the scientific background, the technical requirements as well as the possible technical approaches that are explored in the frame of a project funded by the ANR (Agence Nationale de la Recherche). In particular, we will describe the strategy retained for the design of the QWIP active layer.

Nedelcu, Alexandru; Pantin, Eric

2010-10-01

67

Low Loss BSE imaging with the EsB Detection system on the Gemini Ultra FE-SEM  

Microsoft Academic Search

The sensitivity of the GEMINI Inlens detection systems is worldwide known. Especially the EsB detection provides compositional\\u000a contrast down to the ppm level of concentration. Due to direct detection of the boosted low voltage BSE electrons, a very\\u000a strong signal is generated on the on axis Inlens BSE detector. Additional a filtering of the BSE electrons can be applied. The

Heiner Jaksch

68

Atmospheric Dynamics of Brown Dwarfs and Directly Imaged Giant Planets  

NASA Astrophysics Data System (ADS)

A variety of observations provide evidence for vigorous motion in the atmospheres of brown dwarfs and directly imaged giant planets. Motivated by these observations, we examine the dynamical regime of the circulation in the atmospheres and interiors of these objects. Brown dwarfs rotate rapidly, and for plausible wind speeds, the flow at large scales will be rotationally dominated. We present 3D, global, numerical simulations of convection in the interior, which demonstrate that, at large scales, the convection aligns in the direction parallel to the rotation axis. Convection occurs more efficiently at high latitudes than low latitudes, leading to systematic equator-to-pole temperature differences that may reach ~1 K near the top of the convection zone. The interaction of convection with the overlying, stably stratified atmosphere will generate a wealth of atmospheric waves, and we argue that, as in the stratospheres of planets in the solar system, the interaction of these waves with the mean flow will cause a significant atmospheric circulation at regional to global scales. At large scales, this should consist of stratified turbulence (possibly organizing into coherent structures such as vortices and jets) and an accompanying overturning circulation. We present an approximate analytic theory of this circulation, which predicts characteristic horizontal temperature variations of several to ~50 K, horizontal wind speeds of ~10-300 m/sec, and vertical velocities that advect air over a scale height in ~10^5-10^6 sec. This vertical mixing may help to explain the chemical disequilibrium observed on some brown dwarfs. Moreover, the implied large-scale organization of temperature perturbations and vertical velocities suggests that, near the L/T transition, patchy clouds can form near the photosphere, helping to explain recent observations of brown-dwarf variability in the near-IR.

Showman, Adam P.; Kaspi, Y.

2013-10-01

69

Occulter Based Missions of Different Scales for Terrestrial Planet Imaging  

NASA Astrophysics Data System (ADS)

Free flying occulters are an attractive option as a space mission architecture for imaging exosolar planets, particular ones in the habitable zone. Their appeal is two-fold: the inner working angle is largely decoupled from telescope diameter and, because they suppress starlight before entering the telescope, there is no need for wavefront control. We present the basic operating principles of occulters for high-contrast, including preliminary stationkeeping simulations, and a manufacturing approach being studied as part of NASA's Technology Demonstration for Exoplanet Missions. Our main focus is a comparison of mission architectures employing occulters at varying scales: large flagship observatories (THEIA, NWO), existing large aperture telescopes (JWST), small dedicated telescopes (O3), and small general purpose telescopes (such as a dark energy mission like EUCLID). THEIA, the Telescope for Habitable Exoplanets and Interstellar/Intergalactic Astronomy, is a multi-instrument space-telescope concept employing a 4-m diffraction-limited telescope operating at UV and Visible wavelengths that was developed as part of NASAs Astrophysics Strategic Mission Concept Studies in 2009 and presented to the US Academy's decadal survey review, Astro2010. By combining the telescope with a roughly 40 m occulter, operating at two different telescope-occulter separations, planets as small as Earth can be characterized over a broad band, including R>70 spectra. O3, the Occulting Ozone Observatory, is a smaller mission costing less than 1B that uses a 1 to 2 m telescope combined with a roughly 30 m occulter. O3 is capable of time-resolved photometry over 8 bands, focusing on biomarkers, such as detecting the strong ozone feature, and surface characterization. It also provides the capability for enough repeat visits to support orbit determination. We will compare the science yield and architecture and how different coronagraph and occulter approaches perform at these different mission scales.

Kasdin, N. J.; Spergel, D. N.; Vanderbei, R.; Shaklan, S.; Lisman, D. P.; Savransky, D.; Cady, E.; Soummer, R.

2010-10-01

70

Atmospheric Dynamics of Brown Dwarfs and Directly Imaged Giant Planets  

NASA Astrophysics Data System (ADS)

A variety of observations provide evidence for vigorous motion in the atmospheres of brown dwarfs and directly imaged giant planets. Motivated by these observations, we examine the dynamical regime of the circulation in the atmospheres and interiors of these objects. Brown dwarfs rotate rapidly, and for plausible wind speeds, the flow at large scales will be rotationally dominated. We present three-dimensional, global, numerical simulations of convection in the interior, which demonstrate that at large scales, the convection aligns in the direction parallel to the rotation axis. Convection occurs more efficiently at high latitudes than low latitudes, leading to systematic equator-to-pole temperature differences that may reach ~1 K near the top of the convection zone. The interaction of convection with the overlying, stably stratified atmosphere will generate a wealth of atmospheric waves, and we argue that, as in the stratospheres of planets in the solar system, the interaction of these waves with the mean flow will cause a significant atmospheric circulation at regional to global scales. At large scales, this should consist of stratified turbulence (possibly organizing into coherent structures such as vortices and jets) and an accompanying overturning circulation. We present an approximate analytic theory of this circulation, which predicts characteristic horizontal temperature variations of several to ~50 K, horizontal wind speeds of ~10-300 m s-1, and vertical velocities that advect air over a scale height in ~105-106 s. This vertical mixing may help to explain the chemical disequilibrium observed on some brown dwarfs. Moreover, the implied large-scale organization of temperature perturbations and vertical velocities suggests that near the L/T transition, patchy clouds can form near the photosphere, helping to explain recent observations of brown-dwarf variability in the near-IR.

Showman, Adam P.; Kaspi, Yohai

2013-10-01

71

Project Gemini: A Chronology  

NSDL National Science Digital Library

This internet version of an historical NASA (National Aeronautics and Space Administration) publication contains information about Project Gemini, which laid the groundwork for the Apollo missions. The history of this project is told in three parts. Part I, Concept and Design, discusses the formal initiation of Project Gemini (first designated the Mercury Mark II project). Part II, Chronology, Development and Qualification, spans the years 1963 and 1964 when the main task became translating Gemini designs into working machinery reliable enough for manned space flight. Part III, Flight Tests, chronicles the events of 1965 and 1966, dominated by the 10 manned missions which constitute the main part of the Gemini program. To round out this volume, there are several appendices which summarize, tabulate, and make easily accessible some major aspects of Project Gemini.

Grimwood, James

1968-06-01

72

On the Misalignment of the Directly Imaged Planet ? Pictoris b with the System's Warped Inner Disk  

NASA Astrophysics Data System (ADS)

The vertical warp in the debris disk ? Pictoris —an inclined inner disk extending into a flat outer disk— has long been interpreted as the signpost of a planet on an inclined orbit. Direct images spanning 2004-2010 have revealed ? Pictoris b, a planet with a mass and orbital distance consistent with this picture. However, it was recently reported that the orbit of planet b is aligned with the flat outer disk, not the inclined inner disk, and thus lacks the inclination to warp the disk. We explore three scenarios for reconciling the apparent misalignment of the directly imaged planet ? Pictoris b with the warped inner disk of ? Pictoris: observational uncertainty, an additional planet, and damping of planet b's inclination. We find that, at the extremes of the uncertainties, the orbit of ? Pictoris b has the inclination necessary to produce the observed warp. We also find that if planet b were aligned with the flat outer disk, it would prevent another planet from creating a warp with the observed properties; therefore planet b itself must be responsible for the warp. Finally, planet b's inclination could have been damped by dynamical friction and still produce the observed disk morphology, but the feasibility of damping depends on disk properties and the presence of other planets. More precise observations of the orbit of planet b and the position angle of the outer disk will allow us to distinguish between the first and third scenarios. R.I.D. acknowledges support by NSF Graduate Research Fellowship DGE-1144152 and D.C.F. by NASA Hubble Fellowship HF-51272.01.

Dawson, Rebekah Ilene; Murray-Clay, R. A.; Fabrycky, D. C.

2012-05-01

73

Recent progress on external occulter technology for imaging exosolar planets  

NASA Astrophysics Data System (ADS)

Imaging planets orbiting nearby stars requires a system for suppressing the host starlight by at least ten orders of magnitude. One such approach uses an external occulter, a satellite flying far from the telescope and employing a large screen, or starshade, to suppress the incoming starlight. This trades the added complexity of building the precisely shaped starshade and flying it in formation against simplifications in the telescope since extremely precise wavefront control is no longer necessary. Much progress has been made recently in designing, testing and manufacturing starshade technology. In this paper we describe the design of starshades and report on recent accomplishments in manufacturing and measuring a prototype occulter petal as part of NASA's first Technology Development for Exoplanet Missions (TDEM) program. We demonstrate that the as-built petal is consistent with a full-size occulter achieving better than 10-10 contrast. We also discuss laboratory testing at the Princeton Occulter Testbed. These experiments use sub-scale, long-distance beam propagation to verify the diffraction analysis associated with occulter starlight suppression. We demonstrate roughly 10-10 suppression in the laboratory and discuss the important challenges and limitations.

Kasdin, N. J.; Vanderbei, R. J.; Sirbu, D.; Samuels, J.; Shaklan, S.; Lisman, D.; Thomson, M.; Cady, E.; Martin, S.

74

FIB machining of occulting masks for imaging of extrasolar planets  

NASA Astrophysics Data System (ADS)

We are developing the ability for Focused Ion Beam (FIB) machining of occulting masks for use in coronagraphs. These masks will be used as soft-edged Lyot stops to suppress light from stars and allow direct imaging of extrasolar planets. The FIB approach is attractive because it has the potential for higher precision than mechanical machining and for larger volumes than electron-beam lithography. The mask fabrication process is trifold: 1) a transparent material-currently, poly(methyl methacrylate) (PMMA)-is doped with dyes; 2) the mask shape is FIB milled into the material; and 3) the mask is coated with another layer of index-matching transparent absorber. Using a Zeiss NVision 40 FIB system, we have fabricated conical-shaped masks of various slopes in dye-doped PMMA. Inherent in this process is the advantage of control of the features through programming the ion beam track. We have also optically characterized these masks as well as the dye-doped absorbing material. We have found that the dye-doped PMMA has a very high absorbance, >1 OD.

Raja, Shilpa N.; Aziz, Michael J.; Foley, James W.; Tolls, Volker

2009-08-01

75

Planet Formation Instrument for the Thirty Meter Telescope  

SciTech Connect

In the closing years of the 20th Century humankind began its exploration of the planetary systems in the solar neighborhood. Precision radial velocity measurements have now yielded the discovery of over 160 planets. Direct imaging of these planets, as opposed to detection of the effects of orbital motion on their parent star, is now feasible, and the first young planet in a wide orbit may have been detected using adaptive optics systems. Gemini and the VLT are building the first generation of high contrast adaptive optics systems, which deliver planet-imaging performance within few Airy rings of the host star. These systems will make the first surveys of the outer regions of solar systems by detecting the self-luminous radiation of young planets. These instruments will establish whether Jovian planets form predominantly through 'top-down' (global gravitational instability) or 'bottom-up' (core accretion) processes. The 8-m 'extreme' AO systems cannot see close enough to the host stars to image Doppler planets, and they cannot reach the relatively distant, young clusters and associations where planets are forming. The Planet Formation Instrument will use the nearly four-fold improved angular resolution of TMT to peer into the inner solar systems of Doppler-planet bearing stars to yield a unified sample of planets with known Keplerian orbital elements and atmospheric properties. In star formation regions, where T Tauri stars (young solar type stars) are found in abundance, PFI can see into the snow line, where the icy cores of planets like Jupiter must have formed. Thus, TMT will be the first facility to witness the formation of new planets.

Macintosh, B; Troy, M; Graham, J; Doyon, R

2006-02-22

76

Post processing of differential images for direct extrasolar planet detection from the ground  

Microsoft Academic Search

The direct imaging from the ground of extrasolar planets has become today a major astronomical and biological focus. This kind of imaging requires simultaneously the use of a dedicated high performance Adaptive Optics [AO] system and a differential imaging camera in order to cancel out the flux coming from the star. In addition, the use of sophisticated post-processing techniques is

J.-F. Sauvage; L. Mugnier; T. Fusco; G. Rousset

2006-01-01

77

Adaptive Optics for the Gemini Telescopes  

Microsoft Academic Search

Adaptive optics will play a critical role in achieving the highest possible image quality for the Gemini telescopes. An Adaptive Optics Working Group (R. Racine - chair, B. Ellerbroek, E. Kibblewhite, D. McCarthy, R. Myers, S. Ridgway, F. Roddier) is preparing to recommend an implementation strategy. The recommendations are still under discussion (the prospects for laser beacons are evolving rapidly).

S. Ridgway

1993-01-01

78

Gemini telescope structure design  

NASA Astrophysics Data System (ADS)

The Gemini project is an international collaboration to design, fabricate, and assemble two 8 M telescopes, one on Mauna Kea in Hawaii, the other on Cerro Pachon in Chile. The telescopes will be national facilities designed to meet the Gemini Science Requirements (GSR), a document developed by the Gemini Science Committee (GSC) and the national project scientists. The Gemini telescope group, based on Tucson, has developed a telescope structure to meet the GSR. This paper describes the science requirements that have technically driven the design, and the features that have been incorporated to meet these requirements. This is followed by a brief description of the telescope design. Finally, analyses that have been performed and development programs that have been undertaken are described briefly. Only the designs that have been performed by the Gemini Telescope Structure, Building and Enclosure Group are presented here; control, optical systems, acquisition and guiding, active and adaptive optics, Cassegrain rotator and instrumentation issues are designed and managed by others and will not be discussed here, except for a brief description of the telescope configurations to aid subsequent discussions.

Raybould, Keith; Gillett, Paul E.; Hatton, Peter; Pentland, Gordon; Sheehan, Mike; Warner, Mark

1994-06-01

79

Observations of Mars and its satellites by the Mars Imaging Camera (MIC) on Planet-B  

Microsoft Academic Search

We present the specifications of the Mars Imaging Camera (MIC) on the Planet-B spin-stabilized spacecraft, and key scientific objectives of MIC observations. A non-sun-synchronous orbit of Planet-B with a large eccentricity of about 0.87 around Mars provides the opportunities (1) to observe the same region of Mars at various times of day and various solar phase angles with spatial resolution

Tadashi Mukai; Tokuhide Akabane; Tatsuaki Hashimoto; Hiroshi Ishimoto; Sho Sasaki; A. Inada; Anthony Toigo; Masato Nakamura; Yutaka Abe; Kei Kurita; Takeshi Imamura

1998-01-01

80

The SEEDS Direct Imaging Survey for Planets and Scattered Dust Emission in Debris Disk Systems  

NASA Astrophysics Data System (ADS)

Debris disks around young main-sequence stars often have gaps and cavities which for a long time have been interpreted as possibly being caused by planets. In recent years, several giant planet discoveries have been made in systems hosting disks of precisely this nature, further implying that interactions with planets could be a common cause of such disk structures. As part of the SEEDS high-contrast imaging survey, we are surveying a population of debris-disk-hosting stars with gaps and cavities implied by their spectral energy distributions, in order to attempt to spatially resolve the disk as well as to detect any planets that may be responsible for the disk structure. Here, we report on intermediate results from this survey. Five debris disks have been spatially resolved, and a number of faint point sources have been discovered, most of which have been tested for common proper motion, which in each case has excluded physical companionship with the target stars. From the detection limits of the 50 targets that have been observed, we find that ? Pic b-like planets (~10 M jup planets around G-A-type stars) near the gap edges are less frequent than 15%-30%, implying that if giant planets are the dominant cause of these wide (27 AU on average) gaps, they are generally less massive than ? Pic b.

Janson, Markus; Brandt, Timothy D.; Moro-Martín, Amaya; Usuda, Tomonori; Thalmann, Christian; Carson, Joseph C.; Goto, Miwa; Currie, Thayne; McElwain, M. W.; Itoh, Yoichi; Fukagawa, Misato; Crepp, Justin; Kuzuhara, Masayuki; Hashimoto, Jun; Kudo, Tomoyuki; Kusakabe, Nobuhiko; Abe, Lyu; Brandner, Wolfgang; Egner, Sebastian; Feldt, Markus; Grady, Carol A.; Guyon, Olivier; Hayano, Yutaka; Hayashi, Masahiro; Hayashi, Saeko; Henning, Thomas; Hodapp, Klaus W.; Ishii, Miki; Iye, Masanori; Kandori, Ryo; Knapp, Gillian R.; Kwon, Jungmi; Matsuo, Taro; Miyama, Shoken; Morino, Jun-Ichi; Nishimura, Tetsuro; Pyo, Tae-Soo; Serabyn, Eugene; Suenaga, Takuya; Suto, Hiroshi; Suzuki, Ryuji; Takahashi, Yasuhiro; Takami, Michihiro; Takato, Naruhisa; Terada, Hiroshi; Tomono, Daego; Turner, Edwin L.; Watanabe, Makoto; Wisniewski, John; Yamada, Toru; Takami, Hideki; Tamura, Motohide

2013-08-01

81

Computer vision applications for coronagraphic optical alignment and image processing.  

PubMed

Modern coronagraphic systems require very precise alignment between optical components and can benefit greatly from automated image processing. We discuss three techniques commonly employed in the fields of computer vision and image analysis as applied to the Gemini Planet Imager, a new facility instrument for the Gemini South Observatory. We describe how feature extraction and clustering methods can be used to aid in automated system alignment tasks, and also present a search algorithm for finding regular features in science images used for calibration and data processing. Along with discussions of each technique, we present our specific implementation and show results of each one in operation. PMID:23669856

Savransky, Dmitry; Thomas, Sandrine J; Poyneer, Lisa A; Macintosh, Bruce A

2013-05-10

82

Computer vision applications for coronagraphic optical alignment and image processing  

NASA Astrophysics Data System (ADS)

Modern coronagraphic systems require very precise alignment between optical components and can benefit greatly from automated image processing. We discuss three techniques commonly employed in the fields of computer vision and image analysis as applied to the Gemini Planet Imager, a new facility instrument for the Gemini South Observatory. We describe how feature extraction and clustering methods can be used to aid in automated system alignment tasks, and also present a search algorithm for finding regular features in science images used for calibration and data processing. Along with discussions of each technique, we present our specific implementation and show results of each one in operation.

Savransky, Dmitry; Thomas, Sandrine J.; Poyneer, Lisa A.; Macintosh, Bruce A.

2013-05-01

83

ON THE MISALIGNMENT OF THE DIRECTLY IMAGED PLANET {beta} PICTORIS b WITH THE SYSTEM'S WARPED INNER DISK  

SciTech Connect

The vertical warp in the debris disk {beta} Pictoris-an inclined inner disk extending into a flat outer disk-has long been interpreted as the signpost of a planet on an inclined orbit. Direct images spanning 2004-2010 have revealed {beta} Pictoris b, a planet with a mass and orbital distance consistent with this picture. However, it was recently reported that the orbit of planet b is aligned with the flat outer disk, not the inclined inner disk, and thus lacks the inclination to warp the disk. We explore three scenarios for reconciling the apparent misalignment of the directly imaged planet {beta} Pictoris b with the warped inner disk of {beta} Pictoris: observational uncertainty, an additional planet, and damping of planet b's inclination. We find that, at the extremes of the uncertainties, the orbit of {beta} Pictoris b has the inclination necessary to produce the observed warp. We also find that if planet b were aligned with the flat outer disk, it would prevent another planet from creating a warp with the observed properties; therefore planet b itself must be responsible for the warp. Finally, planet b's inclination could have been damped by dynamical friction and still produce the observed disk morphology, but the feasibility of damping depends on disk properties and the presence of other planets. More precise observations of the orbit of planet b and the position angle of the outer disk will allow us to distinguish between the first and third scenarios.

Dawson, Rebekah I.; Murray-Clay, Ruth A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Fabrycky, Daniel C., E-mail: rdawson@cfa.harvard.edu [UCO/Lick Observatory, University of California, Santa Cruz, CA 95064 (United States)

2011-12-10

84

Visible and Near-IR Imaging of Giant Planets: Outer Manifestations of Deeper Secrets  

NASA Astrophysics Data System (ADS)

Visible and near-infrared imaging of the giant planets -- Jupiter, Saturn, Uranus, and Neptune -- probes the outermost layers of clouds in these gaseous atmospheres. Not only are the images beautiful and striking in their color and diversity of detail, they also provide quantitative clues to the dynamical and chemical processes taking place both at the cloud tops and deeper in the interior: zonal wind profiles can be extracted; wavelength-dependent center-to-limb brightness variations yield valuable data for modeling vertical aerosol structure; the presence of planetary-scale atmospheric waves can sometimes be deduced; variations of cloud color and brightness with latitude provide insight into the underlying mechanisms driving circulation; development and evolution of discrete atmospheric features trace both exogenic and endogenic events. During the 1980's, our understanding of the giant planets was revolutionized by detailed visible-wavelength images taken by the Voyager spacecraft of these planets' atmospheres. However, those images were static: brief snapshots in time of four complex and dynamic atmospheric systems. In short, those images no longer represent the current appearance of these planets. Recently, our knowledge of the atmospheres of the gas giant planets has undergone major new advances, due in part to the excellent imaging capability and longer-term temporal sampling of the Hubble Space Telescope (HST) and the Galileo Mission to Jupiter. In this talk, I provide an update on our current understanding of the gas giants based on recent visible and near-infrared imaging, highlighting results from the collision of Comet Shoemaker-Levy 9 with Jupiter, Saturn's White Spots, intriguing changes in the atmosphere of Uranus, and Neptune's peripatetic clouds.

Hammel, Heidi B.

1996-09-01

85

Phase-induced amplitude apodization of telescope pupils for extrasolar terrestrial planet imaging  

Microsoft Academic Search

In this paper, an alternative to classical pupil apodization techniques (use of an amplitude pupil mask) is proposed. It is shown that an achromatic apodized pupil suitable for imaging of extrasolar planets can be obtained by reflection of an unapodized flat wavefront on two mirrors. By carefully choosing the shape of these two mirrors, it is possible to obtain a

Olivier Guyon

2003-01-01

86

Direct imaging and spectroscopy of habitable planets using JWST and a starshade  

Microsoft Academic Search

A starshade with the James Webb Space Telescope (JWST) is the only possible path forward in the next decade to obtain images and spectra of a planet similar to the Earth, to study its habitability, and search for signs of alien life. While JWST was not specifically designed to observe using a starshade, its near-infrared instrumentation is in principle capable

Rémi Soummer; Jeff Valenti; Robert A. Brown; Sara Seager; Jason Tumlinson; Webster Cash; Ian Jordan; Marc Postman; Tiffany Glassman; Laurent Pueyo; Aki Roberge

2010-01-01

87

Direct imaging and spectroscopy of terrestrial planets with JWST and a starsahde  

Microsoft Academic Search

We present a study for using a starshade with the James Webb Space Telescope (JWST). This concept would enable imaging and spectroscopy of a planet similar to the Earth, the study of its habitability, and the search for signs of alien life. JWST was not specifically designed to observe with a starshade, but its instrumentation and its great sensitivity make

R. Soummer; J. Valenti; R. A. Brown; S. Seager; J. Tumlinson; W. Cash; I. Jordan; M. Postman; T. Glassman; L. Pueyo; A. Roberge

2010-01-01

88

Direct Imaging Discovery of a Fourth Planet at 15AU in the HR 8799 Planetary System  

NASA Astrophysics Data System (ADS)

We present the imaging discovery of a fourth planet at 0.376 arcsec (14.8 AU) projected separation from the young nearby star HR8799. This new object, designated HR8799e, is detected at Ks- and L-band wavelengths using the ADI observing technique with adaptive optics and the Keck II telescope on Mauna Kea. Over a 1-year baseline the object is confirmed as co-moving with the primary, revolving counter-clockwise like the three other known planets of this system, and it has similar brightness at Ks and L to HR8799c and d and hence likely similar mass, 10 times the mass of Jupiter. HR8799 has now been shown to possess the same number of gas giant planets as our Solar System, further adding to the various similarities between the two systems.

Marois, Christian; Macintosh, B.; Konopacky, Q.; Barman, T.; Zuckerman, B.

2011-01-01

89

Planet Earth  

NSDL National Science Digital Library

For those interested in a global view of the weather, Planet Earth is a "real-time 3-D model of the Earth with continuously updating night shadows and clouds." Cloud images are provided by the University of Wisconsin-Madison Space Science and Engineering Center. Planet Earth is shareware with a fee of $29.95.

90

Estimates of the Planet Yield from Ground-based High-contrast Imaging Observations as a Function of Stellar Mass  

NASA Astrophysics Data System (ADS)

We use Monte Carlo simulations to estimate the number of extrasolar planets that are directly detectable in the solar neighborhood using current and forthcoming high-contrast imaging instruments. Our calculations take into consideration the important factors that govern the likelihood for imaging a planet, including the statistical properties of stars in the solar neighborhood, correlations between star and planet properties, observational effects, and selection criteria. We consider several different ground-based surveys, both biased and unbiased, and express the resulting planet yields as a function of stellar mass. Selecting targets based on their youth and visual brightness, we find that strong correlations between star mass and planet properties are required to reproduce high-contrast imaging results to date (i.e., HR 8799, ? Pic). Using the most recent empirical findings for the occurrence rate of gas-giant planets from radial velocity (RV) surveys, our simulations indicate that naive extrapolation of the Doppler planet population to semimajor axes accessible to high-contrast instruments provides an excellent agreement between simulations and observations using present-day contrast levels. In addition to being intrinsically young and sufficiently bright to serve as their own beacon for adaptive optics correction, A-stars have a high planet occurrence rate and propensity to form massive planets in wide orbits, making them ideal targets. The same effects responsible for creating a multitude of detectable planets around massive stars conspire to reduce the number orbiting low-mass stars. However, in the case of a young stellar cluster, where targets are approximately the same age and situated at roughly the same distance, MK-stars can easily dominate the number of detections because of an observational bias related to small number statistics. The degree to which low-mass stars produce the most planet detections in this special case depends upon whether multiple formation mechanisms are at work. Upon relaxing our assumption that planets in ultra-wide (a > 100 AU) orbits resemble the RV sample, our simulations suggest that the companions found orbiting late-type stars (AB Pic, 1RXSJ1609, GSC 06214, etc.) are consistent with a formation channel distinct from that of RV planets. These calculations explain why planets have thus far been imaged preferentially around A-stars and K-, M-stars, but no spectral types in between, despite concerted efforts targeting F-, G-stars.

Crepp, Justin R.; Johnson, John Asher

2011-06-01

91

ESTIMATES OF THE PLANET YIELD FROM GROUND-BASED HIGH-CONTRAST IMAGING OBSERVATIONS AS A FUNCTION OF STELLAR MASS  

SciTech Connect

We use Monte Carlo simulations to estimate the number of extrasolar planets that are directly detectable in the solar neighborhood using current and forthcoming high-contrast imaging instruments. Our calculations take into consideration the important factors that govern the likelihood for imaging a planet, including the statistical properties of stars in the solar neighborhood, correlations between star and planet properties, observational effects, and selection criteria. We consider several different ground-based surveys, both biased and unbiased, and express the resulting planet yields as a function of stellar mass. Selecting targets based on their youth and visual brightness, we find that strong correlations between star mass and planet properties are required to reproduce high-contrast imaging results to date (i.e., HR 8799, {beta} Pic). Using the most recent empirical findings for the occurrence rate of gas-giant planets from radial velocity (RV) surveys, our simulations indicate that naive extrapolation of the Doppler planet population to semimajor axes accessible to high-contrast instruments provides an excellent agreement between simulations and observations using present-day contrast levels. In addition to being intrinsically young and sufficiently bright to serve as their own beacon for adaptive optics correction, A-stars have a high planet occurrence rate and propensity to form massive planets in wide orbits, making them ideal targets. The same effects responsible for creating a multitude of detectable planets around massive stars conspire to reduce the number orbiting low-mass stars. However, in the case of a young stellar cluster, where targets are approximately the same age and situated at roughly the same distance, MK-stars can easily dominate the number of detections because of an observational bias related to small number statistics. The degree to which low-mass stars produce the most planet detections in this special case depends upon whether multiple formation mechanisms are at work. Upon relaxing our assumption that planets in ultra-wide (a > 100 AU) orbits resemble the RV sample, our simulations suggest that the companions found orbiting late-type stars (AB Pic, 1RXSJ1609, GSC 06214, etc.) are consistent with a formation channel distinct from that of RV planets. These calculations explain why planets have thus far been imaged preferentially around A-stars and K-, M-stars, but no spectral types in between, despite concerted efforts targeting F-, G-stars.

Crepp, Justin R.; Johnson, John Asher, E-mail: jcrepp@astro.caltech.edu [California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); NASA Exoplanet Science Institute (NExScI), California Institute of Technology, Mail Code 100-22, 770 South Wilson Avenue, Pasadena, CA 91125 (United States)

2011-06-01

92

Adaptive Optics Images. II. 12 Kepler Objects of Interest and 15 Confirmed Transiting Planets  

NASA Astrophysics Data System (ADS)

All transiting planet observations are at risk of contamination from nearby, unresolved stars. Blends dilute the transit signal, causing the planet to appear smaller than it really is, or producing a false positive detection when the target star is blended with an eclipsing binary. High spatial resolution adaptive optics images are an effective way of resolving most blends. Here we present visual companions and detection limits for 12 Kepler planet candidate host stars, of which 4 have companions within 4''. One system (KOI 1537) consists of two similar-magnitude stars separated by 0.''1, while KOI 174 has a companion at 0.''5. In addition, observations were made of 15 transiting planets that were previously discovered by other surveys. The only companion found within 1'' of a known planet is the previously identified companion to WASP-2b. An additional four systems have companions between 1'' and 4'': HAT-P-30b (3.''7, ?Ks = 2.9), HAT-P-32b (2.''9, ?Ks = 3.4), TrES-1b (2.''3, ?Ks = 7.7), and WASP-P-33b (1.''9, ?Ks = 5.5), some of which have not been reported previously. Depending on the spatial resolution of the transit photometry for these systems, these companion stars may require a reassessment of the planetary parameters derived from transit light curves. For all systems observed, we report the limiting magnitudes beyond which additional fainter objects located 0.''1-4'' from the target may still exist. Based on observations obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

Adams, E. R.; Dupree, A. K.; Kulesa, C.; McCarthy, D.

2013-07-01

93

Post processing of differential images for direct extrasolar planet detection from the ground  

NASA Astrophysics Data System (ADS)

The direct imaging from the ground of extrasolar planets has become today a major astronomical and biological focus. This kind of imaging requires simultaneously the use of a dedicated high performance Adaptive Optics [AO] system and a differential imaging camera in order to cancel out the flux coming from the star. In addition, the use of sophisticated post-processing techniques is mandatory to achieve the ultimate detection performance required. In the framework of the SPHERE project, we present here the development of a new technique, based on Maximum A Posteriori [MAP] approach, able to estimate parameters of a faint companion in the vicinity of a bright star, using the multi-wavelength images, the AO closed-loop data as well as some knowledge on non-common path and differential aberrations. Simulation results show a 10-5 detectivity at 5? for angular separation around 15?/D with only two images.

Sauvage, J.-F.; Mugnier, L.; Fusco, T.; Rousset, G.

2006-07-01

94

The Nine Planets: Mercury  

NSDL National Science Digital Library

This page of Nine Planets highlights details about the planet Mercury. Information includes planet diameter, mass, distance from the Sun, orbit, and mythology. Also covered are composition, surface features, atmosphere and magnetic field data, and the results of exploration spacecraft. The site provides links to images, movies, and more Mercury facts. Unanswered questions about the planet are also discussed.

Arnett, Bill

95

Adaptive optics system for direct imaging of extra-solar planets from the ground  

NASA Astrophysics Data System (ADS)

Direct detection of planets of neighboring stars by imaging from the ground is extremely challenging, and requires bringing together and extending all that has been learned in the past two decades in adaptive optics experiments and development. From a distance of 30 light years, the planet Jupiter would be 10(superscript 9) times dimmer than the sun, and at 0.5 arcsec separation would be lost in the strong glare of scattered light from the central star. In this paper, we lay out the requirements for adaptive optics to allow direct detection with a large telescope. The stellar halo must be suppressed by several orders of magnitude, and speckle noise caused by correlated wavefront errors must be severely reduced to allow efficient smoothing of the halo through averaging of random fluctuations caused by photon noise. For a 6.5 m telescope imaging near 1 micrometer wavelength, suppression of the stellar halo to 10(superscript -6) of the peak intensity allows direct detection of Jupiter-like planets in several hours of integration. A deformable mirror with approximately 10,000 correction elements is needed, updated at 0.5 millisec intervals using a wavefront sensor optimized for use with bright stellar sources. Local filtering of wavefront sensor data is required to overcome correlated errors arising from time delay between sensing and imaging. Correction of the strongest amplitude errors caused by scintillation allows the required integration times to be decreased by a factor of 2. We present results of detailed simulations for an adaptive system which achieves the above goals, for imaging at 1 micrometer wavelength with a 6.5 meter telescope. A simulated image of a solar system twin at 8 parsecs shows Jupiter at the 5 (sigma) level for a 5 hour integration. We plan to develop and use a similar system to conduct a two- hemisphere survey of bright nearby stars on the twin 6.5 m MMT and Magellan telescopes.

Sandler, David G.; Stahl, Steven M.; Angel, J. Roger P.

1995-08-01

96

A laboratory demonstration of the capability to image an Earth-like extrasolar planet.  

PubMed

The detection and characterization of an Earth-like planet orbiting a nearby star requires a telescope with an extraordinarily large contrast at small angular separations. At visible wavelengths, an Earth-like planet would be 1 x 10(-10) times fainter than the star at angular separations of typically 0.1 arcsecond or less. There are several proposed space telescope systems that could, in principle, achieve this. Here we report a laboratory experiment that reaches these limits. We have suppressed the diffracted and scattered light near a star-like source to a level of 6 x 10(-10) times the peak intensity in individual coronagraph images. In a series of such images, together with simple image processing, we have effectively reduced this to a residual noise level of about 0.1 x 10(-10). This demonstrates that a coronagraphic telescope in space could detect and spectroscopically characterize nearby exoplanetary systems, with the sensitivity to image an 'Earth-twin' orbiting a nearby star. PMID:17429394

Trauger, John T; Traub, Wesley A

2007-04-12

97

The Nine Planets: Jupiter  

NSDL National Science Digital Library

This page of Nine Planets contains details about the gas giant planet Jupiter. Information includes planet diameter, mass, distance from the Sun, orbit, and mythology. Also covered are planet composition, surface features, atmosphere and magnetic field data, results from exploration spacecraft, and temperature on the planet. Jupiters' moons are also covered in detail, including Io, Europa, Ganymede, Callisto, and others. The site provides links to more images and facts, and discusses unanswered questions about Jupiter and its moons.

Arnett, Bill

98

Multiplicity in transiting planet-host stars. A lucky imaging study of Kepler candidates  

NASA Astrophysics Data System (ADS)

Context. In the exoplanetary era, the Kepler spacecraft is causing a revolution by discovering thousands of new planet candidates. However, a follow-up program is needed to reject false candidates and fully characterize the bona-fide exoplanets. Aims: Our main aims are to 1./ detect and analyze close companions inside the typical Kepler point spread function (PSF) to study whether they are the responsible for the dimming found in Kepler light curves, 2./ study the change in the stellar and planetary parameters caused by an unresolved object, 3./ help validate the Kepler objects of interest (KOI) that do not have any object inside the Kepler PSF, and 4./ study the multiplicity rate of planet-host candidates. Such a large sample of observed planet-host candidates allows us to derive statistics for close (visual or bounded) companions to the harboring star. Methods: We present lucky imaging observations for a total of 98 KOIs. This technique is based on the acquisition of thousands of very-short-exposure-time images. A selection and combination of a small amount of the highest quality frames provides a high resolution image with objects having a 0.1 arcsec PSF. We apply this technique to carry out observations in the Sloan i and z filters of our Kepler candidates. Results: We find blended objects inside the Kepler PSF for a significant percentage of KOIs. On the one hand, only 58.2% of the hosts do not have any object within 6 arcsec. On the other hand, we find 19 companions closer than 3 arcsec in 17 KOIs. According to their magnitudes and i - z colors, 8 of them could be physically bound to the host star.

Lillo-Box, J.; Barrado, D.; Bouy, H.

2012-10-01

99

Gemini G.E.L. online catalogue raisonne  

NSDL National Science Digital Library

The National Gallery of Art presents the Gemini G.E.L. (Graphic Editions Limited) online catalogue raisonne, a listing of prints produced at this Los Angeles studio from 1966 through 1996. At Gemini, artists including Robert Rauschenberg, Ellsworth Kelly, Jasper Johns, David Hockney, Sam Francis, Roy Lichtenstein, Jonathan Borofsky, and Richard Serra worked with master printers to produce editions of prints. Initially the online catalogue raisonne seems difficult to browse, but the search area provides drop-down boxes for artists' names, dates, and series titles, so without prior knowledge that Frank Stella worked at Gemini, one can still retrieve 93 Stella prints. In the essay section, users can read a series of illustrated sections on the history of Gemini, individual artists, and decades, and link to larger images. The guide section explains the metadata fields in each catalog record, such as artist, series, title, and less obvious aspects such as "support," which refers to the support each print is on, almost always paper, or start date (year the artists began collaborating with Gemini) vs. signature date (year the artist signed the edition) vs. publication date (year the edition was made available).

2001-01-01

100

Direct imaging and spectroscopy of terrestrial planets with JWST and a starsahde  

NASA Astrophysics Data System (ADS)

We present a study for using a starshade with the James Webb Space Telescope (JWST). This concept would enable imaging and spectroscopy of a planet similar to the Earth, the study of its habitability, and the search for signs of alien life. JWST was not specifically designed to observe with a starshade, but its instrumentation and its great sensitivity make it capable of achieving major results in the study of terrestrial-mass exoplanets. However, there are some challenges for the starshade designs mainly due to the very large wavelength sensitivity of the HgCdTe detectors. We discuss the combination of a starshade with internal filters in NIRCam and NIRSpec to optimize both science return and starshade performance. We discuss a possible filter upgrade to enable feasible observations of Earth-like planets and in particular spectroscopic characterization in the near infrared. The new filter would not affect NIRSpec's scientific performance nor its operations, but it would dramatically reduce the risk of adding a starshade to JWST in the future and enhance the performance of any starshade that is built.

Soummer, R.; Valenti, J.; Brown, R. A.; Seager, S.; Tumlinson, J.; Cash, W.; Jordan, I.; Postman, M.; Mountain, M.; Glassman, T.; Pueyo, L.; Roberge, A.; NWP Team

2010-10-01

101

Map-a-Planet  

NSDL National Science Digital Library

Explore global imagery of the planets and satellites from a variety of missions in an easy to use web interface. Customize and download your own image maps of the Moon, Mars, Venus, and other planets and moons. The user can select a planet or a moon and then examine different data sets of that object.

2008-12-15

102

All Planet Sizes  

NSDL National Science Digital Library

This image, from the Lunar and Planetary Laboratory, illustrates the approximate relative sizes of the Sun and planets and their relative locations. Although distance is not to scale, viewers can see that the small rocky planets are located close to the Sun and large gaseous planets are further away.

103

Gemini primary mirror cell design  

Microsoft Academic Search

To minimize the wind buffeting effect on the primary mirror figure, the Gemini primary mirror cell is designed to provide additional mirror stiffness by coupling the mirror to the cell structure through a six-zone hydraulic support system. Therefore the cell structure is designed as though it were a light weight mirror for minimum top surface distortion. This paper describes the

Eugene W. Huang

1997-01-01

104

A High-Contrast Imaging Survey of SIM Lite Planet Search Targets  

NASA Astrophysics Data System (ADS)

With the development of extreme high contrast ground-based adaptive optics instruments and space missions aimed at detecting and characterizing Jupiter- and terrestrial-mass planets, it is critical that each target star be thoroughly vetted to determine whether it is a viable target, given both the instrumental design and scientific goals of the program. With this in mind, we have conducted a high-contrast imaging survey of mature AFGKM stars with the PALAO/PHARO instrument on the Palomar 200 inch telescope. The survey reached sensitivities sufficient to detect brown dwarf companions at separations of >50 AU. The results of this survey will be utilized both by future direct imaging projects such as GPI, SPHERE, and P1640 and indirect detection missions such as SIM Lite. Out of 84 targets, all but one have no close-in (0.45-1") companions and 64 (76%) have no stars at all within the 25" field of view. The sensitivity contrasts in the Ks passband ranged from 4.5 to 10 for this set of observations. These stars were selected as the best nearby targets for habitable planet searches because of their long-lived habitable zones (>1 billion years). We report two stars, GJ 454 and GJ 1020, with previously unpublished proper motion companions. In both cases, the companions are stellar in nature and are most likely M dwarfs based on their absolute magnitudes and colors. Based on our mass sensitivities and level of completeness, we can place an upper limit of ˜17% on the presence of brown dwarf companions with masses >40 MJ at separations of >1". We also discuss the importance of including statistics on those stars with no detected companions in their field of view for the sake of future companion searches and an overall understanding of the population of low-mass objects around nearby stars.

Tanner, Angelle M.; Gelino, Christopher R.; Law, Nicholas M.

2010-10-01

105

Astrometry and photometry in high contrast imaging  

NASA Astrophysics Data System (ADS)

The direct exoplanet imaging field will strongly benefit from the larger aperture and the higher angular resolution achieved by next generation 30+m telescopes. To fully take advantage of these new facilities, one of the biggest challenges that ground-based adaptive optics imaging must overcome is to be able to derive accurate astrometry and photometry with realistic estimate of residual errors. The planet photometry and its astrometry are used to compare with atmospheric models and to fit orbits. If erroneous numbers are found, or if errors are underestimated, spurious fits can lead to unphysical planet characteristics or wrong/unstable orbits. Overestimating the errors also needs to be avoided as it degrades the value of the data. In the high-contrast planet imaging context, we will present various photometry/astrometry biases induced by several noise sources (anisoplanatism, non-Gaussian noise, etc.) or processing techniques (ADI/SSDI/LOCI) that we have uncovered during our ongoing direct exoplanet imaging campaign at Gemini, VLT and Keck. We will describe the procedures that we have implemented to properly estimate those biases. These solutions will be implemented in the Gemini Planet Imager campaign data pipeline and we expect that they will also play a crucial role in any future 30+m survey.

Galicher, Raphael; Marois, Christian

2011-09-01

106

The Planets  

NSDL National Science Digital Library

The students will learn about the planets and about their attributes. What do they need to support human life? What are the names of the planets in the solar system? The Nine Planets What are the physical properties of each planet? The Solar System - Pictures of the planets Now you can make your own planet! Make Your Own Planet ...

Rindlisbacher, Ms.

2006-10-04

107

Uranus' cloud structure and seasonal variability from Gemini-North and UKIRT observations  

NASA Astrophysics Data System (ADS)

Observations of Uranus were made in September 2009 with the Gemini-North telescope in Hawaii, using both the NIFS and NIRI instruments. Observations were acquired in Adaptive Optics mode and have a spatial resolution of approximately 0.1?. NIRI images were recorded with three spectral filters to constrain the overall appearance of the planet: J, H-continuum and CH 4(long), and long slit spectroscopy measurements were also made (1.49-1.79 ?m) with the entrance slit aligned on Uranus' central meridian. To acquire spectra from other points on the planet, the NIFS instrument was used and its 3? × 3? field of view stepped across Uranus' disc. These observations were combined to yield complete images of Uranus at 2040 wavelengths between 1.476 and 1.803 ?m. The observed spectra along Uranus central meridian were analysed with the NEMESIS retrieval tool and used to infer the vertical/latitudinal variation in cloud optical depth. We find that the 2009 Gemini data perfectly complement our observations/conclusions from UKIRT/UIST observations made in 2006-2008 and show that the north polar zone at 45°N has continued to steadily brighten while that at 45°S has continued to fade. The improved spatial resolution of the Gemini observations compared with the non-AO UKIRT/UIST data removes some of the earlier ambiguities with our previous analyses and shows that the opacity of clouds deeper than the 2-bar level does indeed diminish towards the poles and also reveals a darkening of the deeper cloud deck near the equator, perhaps coinciding with a region of subduction. We find that the clouds at 45°N,S lie at slightly lower pressures than the clouds at more equatorial latitudes, which suggests that they might possibly be composed of a different condensate, presumably CH 4 ice, rather than H 2S or NH 3 ice, which is assumed for the deeper cloud. In addition, analysis of the centre-to-limb curves of both the Gemini/NIFS and earlier UKIRT/UIST IFU observations shows that the main cloud deck has a well-defined top, and also allows us to better constrain the particle scattering properties. Overall, Uranus appeared to be less convectively active in 2009 than in the previous 3 years, which suggests that now the northern spring equinox (which occurred in 2007) is passed the atmosphere is settling back into the quiescent state seen by Voyager 2 in 1986. However, a number of discrete clouds were still observed, with one at 15°N found to lie near the 500 mb level, while another at 30°N, was seen to be much higher at near the 200 mb level. Such high clouds are assumed to be composed of CH 4 ice.

Irwin, P. G. J.; Teanby, N. A.; Davis, G. R.; Fletcher, L. N.; Orton, G. S.; Tice, D.; Kyffin, A.

2011-03-01

108

The Planet Pipeline: enabling data mining and citizen science with Hubble images of the Solar System  

NASA Astrophysics Data System (ADS)

In 15 years of service, the Wide Field Planetary Camera 2 (WFPC2) onboard the Hubble Space Telescope (HST) obtained over 10,000 frames of Solar System data. Since standard data reduction pipelines are typically not optimized for movingtarget data, our "planet pipeline" will uniformly reprocess and catalog this WFPC2 image collection to make it more immediately science-ready. Some of our processing steps will utilize citizen scientists to perform visual inspections. Our corresponding database will enable robust queries which are more specific to planetary science, helping archival researchers quickly find and utilize the prepared images within our collection for a wide range of scientific analyses. We welcome suggestions (especially from veteran WFPC2 users) on the optimal treatment and organization of this data collection, and also to identify a broad range of analyses that might only be possible with visual inspections by citizen scientists. Our processed images and associated catalogs will be made available as High Level Science Products (HLSP) in the Multimission Archive at STScI (MAST): http://archive.stsci.edu/prepds/planetpipeline

Mutchler, M.; Wong, M. H.; Higgins, J.; Gay, P. L.; Conti, A.; Deustua, S.; Golombek, D.; Grunsfeld, J.; Lerner, T.

2011-10-01

109

BIGRE: A Low Cross-Talk Integral Field Unit Tailored for Extrasolar Planets Imaging Spectroscopy  

NASA Astrophysics Data System (ADS)

Integral field spectroscopy represents a powerful technique for the detection and characterization of extrasolar planets through high-contrast imaging since it allows us to obtain simultaneously a large number of monochromatic images. These can be used to calibrate and then to reduce the impact of speckles, once their chromatic dependence is taken into account. The main concern in designing integral field spectrographs for high-contrast imaging is the impact of the diffraction effects and the noncommon path aberrations together with an efficient use of the detector pixels. We focus our attention on integral field spectrographs based on lenslet arrays, discussing the main features of these designs: the conditions of appropriate spatial and spectral sampling of the resulting spectrograph's slit functions and their related cross-talk terms when the system works at the diffraction limit. We present a new scheme for the integral field unit based on a dual-lenslet device (BIGRE), that solves some of the problems related to the classical Traitement Intégral des Galaxies par l'Étude de leurs Rays (TIGER) design when used for such applications. We show that BIGRE provides much lower cross-talk signals than TIGER, allowing a more efficient use of the detector pixels and a considerable saving of the overall cost of a lenslet-based integral field spectrograph.

Antichi, Jacopo; Dohlen, Kjetil; Gratton, Raffaele G.; Mesa, Dino; Claudi, Riccardo U.; Giro, Enrico; Boccaletti, Anthony; Mouillet, David; Puget, Pascal; Beuzit, Jean-Luc

2009-04-01

110

Large Ground-Based Telescopes with High Order Adaptive Optics for Imaging Faint Objects and ExtraSolar Planets  

Microsoft Academic Search

\\u000a The new 6-8 m class ground based telescopes equiped with very high-resolution adaptive optics have the potential to detect\\u000a Jupiter-like planets around nearby stars. Direct detection will allow discoveries of planets, beyond the angular radius where\\u000a Doppler spectroscopy achieves maximum sensitivity. In addition, direct imaging (and spectroscopy) will allow confirmation\\u000a for those indirect detections which lie within 0.3–2 arcseconds in

M. Langlois; D. Sandler; D. McCarthy

1999-01-01

111

Welcome to the Planets  

NSDL National Science Digital Library

This is a collection of over 200 of the best images from NASA's planetary exploration program. There are captioned images from the major planets, small bodies, and the space craft used for the images.

1995-01-01

112

Gemini high-resolution optical spectrograph conceptual design  

NASA Astrophysics Data System (ADS)

A multiplexed moderate resolution (R = 34,000) and a single object high resolution (R = 90,000) spectroscopic facility for the entire 340 - 950nm wavelength region has been designed for Gemini. The result is a high throughput, versatile instrument that will enable precision spectroscopy for decades to come. The extended wavelength coverage for these relatively high spectral resolutions is achieved by use of an Echelle grating with VPH cross-dispersers and for the R = 90,000 mode utilization of an image slicer. The design incorporates a fast, efficient, reliable system for acquiring targets over the7 arcmin field of Gemini. This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory as one of the three competing organizations to conduct a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study.

Szeto, Kei; McConnachie, Alan; Anthony, André; Bohlender, David; Crampton, David; Desaulniers, Pierre; Dunn, Jennifer; Hardy, Tim; Hill, Alexis; Monin, Dmitry; Pazder, John; Schwab, Christian; Spano, Paola; Starkenburg, Else; Thibault, Simon; Walker, Gordon; Venn, Kim; Zhang, Hu

2012-09-01

113

Direct imaging and spectroscopy of habitable planets using JWST and a starshade  

NASA Astrophysics Data System (ADS)

A starshade with the James Webb Space Telescope (JWST) is the only possible path forward in the next decade to obtain images and spectra of a planet similar to the Earth, to study its habitability, and search for signs of alien life. While JWST was not specifically designed to observe using a starshade, its near-infrared instrumentation is in principle capable of doing so and could achieve major results in the study of terrestrialmass exoplanets. However, because of technical reasons associated with broadband starlight suppression and filter red-leak, NIRSpec would need a slight modification to one of its target acquisition filters to enable feasible observations of Earth-like planets. This upgrade would 1) retire the high risk associated with the effects of the current filter red leak which are difficult to model given the current state of knowledge on instrument stray light and line spread function at large separation angles, 2) enable access to the oxygen band at 0.76 ?m in addition to the 1.26 ?m band, 3) enable a smaller starshade by relaxing requirements on bandwidth and suppression 4) reduce detector saturation and associated long recovery times. The new filter would not affect neither NIRSpecs scientific performance nor its operations, but it would dramatically reduce the risk of adding a starshade to JWST in the future and enhance the performance of any starshade that is built. In combination with a starshade, JWST could be the most capable and cost effective of all the exoplanet hunting missions proposed for the next decade, including purpose built observatories for medium-size missions.

Soummer, Rémi; Valenti, Jeff; Brown, Robert A.; Seager, Sara; Tumlinson, Jason; Cash, Webster; Jordan, Ian; Postman, Marc; Mountain, Matt; Glassman, Tiffany; Pueyo, Laurent; Roberge, Aki

2010-07-01

114

SPICA coronagraph instrument: characterization of atmospheres and physical parameters of giant planets by direct imaging and spectroscopy  

NASA Astrophysics Data System (ADS)

We present the current status of the development of the SPICA Coronagraph Instrument (SCI). SPICA is a next-generation 3-meter class infrared telescope, which will be launched in 2022. SCI is high-contrast imaging, spectroscopic instrument mainly for direct detection and spectroscopy of extra-solar planets in the near-to-mid infrared wavelengths to characterize their atmospheres, physical parameters and evolutionary scenarios. SCI is now under the international review process. In this paper, we present a science case of SCI. The main targets of SCI, not only for direct imaging but also for spectroscopy, are young to matured giant planets. We will also show that some of known exoplanets by ground-based direct detection are good targets for SCI, and a number of direct detection planets that are suitable for SCI will be significantly increased in the next decade. Second, a general design of SCI and a key technology including a new high-throughput binary mask coronagraph, will be presented. Furthermore, we will show that SCI is potentially capable of achieving 10-6 contrast by a PSF subtraction method, even with a telescope pointing error. This contrast enhancement will be important to characterize low-mass and cool planets.

Kotani, T.; Enya, K.; Nakagawa, T.; Matsuhara, H.; Kataza, H.; Kawada, M.; Mita, M.; Komatsu, K.; Uchida, H.; Fujiwara, K.; Mitani, S.; Sakai, S.; Haze, K.; Kaneda, H.; Oyabu, S.; Ishihara, D.; Miyata, T.; Sako, S.; Nakamura, T.; Asano, K.; Tamura, M.; Nishikawa, J.; Yamashita, T.; Narita, N.; Hayano, H.; Oya, S.; Kokubo, E.; Itoh, Y.; Matsuo, T.; Fukagawa, M.; Shibai, H.; Honda, M.; Baba, N.; Murakami, N.; Okamoto, Y. K.; Ida, S.; Takami, M.; Abe, L.; Guyon, O.; Yamamuro, T.

2012-09-01

115

Early Results from the Gemini Multi-Object Spectrograph  

NASA Astrophysics Data System (ADS)

We present examples of early science results achieved with the newly commissioned Gemini Multi-Object Spectrograph (GMOS) on the Gemini North 8-m Telescope. GMOS provides long- and multi-slit spectroscopy and imaging over a 5.5 arcmin field of view, and these three modes were successfully commissioned during the second half of 2001. GMOS was built by a collaboration between the UK (Astronomical Technology Centre at ROE and University of Durham) and Canada (HIA). As part of System Verification (SV) we have executed several imaging, long-slit, and multi-object spectroscopic programs designed to test and demonstrate the scientific capabilities of GMOS. Two of these programs, for which we present the imaging and preliminary MOS results, target the fields around RXJ0142.0+2131 and UM224. The first program is aimed at investigating galaxy evolution through observations of a rich cluster at intermediate redshift (z=0.28) and measuring stellar populations and dynamics of the member galaxies. The goal of the second program is to measure redshifts of galaxies in the field of a high redshift QSO (z=2.08) with intervening metal-line absorption in order to identify which galaxies may be responsible for the absorption and investigate their group/clustering properties. All data obtained as part of SV will become public within a few months. We are currently in the final stages of SV observations including full commissioning of the IFU, and have begun obtaining data for the community as of November 2001. The Gemini Observatory is operated by AURA, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: NSF (United States), PPARC (United Kingdom), NRC (Canada), CONICYT (Chile), ARC (Australia), CNPq (Brazil) and CONICET (Argentina).

Roth, K. C.; Jorgensen, I.; Hook, I. M.; Takamiya, M. Y.

2001-12-01

116

Summary Analysis of the Gemini Entry Aerodynamics.  

National Technical Information Service (NTIS)

The aerodynamic data that were derived in 1967 from the analysis of flight-generated data for the Gemini entry module are presented. These data represent the aerodynamic characteristics exhibited by the vehicle during the entry portion of Gemini 2, 3, 5, ...

A. M. Whitnah D. B. Howes

1972-01-01

117

Band-limited image plane masks for the Terrestrial Planet Finder coronagraph: materials and designs for broadband performance.  

PubMed

Coronagraphs for detection and characterization of exosolar earthlike planets require accurate masks with broadband performance in the visible and near infrared spectrum. Design and fabrication of image plane masks capable of suppressing broadband starlight to 10(-10) level contrast presents technical challenges. We discuss basic approaches, material choices, designs, and fabrication options for image plane masks with particular focus on material properties to obtain adequate spectral performance. Based on theoretical analysis, we show that metals such as Pt and Ni, and alloys such as Inconel, may be employed as promising mask materials that can meet broadband performance requirements. PMID:18188191

Balasubramanian, Kunjithapatham

2008-01-10

118

Characterizing Extra-Solar Planets with Low Resolution Spectroscopy  

NASA Astrophysics Data System (ADS)

In the next few years, several high contrast imaging instruments equipped with integral field spectrographs will allow the direct spectral characterization of a variety of companions, from low-mass stars to Jupiter-mass extra-solar planets, at Solar System-like separations (4-40 AU). The spectra obtained by these instruments will be low resolution (R 30-60), making detailed thermo-chemical analysis difficult. Therefore, we have developed a technique that quantitatively compares observed low-resolution spectra with a set of synthetic spectra in order to obtain physical parameters, such as temperature and surface gravity, quickly and robustly. The technique requires no assumptions about age, mass, radius or metallicity of the companion or the primary. We describe this technique and demonstrate its effectiveness with simulated and observed spectra from Project 1640, the high contrast imager and integral field spectrograph on Palomar. The technique can also be used to optimize observing efficiency by determining the ideal wavelength range (for multi-filter instruments such as the Gemini Planet Imager) and signal to noise ratio for a desired precision and accuracy of inferred parameters. The current analysis uses the PHOENIX models as a basis for comparison, but the technique can be applied to any set of models and even used to quantify the differences between models created by different groups. This tool provides a necessary, fast, and comprehensive method of characterizing faint companions of stars, whether they be stellar, sub-stellar or planetary in nature.

Rice, Emily L.; Oppenheimer, B. R.; Zimmerman, N.; Roberts, L. C., Jr.; Hinkley, S.

2012-01-01

119

Celestial Exoplanet Survey Occulter: A Concept for Direct Imaging of Extrasolar Earth-like Planets from the Ground  

NASA Astrophysics Data System (ADS)

We present a new concept for detecting and characterizing extrasolar planets down to Earth size or smaller through direct imaging. The New Worlds Observer (NWO) occulter developed by Cash and coworkers is placed in a particular geometrical setup in which fuel requirements are small and the occulter is used in combination with ground-based telescopes, presumably leading to an extreme cost efficiency compared to other concepts with similar science goals. We investigate the various aspects of the given geometry, such as the dynamics and radiation environment of the occulter, and construct a detailed example target list to ensure that an excellent science case can be maintained despite the limited sky coverage. It is found that more than 200 systems can be observed with two to three visits per system, using only a few tons of fuel. For each system, an Earth-sized planet with an Earth-like albedo can be found in the habitable zone in less than 2 hr.

Janson, M.

2007-02-01

120

Active optics methods for exoplanet direct imaging. Stress polishing of supersmooth aspherics for VLT-SPHERE planet finder  

NASA Astrophysics Data System (ADS)

Context. The next generation of exoplanet hunters will be targeting hot Jupiter-like exoplanets orbiting around nearby stars through direct imaging. The high contrast needed for such planet finders requires optical surfaces free of high spatial frequency ripples that might remain in the post-coronagraphic image as quasi-static speckles. Aims: We report results on the manufacturing of three supersmooth aspherical mirrors for the ESO/VLT-SPHERE instrument. The excellent optical quality obtained will allow the future planet hunter to increase the level of achievable contrast by a strong reduction of the noise level and residual quasi-static speckles on the image plane. Methods: The stress polishing method used on these mirrors is well suited to superpolishing aspheric components for astronomy. The main advantage of this technique is the very high optical quality obtained either on the form errors or on the high spatial frequency errors. Furthermore, the roughness can be decreased to a few angstroms, thanks to the classical polishing with a large pitch tool. Results: Interferograms obtained during polishing and in the final stage show the supersmooth quality of each mirror. Errors in the high spatial frequency range are lower than 4 nm rms WF, thereby avoiding the degradation of the post-coronagraphic image. A comparison of the power spectral density (PSD) obtained by stress polishing and the PSD of the VLT-UT3 primary mirror demonstrates that the contrast capabilities will not be limited by the aspherical mirrors.

Hugot, E.; Ferrari, M.; El Hadi, K.; Costille, A.; Dohlen, K.; Rabou, P.; Puget, P.; Beuzit, J. L.

2012-02-01

121

Diastereotopic and deuterium effects in gemini.  

PubMed

Changing the geminal methyl groups on 1?,25-dihydroxyvitamin D3 and its analogues to the deuterio versions generally improves the bioactivity. Derivatives of 1?,25-dihydroxyvitamin D3 with two chains emanating at C20, commonly referred to as gemini, are subject to the same phenomenon. Additionally, gemini with different side chains are susceptible to bioactivity differentials where the C17-C20 threo configuration usually imparts higher activity than the corresponding erythro arrangement. In an effort to analyze the deuterium effect on gemini with minimal diastereotopic distortion, we synthesized gemini with equal side chains but introduced deuterium diastereospecifically on either chain. We solved the crystal structures of these compounds in the zebra fish zVDR ligand binding domain as complexes with NCoA-2 coactivator peptide and correlated the findings with growth inhibition in a breast cancer cell line. PMID:23566225

Maehr, Hubert; Rochel, Natacha; Lee, Hong Jin; Suh, Nanjoo; Uskokovic, Milan R

2013-05-09

122

Optical Images of an Exosolar Planet 25 Light Years from Earth  

SciTech Connect

Fomalhaut is a bright star 7.7 parsec (25 light years) from Earth that harbors a belt of cold dust with a structure consistent with gravitational sculpting by an orbiting planet. Here, we present optical observations of an exoplanet candidate, Fomalhaut b. In the plane of the belt, Fomalhaut b lies approximately 119 astronomical units (AU) from the star, and within 18 AU of the dust belt. We detect counterclockwise orbital motion using Hubble Space Telescope observations separated by 1.73 years. Dynamical models of the interaction between the planet and the belt indicate that the planet's mass is at most three times that of Jupiter for the belt to avoid gravitational disruption. The flux detected at 0.8 {micro}m is also consistent with that of a planet with mass no greater than a few times that of Jupiter. The brightness at 0.6 {micro}m and the lack of detection at longer wavelengths suggest that the detected flux may include starlight reflected off a circumplanetary disk, with dimension comparable to the orbits of the Galilean satellites. We also observed variability of unknown origin at 0.6 {micro}m.

Kalas, P; Graham, J R; Chiang, E; Fitzgerald, M P; Clampin, M; Kite, E S; Stapelfeldt, K; Krist, J

2008-11-12

123

Study of Spin-Scan Imaging for Outer Planets Missions: Executive Summary.  

National Technical Information Service (NTIS)

The development and characteristics of spin-scan imagers for interplanetary exploration are discussed. The spin-scan imaging photopolarimeter instruments of Pioneer 10 and 11 are described. In addition to the imaging function, the instruments are also use...

E. E. Russell R. A. Chandos J. C. Kodak S. F. Pellicori M. G. Tomasko

1974-01-01

124

Women Astronomers at Gemini: A Success Story  

NASA Astrophysics Data System (ADS)

Gemini Observatory has been very successful at attracting, hiring and retaining female Scientists. We present data on the growth of the scientific staff since the start of the Observatory, and science fellow recruiting from 2006-2008. At Gemini 31% of the Science Staff holding PhDs are female compared with 13.9% within the United States. The Science Management is 75% female, as is 50% of the Gemini Directorate. This critical mass of female representation within the science staff and management appears to have had a positive effect on female recruitment and hiring. The science fellow recruitment during the past 3 years has attracted 21-38% female applicants and 57% of new hires during this period have been female scientists. Perhaps even more significant, the retention rate of female science staff at Gemini is 88%, compared to 64% for male science staff. There are likely many factors that contribute to this success, but the conclusion is that Gemini has earned a reputation in the scientific community as a place where female scientists are valued and can be successful.

Rodgers, Bernadette; Jorgensen, I.; Barker, N.; Edwards, M.; Trancho, G.

2010-01-01

125

Planet migration  

Microsoft Academic Search

A planetary system may undergo significant radial rearrangement during the early part of its lifetime. Planet migration can come about through interaction with the surrounding planetesimal disk and the gas disk--while the latter is still present--as well as through planet-planet interactions. We review the major proposed migration mechanisms in the context of the planet formation process, in our Solar System

Edward W. Thommes; Jack J. Lissauer

2002-01-01

126

Planet Formation  

Microsoft Academic Search

Modern theories for the origin of the planets are based on observations of the solar system and star-forming regions elsewhere in the galaxy, together with the results of numerical models. Some key observations are: - The solar system contains eight large planets with roughly circular, coplanar orbits lying 0.4-30 AU from the Sun. There are few locations between the planets

J. E. Chambers

2003-01-01

127

Live from Gemini: Expanding the Walls of the Classroom Globally  

NASA Astrophysics Data System (ADS)

Live from Gemini has been designed to share Gemini Observatory's resources with a diverse range of learners and expand the walls of the classroom globally. The program is inquiry-based and adaptable to a wide range of learners who participate in a live one-on-one videoconference with an expert astronomer/educator host from one of the Gemini observatory control rooms.

Harvey, J.; Michaud, P.; Valcourt, R.

2011-09-01

128

Ocean Planet  

NSDL National Science Digital Library

_Ocean Planet_ is a Smithsonian Institution Traveling Exhibition that now has a companion on-line exhibition. It covers varied topics associated with the ocean, such as the science of the ocean, the animals, people, and communities who use the ocean, and pollution problems currently endangering ocean resources. The exhibit features all of the text and a good portion of the images from the traveling exhibit. The curator of this exhibit has put together six special interest tours including Biodiversity, Women and the Sea, and Pollution. Users can also build their own special tour from a list of key words. The current list contains only four words, but is expected to grow in the future. Visitors can also consult a comprehensive list of educational materials and ocean resources.

1995-01-01

129

Antifungal activity of gemini quaternary ammonium salts.  

PubMed

A series of gemini quaternary ammonium chlorides and bromides with various alkyl chain and spacer lengths was synthesized. The most active compounds against fungi were chlorides with 10 carbon atoms within the hydrophobic chain. Among these compounds were few with no hemolytic activity at minimal inhibitory concentrations. None of the tested compounds were cytotoxic and mutagenic. Cationic gemini surfactants poorly reduced the adhesion of microorganisms to the polystyrene plate, but inhibited the filamentation of Candida albicans. One of the tested compounds eradicated C. albicans and Rodotorula mucilaginosa biofilm, what could be important in overcoming catheter-associated infections. It was also shown that gemini surfactants enhanced the sensitivity of C. albicans to azoles and polyenes, thus they might be potentially used in combined therapy against fungi. PMID:23827647

Ob??k, Ewa; Piecuch, Agata; Krasowska, Anna; Luczy?ski, Jacek

2013-07-01

130

Exploring the Planets: Pluto  

NSDL National Science Digital Library

Information on this site about the planet Pluto includes mean distance from the Sun, length of a year, rotation period, mean orbital velocity, inclination of axis, temperature, diameter, and number of observed satellites. The unusual inclination from the plane of the ecliptic and eccentricity of the orbit of Pluto is discussed and diagramed. The composition of Pluto and Charon are discussed, as is their unusual relationship as a double planet. Hubble images of Pluto and Charon reveal surface features never before seen.

131

First Light LBT AO Images of HR 8799 bcde at 1.6 and 3.3 ?m: New Discrepancies between Young Planets and Old Brown Dwarfs  

NASA Astrophysics Data System (ADS)

As the only directly imaged multiple planet system, HR 8799 provides a unique opportunity to study the physical properties of several planets in parallel. In this paper, we image all four of the HR 8799 planets at H band and 3.3 ?m with the new Large Binocular Telescope adaptive optics system, PISCES, and LBTI/LMIRCam. Our images offer an unprecedented view of the system, allowing us to obtain H and 3.3 ?m photometry of the innermost planet (for the first time) and put strong upper limits on the presence of a hypothetical fifth companion. We find that all four planets are unexpectedly bright at 3.3 ?m compared to the equilibrium chemistry models used for field brown dwarfs, which predict that planets should be faint at 3.3 ?m due to CH4 opacity. We attempt to model the planets with thick-cloudy, non-equilibrium chemistry atmospheres but find that removing CH4 to fit the 3.3 ?m photometry increases the predicted L' (3.8 ?m) flux enough that it is inconsistent with observations. In an effort to fit the spectral energy distribution of the HR 8799 planets, we construct mixtures of cloudy atmospheres, which are intended to represent planets covered by clouds of varying opacity. In this scenario, regions with low opacity look hot and bright, while regions with high opacity look faint, similar to the patchy cloud structures on Jupiter and L/T transition brown dwarfs. Our mixed-cloud models reproduce all of the available data, but self-consistent models are still necessary to demonstrate their viability. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are as follows: The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di AstroÞsica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University, and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota, and University of Virginia.

Skemer, Andrew J.; Hinz, Philip M.; Esposito, Simone; Burrows, Adam; Leisenring, Jarron; Skrutskie, Michael; Desidera, Silvano; Mesa, Dino; Arcidiacono, Carmelo; Mannucci, Filippo; Rodigas, Timothy J.; Close, Laird; McCarthy, Don; Kulesa, Craig; Agapito, Guido; Apai, Daniel; Argomedo, Javier; Bailey, Vanessa; Boutsia, Konstantina; Briguglio, Runa; Brusa, Guido; Busoni, Lorenzo; Claudi, Riccardo; Eisner, Joshua; Fini, Luca; Follette, Katherine B.; Garnavich, Peter; Gratton, Raffaele; Guerra, Juan Carlos; Hill, John M.; Hoffmann, William F.; Jones, Terry; Krejny, Megan; Males, Jared; Masciadri, Elena; Meyer, Michael R.; Miller, Douglas L.; Morzinski, Katie; Nelson, Matthew; Pinna, Enrico; Puglisi, Alfio; Quanz, Sascha P.; Quiros-Pacheco, Fernando; Riccardi, Armando; Stefanini, Paolo; Vaitheeswaran, Vidhya; Wilson, John C.; Xompero, Marco

2012-07-01

132

Adsorption of Gemini surfactants onto clathrate hydrates.  

PubMed

This work addresses the adsorption of two Gemini surfactants at the cyclopentane (CP) hydrate-water interface. The Gemini surfactants investigated here are Dowfax C6L and Dowfax 2A1 that have two anionic head groups and one hydrophobic tail group. The adsorption of these surfactants was quantified using adsorption isotherms and the adsorption isotherms were determined using liquid-liquid titrations. Even if the Gemini surfactant adsorption isotherms show multi-layer adsorption, they possess the first Langmuir layer with the second adsorption layer only evident in the 2A1 adsorption isotherm. Zeta potentials of CP hydrate particles in the surfactant solution of various concentrations of Dowfax C6L and Dowfax 2A1 were measured to further explain their adsorption behavior at the CP hydrate-water interface. Zeta potentials of alumina particles as a model particle system in different concentrations of sodium dodecyl sulfate (SDS), Dowfax C6L and Dowfax 2A1 were also measured to confirm the configuration of all the surfactants at the interface. The determination of the isotherms and zeta-potentials provides an understanding framework for the adsorption behavior of the two Gemini surfactants at the hydrate-water interface. PMID:24144366

Salako, O; Lo, C; Couzis, A; Somasundaran, P; Lee, J W

2013-09-17

133

Extrasolar planets  

PubMed Central

The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However, these models require some modifications to explain the properties of the observed extrasolar planetary systems.

Lissauer, Jack J.; Marcy, Geoffrey W.; Ida, Shigeru

2000-01-01

134

Extrasolar planets.  

PubMed

The first known extrasolar planet in orbit around a Sun-like star was discovered in 1995. This object, as well as over two dozen subsequently detected extrasolar planets, were all identified by observing periodic variations of the Doppler shift of light emitted by the stars to which they are bound. All of these extrasolar planets are more massive than Saturn is, and most are more massive than Jupiter. All orbit closer to their stars than do the giant planets in our Solar System, and most of those that do not orbit closer to their star than Mercury is to the Sun travel on highly elliptical paths. Prevailing theories of star and planet formation, which are based on observations of the Solar System and of young stars and their environments, predict that planets should form in orbit about most single stars. However, these models require some modifications to explain the properties of the observed extrasolar planetary systems. PMID:11035782

Lissauer, J J; Marcy, G W; Ida, S

2000-11-01

135

Planet X  

NASA Astrophysics Data System (ADS)

A name given to a hypothetical tenth major planet once believed to exist in the outer solar system, beyond the orbit of Neptune. The `X', which stood for `unknown', was also appropriate as the roman numeral for `ten'. The label `Planet X' was originated by Percival Lowell. From the late nineteenth century, he and others, including William H Pickering, worked out orbits for a large tenth planet wh...

Murdin, P.

2000-11-01

136

The Planets  

NSDL National Science Digital Library

This tool allows users to find when planets are visible in a given year. The years covered by this site are 1900 to 2100. The positions given are for the 1st of the month, at 9 pm, and generally hold true for the entire month. Positions are noted by which constellation the planet is located in. The planets given are Venus, Mars, Jupiter, Saturn, Neptune, Uranus, and Pluto. Additional comments for Venus and Mars note their location and viewing times.

137

Asteroid (19) Fortuna: Triaxial Ellipsoid Dimensions and Rotational Pole with AO at Gemini North  

NASA Astrophysics Data System (ADS)

The triaxial ellipsoid dimensions and rotational pole of the large asteroid (19) Fortuna were found from only three nights of adaptive optics images in November 2009 at the 8 meter Gemini North telescope at ¸ = 2.15?m. The dimensions and pole, as well as images, are supported by the model derived from lightcurve inversions [4] and stellar occultations. Fortuna should perhaps be considered a candidate for a Standard Triaxial Ellipsoid [2].

Drummond, J.; Merline, W. J.; Conrad, A.; Christou, J.; Tamblyn, P.; Carry, B.

2011-10-01

138

Updates from the California Planet Survey  

NASA Astrophysics Data System (ADS)

We present the latest results from the California Planet Survey. The CPS a Doppler-based planet search at Lick and Keck Observatories that encompasses a wide variety of expolanetary science goals, and operates with a well-defined, publicly available star list and Exoplanet Database. Specific detections from this past year include 4 and 9 Earth-mass (msini) planets from the Eta-Earth program, three giant planets orbiting M dwarfs, updated multi-planet systems, five confirmed transiting planets from the Kepler mission, and 20 planets orbiting "retired" A-type stars. These discoveries have shed light onto the mass function of exoplanets over 3 orders of magnitude, increased our knowledge of planets beyond the ice line, revealed strong correlation between planet occurrence and stellar properties (metallicity and mass), and pointed the way to finding planets with the next generation of search methods such as direct imaging and astrometry.

Johnson, John; Wright, Jason; Howard, Andrew; Marcy, Geoff; Fischer, Debra; Anderson, Jay; Valenti, Jeff; Isaacson, Howard; Spronck, Julien

2010-05-01

139

Planet formation  

Microsoft Academic Search

Models of planetary formation are developed using the present single example of a planetary system, supplemented by limited astrophysical observations of star-forming regions and circumstellar disks. The solar nebula theory and the planetesimal hypothesis are discussed. The latter is found to provide a viable theory of the growth of the terrestrial planets, the cores of the giant planets, and the

Jack J. Lissauer

1993-01-01

140

Planet Business  

NSDL National Science Digital Library

The directory Planet Business aims to provide a "great gateway between Africa, America, Asia, Europe and Oceania." Business metasites from around the world are listed in an A-Z index and by region, and the new Marketplace of Planet Business connects potential business partners among importers, exporters, traders, and distributors.

1996-01-01

141

Nine Planets: Planetary Picture List  

NSDL National Science Digital Library

This section of The Nine Planets provides links to internet solar system images of the nine planets and their moons. Images include the Sun, Mercury, Venus, the Earth and Moon, Mars (Phobos, Deimos), Jupiter (Amalthea, Io, Europa, Ganymede, Callisto), Saturn (Pan, Atlas, Prometheus, Pandora, Epimetheus, Janus, Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus, Phoebe), Uranus (Puck, Miranda, Ariel, Umbriel, Titania, Oberon), Neptune (Triton, Proteus), and Pluto with Charon. Miscellanous images include asteroids, comets, meteorites, and spacecraft.

142

KEOPS: Kiloparsec Explorer for Optical Planet Search, a direct-imaging optical array at Dome C of Antarctica  

NASA Astrophysics Data System (ADS)

Recent site seeing testing campaigns conducted by our team from University of Nice1 show that Dome C represents the best site on Earth for astronomical high angular resolution (HAR) observations at optical and IR wavelengths. The dramatic gain over relevant HAR parameters r0, L0, ?0 and ?0, added to very low temperatures during the polar winter nights (-70°C), the dry atmosphere and the possibility of continuous observations during several nights make Dome C the ideal site for deploying a kilometric optical interferometer before the 2015 horizon. Here we describe the concept of Kiloparsec Explorer for Optical Planet Search (KEOPS) that is studied by our group at LUAN. KEOPS is an interferometric array of 36 off-axis telescopes, each 1.5m in diameter. Its kilometric baselines open sub-mas snap-shot imaging possibilities to detect and characterize extra-solar planetary systems, especially exo-Earths out to 300 parsecs from the visible to the thermal IR. KEOPS can be considered as a DARWIN/TPF challenger but at a much lower cost.

Vakili, Farrokh; Belu, Adrian; Aristidi, Eric; Fossat, Eric; Maillard, A.; Abe, Lyu; Agabi, Karim; Vernin, Jean; Baptiste Daban, Jean; Hertmanni, Wilfried; Schmider, Francois-Xavier; Assus, Pierre; Coudé du Foresto, Vincent; Swain, Mark R.

2004-10-01

143

880 {mu}m IMAGING OF A TRANSITIONAL DISK IN UPPER SCORPIUS: HOLDOVER FROM THE ERA OF GIANT PLANET FORMATION?  

SciTech Connect

We present 880 {mu}m images of the transition disk around the star [PZ99] J160421.7-213028, a solar mass star in the nearby Upper Scorpius association. With a resolution down to 0.''34, we resolve the inner hole in this disk, and via model fitting to the visibilities and spectral energy distribution we determine both the structure of the outer region and the presence of sparse dust within the cavity. The disk contains {approx}0.1 M{sub Jup} of millimeter-emitting grains, with an inner disk edge of about 70 AU. The inner cavity contains a small amount of dust with a depleted surface density in a region extending from about 20 to 70 AU. Taking into account prior observations indicating little to no stellar accretion, the lack of a binary companion, and the presence of dust near {approx}0.1 AU, we determine that the most likely mechanism for the formation of this inner hole is the presence of one or more giant planets.

Mathews, Geoffrey S.; Williams, Jonathan P. [Institute for Astronomy (IfA), University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Menard, Francois, E-mail: gmathews@ifa.hawaii.edu [Universite Joseph-Fourier Grenoble 1/CNRS, Laboratoire d'Astrophysique de Grenoble (LAOG) UMR 5571, BP 53, F-38041 Grenoble Cedex 09 (France)

2012-07-01

144

Oligomeric interfaces under the lens: gemini.  

PubMed

The assembly of subunits in protein oligomers is an important topic to study as a vast number of proteins exists as stable or transient oligomer and because it is a mechanism used by some protein oligomers for killing cells (e.g., perforin from the human immune system, pore-forming toxins from bacteria, phage, amoeba, protein misfolding diseases, etc.). Only a few of the amino acids that constitute a protein oligomer seem to regulate the capacity of the protein to assemble (to form interfaces), and some of these amino acids are localized at the interfaces that link the different chains. The identification of the residues of these interfaces is rather difficult. We have developed a series of programs, under the common name of Gemini, that can select the subset of the residues that is involved in the interfaces of a protein oligomer of known atomic structure, and generate a 2D interaction network (or graph) of the subset. The graphs generated for several oligomers demonstrate the accuracy of the selection of subsets that are involved in the geometrical and the chemical properties of interfaces. The results of the Gemini programs are in good agreement with those of similar programs with an advantage that Gemini programs can perform the residue selection much more rapidly. Moreover, Gemini programs can also perform on a single protein oligomer without the need of comparison partners. The graphs are extremely useful for comparative studies that would help in addressing questions not only on the sequence specificity of protein interfaces but also on the mechanism of the assembly of unrelated protein oligomers. PMID:20360856

Feverati, Giovanni; Lesieur, Claire

2010-03-25

145

Planet Pals  

NSDL National Science Digital Library

Created by designer, illustrator, and educator Judith Ann Gorgone, the Planet Pals Web site provides good material for young kids related to the health of the planet. The colorful pages contain basic information about the earth, energy, recycling, water conservation, pollution, and more. The fun and interactive Meet the Planet Pals area is especially interesting, where kids can listen to animated cartoons talk about various aspects of conservation. Even though the site is geared towards young children, they may have difficulty finding the educational specific pages by themselves; so, a parent's or teacher's assistance would most likely be helpful.

Gorgone, Judith.

1991-01-01

146

On the possibility of ground-based direct imaging detection of extra-solar planets: the case of TWA-7  

NASA Astrophysics Data System (ADS)

We show that ground-based direct imaging detection of extra-solar planets is possible with current technology. As an example, we present evidence for a possible planetary companion to the young T Tauri star 1RXSJ104230.3-334014 (=TWA-7), discovered by ROSAT as a member of the nearby TW Hya association. In an HST NICMOS F160W image, an object is detected that is more than 9 mag fainter than TWA-7, located 2.445 +/- 0.035'' south-east at a position angle of 142.24 +/- 1.34deg. One year later using the ESO-NTT with the SHARP speckle camera, we obtained H- and K-band detections of this faint object at a separation of 2.536 +/- 0.077'' and a position angle of 139.3 +/- 2.1deg. Given the known proper motion of TWA-7, the pair may form a proper motion pair. If the faint object orbits TWA-7, then its apparent magnitudes of H=16.42 +/- 0.11 and K=16.34 +/- 0.15 mag yield absolute magnitudes consistent with a ~ 106.5 yr old ~ 3 M_jup mass object according to the non-gray theory by Burrows et al. (1997). At ~ 55 pc, the angular separation of ~ 2.5'' corresponds to ~ 138 AU, clearly within typical disk sizes. However, position angles and separations are slightly more consistent with a background object than with a companion. Based on observations obtained at the European Southern Observatory, La Silla (ESO Proposals 62.I-0418 and 63.N-0178), and on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc., under the NASA contract NAS 5-26555.

Neuhäuser, R.; Brandner, W.; Eckart, A.; Guenther, E.; Alves, J.; Ott, T.; Huélamo, N.; Fernández, M.

2000-02-01

147

Ocean Planet Exhibition  

NSDL National Science Digital Library

This virtual tour of the Smithsonian Institution's Ocean Planet exhibit can be navigated by clicking on the floor plan which is pictured, or it can be searched by image, subject, or topic outline. Links to educational materials and to a special curator's tour are also included.

148

Planet Slayer  

NSDL National Science Digital Library

The Australian Broadcasting Company offers a fun, interactive way to learn about environmentally responsible consumption. Visitors are invited to follow Greena, eco-chic Warrior Princess, as she navigates the world of green living. The Web site contains loads of engaging animated features, such as the Adventures of Greena, a cartoon in which Greena battles some environmental ill in each chapter. In the Planet Slayer Game, players choose to play earnestly as Greena and save the planet or ironically as a pink-swathed Barbie-like character to slay the planet. With the Greenhouse Calculator, users can figure out their toll on the planet in terms of carbon dioxide emissions -- a service you could find easily enough on the Web, but this one features exploding pigs. Lots of other great features are available, as is a set of well-selected links for more information on ethical investing, Kyoto Protocol, the 2002 Johannesburg World Summit on Sustainable Development, and more.

149

Planet Formation  

Microsoft Academic Search

Motivating the study of planet formation is not difficult for any curious audience. One of the fundamental human questions\\u000a is that of origins: “where did I come from?„. Breaking this down into constituents produces a series of questions. How did\\u000a the Universe begin? How did stars form? How did planets form? How did life begin? How did intelligent life develop?

Thomas Quinn

2005-01-01

150

Puzzling Planets  

NSDL National Science Digital Library

In this lesson, students learn the order of the planets, research their main characteristics, and explore the basic structure of our solar system. Students will also be able to explain why we could not live on other planets without special equipment. They will demonstrate their knowledge, using an online learning tool. This site provides an overview of the lesson, detailed procedures for the teacher, including a list of research sites, and an organizational path for the students.

151

NFIRAOS High-Contrast Exoplanet Imaging Capabilities  

NASA Astrophysics Data System (ADS)

The TMT offers great potential to find and study nearby planetary systems, possibly imaging down to super-Earth size planets or still accreting distant planets in very young star forming regions. Since no first generation dedicated exoplanet finding instruments have been selected, initial direct exoplanet imaging will have to rely on the NFIRAOS facility AO system. I will present end-to-end Fresnel NFIRAOS simulations using its current optical design to evaluate its multi-wavelength high-contrast imaging capabilities. Long exposures have been simulated using the expected AO-delivered phase screens and the estimated speckle lifetime. It is shown that NFIRAOS will offer contrasts comparable to GPI (an optimized NIR planet-finding instrument that will soon be installed on the Gemini South 8-m telescope). Without coronograph and higher order correction, NFIRAOS will not be able to achieve high contrast at very small IWA, which are potentially accessible with a 30-meter telescope. However, TMT, with its larger aperture and better angular resolution, will acquire higher SNR planet spectra and will achieve an astrometric accuracy three times smaller than GPI, resulting in better atmospheric characterization and faster orbital parameters determination.

Marois, Christian; Veran, Jean-Pierre

2011-09-01

152

Planet Formation  

NASA Astrophysics Data System (ADS)

1. Historical notes on planet formation Bodenheimer; 2. The formation and evolution of planetary systems Bouwman et al.; 3. Destruction of protoplanetary disks by photoevaporation Richling, Hollenbach and Yorke; 4. Turbulence in protoplanetary accretion disks Klahr, Rozyczka, Dziourkevitch, Wunsch and Johansen; 5. The origin of solids in the early solar system Trieloff and Palme; 6. Experiments on planetesimal formation Wurm and Blum; 7. Dust coagulation in protoplanetary disks Henning, Dullemond, Wolf and Dominik; 8. The accretion of giant planet cores Thommes and Duncan; 9. Planetary transits: direct vision of extrasolar planets Lecavelier des Etangs and Vidal-Madjar; 10. The core accretion - gas capture model Hubickyj; 11. Properties of exoplanets Marcy, Fischer, Butler and Vogt; 12. Giant planet formation: theories meet observations Boss; 13. From hot Jupiters to hot Neptures … and below Lovis, Mayor and Udry; 14. Disk-planet interaction and migration Masset and Kley; 15. The Brown Dwarf - planet relation Bate; 16. From astronomy to astrobiology Brandner; 17. Overview and prospective Lin.

Klahr, Hubert; Brandner, Wolfgang

2011-02-01

153

Piercing the Glare: A Direct Imaging Search for Planets in the Sirius System  

NASA Astrophysics Data System (ADS)

Astrometric monitoring of the Sirius binary system over the past century has yielded several predictions for an unseen third system component, the most recent one suggesting a lsim50 M Jup object in a ~6.3 year orbit around Sirius A. Here we present two epochs of high-contrast imaging observations performed with Subaru IRCS and AO188 in the 4.05 ?m narrowband Br ? filter. These data surpass previous observations by an order of magnitude in detectable companion mass, allowing us to probe the relevant separation range down to the planetary-mass regime (6-12 M Jup at 1'', 2-4 M Jup at 2'', and 1.6 M Jup beyond 4''). We complement these data with one epoch of M-band observations from MMT/AO Clio, which reach comparable performance. No data set reveals any companion candidates above the 5? level, allowing us to refute the existence of Sirius C as suggested by the previous astrometric analysis. Furthermore, our Br ? photometry of Sirius B confirms the lack of an infrared excess beyond the white dwarf's blackbody spectrum. Based on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan, and at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution.

Thalmann, C.; Usuda, T.; Kenworthy, M.; Janson, M.; Mamajek, E. E.; Brandner, W.; Dominik, C.; Goto, M.; Hayano, Y.; Henning, T.; Hinz, P. M.; Minowa, Y.; Tamura, M.

2011-05-01

154

PIERCING THE GLARE: A DIRECT IMAGING SEARCH FOR PLANETS IN THE SIRIUS SYSTEM  

SciTech Connect

Astrometric monitoring of the Sirius binary system over the past century has yielded several predictions for an unseen third system component, the most recent one suggesting a {approx}<50 M{sub Jup} object in a {approx}6.3 year orbit around Sirius A. Here we present two epochs of high-contrast imaging observations performed with Subaru IRCS and AO188 in the 4.05 {mu}m narrowband Br {alpha} filter. These data surpass previous observations by an order of magnitude in detectable companion mass, allowing us to probe the relevant separation range down to the planetary-mass regime (6-12 M{sub Jup} at 1'', 2-4 M{sub Jup} at 2'', and 1.6 M{sub Jup} beyond 4''). We complement these data with one epoch of M-band observations from MMT/AO Clio, which reach comparable performance. No data set reveals any companion candidates above the 5{sigma} level, allowing us to refute the existence of Sirius C as suggested by the previous astrometric analysis. Furthermore, our Br {alpha} photometry of Sirius B confirms the lack of an infrared excess beyond the white dwarf's blackbody spectrum.

Thalmann, C.; Dominik, C. [Anton Pannekoek Astronomical Institute, University of Amsterdam (Netherlands); Usuda, T.; Hayano, Y.; Minowa, Y. [Subaru Telescope, Hilo, Hawai'i (United States); Kenworthy, M. [Leiden Observatory, Leiden University, P.O. Box 9513, 2300 RA Leiden (Netherlands); Janson, M. [Department of Astronomy and Astrophysics, University of Toronto, Toronto (Canada); Mamajek, E. E. [Department of Physics and Astronomy, University of Rochester, Rochester, NY (United States); Brandner, W.; Goto, M.; Henning, T. [Max Planck Institute for Astronomy, Heidelberg (Germany); Hinz, P. M. [Steward Observatory, University of Arizona, Tucson, AZ (United States); Tamura, M., E-mail: thalmann@uva.nl [National Astronomical Observatory of Japan, Tokyo (Japan)

2011-05-10

155

Dicationic Alkylammonium Bromide Gemini Surfactants. Membrane Perturbation and Skin Irritation  

Microsoft Academic Search

Dicationic alkylammonium bromide gemini surfactants represent a class of amphiphiles potentially effective as skin permeation enhancers. However, only a limited number of studies has been dedicated to the evaluation of the respective cytotoxicity, and none directed to skin irritation endpoints. Supported on a cell viability study, the cytotoxicity of gemini surfactants of variable tail and spacer length was assessed. For

João A. S. Almeida; Henrique Faneca; Rui A. Carvalho; Eduardo F. Marques; Alberto A. C. C. Pais

2011-01-01

156

The Gemini MCAO bench: system overview and lab integration  

Microsoft Academic Search

We present Canopus, the AO bench for Gemini's Multi Conjugate Adaptive Optics System (GEMS), a unique facility for the Gemini South telescope located at Cerro Pachon in Chile. The MCAO system uses five laser beacons in conjunction with different natural guide stars configurations. A deployable fold mirror located in the telescope Acquisition and Guiding Unit (A&G) sends the telescope beam

Matthieu Bec; Francois J. Rigaut; Ramon Galvez; Gustavo Arriagada; Maxime Boccas; Gaston Gausachs; Damien Gratadour; Eric James; Roberto Rojas; Rolando Rogers; Michael P. Sheehan; Gelys Trancho; Tomislav Vucina

2008-01-01

157

Performance of the Gemini near-infrared spectrograph  

Microsoft Academic Search

The Gemini Near-Infrared Spectrograph (GNIRS) has been in successful use on the Gemini South 8-m telescope for over two years. We describe the performance of the instrument and discuss how it matches the expectations from the design. We also examine the lessons to be learned regarding the design and operation of similar large cryogenic facility instruments.

Jonathan H. Elias; Bernadette Rodgers; Richard R. Joyce; Manuel Lazo; Gregory Doppmann; Claudia Winge; Alberto Rodríguez-Ardila

2006-01-01

158

Extreme Contrast Direct Imaging of Planets and Debris disks with the Palomar P3K Adaptive Optics System and the Vector Vortex Coronagraph  

NASA Astrophysics Data System (ADS)

We present first results from using the PALM-3000 extreme adaptive optics system and imaging camera on the Hale 5m telescope. Observations using the vector vortex coronagraph have given us direct detections of the planets in the HR8799 system and the dusty debris disk around the star HD141569A. Due to the unprecedented inner working angle of the VVC, the data show a clearing within the inner ring inwards to ~20AU along the projected semi-major axis. Our observations of the disk in the K band (2.2 ?m) demonstrate the power of the next generation of adaptive optics systems coupled with phase mask coronagraphy. We also show a comparison of the data reduction techniques currently being implemented in the direct imaging field. Specifically, the Locally Optimized Combination of Images (LOCI) and the Karhunen-Loeve Image Processing (KLIP) algorithms, the latter being a more robust method for resolving debris disks.

Wahl, Matthew; Metchev, S. A.; Patel, R.; Serabyn, G.; PALM-3000 Adaptive Optics Team

2013-01-01

159

FIRST LIGHT LBT AO IMAGES OF HR 8799 bcde AT 1.6 AND 3.3 {mu}m: NEW DISCREPANCIES BETWEEN YOUNG PLANETS AND OLD BROWN DWARFS  

SciTech Connect

As the only directly imaged multiple planet system, HR 8799 provides a unique opportunity to study the physical properties of several planets in parallel. In this paper, we image all four of the HR 8799 planets at H band and 3.3 {mu}m with the new Large Binocular Telescope adaptive optics system, PISCES, and LBTI/LMIRCam. Our images offer an unprecedented view of the system, allowing us to obtain H and 3.3 {mu}m photometry of the innermost planet (for the first time) and put strong upper limits on the presence of a hypothetical fifth companion. We find that all four planets are unexpectedly bright at 3.3 {mu}m compared to the equilibrium chemistry models used for field brown dwarfs, which predict that planets should be faint at 3.3 {mu}m due to CH{sub 4} opacity. We attempt to model the planets with thick-cloudy, non-equilibrium chemistry atmospheres but find that removing CH{sub 4} to fit the 3.3 {mu}m photometry increases the predicted L' (3.8 {mu}m) flux enough that it is inconsistent with observations. In an effort to fit the spectral energy distribution of the HR 8799 planets, we construct mixtures of cloudy atmospheres, which are intended to represent planets covered by clouds of varying opacity. In this scenario, regions with low opacity look hot and bright, while regions with high opacity look faint, similar to the patchy cloud structures on Jupiter and L/T transition brown dwarfs. Our mixed-cloud models reproduce all of the available data, but self-consistent models are still necessary to demonstrate their viability.

Skemer, Andrew J.; Hinz, Philip M.; Rodigas, Timothy J.; Close, Laird; McCarthy, Don; Kulesa, Craig; Apai, Daniel; Bailey, Vanessa [Steward Observatory, Department of Astronomy, University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721 (United States); Esposito, Simone; Arcidiacono, Carmelo; Mannucci, Filippo; Agapito, Guido; Argomedo, Javier; Briguglio, Runa [Istituto Nazionale di Astrofisica, Osservatorio Astrofisico di Arcetri, Largo E Fermi 5, 50125 Firenze (Italy); Burrows, Adam [Department of Astronomy, Princeton University, 4 Ivy Lane, Princeton, NJ 08544 (United States); Leisenring, Jarron [Institute for Astronomy, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Skrutskie, Michael [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Desidera, Silvano; Mesa, Dino [Istituto Nazionale di Astrofisica, Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, I-35122 Padova (Italy); Boutsia, Konstantina [Large Binocular Telescope Observatory, University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721 (United States); and others

2012-07-01

160

Tumbling and spaceflight: the Gemini VIII experience.  

PubMed

A malfunctioning orbital flight attitude thruster during the flight of Gemini VIII led to acceleration forces on astronauts Neil Armstrong (commander) and David Scott (pilot) that created the potential for derogation of oculo-vestibular and eye-hand coordination effects. The spacecraft attained an axial tumbling rotation of 50 rpm and would have exceeded this had not the commander accurately diagnosed the problem and taken immediate corrective action. By the time counter-measure controls were applied, both astronauts were experiencing vertigo and the physiological effects of the tumbling acceleration. Data from the recorders reveal that one astronaut experienced -Gy of 0.92 G-units, and the other +Gy of 0.92 for approximately 46 s. Both received a -Gz of 0.89 G-units from the waist up with a +Gz of 0.05 from the waist down. A substantial increase of time and/or an increase in rpm would ultimately have produced incapacitation of both astronauts. NASA corrected the Gemini thruster problem by changing the ignition system wiring. Future space-craft undertaking long-term missions could be equipped with unambiguous thruster fault displays and could have computer-controlled automatic cutoffs to control excessive thruster burns. PMID:2302130

Mohler, S R; Nicogossian, A E; McCormack, P D; Mohler, S R

1990-01-01

161

Planet Surfing  

NSDL National Science Digital Library

In this astronomy activity (page 6 of the PDF), learners will compare and contrast two planets in the solar system using data obtained from the internet. They will convert distances from light years to miles and vice versa. Although this activity was created as a post visit for a workshop about astronomy, it also makes an excellent stand alone activity.

Cosi

2009-01-01

162

New approaches for the search for binary planets and moons of extrasolar planets  

Microsoft Academic Search

The perspective that life may develop on Europa-like moons of extrasolar planets encourages to try to detect them. The direct imaging, aiming at their angular separation from their parent planet, will have to wait for very large interferometers. In the meantime, it is possible the detect them by transit of the planet-satellite system in front of the parent star (Sartoretti

J. Schneider; L. Arnold; V. Borkowski

2003-01-01

163

Validation of a Monte Carlo simulation of the Philips Allegro/GEMINI PET systems using GATE  

NASA Astrophysics Data System (ADS)

A newly developed simulation toolkit, GATE (Geant4 Application for Tomographic Emission), was used to develop a Monte Carlo simulation of a fully three-dimensional (3D) clinical PET scanner. The Philips Allegro/GEMINI PET systems were simulated in order to (a) allow a detailed study of the parameters affecting the system's performance under various imaging conditions, (b) study the optimization and quantitative accuracy of emission acquisition protocols for dynamic and static imaging, and (c) further validate the potential of GATE for the simulation of clinical PET systems. A model of the detection system and its geometry was developed. The accuracy of the developed detection model was tested through the comparison of simulated and measured results obtained with the Allegro/GEMINI systems for a number of NEMA NU2-2001 performance protocols including spatial resolution, sensitivity and scatter fraction. In addition, an approximate model of the system's dead time at the level of detected single events and coincidences was developed in an attempt to simulate the count rate related performance characteristics of the scanner. The developed dead-time model was assessed under different imaging conditions using the count rate loss and noise equivalent count rates performance protocols of standard and modified NEMA NU2-2001 (whole body imaging conditions) and NEMA NU2-1994 (brain imaging conditions) comparing simulated with experimental measurements obtained with the Allegro/GEMINI PET systems. Finally, a reconstructed image quality protocol was used to assess the overall performance of the developed model. An agreement of <3% was obtained in scatter fraction, with a difference between 4% and 10% in the true and random coincidence count rates respectively, throughout a range of activity concentrations and under various imaging conditions, resulting in <8% differences between simulated and measured noise equivalent count rates performance. Finally, the image quality validation study revealed a good agreement in signal-to-noise ratio and contrast recovery coefficients for a number of different volume spheres and two different (clinical level based) tumour-to-background ratios. In conclusion, these results support the accurate modelling of the Philips Allegro/GEMINI PET systems using GATE in combination with a dead-time model for the signal flow description, which leads to an agreement of <10% in coincidence count rates under different imaging conditions and clinically relevant activity concentration levels.

Lamare, F.; Turzo, A.; Bizais, Y.; Cheze LeRest, C.; Visvikis, D.

2006-02-01

164

Exploring the Planets: Venus  

NSDL National Science Digital Library

This site contains most of the up-to-date information known about the planet Venus, including mean distance from Sun, length of year, rotation period, mean orbital velocity, inclination of axis, average temperature (day and night), and diameter. Many discoveries about Venus have been made using Earth-based radio telescopes, however the images of Venus in this exhibit were collected by the Magellan spacecraft. Magellan used radar to produce the first high-resolution global map of Venus. Since Venus has no water erosion and little wind, volcanic eruptions are a major force reshaping the landscape. Geologic forces at work beneath the crust create mountains, rifts, and patterns of fractures, while the sluggish winds sculpt the surface in subtler ways but many mysteries remain. This site includes numerous images of the planet.

165

Catalogue of Spaceborne Imaging: A Guide to NSSDC 's Planetary Image Archives  

NSDL National Science Digital Library

This image archive, supported by the NASA National Space Science Data Center (NSSDC), features photos taken during NASA space missions (Apollo, Gemini, Mariner, Voyager, and others) and the Soviet Venera probes to Venus. The photos are organized by subject: each of the planets, Earth's Moon, and other objects in the solar system such as comets and asteroids. Each subject category includes a fact sheet with information such as orbital parameters, bulk parameters, and other details about the objects photographed. Each image is accompanied by a brief description and information about location and time when the photo was taken, imaging properties, and ordering information. The photos are also indexed by mission, with links to pages of the NSSDC site describing the mission. The photos may be downloaded in high- and low-resolution versions, or ordered as hard copies (prints, transparencies, or 35 mm slides).

166

Lonely Planet  

NSDL National Science Digital Library

"Don't worry about whether your trip will work out. Just go!" This is the travel philosophy of Lonely Planet, one of the most respected publishers of off-the-beaten-path travel guidebooks worldwide. Whether you already know where you're going, or are looking for suggestions for your next trip, Lonely Planet's site is packed with information that you can actually use to plan your trip. Search or browse the section "DestiNATIONS" to find maps, facts and figures, and information on local history, culture, and transportation for 8 world regions, over 80 countries, and 20 different cities. Much of the health information found in LP's print guides is also now available here. In addition, there are links to destination-related newsgroups, tips on travel photography, and "Postcards," a forum in which travelers share experiences and give advice.

1997-01-01

167

STEM Planet  

NSDL National Science Digital Library

STEM Planet is a well designed website that is aimed at students of all levels and ages. The site is comprised of "employees of the National Network of Digital Schools (NNDS), a non-profit developer of the Lincoln Interactive online curriculum." These employees believe that students "succeed when their educational program offers a wide variety of learning opportunities." Visitors to the site will find that the learning opportunities consist of DIY experiments, discussion topics, polls, quizzes and activities. Some examples include making a homemade battery, origami engineering, taking a quiz on space phenomena, and exploring quantum mechanics. Visitors can join and comment on the Science, Technology, Engineering and Math "discussions" by simply registering on the site. Those only interested in reading the comments made in the forums under the discussion tab need not register. The "Experts" tab allows visitors to see all the great minds behind STEM Planet, including an extremely bright 14 year old.

2012-02-07

168

Planet Ocean  

NSDL National Science Digital Library

From DiscoverySchool.com, Planet Ocean is a Web site developed for students in grade 5-8 to learn about the abundant life found in the world's vast marine environments. Students are introduced to oceanography, marine biology, food chains, and ecosystems. Teachers will appreciate the tips for using this site in the classroom and related resources, and almost anyone will appreciate the Amazing Facts found under each topic.

2002-01-01

169

Kid's Planet  

NSDL National Science Digital Library

A Web sitedesigned just for kids by Defenders of Wildlife, Kid's Planet has much to offer for teachers and students. Teacher's Table contains downloadable .pdf lesson plans and activities. Designed primarily for middle school students, these lesson plans and essay contests cover topics like wolves and sea otters. With electronic fact sheets on over 50 species, the section titled Get the Facts may prove useful. This editor particularly enjoyed weaving through the Web of Life with the garden spider.

2002-01-01

170

Maintaining the Telescope Bibliography at Gemini Observatory  

NASA Astrophysics Data System (ADS)

The library profession benefits tremendously from ever-changing web technologies. In maintaining a telescope bibliography, web-publishing revolutionized the way librarians track relevant publications. Thanks to the search abilities provided by the NASA Astrophysics Data System, arXiv, publishers, as well as Google Scholar, and other such resources, online searching for Gemini-based publications has replaced the tedious perusing of print journals. However, we should keep in mind that online searching is neither flawless nor simple — different content providers require different search strategies. Sometimes the retrievals are not as complete as one expects. Information providers should be constantly improving their searching abilities in order to make the task of electronic publication tracking more reliable and efficient.

Zhang, X.

2010-10-01

171

GEMINI: A Natural Language System for Spoken-Language Understanding  

Microsoft Academic Search

Gemini is a natural language understanding system developed for spoken language applications. This paper describes the details of the system, and includes relevant measurements of size, efficiency, and performance of each of its sub-components in detail.

John Dowding; Jean Mark Gawron; Douglas E. Appelt; John Bear; Lynn Cherny; Robert C. Moore; Douglas B. Moran

1993-01-01

172

The Nine Planets: The Sun  

NSDL National Science Digital Library

This page of the Nine Planets gives detailed data about the Sun, including diameter, mass, temperature, how energy is made, mythology, composition, and recent data collected from spacecraft. Layers of the Sun are discussed, including the corona, chromosphere, and photosphere. Images and links to additional images and movies are provided, as well as questions still unanswered about the sun.

Arnett, Bill

173

GEMINI: integrative exploration of genetic variation and genome annotations.  

PubMed

Modern DNA sequencing technologies enable geneticists to rapidly identify genetic variation among many human genomes. However, isolating the minority of variants underlying disease remains an important, yet formidable challenge for medical genetics. We have developed GEMINI (GEnome MINIng), a flexible software package for exploring all forms of human genetic variation. Unlike existing tools, GEMINI integrates genetic variation with a diverse and adaptable set of genome annotations (e.g., dbSNP, ENCODE, UCSC, ClinVar, KEGG) into a unified database to facilitate interpretation and data exploration. Whereas other methods provide an inflexible set of variant filters or prioritization methods, GEMINI allows researchers to compose complex queries based on sample genotypes, inheritance patterns, and both pre-installed and custom genome annotations. GEMINI also provides methods for ad hoc queries and data exploration, a simple programming interface for custom analyses that leverage the underlying database, and both command line and graphical tools for common analyses. We demonstrate GEMINI's utility for exploring variation in personal genomes and family based genetic studies, and illustrate its ability to scale to studies involving thousands of human samples. GEMINI is designed for reproducibility and flexibility and our goal is to provide researchers with a standard framework for medical genomics. PMID:23874191

Paila, Umadevi; Chapman, Brad A; Kirchner, Rory; Quinlan, Aaron R

2013-07-18

174

Extrasolar Carbon Planets  

Microsoft Academic Search

We suggest that some extrasolar planets <~ 60 Earth masses will form substantially from silicon carbide and other carbon compounds. Pulsar planets and low-mass white dwarf planets are especially good candidate members of this new class of planets, but these objects could also conceivably form around stars like the Sun. This planet-formation pathway requires only a factor of two local

Marc J. Kuchner; S. Seager

2005-01-01

175

Make a Planet!  

NSDL National Science Digital Library

Make your own planet on this website! You can change the color of your planet and add land, water, trees, and weather. You can then name your planet and write a short story about it. For even more fun, compare the planets in our solar system with your planet!

2010-01-01

176

Extreme Planet Makeover  

NSDL National Science Digital Library

A multimedia, web-based interactive game from NASA and CalTech scientists lets you create your own planet by varying parameters such as star type, distance from star, planet size, and planet age. You get a descripion of how each parameter might affect habitability on your planet, you can then download the planet you create.

Technology, California I.

177

Planet Under Pressure  

NSDL National Science Digital Library

Planet Under Pressure is a six-part British Broadcasting Company (BBC) News Online series looking at some of the most pressing environmental issues facing the human race today. The series takes a detailed look at six areas where most experts agree that a crisis is brewing. They include food, water, energy, climate change, biodiversity, and pollution. In addition there are special features including: an animated guide that shows how the greenhouse effect might shape our climate; before and after images of the effects of climate change; the European Union (EU) emissions trading scheme and the carbon revolution; opinions about the Kyoto Protocol; graphic climate evidence of a warming world, rising sea, and melting ice; teenagers' opinions on how they would tackle environmental damage; the results of an eco-friendly garden competition; pictures of environmental change around the world; and a link to a BBC website exploring the UN's goals for the planet in 2015.

178

Properties of Ellipticity Correlation with Atmospheric Structure From Gemini South  

SciTech Connect

Cosmic shear holds great promise for a precision independent measurement of {Omega}{sub m}, the mass density of the universe relative to the critical density. The signal is expected to be weak, so a thorough understanding of systematic effects is crucial. An important systematic effect is the atmosphere: shear power introduced by the atmosphere is larger than the expected signal. Algorithms exist to extract the cosmic shear from the atmospheric component, though a measure of their success applied to a range of seeing conditions is lacking. To gain insight into atmospheric shear, Gemini South imaging in conjunction with ground condition and satellite wind data were obtained. We find that under good seeing conditions Point-Spread-Function (PSF) correlations persist well beyond the separation typical of high-latitude stars. Under these conditions, ellipticity residuals based on a simple PSF interpolation can be reduced to within a factor of a few of the shot-noise induced ellipticity floor. We also find that the ellipticity residuals are highly correlated with wind direction. Finally, we correct stellar shapes using a more sophisticated procedure and generate shear statistics from stars. Under all seeing conditions in our data set the residual correlations lie everywhere below the target signal level. For good seeing we find that the systematic error attributable to atmospheric turbulence is comparable in magnitude to the statistical error (shape noise) over angular scales relevant to present lensing surveys.

Asztalos, Stephen J.; /LLNL, Livermore; de Vries, W.H.; /UC, Davis /LLNL, Livermore; Rosenberg, L.J; Treadway, T.; /LLNL, Livermore; Burke, D.; /SLAC; Claver, C.; Saha, A.; /NOAO, Tucson; Puxley, P.; /Gemini Observ., La Serena

2007-01-17

179

Resolved debris disc emission around ? Telescopii: a young solar system or ongoing planet formation?  

NASA Astrophysics Data System (ADS)

Aims: Sixty percent of the A star members of the 12 Myr old ? Pictoris moving group (BPMG) show significant excess emission in the mid-infrared, several million years after the proto-planetary disc is thought to disperse. Theoretical models suggest this peak may coincide with the formation of Pluto-sized planetesimals in the disc, stirring smaller bodies into collisional destruction. Here we present resolved mid-infrared imaging of the disc of ? Tel (A0V in the BPMG) and consider its implications for the state of planet formation in this system. Methods: The source was observed at 11.7 and 18.3 ?m using T-ReCS on Gemini South. The resulting images were compared to simple disc models to constrain the radial distribution of the emitting material. Results: The emission observed at 18.3 ?m is shown to be significantly extended beyond the PSF along a position angle 8°. This is the first time dust emission has been resolved around ? Tel. Modelling indicates that the extension arises from an edge-on disc of radius 0.5 arcsec (~24 AU). Combining the spatial constraints from the imaging with those from the spectral energy distribution shows that >50% of the 18 ?m emission comes from an unresolved dust component at ~4 AU. Conclusions: The radial structure of the ? Tel debris disc is reminiscent of the Solar System, suggesting that this is a young Solar System analogue. For an age of 12 Myr, both the radius and dust level of the extended cooler component are consistent with self-stirring models for a protoplanetary disc of 0.7 times minimum mass solar nebula. The origin of the hot dust component may arise in an asteroid belt undergoing collisional destruction or in massive collisions in ongoing terrestrial planet formation.

Smith, R.; Churcher, L. J.; Wyatt, M. C.; Moerchen, M. M.; Telesco, C. M.

2009-01-01

180

The Extrasolar Planets Encyclopaedia  

NSDL National Science Digital Library

A full list of currently known Extrasolar Planets with frequently updated information on detection methods, current searches, and the Extrasolar Planets themselves. The site also includes information on reports and meetings concerning Extrasolar Planets.

Schneider, Jean

2005-06-07

181

Review article: Mars - the Red Planet  

Microsoft Academic Search

A summary of our current knowledge of Mars, and methods of observing the planet. Printing Options Send high resolution image to Level 2 Postscript Printer Send low resolution image to Level 2 Postscript Printer Send low resolution image to Level 1 Postscript Printer Get high resolution PDF image Get low resolution PDF Send 300 dpi image to PCL Printer Send

R. Baum

1983-01-01

182

GEO-ENGINEERING MODELING THROUGH INTERNET INFORMATICS (GEMINI)  

SciTech Connect

GEMINI (Geo-Engineering Modeling through Internet Informatics) is a public-domain web application focused on analysis and modeling of petroleum reservoirs and plays (http://www.kgs.ukans.edu/Gemini/index.html). GEMINI creates a virtual project by ''on-the-fly'' assembly and analysis of on-line data either from the Kansas Geological Survey or uploaded from the user. GEMINI's suite of geological and engineering web applications for reservoir analysis include: (1) petrofacies-based core and log modeling using an interactive relational rock catalog and log analysis modules; (2) a well profile module; (3) interactive cross sections to display ''marked'' wireline logs; (4) deterministic gridding and mapping of petrophysical data; (5) calculation and mapping of layer volumetrics; (6) material balance calculations; (7) PVT calculator; (8) DST analyst, (9) automated hydrocarbon association navigator (KHAN) for database mining, and (10) tutorial and help functions. The Kansas Hydrocarbon Association Navigator (KHAN) utilizes petrophysical databases to estimate hydrocarbon pay or other constituent at a play- or field-scale. Databases analyzed and displayed include digital logs, core analysis and photos, DST, and production data. GEMINI accommodates distant collaborations using secure password protection and authorized access. Assembled data, analyses, charts, and maps can readily be moved to other applications. GEMINI's target audience includes small independents and consultants seeking to find, quantitatively characterize, and develop subtle and bypassed pays by leveraging the growing base of digital data resources. Participating companies involved in the testing and evaluation of GEMINI included Anadarko, BP, Conoco-Phillips, Lario, Mull, Murfin, and Pioneer Resources.

W. Lynn Watney; John H. Doveton

2004-05-13

183

Disposable Planet  

NSDL National Science Digital Library

BBC Online presents this six-part special on sustainable development. Created in anticipation of the now concluded Johannesburg Summit, this Web site provides a valuable resource for viewers wishing to learn more about sustainable development and related issues. The Web site consists of an overview and six sections: Population, Food, Cities, Waste, Tourism, and Energy. The sections offer an in-depth look at each topic and include audio clips of related interviews and news stories. The discussion forums are now closed, but visitors may read the occasionally insightful and often times heated comments that have already been posted. View the slide show to get a quick, visceral sense of human impact on the planet -- past, present, and future. Visitors may also take a quiz to calculate their ecological footprint, or how much of the earth's resources they individually consume each year.

2002-01-01

184

PLANET-PLANET SCATTERING IN PLANETESIMAL DISKS  

SciTech Connect

We study the final architecture of planetary systems that evolve under the combined effects of planet-planet and planetesimal scattering. Using N-body simulations we investigate the dynamics of marginally unstable systems of gas and ice giants both in isolation and when the planets form interior to a planetesimal belt. The unstable isolated systems evolve under planet-planet scattering to yield an eccentricity distribution that matches that observed for extrasolar planets. When planetesimals are included the outcome depends upon the total mass of the planets. For M {sub tot} {approx}> 1 M{sub J} the final eccentricity distribution remains broad, whereas for M {sub tot} {approx}< 1 M{sub J} a combination of divergent orbital evolution and recircularization of scattered planets results in a preponderance of nearly circular final orbits. We also study the fate of marginally stable multiple planet systems in the presence of planetesimal disks, and find that for high planet masses the majority of such systems evolve into resonance. A significant fraction leads to resonant chains that are planetary analogs of Jupiter's Galilean satellites. We predict that a transition from eccentric to near-circular orbits will be observed once extrasolar planet surveys detect sub-Jovian mass planets at orbital radii of a {approx_equal} 5-10 AU.

Raymond, Sean N. [Center for Astrophysics and Space Astronomy, 389 UCB, University of Colorado, Boulder, CO 80309 (United States); Armitage, Philip J. [Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Gorelick, Noel [Google, Inc., 1600 Amphitheatre Parkway, Mountain View, CA 94043 (United States)], E-mail: sean.raymond@colorado.edu

2009-07-10

185

External Resource: Making a Model Planet  

NSDL National Science Digital Library

This PDF worksheet from NASA's I.M.A.G.E. Satellite Program challenges learners/students to work like Astronomers. Learners/students make predictions of what the interior of planets look like by carefully measuring the mass of the planet and its radius. S

1900-01-01

186

Terrestrial Planet Geophysics  

NASA Astrophysics Data System (ADS)

Terrestrial planet geophysics beyond our home sphere had its start arguably in the early 1960s, with Keith Runcorn contending that the second-degree shape of the Moon is due to convection and Mariner 2 flying past Venus and detecting no planetary magnetic field. Within a decade, in situ surface geophysical measurements were carried out on the Moon with the Apollo program, portions of the lunar magnetic and gravity fields were mapped, and Jack Lorell and his colleagues at JPL were producing spherical harmonic gravity field models for Mars using tracking data from Mariner 9, the first spacecraft to orbit another planet. Moreover, Mariner 10 discovered a planetary magnetic field at Mercury, and a young Sean Solomon was using geological evidence of surface contraction to constrain the thermal evolution of the innermost planet. In situ geophysical experiments (such as seismic networks) were essentially never carried out after Apollo, although they were sometimes planned just beyond the believability horizon in planetary mission queues. Over the last three decades, the discipline of terrestrial planet geophysics has matured, making the most out of orbital magnetic and gravity field data, altimetric measurements of surface topography, and the integration of geochemical information. Powerful constraints are provided by tectonic and volcanic information gleaned from surface images, and the engagement of geologists in geophysical exercises is actually quite useful. Accompanying these endeavors, modeling techniques, largely adopted from the Earth Science community, have become increasingly sophisticated and have been greatly enhanced by the dramatic increase in computing power over the last two decades. The future looks bright with exciting new data sets emerging from the MESSENGER mission to Mercury, the promise of the GRAIL gravity mission to the Moon, and the re-emergence of Venus as a worthy target for exploration. Who knows? With the unflagging optimism and persistence of a few diehards, we may eventually have a seismic and heat flow network on Mars.

Phillips, R. J.

2008-12-01

187

Dance of the Planets  

ERIC Educational Resources Information Center

|As students continue their monthly plotting of the planets along the ecliptic they should start to notice differences between inner and outer planet orbital motions, and their relative position or separation from the Sun. Both inner and outer planets have direct eastward motion, as well as retrograde motion. Inner planets Mercury and Venus,…

Riddle, Bob

2005-01-01

188

Gemini imidazolium surfactants: synthesis and their biophysiochemical study.  

PubMed

New gemini imidazolium surfactants 9-13 have been synthesized by a regioselective epoxy ring-opening reaction under solvent-free conditions. The surface properties of these new gemini surfactants were evaluated by surface tension and conductivity measurements. These surfactants have been found to have low critical micelle concentration (cmc) values as compared to other categories of gemini cationic surfactants and also showed the tendency to form premicellar aggregates in solution at sufficiently low concentration below their cmc values. The thermal degradation of these surfactants was determined by thermograviometry analysis (TGA). These new cationic surfactants have a good DNA binding capability as determined by agarose gel electrophoresis and ethidium bromide exclusion experiments. They have also been found to have low cytotoxicity by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay on the C6 glioma cell line. PMID:22845861

Kamboj, Raman; Singh, Sukhprit; Bhadani, Avinash; Kataria, Hardeep; Kaur, Gurcharan

2012-08-10

189

Planet Watch  

NSDL National Science Digital Library

This activity explores the potential impact of climate variability and change on one of Earth's increasingly vulnerable resources, forests. Although this activity is designed to tap specific skills and knowledge through scientific inquiry, its broader intent is to stimulate thought about the long-term impacts of a warmer planet. The activity focuses on a specific aspect of the climate variability and change issue - the impact of climate variability and change on New England forests. Its scenario invites students to examine higher level issues of climate variability and change by creating a practical, scientifically sound model to address specific points of a localized socioeconomic situation. Students will explore contemporary thought about the issue of climate variability and change, examine the issues as they relate to a specific, socially relevant situation, investigate claims supporting opposing viewpoints, determine whether the issues constitute a realistic problem, analyze scientific evidence about the situation, and present and defend their recommendations for action. This module is one of twelve of an overall series entitled The Potential Consequences of Climate Variability and Change.

Hornyak, John

190

Synthesis and characterization of glucosamide-based trisiloxane gemini surfactants  

Microsoft Academic Search

A new family of glucosamide-based trisiloxane gemini surfactants of the general formula (CH2OCH2)n (Me3SiOSiMeR1OSiMe3)2 (where R1=(CH2)3NR2(CH2)2NHCO (CHOH)4CH2OH; R2=CH2CH(OH)CH2OCH2; and n=0, 1, or 2) was prepared and characterized, both structurally and as aqueous surfactants. The monomer was prepared\\u000a by amidation of the precursor amine functional trisiloxane with d-gluconic acid ?-lactone. Gemini surfactants were then prepared by the alkylation of the precursor

Fu Han; Gaoyong Zhang

2004-01-01

191

Distributed user support and the Gemini Observatory help desk  

NASA Astrophysics Data System (ADS)

The Gemini Observatory HelpDesk was activated early in 2000 to aid in the rapid and accurate resolution of queries concerning the Gemini telescopes and their capabilities. This system co- ordinates user support amongst staff within the Observatory and at National Offices in each partner country. The HelpDesk is based on a commercial product from Remedy Corporation that logs, tracks, forwards and escalates queries and self- generates a knowledgebase of previously asked questions. Timestamping of these events in the life cycle of a request and analysis of associated information provides valuable feedback on the static web content and performance of user support.

Chan, Simon; Puxley, Phil J.

2000-07-01

192

Quick-MESS: A Fast Statistical Tool for Exoplanet Imaging Surveys  

NASA Astrophysics Data System (ADS)

Several tools have been developed in the past few years for the statistical analysis of the exoplanet search surveys, mostly using a combination of Monte Carlo simulations or a Bayesian approach. Here we present Quick-MESS, a grid-based, non-Monte Carlo tool aimed to perform statistical analyses on results from direct imaging surveys, as well as help with the planning of these surveys. Quick-MESS uses the (expected) contrast curves for direct imaging surveys to assess for each target the probability that a planet of a given mass and semimajor axis can be detected. By using a grid-based approach, Quick-MESS is typically more than an order of magnitude faster than tools based on Monte Carlo sampling of the planet distribution. In addition, Quick-MESS is extremely flexible, enabling the study of a large range of parameter space for the mass and semimajor axes distributions without the need of resimulating the planet distribution. In order to show examples of the capabilities of Quick-MESS, we present the analysis of the Gemini Deep Planet Survey and the predictions for upcoming surveys with extreme-AO instruments.

Bonavita, M.; de Mooij, E. J. W.; Jayawardhana, R.

2013-07-01

193

Exploring the Planets: Comparing the Planets  

NSDL National Science Digital Library

Comparative planetology is a scientific discipline in which researchers seek to understand the planets by comparing their similarities and examining their differences. Some planets have similarities because the materials of which they are made and the processes that have shaped them are similar. However, each planet has a unique character, due to the intensity and length of time the processes have operated. At this site, selected planets are compared on the basis of their atmospheres, volcanoes, impact craters, wind, water and ice. In each instance, photographs are displayed side by side for direct comparison.

194

The Dependence of Signal-To-Noise Ratio (S/N) Between Star Brightness and Background on the Filter Used in Images Taken by the Vulcan Photometric Planet Search Camera  

NASA Astrophysics Data System (ADS)

The Vulcan Photometric Planet Search is the ground-based counterpart of Kepler Mission Proposal. The Kepler Proposal calls for the launch of telescope to look intently at a small patch of sky for four year. The mission is designed to look for extra-solar planets that transit sun-like stars. The Kepler Mission should be able to detect Earth-size planets. This goal requires an instrument and software capable of detecting photometric changes of several parts per hundred thousand in the flux of a star. The goal also requires the continuous monitoring of about a hundred thousand stars. The Kepler Mission is a NASA Discovery Class proposal similar in cost to the Lunar Prospector. The Vulcan Search is also a NASA project but based at Lick Observatory. A small wide-field telescope monitors various star fields successively during the year. Dozens of images, each containing tens of thousands of stars, are taken any night that weather permits. The images are then monitored for photometric changes of the order of one part in a thousand. These changes would reveal the transit of an inner-orbit Jupiter-size planet similar to those discovered recently in spectroscopic searches. In order to achieve a one part in one thousand photometric precision even the choice of a filter used in taking an exposure can be critical. The ultimate purpose of an filter is to increase the signal-to-noise ratio (S/N) of one's observation. Ideally, filters reduce the sky glow cause by street lights and, thereby, make the star images more distinct. The higher the S/N, the higher is the chance to observe a transit signal that indicates the presence of a new planet. It is, therefore, important to select the filter that maximizes the S/N.

Mena-Werth, Jose

1998-10-01

195

Merging the CEM2k and LAQGSM Codes with GEMINI  

SciTech Connect

An improved version of the Cascade-Exciton Model (CEM) of nuclear reactions contained in the code CEM2k and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) are merged with the well-known sequential-binary-decay model GEMINI by Charity. We present some results on proton-induced fragmentation, fission-product yields and on particle spectra predicted by these extended versions of CEM2k and LAQGSM. We show that merging CEM2k and LAQGSM with GEMINI allows us to describe many fission and fragmentation reactions in addition to the spallation and evaporation reactions which are already described well by these codes. Nevertheless, the current version of GEMINI merged with CEM2k and LAQGSM does not provide a completely satisfactory description of some complex-particle spectra, fragment emission, and spallation yields for some reactions, and is not yet a universal tool for applications. Our results show that GEMINI contains a powerful model to describe evaporation/fission/fragmentation reactions and often provides better results when compared to other models, especially for emission of heavy fragments from reactions on medium-heavy nuclei (where most other models simply fail), but it must be further extended and improved in order to properly describe arbitrary reactions.

Baznat, M.I.; Gudima, K.K. [Institute of Applied Physics, Academy of Science of Moldova, Chisinau, MD-2028 (Moldova, Republic of); Mashnik, S.G.; Prael, R.E. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2005-05-24

196

Surface properties of Gemini surfactants with pyrrolidinium head groups.  

PubMed

Gemini surfactants C(n)-4-(n)PB (where n represents the alkyl chain length of 10, 12, 14 and 16) were synthesized and characterized. Their surface activity, thermodynamic properties, and aggregation behavior were investigated by means of surface tension, electrical conductivity, and steady-state fluorescence. It was found that the Gemini surfactants C(n)-4-(n)PB have superior surface activity to their corresponding monomer surfactants C(n)MPB as expected. Additionally, these compounds have lower cmc and surface tension in comparison with conventional cationic Gemini surfactants m-4-m. Thermodynamic parameters (?G(m)(0),?H(m)(0),T?S(m)(0)) show that the micellization is an entropy driven process with shorter hydrophobic chain lengths but instead is enthalpy driven for longer hydrophobic chain lengths. The effect of the hydrophobic alkyl chain length and the addition of inorganic salt NaBr on the surface activity and micellization are in line with the conventional cationic Gemini surfactants. PMID:22261268

Cai, Bo; Li, Xuefeng; Yang, Yi; Dong, Jinfeng

2011-12-27

197

GEMINI-GMOS spectroscopy in the Antlia cluster  

NASA Astrophysics Data System (ADS)

: We present preliminary results of a spectroscopic study performed in the Antlia cluster through GEMINI-GMOS data. They are related with new radial velocities that allow us to confirm the cluster membership of several new faint galaxies, as well as to identify very interesting background objects.

Faifer, F.; Smith Castelli, A. V.; Bassino, L. P.; Richtler, T.; Cellone, S. A.

198

Gemini Near-IR Photometry of the Arches Cluster Near the Galactic Center  

NASA Astrophysics Data System (ADS)

We present Near-IR photometry of the Arches cluster, a young and massive stellar cluster near the Galactic center. We have analyzed the high resolution (FWHM ~ 0.2'') H and K' band images in the Galactic Center Demonstration Science Data Set, which were obtained with the Gemini/Hokupa's adaptive optics (AO) system. We present the color-magnitude diagram, the luminosity function and the initial mass function (IMF) of the stars in the Arches cluster in comparison with the HST/NICMOS data. The IMF slope for the range of 1.0< log (M/M_sun) <2.1 is estimated to be Gamma = -0.79+/-0.16 , in good agreements with the earlier result based on the HST/NICMOS data [Figer et al. 1999, ApJ, 525, 750]. These results strengthen the evidence that the IMF of the bright stars close to the Galactic center is much flatter than that for the solar neighborhood. This is also consistent with a recent finding that the IMFs of the bright stars in young clusters in M33 get flatter as the galactocentric distance decreases [Lee et al. 2001, astro-ph 0109258]. It is found that the power of the Gemini/AO system is comparable, with some limits, to that of the HST/NICMOS.

Yang, Yujin; Park, Hong Soo; Lee, Myung Gyoon; Lee, Sang-Gak

2002-09-01

199

Active compensation of flexure on the High-Resolution Optical Spectrograph for Gemini  

NASA Astrophysics Data System (ADS)

Gravity-induced flexure has been a long-standing challenge in Cassegrain spectrographs at 4-meter class telescopes; it is the more so at the scale of 8-meter telescopes. This is of particular concern for the Gemini high resolution optical spectrograph, which will be Cassegrain-mounted for its routine mode of operation. In this paper we address the general flexure problem, and how to solve it with the use of active optics. We also present the results of an experimental active flexure compensation system for the ISIS (intermediate- dispersion spectroscopic and imaging system) spectrograph on the 4.2 m William Herschel Telescope (WHT). This instrument, called ISAAC (ISIS spectrograph automatic active collimator), is based on the concept of active correction, where spectrum drifts, due to the spectrograph flexing under the effect of gravity, are compensated by the movement of an active optical element (in this case a fine steering tip-tilt collimator mirror). The experiment showed that active compensation can reduce flexure down to less than 3 micrometer over four hours of telescope motions, dramatically improving the spectrograph performance. The results of the experiment are used to discuss a flexure compensation system for the high resolution optical spectrograph (HROS) for the 8 m Gemini telescope.

D'Arrigo, P.; Diego, Francisco; Walker, David D.

1997-03-01

200

Quaternary ammonium-type gemini surfactants synthesized from oleic acid: aqueous solution properties and adsorption characteristics.  

PubMed

Cationic gemini surfactants having a quaternary ammonium headgroup have been synthesized from oleic acid. The hydrocarbon chain is covalently bound to the terminal carbonyl group of oleic acid via an amide bond, while the quaternary ammonium headgroup is introduced onto the cis double bond of oleic acid. The Krafft temperature of these surfactants drops below room temperature (ca. 25°C) when the counterion is exchanged from Br? to Cl?. The aqueous solution properties of the Cl series of surfactants have been assessed by means of pyrene fluorescence, dynamic light scattering (DLS), and static surface tension measurements. An increased hydrocarbon chain length results in a lower critical micelle concentration (cmc) and a higher adsorption efficiency at the air/aqueous solution interface. Surface tension measurements suggest the formation of premicelles at concentrations below cmc, whereas, above cmc, DLS indicates the formation of micellar aggregates whose diameter ranges from 5 to 10 nm. We, furthermore, characterized the adsorption of these surfactants to the silica/aqueous solution interface and observed their spontaneous adsorption to the solid surface by electrostatic and intermolecular hydrophobic interactions. The combination of soft-contact imaging atomic force microscopy (AFM) and force-curve data suggests bilayer formation above cmc, which is reflective of the large packing parameter of the gemini surfactants. Interestingly, we found the repulsive interaction observed during compression of the adsorbed layer to be relatively weak, as a result of the low adsorption density and/or the loose molecular packing arrangement, which arises from the asymmetric structure. PMID:23823915

Sakai, Kenichi; Saito, Yuki; Uka, Akihito; Matsuda, Wataru; Takamatsu, Yuichiro; Kitiyanan, Boonyarach; Endo, Takeshi; Sakai, Hideki; Abe, Masahiko

2013-01-01

201

The structure and morphology of gold nanoparticles produced in cationic gemini surfactant systems  

NASA Astrophysics Data System (ADS)

Potential applications of gold nanoparticles (GNP) are strictly connected with their size and shape. The influence of different dicationic (gemini) surfactants, alkyloxymethylimidazolium derivatives derivatives, on the structure and morphology of GNP was studied. The synthesis of nanoparticles was performed in the presence of various gemini surfactants—dodecyloxymethylimidazolium nitrate (IMI_NO3_C4_C12), propionate (IMI_PROP_C4_C12) and 3,3'-[1,9-(2,8-dioxanonane)]bis-(1-nonyloxymethylimidazolium) chloride (IMI_Cl_oxyC7_C9), used as stabilizers and templates for obtaining different size and shape of gold nanoparticles. The samples obtained were examined using transmission electron microscopy (TEM), small angle scattering of synchrotron radiation (SAXS), UV–vis spectroscopy and NMR PFG spectroscopy. For the obtained solutions of nanoparticles the plasmon resonance was observed at the wavelengths corresponding to the presence of gold nanoparticles of sizes ranging from 5–100 nm, with a significant shift towards higher wavelength for the samples prepared with addition of dicationic surfactants. TEM images evidence the presence of gold nanoparticles with tetrahedral and spherical morphology in solutions prepared with the surfactants IMI_PROP_C4_C12, IMI_NO3_C4_C12, and those of spherical morphology, but strongly aggregated, in the solution with the cationic surfactant IMI_Cl_oxyC7_C9.

Murawska, Magdalena; Wiatr, Michalina; Nowakowski, Pawe?; Szutkowski, Kosma; Skrzypczak, Andrzej; Kozak, Maciej

2013-12-01

202

Further Evidence of the Planetary Nature of HD 95086 b from Gemini/NICI H-band Data  

NASA Astrophysics Data System (ADS)

We present our analysis of the Gemini/NICI H-band data of HD 95086, following the discovery of the planet HD 95086 b in L'. The H-band data reach a contrast of 12.7 mag relative to the host star at 5? levels in the location of HD 95086 b, and no point source is found. Our non-detection and H – L' color limit rules out the possibility that the object is a foreground L/T dwarf and that, if it is bound to HD 95086, it is a genuine planetary mass object. We estimate a new pre-main-sequence isochronal age for HD 95086 of 17 ± 4 Myr, which is commensurate with previous mean age estimates for the Lower Cen-Crux subgroup. Adopting an age of 17 Myr, the color limit is inconsistent with the COND model, marginally consistent with the BT-SETTL model, and consistent with the DUSTY model.

Meshkat, T.; Bailey, V.; Rameau, J.; Bonnefoy, M.; Boccaletti, A.; Mamajek, E. E.; Kenworthy, M.; Chauvin, G.; Lagrange, A.-M.; Su, K. Y. L.; Currie, T.

2013-10-01

203

Jovian Planet Finder optical system  

NASA Astrophysics Data System (ADS)

The Jovian Planet Finder (JPF) is a proposed NASA MIDEX mission to place a highly optimized coronagraphic telescope on the International Space Station (ISS) to image Jupiter-like planets around nearby stars. The optical system is an off-axis, unobscured telescope with a 1.5 m primary mirror. A classical Lyot coronagraph with apodized occulting spots is used to reduce diffracted light from the central star. In order to provide the necessary contrast for detection of a planet, scattered light from mid-spatial-frequency errors is reduced by using super-smooth optics. Recent advances in polishing optics for extreme-ultraviolet lithography have shown that a factor of >30 reduction in midfrequency errors relative to those in the Hubble Space Telescope is possible (corresponding to a reduction in scattered light of nearly 1000x). The low level of scattered and diffracted light, together with a novel utilization of field rotation introduced by the alt-azimuth ISS telescope mounting, will provide a relatively low-cost facility for not only imaging extrasolar planets, but also circumstellar disks, host galaxies of quasars, and low-mass substellar companions such as brown dwarfs.

Krist, John E.; Clampin, Mark; Petro, Larry; Woodruff, Robert A.; Ford, Holland C.; Illingworth, Garth D.; Ftaclas, Christ

2003-02-01

204

Diamond turned high precision PIAA optics and four mirror PIAA system for high contrast imaging of exo-planets  

Microsoft Academic Search

Off-axis, high-sag PIAA optics for high contrast imaging present challenges in manufacturing and testing. With smaller form factors and consequently smaller surface deformations (< 80 microns), diamond turned fabrication of these mirrors becomes feasible. Though such a design reduces the system throughput, it still provides 2lambda\\/D inner working angle. We report on the design, fabrication, measurements, and initial assessment of

Kunjithapatham Balasubramanian; Eric Cady; Laurent Pueyo; Xin An; Stuart Shaklan; Olivier Guyon; Ruslan Belikov

2011-01-01

205

Habitable Planets for Man.  

National Technical Information Service (NTIS)

Habitable Planets for Man examines and estimates the probabilities of finding planets habitable to human beings, where they might be found, and the number there may be in our own galaxy. The author presents in detail the characteristics of a planet that c...

S. H. Dole

2007-01-01

206

Peeking at the Planets.  

ERIC Educational Resources Information Center

|Provides information about each of the planets in our solar system. Focuses on information related to the space missions that have visited or flown near each planet, and includes a summary of what is known about some of the features of each planet. (DDR)|

Riddle, Bob

2002-01-01

207

Evaporation of extrasolar planets  

Microsoft Academic Search

This article presents a review on the observations and theoretical modeling of the evaporation of extrasolar planets. The observations and the resulting constraints on the upper atmosphere (thermosphere and exosphere) of the ``hot-Jupiters'' are described. The early observations of the first discovered transiting extrasolar planet, HD209458b, allowed the discovery that this planet has an extended atmosphere of escaping hydrogen. Subsequent

A. Lecavelier Des Etangs

2010-01-01

208

THE DIRECTLY IMAGED PLANET AROUND THE YOUNG SOLAR ANALOG 1RXS J160929.1 - 210524: CONFIRMATION OF COMMON PROPER MOTION, TEMPERATURE, AND MASS  

SciTech Connect

Giant planets are usually thought to form within a few tens of AU of their host stars, and hence it came as a surprise when we found what appeared to be a planetary mass ({approx}0.008 M {sub sun}) companion around the 5 Myr old solar mass star 1RXS J160929.1 - 210524 in the Upper Scorpius association. At the time, we took the object's membership in Upper Scorpius-established from near-infrared, H- and K-band spectroscopy-and its proximity (2.''2 or 330 AU) to the primary as strong evidence for companionship, but could not verify their common proper motion. Here, we present follow-up astrometric measurements that confirm that the companion is indeed comoving with the primary star, which we interpret as evidence that it is a truly bound planetary mass companion. We also present new J-band spectroscopy and 3.0-3.8 {mu}m photometry of the companion. Based on a comparison with model spectra, these new measurements are consistent with the previous estimate of the companion effective temperature of 1800 {+-} 200 K. We present a new estimate of the companion mass based on evolution models and the calculated bolometric luminosity of the companion; we obtain a value of 0.008{sup +0.003} {sub -0.002} M {sub sun}, again consistent with our previous result. Finally, we present angular differential imaging observations of the system allowing us to rule out additional planets in the system more massive than 1 M {sub Jup}, 2 M {sub Jup}, and 8 M {sub Jup} at projected separations larger than 3'' ({approx}440 AU), 0.''7 ({approx}100 AU), and 0.''35 ({approx}50 AU), respectively. This companion is the least massive known to date at such a large orbital distance; it shows that objects in the planetary mass range exist at orbital separations of several hundred AU, posing a serious challenge for current formation models.

Lafreniere, David [Departement de Physique, Universite de Montreal, C.P. 6128 Succ. Centre-Ville, Montreal, QC H3C 3J7 (Canada); Jayawardhana, Ray; Van Kerkwijk, Marten H., E-mail: david@astro.umontreal.c [Department of Astronomy and Astrophysics, University of Toronto, 50 St. George Street, Toronto, ON M5S 3H4 (Canada)

2010-08-10

209

HIGH-CONTRAST 3.8 {mu}m IMAGING OF THE BROWN DWARF/PLANET-MASS COMPANION TO GJ 758  

SciTech Connect

We present L'-band (3.8 {mu}m) MMT/Clio high-contrast imaging data for the nearby star GJ 758, which was recently reported by Thalmann et al. to have one -- possibly two -- faint comoving companions (GJ 758B and 'C', respectively). GJ 758B is detected in two distinct data sets. Additionally, we report a possible detection of the object identified by Thalmann et al. as 'GJ 758C' in our more sensitive data set, though it is likely a residual speckle. However, if it is the same object as that reported by Thalmann et al. it cannot be a companion in a bound orbit. GJ 758B has an H - L' color redder than nearly all known L-T8 dwarfs. Based on comparisons with the COND evolutionary models, GJ 758B has T {sub e} {approx} 560 K{sup +150K}{sub -90 K}{sup +150 K) and a mass ranging from {approx}10-20 M{sub J} if it is {approx}1 Gyr old to {approx} 25-40 M{sub J} if it is 8.7 Gyr old. GJ 758B is likely in a highly eccentric orbit, e {approx} 0.73{sup +0.12}{sub -0.21}, with a semimajor axis of {approx}44 AU{sup +32 AU){sub -14 AU}. Though GJ 758B is sometimes discussed within the context of exoplanet direct imaging, its mass is likely greater than the deuterium-burning limit and its formation may resemble that of binary stars rather than that of Jovian-mass planets.

Currie, Thayne [NASA-Goddard Space Flight Center, Greenbelt, MD (United States); Bailey, Vanessa; Rodigas, Timothy; Hinz, Phil [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Fabrycky, Daniel; Murray-Clay, Ruth [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2010-10-01

210

Exploring the Planets: Mars  

NSDL National Science Digital Library

Students will learn that Mars, and each planet in the solar system, is unique due to the materials from which it is made and the processes that shaped it. Images and information from Mars exploration voyages, including the Viking Mission in 1975, the Pathfinder Landing in 1997, the Mars Global Surveyor project, the Mars Odyssey and Mars Express spacecrafts, the Mars Exploration Rovers, and the Reconnaissance Orbiter are presented. Students will learn about Mars mean distance from Sun, length of year, rotation period, mean orbital velocity, inclination of axis, average temperature (day and night), diameter, inclination to ecliptic, and number of observed satellites. The seasons, volcanoes, canyons and plains, craters, water, wind patterns, and two moons of Mars are also discussed.

211

Diamond turned high precision PIAA optics and four mirror PIAA system for high contrast imaging of exo-planets  

NASA Astrophysics Data System (ADS)

Off-axis, high-sag PIAA optics for high contrast imaging present challenges in manufacturing and testing. With smaller form factors and consequently smaller surface deformations (< 80 microns), diamond turned fabrication of these mirrors becomes feasible. Though such a design reduces the system throughput, it still provides 2?/D inner working angle. We report on the design, fabrication, measurements, and initial assessment of the novel PIAA optics in a coronagraph testbed. We also describe, for the first time, a four mirror PIAA coronagraph that relaxes apodizer requirements and significantly improves throughput while preserving the low-cost benefits.

Balasubramanian, Kunjithapatham; Cady, Eric; Pueyo, Laurent; An, Xin; Shaklan, Stuart; Guyon, Olivier; Belikov, Ruslan

2011-09-01

212

Probing the Gas in the Planet Forming Regions of Protoplanetary Disks  

NASA Astrophysics Data System (ADS)

By studying the inner, planet-forming regions of circumstellar disks around low-mass pre-main sequence stars we can refine theories of giant planet formation and develop timescales for the evolution of disks and their planets. Spitzer low-resolution IRS observations of T Tauri stars (TTS) in the Chamaeleon, IC 348, and NGC 2068/2071 star-forming regions have given us an unprecedented look at dust evolution in young objects spanning 1-3 Myr. However, despite this ground breaking progress in studying the dust in young disks, the gas properties of the inner disk remain essentially unknown. With high resolution IRS, we propose to search for 12.81 micron Neon fine structure emission originating in the innermost disk regions of classical TTS in different stages of evolution with the objective of revealing the timescales of gas dissipation and its relationship to dust evolution. These observations will complement ground-based gas studies with Magellan/MIKE and Gemini/Phoenix. With the combined results of Spitzer, Gemini, and Magellan, our theoretical analysis will unveil the state of the dust and gas in disks in which planets may already be forming and starting to open gaps.

Calvet, Nuria; Bergin, Edwin; Espaillat, Catherine; Furlan, Elise; Hartmann, Lee; Miller, Jon; Muzzerolle, James

2007-05-01

213

A Strange New Planet  

NSDL National Science Digital Library

Scientists have been looking for extra-solar planets for decades, but only recently, with better equipment and improved techniques, have they finally unveiled new and unusual planets. Since 1995, over 155 planets have been discovered orbiting stars other than our Sun. This video segment, adapted from a NOVA television broadcast, gives an account of the discovery of the first confirmed extra-solar planet, a Jupiter-sized giant orbiting the star 51 Pegasi, and discusses the search for other extra-solar planets. The segment is three minutes nine seconds in length.

2011-05-05

214

The Trojan minor planets  

NASA Astrophysics Data System (ADS)

There are (March, 1988) 3774 minor planets which have received a permanent number. Of these, there are some whose mean distance to the sun is very nearly equal to that of Jupiter, and whose heliocentric longitudes from that planet are about 60°, so that the three bodies concerned (sun, Jupiter, minor planet) make an approximate equilateral triangle. These minor planets, which occur in two distinct groups, one preceding Jupiter and one following, have received the names of the heroes of the Trojan war. This paper concerns the 49 numbered minor planets of this group.

Spratt, Christopher E.

1988-08-01

215

A Strange New Planet  

NSDL National Science Digital Library

Scientists have been looking for extra-solar planets for decades, but only recently, with better equipment and improved techniques, have they finally unveiled new and unusual planets. Since 1995, over 155 planets have been discovered orbiting stars other than our Sun. This video segment, adapted from a NOVA television broadcast, gives an account of the discovery of the first confirmed extra-solar planet, a Jupiter-sized giant orbiting the star 51 Pegasi, and discusses the search for other extra-solar planets. The segment is three minutes nine seconds in length.

216

Gemini Observatory Takes its Local Communities on an Expanding Journey  

NASA Astrophysics Data System (ADS)

Currently in its 7th year (2011) Hawaii's annual Journey through the Universe (JttU) program is a flagship Gemini Observatory public education/outreach initiative involving a broad cross-section of the local Hawai'i Island astronomical community, the public, educators, businesses, local government officials, and thousands of local students. This paper describes the program, its history, planning, implementation, as well as the program's objectives and philosophy. The success of this program is documented here, as measured by continuous and expanding engagement of educators, the community, and the public, along with formal evaluation feedback and selected informal verbal testimony. The program's success also serves as justification for the planned adaptation of a version of the program in Chile in 2011 (adapted for Chilean educational and cultural differences). Finally, lessons learned are shared which have refined the program for Gemini's host communities but can also apply to any institution wishing to initiate a similar program.

Harvey, Janice; Michaud, Peter

2012-08-01

217

FORMATION, SURVIVAL, AND DETECTABILITY OF PLANETS BEYOND 100 AU  

SciTech Connect

Direct imaging searches have begun to detect planetary and brown dwarf companions and to place constraints on the presence of giant planets at large separations from their host star. This work helps to motivate such planet searches by predicting a population of young giant planets that could be detectable by direct imaging campaigns. Both the classical core accretion and the gravitational instability model for planet formation are hard pressed to form long-period planets in situ. Here, we show that dynamical instabilities among planetary systems that originally formed multiple giant planets much closer to the host star could produce a population of giant planets at large ({approx} 10{sup 2}-10{sup 5} AU) separations. We estimate the limits within which these planets may survive, quantify the efficiency of gravitational scattering into both stable and unstable wide orbits, and demonstrate that population analyses must take into account the age of the system. We predict that planet scattering creates detectable giant planets on wide orbits that decreases in number on timescales of {approx} 10 Myr. We demonstrate that several members of such populations should be detectable with current technology, quantify the prospects for future instruments, and suggest how they could place interesting constraints on planet formation models.

Veras, Dimitri; Crepp, Justin R.; Ford, Eric B. [Astronomy Department, University of Florida, 211 Bryant Space Sciences Center, Gainesville, FL 32111 (United States)], E-mail: veras@astro.ufl.edu

2009-05-10

218

[Selective algicidal activity of Gemini1231 biquaternary ammonium salt].  

PubMed

The growth-inhibiting effects of Gemini1231 surfactant on Prorocentrum donghaiense, Alexandrium tamarense, Gymnodinium sp., Heterosigma akashiwo, Skeletonema costatum , Platymonas helgolanidica and Platymonas subcordiforus were investigated. The results demonstrate that the growth of P. donghaiense, A. tamarense and H. akashiwo was strongly inhibited in medium containing Gemini1231 from 0.2 to 0.5 mg x L(-1), and the S. costatum was also inhibited at concentrations above 0.5 mg x L(-1). However, the effects of this surfactant on the growth of Gymnodinium sp. and two beneficial green microalgae tested were negligible under the same treatment, indicating the potential for the selective control of red tide organisms. In addition, the analysis of the correlation between the inhibitory effect of the Gemini1231 on the algae tested and fatty acid composition of the algae implied that the differences in the fatty acid composition, especially the proportion of PUFAs, were responsible for the species-specific responses to biquaternary ammonium salt. PMID:16850823

Wang, Xiu-lin; Li, Yan-bin; Gong, Liang-yu; Lu, Jin-ren; Han, Xiu-rong; Zhu, Chen-jian

2006-05-01

219

Increasing sky coverage with the Gemini North ALTAIR/LGS AO system  

NASA Astrophysics Data System (ADS)

The Gemini North (GN) AO system, Altair, has been routinely operating in LGS mode since 2007. Due to the initial optical design, the NGS field-of-view (FoV) is limited to a radius ~ 25" which limits the potential science. To improve this, we have tested the AO/LGS operation using a peripheral wavefront sensor (PWFS) whose patrol field is ~ 4'-7' from the target. This expanded NGS FoV permits greater sky coverage but with decreased resolution, FWHM ~ 0.1" - 0.2" making this mode very suitable for non-imaging spectrographic and integral field unit observations. We present the hardware and software upgrades to PWFS and Altair as well as the software necessary for making this observing mode a routine and integral part of GN operations. Characterization and performance of this new operation mode, known as LGS+P1, are presented.

Christou, Julian C.; Boccas, Maxime; Ebbers, Angelic; McDermid, Richard M.; Oram, Richard; Trujillo, Chadwick; Walls, Brian

2012-07-01

220

ConcepTest: Relative Planet Ages  

NSDL National Science Digital Library

How old are other planets in the Universe in comparison to the planets in our Solar System? a. Other planets are older than the planets in our Solar System. b. Other planets are younger than the planets in our ...

221

NICMOS Imaging of Massive Galaxies at z ~ 2  

NASA Astrophysics Data System (ADS)

We propose NICMOS F160W imaging of a sample of massive red galaxies from the Gemini Deep Deep Survey. These galaxies dominate the stellar mass density at 1.5< z < 2 and are our best link to early galaxy formation. The NICMOS images will be used in conjunction with our ACS images and deep Gemini spectra to examine the formation and early evolution of massive ellpitcal galaxy progenitors. We waive all propretary rights to the data and wil make them available on our web site as we have done with the Gemini Deep Deep Survey spectra, catalogs and ACS images.

McCarthy, Patrick

2004-07-01

222

The planet Saturn from 1973 to 1976  

Microsoft Academic Search

Observations of Saturn made from 1973 to 1976 are highlighted. Difficulties encountered in photographing the planet are discussed, and images made by different observers are presented and compared. Special attention is given to microphotometric studies of images of Saturn made at the Vitorre Observatory (Bologne) and the Anacapri Observatory (Naples). Although the albedo of the rings is more or less

J. Dragesco

1977-01-01

223

Observations of Rosetta Target (21) Lutetia with Keck and Gemini Adaptive Optics  

NASA Astrophysics Data System (ADS)

In support of the NASA/ESA Rosetta mission’s plans to observe asteroid (21) Lutetia during a 2010 July flyby, and in conjunction with a larger ground-based plus HST campaign to support this mission, we observed Lutetia from Keck and Gemini-North during several nights spanning 2008 Oct through 2009 Jan. Observations were made using adaptive optics in the near-IR, primarily at K-band (2.1 micron), and were timed to coincide with the asteroid's most recent opposition at a distance of about 1.4 AU. From these data, we determined Lutetia’s triaxial size and shape to be 132 x 101 x 76 km, with maximum expected uncertainties of 4 x 3 x 31 km. The spin pole is found to be at (RA, Dec) = (48, +9) deg or ecliptic (long, lat) = (49,-8) deg, with a formal uncertainty radius (not including systematics) of 3 deg. We have calibrated our technique of deriving dimensions of asteroids from AO images against Pluto and 4 satellites of Saturn with accurate diameters, and we expect that our systematics (included in the size uncertainties above) are no more than 3%. We also searched for satellites and our preliminary results indicate no detection of a satellite larger than about 1 km over a significant fraction of the Hill sphere (10-240 asteroid radii). Improved limits are expected from a more refined analysis. We are grateful for telescope time made available to us by S. Kulkarni and M. Busch (Cal Tech) for a portion of this dataset. We also thank our collaborators on Team Keck, the Keck science staff, for making possible some of these observations and for observing time granted at Gemini under NOAO time allocation. Plane-of-sky short and long axes of (21) Lutetia taken from Keck AO images on 2008 Dec 2.

Conrad, A. R.; Merline, W. J.; Drummond, J.; Carry, B.; Tamblyn, P. M.; Chapman, C. R.; Dumas, C.; Weaver, H. A.

2009-12-01

224

A giant planet around HD95086 ?  

NASA Astrophysics Data System (ADS)

Understanding planetary systems formation and evolution has become one of the challenges in as- tronomy, since the discovery of the first exoplanet around the solar-type star 51 Peg in the 90's. While more than 800 planets (mostly giants) closer than a few AU have been identified with radial velocity and transit techniques, very few have been imaged and definitely confirmed around stars, at separations below a hundred of astronomical units. Direct imaging detection of exoplanet is indeed a major frontier in planetary astrophysics. It surveys a region of semi-major axes (> 5 AU) that is almost inaccessible to other methods. Moreover, the planets imaged so far orbit young stars; indeed the young planets are still hot and the planet-star contrasts are compatible with the detection limits currently achievable, in contrast with similar planets in older systems. Noticeably, the stars are of early-types, and surrounded by debris disks, i.e. disks populated at least by small grains with lifetimes so short that they must be permanently produced, probably by destruction (evaporation, collisions) of larger solid bodies. Consequently, every single discovery has a tremendous impact on the understanding of the formation, the dynamical evolution, and the physics of giant planets. In this context, I will present our recent discovery of one faint companion to a nearby, dusty, and young A-type star (at 56 AU projected separation). Background contaminants are rejected with high confidence level based on both astrometry and photometry with three dataset at more than a year-time-laps and two different wavelength regimes. From the system age (10 to 17 Myr) and from model-dependent luminosity estimates, we derive mass of 4 to 5 Jupiter mass. This planet is therefore the one with the lowest mass ever imaged around a star. Given its orbital and physical properties, I will discuss the implication on its atmosphere with respect to other imaged companions but also on its formation.

Rameau, Julien; Chauvin, Gaël; Lagrange, Anne-Marie; Meshkat, Tiffany; Boccaletti, Anthony; Quanz, Sascha P.; Bonnefoy, Mickaël; Bailey, Vanessa; Kenworthy, Matthew; Currie, Thayne; Girard, Julien H.; Delorme, Philippe; Desidera, Silvano; Dumas, Christophe; Mordasini, Christoph; Klahr, Hubert; Bonavita, Mariangela

2013-07-01

225

Separation of acidic and basic proteins by capillary electrophoresis using gemini surfactants and gemini-capped nanoparticles as buffer additives  

Microsoft Academic Search

This paper demonstrated simultaneous separation of acidic and basic proteins using cationic gemini surfactants as buffer additives\\u000a in capillary electrophoresis. We showed that even at a low concentration (0.1 mmol·L?1) of alkanediyl-?,?-bis(dimethyloctadecylammonium bromide) (18-s-18), the wall adsorption of both acidic and basic proteins could be effectively suppressed under acidic conditions. Smaller\\u000a micelle size (e.g., s = 5–8) is more effective

Qian Liu; YanQing Li; YanMin Yang; ShouZhuo Yao

2009-01-01

226

Formation of Giant Planets  

NASA Astrophysics Data System (ADS)

The observed properties of giant planets, models of their evolution, and observations of protoplanetary disks provide constraints on the formation of gas giant planets. The four largest planets in our solar system contain considerable quantities of hydrogen and helium; these gases could not have condensed into solid planetesimals within the protoplanetary disk. Jupiter and Saturn are mostly hydrogen and helium, but have larger abundances of heavier elements than does the Sun. Neptune and Uranus are primarily composed of heavier elements. The transiting extrasolar planet HD149026b, which is slightly more massive than Saturn, appears to have comparable amounts of light gases and heavy elements. The other observed transiting exoplanets are primarily hydrogen and helium, but may contain supersolar abundances of heavy elements. Spacecraft flybys and observations of satellite orbits provide estimates of the gravitational moments of the giant planets in our solar system, which in turn provide information on the internal distribution of matter within Jupiter, Saturn, Uranus, and Neptune. Atmospheric thermal structure and heat flow measurements constrain the interior temperatures of these planets. Internal processes may cause giant planets to become more compositionally differentiated or alternatively more homogeneous; high-pressure laboratory experiments provide data useful for modeling these processes. The preponderance of evidence supports the core nucleated gas accretion model. According to this model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the giant planet cores grow massive enough to accumulate substantial amounts of gas before the protoplanetary disk dissipates. The primary question regarding the core nucleated growth model is under what conditions can planets develop cores sufficiently massive to accrete gas envelopes within the lifetimes of gaseous protoplanetary disks.

Lissauer, J. J.; Stevenson, D. J.

227

The Amazing Red Planet  

NSDL National Science Digital Library

The purpose of this lesson is to introduce students to the planet Mars. This lesson will begin by discussing the location and size of Mars relative to Earth, as well as introduce many interesting facts about this red planet. Next, the history of Martian exploration is reviewed and students discover why scientists are so interested in studying this mysterious planet. The lesson concludes with students learning about future plans to visit Mars.

Integrated Teaching And Learning Program

228

Planet Exploration Mission  

NSDL National Science Digital Library

In this activity, learners design a scientific exploration mission to a planet or moon of their choice. Learners must consider questions such as which planet or moon to explore, distance of mission space travel, manned or unmanned mission, atmosphere and possible lifeforms on the destination moon or planet, and technology needed to explore the destination planet. This activity can be coordinated with the Habitable Worlds and Extreme Lifestyles activities found in the same astrobiology guide. This activity can be found on pages 52-53 of the activity guide.

Terc

2007-01-01

229

Terrestrial planet formation  

PubMed Central

Advances in our understanding of terrestrial planet formation have come from a multidisciplinary approach. Studies of the ages and compositions of primitive meteorites with compositions similar to the Sun have helped to constrain the nature of the building blocks of planets. This information helps to guide numerical models for the three stages of planet formation from dust to planetesimals (?106 y), followed by planetesimals to embryos (lunar to Mars-sized objects; few × 106 y), and finally embryos to planets (107–108 y). Defining the role of turbulence in the early nebula is a key to understanding the growth of solids larger than meter size. The initiation of runaway growth of embryos from planetesimals ultimately leads to the growth of large terrestrial planets via large impacts. Dynamical models can produce inner Solar System configurations that closely resemble our Solar System, especially when the orbital effects of large planets (Jupiter and Saturn) and damping mechanisms, such as gas drag, are included. Experimental studies of terrestrial planet interiors provide additional constraints on the conditions of differentiation and, therefore, origin. A more complete understanding of terrestrial planet formation might be possible via a combination of chemical and physical modeling, as well as obtaining samples and new geophysical data from other planets (Venus, Mars, or Mercury) and asteroids.

Righter, K.; O'Brien, D. P.

2011-01-01

230

solar system/planets  

NSDL National Science Digital Library

In approximately 21 days, 4 hours, 38 minuets and 6 seconds, you will take off on an exploration into space to the planet of your choice. Be ready to explore, raid and escape the space creatures on your planet. The Task: Students are to research a planet of their choice using the resources provided below. Once they feel they have decided on a plant of their choice, they will construct a power point on what they would encounter and see on their visit to this planet. They will also ...

Williams, Mr.

2010-11-18

231

Further seasonal changes in Uranus' cloud structure observed by Gemini-North and UKIRT  

NASA Astrophysics Data System (ADS)

Near-infrared observations of Uranus were made in October/November 2010 with the Gemini-North telescope in Hawaii, using NIFS, an integral field spectrograph, and the NIRI instrument in imaging mode. Observations were acquired using adaptive optics and have a spatial resolution of approximately 0.1-0.2?. The observed spectra along Uranus' central meridian were analysed using a multiple-scattering retrieval algorithm to infer the vertical/latitudinal variation in cloud optical depth, which we compare with previous observations made by Gemini-North/NIFS in 2009 and UKIRT/UIST observations made between 2006 and 2008. Assuming a continuous distribution of small particles (r ˜ 1 ?m, and refractive index of 1.4 + 0i) with the single scattering albedo set to 0.75 and using a Henyey-Greenstein phase function with asymmetry parameter set to 0.7 at all wavelengths and latitudes, the retrieved cloud density profiles show that the north polar zone at 45°N has continued to steadily brighten while the south polar zone at 45°S has continued to fade. As with our previous analyses we find that, assuming that the methane vertical profile is the same at all latitudes, the clouds forming these polar zones at 45°N and 45°S lie at slightly lower pressures than the clouds at more equatorial latitudes. However, we also find that the Gemini data can be reproduced by assuming that the main cloud remains fixed at ˜2 bar at all latitudes and adjusting the relative humidity of methane instead. In this case we find that the deep cloud is still more opaque at the equator and at the zones at 45°N and 45°S and shows the same seasonal trends as when the methane humidity remain fixed. However, with this approach the relative humidity of methane is seen to rise sharply from approximately 20% at polar latitudes to values closer to 80% for latitudes equatorward of 45°S and 45°N, consistent with the analysis of 2002 HST observations by Karkoschka and Tomasko (Karkoschka, E., Tomasko, M. [2009]. Icarus 202, 287-302), with a possible indication of seasonal variability. Overall, Uranus appeared to be less convectively active in 2010 than in the previous 4 years, supporting the conclusion that now the northern spring equinox (which occurred in 2007) has passed, the atmosphere is settling back into the more quiescent state seen by Voyager 2 in 1986.

Irwin, P. G. J.; Teanby, N. A.; Davis, G. R.; Fletcher, L. N.; Orton, G. S.; Calcutt, S. B.; Tice, D. S.; Hurley, J.

2012-03-01

232

Direct Detection of Extrasolar Planets with the Thirty Meter Telescope  

Microsoft Academic Search

20-40m Extremely Large Telescopes (ELTs) may become operational in the next decade, with revolutionary scientific capabilities in several areas, including direct detection of extrasolar planets. One such project is the massively-segmented Thirty Meter Telescope. I will briefly discuss planet detection phase space and the potential TMT roles and present a possible TMT Extreme AO\\/coronagraph instrument architecture, the Planet Formation Imager.

B. Macintosh

2007-01-01

233

75 FR 14644 - Gemini Investors IV, L.P., Notice Seeking Exemption Under Section 312 of the Small Business...  

Federal Register 2010, 2011, 2012, 2013

...ADMINISTRATION [License No. 01/01-0410] Gemini Investors IV, L.P., Notice Seeking...of Interest Notice is hereby given that Gemini Investors IV, L.P., 20 William Street...and Regulations (13 CFR 107.730). Gemini Investors IV, L.P. proposes to...

2010-03-26

234

Photometry and dynamics of the minor merger AM 1219-430 with Gemini GMOS-S  

NASA Astrophysics Data System (ADS)

We present an observational study of the interaction effect on the dynamics and morphology of the minor merger AM 1219-430. This work is based on r' and g' images and long-slit spectra obtained with the Gemini Multi-Object Spectrograph at the Gemini South Telescope. We detected a tidal tail in the main galaxy (AM 1219A) and a bridge of material connecting the galaxies. In luminosity, AM 1219A is about 3.8 times brighter than the secondary (AM 1219B). The surface brightness profile of AM 1219A was decomposed into bulge and disc components. The profile shows a light excess of ˜53 per cent due to the contribution of star-forming regions, which is typical of starburst galaxies. On the other hand, the surface brightness profile of AM 1219B shows a lens structure in addition to the bulge and disc. The scalelengths and central magnitudes of the disc structure of both galaxies agree with the average values derived for galaxies with no sign of ongoing interaction or disturbed morphology. The Sérsic index (n < 2), the effective and scale radii of the bulge of both galaxies are typical of pseudo-bulges. The rotation curve of AM 1219A derived from the emission line of ionized gas is quite asymmetric, suggesting a gas perturbed by interaction. We explore all possible values of stellar and dark matter masses. The overall best-fitting solution for the mass distribution of AM 1219A was found with M/L for bulge and disc of Upsilon _b=2.8_{-0.4}^{+0.4} and Upsilon _d=2.4_{-0.2}^{+0.3}, respectively, and a Navarro et al. profile of M_{200}=2.0_{-0.4}^{+0.5}× 10^{12} M_{{?}} and c=16.0_{-1.1}^{+1.2}. The estimated dynamical mass is 1.6 × 1011 M?, within a radius of ˜10.6 kpc.

Hernandez-Jimenez, J. A.; Pastoriza, M. G.; Rodrigues, I.; Krabbe, A. C.; Winge, Cláudia; Bonatto, C.

2013-11-01

235

March of the Planets  

ERIC Educational Resources Information Center

|The motion of the planets in their orbits can be demonstrated to students by using planetarium software programs. These allow time to be sped up so that the relative motions are readily observed. However, it is also valuable to have the students understand the real speed of the planets in their orbits. This paper describes an exercise that gives…

Thompson, Bruce

2007-01-01

236

Kepler Circumbinary Planets  

NASA Astrophysics Data System (ADS)

In the past 16 months Kepler has detected six transiting circumbinary planets, and several more candidate systems are under investigation. I will present a summary of these discoveries and the latest results on the search for more systems, including non-transiting planets.

Welsh, William F.; Kepler Team

2013-01-01

237

PLANet: An Active Internetwork  

Microsoft Academic Search

We present PLANet: an active network architecture and im- plementation. In addition to a standard suite of Internet-like services, PLANet has two key programmability features: 1. all packets contain programs 2. router functionality may be extended dynamically Packet programs are written in our special purpose programming language PLAN, the Packet Language for Active Networks, while dynamic router extensions are written

Michael W. Hicks; Jonathan T. Moore; D. Scott Alexander; Carl A. Gunter; Scott M. Nettles

1999-01-01

238

What is a Planet  

NSDL National Science Digital Library

Using 3D animation, this video was created to better illustrate the history behind the discussion defining "What is a Planet?" and to outline some of the traits that may be associated with the definition of a planet. (Length: 7:54 minutes)

Nasa

2010-01-01

239

More About “Planet Earth”  

NASA Astrophysics Data System (ADS)

Seven programs, each 1 hour in length, form the centerpiece of Planet Earth: The Living Machine, The Blue Planet, The Climate Puzzle, Tales from Other Worlds, Gifts from the Earth, The Solar Sea, Fate of the EarthMost public television stations will broadcast the series on Wednesday evenings; check local listings for the correct time and station.

240

Characterizing extrasolar planets  

Microsoft Academic Search

Transiting extrasolar planets provide the best current opportunities for characterizing the physical properties of extrasolar planets. In this review, I first describe the geometry of planetary transits, and methods for detecting and refining the observations of such transits. I derive the methods by which transit light curves and radial velocity data can be analyzed to yield estimates of the planetary

Timothy M. Brown

2008-01-01

241

Name That Planet!  

ERIC Educational Resources Information Center

|Presents an activity in which students in groups explore one planet in the solar system and present their findings to the whole class. Focuses on the planet's location in the solar system, geological features, rate of revolutions, and calendar year. (YDS)|

Beck, Judy; Rust, Cindy

2002-01-01

242

Planets in Motion  

ERIC Educational Resources Information Center

|All the planets in the solar system revolve around the Sun in the same direction, clockwise when viewed from above the North Pole. This is referred to as direct motion. From the perspective on the Earth's surface, the planets travel east across the sky in relation to the background of stars. The Sun also moves eastward daily, but this is an…

Riddle, Bob

2005-01-01

243

Outer Planet Flagship Mission  

Microsoft Academic Search

Studies for Outer Planet Missions have been ongoing for many years, but in 2007 NASA commissioned four specific studies to be considered for further examination; the Europa Explorer, Titan Explorer, Enceladus Mission and Jupiter Science Orbiter. During the same time frame ESA invited Outer Planet proposals under the Cosmic Vision call. Two were submitted, TandEm and LaPlace, which focused on

James Cutts; C. Niebur; L. Dudzinski; M. Coradini; J. Lebreton

2008-01-01

244

Outer Planet Flagship Missions  

Microsoft Academic Search

Studies for Outer Planet Missions have been ongoing for many years, but in 2007 NASA commissioned four specific studies to be considered for further examination; the Europa Explorer, Titan Explorer, Enceladus Mission and Jupiter Science Orbiter. During the same time frame ESA invited Outer Planet proposals under the Cosmic Vision call. Two were submitted, TandEM and LaPlace, which focused on

C. Niebur; L. Dudzinski; M. Coradini; J. Lebreton; J. A. Cutts

2008-01-01

245

Outer planet satellites  

Microsoft Academic Search

Recent findings on the outer-planet satellites are presented, with special consideration given to data on the rheologic properties of ice on icy satellites, the satellite surfaces and exogenic processes, cratering on dead cratered satellites, volcanism, and the interiors of outer-planet satellites. Particular attention is given to the state of Titan's surface and the properties of Triton, Pluto, and Charon.

Paul M. Schenk

1991-01-01

246

Are Exoplanets Really Planets?  

NSDL National Science Digital Library

This newsbrief, from Science magazine's electronic news source, Science now, airs the skepticism of three astronomers, who state that most of the 50 recently discovered "planets" orbiting stars other than our sun may not really be planets, but rather brown dwarfs. So, what are they? Read up, and form your own opinion.

2000-01-01

247

Pluto: Planet or  

Microsoft Academic Search

In August 2006 during the XXVI General Assembly of the International Astronomical Union (IAU), taken place in Prague, Czech Republic, new parameters to define a planet were established. According to this new definition Pluto will be no more the ninth planet of the Solar System but it will be changed to be a \\

M. R. Voelzke; M. S. T. de Araújo

2010-01-01

248

Extreme Planet Makeover  

NSDL National Science Digital Library

You may have heard of elaborate makeover television shows where some individual wishes to have various body enhancements performed or a new house is built in seven days. This fascinating extreme makeover website, from NASA and the Jet Propulsion Laboratory at the California Institute of Technology, is much more edifying. Here, visitors will have the opportunity to make their own planet via a series of customizable bells and whistles. Visitors can use the controls on the site to adjust key planetary attributes such as distance from a star, planet size, and planet age. After making these adjustments, visitors can learn about the planet they have created, and also compare it with other existing planets and outer-space bodies.

249

Ocean Planet: Rough Planet Earth without Ocean  

NSDL National Science Digital Library

The Ocean Planet is a traveling exhibition from the Smithsonian Institution which opened in Washington DC on April 22, 1995. A part of the exhibition was a computer flyby of the Pacific Ocean developed in the SVS. This animation represents a stage in the development of that flyby.

Pape, Dave; Feldman, Gene

1994-04-29

250

How Do We Find Planets Around Other Stars?  

NSDL National Science Digital Library

This fun and simple hands-on astronomy activity describes techniques scientists use to find planets orbiting other stars. Learners will spin âstarsâ to simulate star wobble (astrometry and radial velocity) and will explore the transit method and direct imaging of planets. The pdf contains step-by-step instructions, photos, presentation tips, and links to background information.

Pacific, Astronomical S.

2012-12-26

251

Lab results of the circular phase mask concepts for high-contrast imaging of exoplanets  

NASA Astrophysics Data System (ADS)

Circular phase mask concepts represent promising options for high contrast imaging and spectroscopy of exo-planets. Depending on their design, they can either work as a diffraction suppression system or as a focal plane wavefront sensor. While the apodized Roddier coronagraph uses a ?-phase mask to obtain complete suppression of the star image in monochromatic light, the Zernike sensor uses a ?/2-phase mask to measure the residual aberrations in the focal plane by encoding them into intensity variations in the relayed pupil. Implementations of the Zernike sensor can be considered in exoplanet imagers such as VLT-SPHERE, Gemini planet imager, Palomar-P1640 or Subaru-SCExAO to enlarge their capabilities. However, such concepts have not been validated experimentally up to now. Our goal is to perform lab demonstration of this concept on our visible coronagraph testbed at LAM and to propose an upgrade design for SPHERE. In this communication, we report on results of lab measurements of the Zernike sensor and determine its sensitivity to small wavefront errors.

N'Diaye, Mamadou; Dohlen, Kjetil; Fusco, Thierry; El Hadi, Kacem; Soummer, Rémi; Cuevas, Salvador; Zerrad, Myriam; Ferrari, Marc

2012-09-01

252

A Metric for Exo-Planet Detectability  

NASA Astrophysics Data System (ADS)

There are many architectures being proposed for direct imaging of planets around other stars. To compare the performance of these systems, we need a consistent metric to quantify whether and how well a given planet or range of planets can be observed. This is also critical for deriving a specific mission design for a given architecture. In this paper, we look at this issue in the context of the New Worlds Observer (NWO) architecture. We develop a metric for how well a given planet can be seen by a given system. We then apply this metric to a range of NWO systems and explore how this affects the mission design. We find that the central starlight suppression and the geometrical Inner Working Angle (IWA) are not good ways to describe an external occulter system's ability to detect an exo-planet. Instead, for a given mission design, there will be a range of IWA depending on the relationship between the planet brightness and the suppression provided by the starshade. We explore this relationship and discuss its implications for the design of an NWO mission.

Glassman, Tiffany M.; Polidan, R.; Lo, A.

2007-12-01

253

Planet Formation at Wide Separations: Constraints from HR 8799  

NASA Astrophysics Data System (ADS)

The three gas giants directly-imaged orbiting HR 8799 comprise the first planetary system detected at wide separations around a main sequence star. Core accretion scenarios, already strained at the outer limits of our solar system, have difficulty explaining planet formation at the larger distances of the HR 8799 planets, even around a central A star. Formation by gravitational instability (GI) is most plausible for massive planets at large separations. We demonstrate that for GI to form the planets around HR 8799, the protoplanetary disk must have passed through a fine-tuned region of parameter space at its transition from the Class I to the Class II phase. Orbital stability requirements imply that the HR 8799 planets occupy at least one and possibly two mean motion resonances, suggesting that they migrated toward one another and may have migrated substantially from their formation locations. We will discuss how the HR 8799 system constrains the formation and migration of distant planets.

Murray-Clay, Ruth; Kratter, K.; Youdin, A.

2009-09-01

254

First On-sky Results with GeMS, the Gemini Multi-conjugate AO System  

NASA Astrophysics Data System (ADS)

GeMS, the Gemini Multi-Conjugate Adaptive Optics (MCAO) System, is the first multi-sodium based Laser Guide Star (LGS) Adaptive Optics (AO) system used for astronomy. It uses five LGSs distributed on a 1 arcmin constellation to measure and compensate for atmospheric distortions and delivers a uniform, close to diffraction- limited Near-Infrared (NIR) image over an extended FoV of 2arcmin. GeMS first light occured in December 2011. The first compensated images demonstrate H-band Strehl Ratios (SR) in excess of 35% and Full-Width Half Maximum (FWHM) of or below 50 mas, in good seeing condition, averaged over a field of view of 85x85 arcsec In this paper we report on these early results, analyzing image quality in term of FWHM, SR, and field uniformity thereof. The PSF shape is analyzed, and the factor limiting performance are discussed. Finally, we present a first astrometric analysis, demonstrating astrometric errors as low as 420 microarcsecond for the data analyzed in this paper.

Neichel, Benoit; Rigaut, F.; Arriagada, G.; Serio, A.; Araujo, C.; Boccas, M.; Carrasco, R.; Collao, F.; Diggs, S.; d'Orgeville, C.; Fesquet, V.; Galvez, R.; Gausachs, G.; Luhrs, J.; Marchant, C.; Montes, V.; Moreno, C.; Pessev, P.; Rambold, W.; Trujillo, C. A.; Urrutia, C.; Vidal, F.; Vucina, T.

2013-01-01

255

The SARG Planet Search  

NASA Astrophysics Data System (ADS)

We present the radial velocity planet search in moderately wide binaries with similar components (twins) ongoing at Telescopio Nazionale Galileo (TNG) using the Galileo High Resolution Spectrograph (Spettrografo Alta Risoluzione Galileo, SARG). We discuss the sample selection, the observing and analysis procedures, the main results of the radial velocity monitoring and the implications in terms of planet frequency in binary systems. We also briefly discuss the second major science goal of the SARG survey, the search for abundance anomalies caused by the ingestion of planetary material by the central star. Finally, we present some preliminary conclusions regarding the frequency of planets in binary systems.

Desidera, S.; Gratton, R.; Martinez Fiorenzano, A.; Endl, M.; Claudi, R.; Cosentino, R.; Scuderi, S.; Bonavita, M.; Barbieri, M.; Bonanno, G.; Cecconi, M.; Lucatello, S.; Marzari, F.

2010-04-01

256

Exploring the Planets: Mercury  

NSDL National Science Digital Library

This site contains most of the up-to-date information known about the planet Mercury. Facts about the planet include: mean distance from Sun, length of year, rotation period, mean orbital velocity, inclination of axis, average temperature (day and night), and diameter. The site explains why earth-based views of Mercury are so poor and describes the surface of the planet on the basis of probe photographs. The photographs do not prove whether the material on the surface is impact ejecta or volcanic. However, a colored digital mosaic of Mercury taken by Mariner 10 suggests that at least some of the mercurian smooth plains are the products of volcanism.

257

Pulse of the Planet  

NSDL National Science Digital Library

This site contains the archive for Pulse of the Planet, which provides its listeners with a two-minute sound portrait of Planet Earth, tracking the rhythms of nature, culture and science worldwide and blending interviews and extraordinary natural sound. Pulse of the Planet is broadcast over 320 public and commercial stations around the world and on the Voice of America and the Armed Forces Radio Network. In addition to the sound clips there are associated feature stories on everything from particle physics to the birds of the Pantanal and seasonal stories describing the ways that people interact with their environment.

2008-04-14

258

Share Your Planet  

NSDL National Science Digital Library

In this cooperative game, learners devise strategies about sharing a small space with each other. Similar to musical chairs, this game has players sharing a smaller and smaller number of "planets" (circles on the floor) until they find a way to share just one remaining planet. After the game, learners discuss how they managed to fit everyone in one planet, what "rules" of sharing they made up as they went along, and whether there were disagreements. This game can be a great activity for indoor recess. This activity can be found on pages 12-13 of the activity guide.

Terc

2007-01-01

259

Coating the 8-m Gemini telescopes with protected silver  

NASA Astrophysics Data System (ADS)

The Gemini telescopes were designed to be infrared-optimized. Among the features specified for optimal performance is the use of silver-based coatings on the mirrors. The feasibility study contracted by Gemini in 1994-1995 provided both techniques and recipes to apply these high-reflectivity and low-emissivity films. All this effort is now being implemented in our coating plants. At the time of the study, sputtering experiments showed that a reflectivity of 99.1% at 10?m was achievable. We have now produced bare and protected silver sputtered films in our coating plants and conducted environmental testing, both accelerated and in real-life conditions, to assess the durability. We have also already applied, for the first time ever, protected-silver coatings on the main optical elements (M1, M2 and M3) of an 8-m telescope. We report here the progress to date, the performance of the films, and our long-term plans for mirror coatings and maintenance.

Boccas, Maxime; Vucina, Tomislav; Araya, Claudio; Vera, Esteban; Ahhee, Clayton

2004-09-01

260

Searching for “First Light” with the Gemini telescopes  

NASA Astrophysics Data System (ADS)

Astronomers from across the Gemini partnership have embarked on an ambitious mission to discover the first stars and forming galaxies during the epoch of reionization (6 < z < 15). Observers are using new techniques and technologies to make this dream a reality. In this article I provide an overview of a few of these programs, focusing primarily on experiments searching for objects with redshifts z > 7, which must be observed and studied at near-IR wavelengths (1-2.5 ?m). Programs currently in progress include searches for high-redshift galaxies lensed by foreground galaxy clusters, the use of narrow-band filters to improve the signal-to-noise ratio by reducing the background, and near-IR spectroscopic follow-up of optical drop-out high-redshift candidates. Other programs seek to identify and observe high-redshift gamma-ray bursts. Finally, I describe Gemini's plans for the future, and ways that objects with z > 7 may be identified in the next few years.

Jensen, Joseph B.

2006-03-01

261

Polymerizable semi-fluorinated gemini surfactants designed for antimicrobial materials.  

PubMed

Introduction of biocide monomers during the process of polymerization is one of promising approaches in the development of new permanent non leaching biocide materials. In this perspective, new polymerizable semi-fluorinated gemini surfactants, with quaternary ammonium groups as polar heads and an acrylic function as the polymerizable moiety, were synthesized and tested to evaluate their surface active properties alongside with their antibacterial and antifungal properties. Four microbial strains, known for their implication in nosocomial infections, were used to perform the study: Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans and Aspergillus niger. The biocide efficacy measured by bacterial and fungal growth inhibition expressed as MIC (minimal inhibitory concentration) and MLC (minimal lethal concentration) values was discussed as a function of molecular parameters. As compared to homologue compounds without acrylic part, this study shows that even the introduction of a polymerizable moiety allows to keep remarkable both surfactant and bacteriostatic activities, and allows us to envisage the use of these surfactant monomers to build up advanced biocide materials. Moreover, semi-fluorinated gemini surfactant monomers with an amide connector came out as broad spectrum biocides (against Gram positive and negative bacteria and fungi). PMID:19144354

Caillier, Laurent; Taffin de Givenchy, Elisabeth; Levy, Richard; Vandenberghe, Yves; Geribaldi, Serge; Guittard, Frederic

2008-12-24

262

High Dynamic Range Direct Imaging of Exoplanets with an Off-axis Antarctic Telescope  

NASA Astrophysics Data System (ADS)

This thesis presents an analysis of the potential for high dynamic range direct imaging of exoplanets with a propsed off-axis Antarctic telescope named the Large Antarctic Plateau Clear-Aperture Telescope (LAPCAT). LAPCAT is a proposed 8.4 metre off-axis telescope with a deformable 1 m secondary mirror to be located at Dome C in Antarctica. The low atmospheric temperatures and minimal high altitude turbulence make Dome C a unique site for astronomical observations. The low wind speeds, the absence of dust in the atmosphere and minimal seismic activity make this a very stable site. The off-axis design of LAPCAT will assist in reducing the emissitivity of the secondary mirror and spider arms which are likely to dominate the infra-red background at these low temperatures. Low sky emissivity is also desirable for high contrast direct imaging of faint infrared sources such as exoplanets. The performance due to LAPCAT's off-axis design, adaptive optics system, and Antarctic location is quantified here. Simulations have been run to compare the point spread functions of LAPCAT, two existing mid-latitude on-axis telescopes, and a hypothetical on-axis Antarctic telescope. For comparison I chose the Keck II telescope located at Mauna Kea, Hawaii, and Gemini South situated on Cerro Paranal, Chile. Keck II is an on-axis segmented telescope and Gemini is an on-axis monolithic telescope. Under diffraction-limited, seeing-limited and adaptive-optics-corrected seeing conditions the telescopes' PSFs is compared at six different wavelengths. Simulations were run at 1.25, 1.26, 2.2, 3.4, 5, and 10 ?m, using Performance of Adaptive Optics for Large Apertures (PAOLA), an analytical adaptive optics simulation package written in IDL. Having studied the effects of a typical Antarctic atmospheric turbulence profile on the PSF, LAPCAT can be expected to out-perform similar aperture telescopes located at temperate sites. Results demonstrate the intended adaptive optics system for LAPCAT allows the telescope to reach the diffraction limit. LAPCAT is able to detect a 20 MJ 5 Gyr old planet out to 10 pc, and a 5 Gyr planet less than 40 MJ out to 100 pc at 5 ?m. For 1 Gyr planets the best observing wavelengths are 5 ?m and 10 ?m. The results demonstrate that LAPCAT is more sensitive to hot young extrasolar giant planets but is unable to directly image an exoplanet with a mass less than 4 MJ.

Britton, Tui Rose

2009-05-01

263

Trojan planets in HD108874?  

Microsoft Academic Search

Today there are about 190 extrasolar planets in 156 extrasolar systems confirmed. We have only observational evidence for planets from 7 (Gliese 876 d) earth masses up to several Jupiter masses; and up to now no planet with a mass comparable to the Earth was found. To ensure that an orbit of such a planet is stable in the so-called

R. Schwarz; R. Dvorak; E. Pilat-Lohinger; B. Erdi

2006-01-01

264

Disk's Spiral Arms Point to Possible Planets  

NASA Video Gallery

Simulations of young stellar systems suggest that planets embedded in a circumstellar disk can produce many distinctive structures, including rings, gaps and spiral arms. This video compares computer simulations of hypothetical systems to an image of system SAO 206462 taken by the Subaru Telescope and its HiCIAO instrument. Credit: NASA Goddard Space Flight Center/NCSA

gsfcvideo

2011-10-18

265

The Nine 8 Planets: A Multimedia Tour of the Solar System  

NSDL National Science Digital Library

The Nine 8 Planets is an overview of the history, mythology, and current scientific knowledge of the planets, moons and other objects in our solar system. Each page has text and images, with some including sound and movies. Information about planets outside our solar system is also provided along with references to additional information and resources.

Arnett, Bill

2004-07-17

266

Students Discover Unique Planet  

NASA Astrophysics Data System (ADS)

Three undergraduate students, from Leiden University in the Netherlands, have discovered an extrasolar planet. The extraordinary find, which turned up during their research project, is about five times as massive as Jupiter. This is also the first planet discovered orbiting a fast-rotating hot star. Omega Centauri ESO PR Photo 45a/08 A planet around a hot star The students were testing a method of investigating the light fluctuations of thousands of stars in the OGLE database in an automated way. The brightness of one of the stars was found to decrease for two hours every 2.5 days by about one percent. Follow-up observations, taken with ESO's Very Large Telescope in Chile, confirmed that this phenomenon is caused by a planet passing in front of the star, blocking part of the starlight at regular intervals. According to Ignas Snellen, supervisor of the research project, the discovery was a complete surprise. "The project was actually meant to teach the students how to develop search algorithms. But they did so well that there was time to test their algorithm on a so far unexplored database. At some point they came into my office and showed me this light curve. I was completely taken aback!" The students, Meta de Hoon, Remco van der Burg, and Francis Vuijsje, are very enthusiastic. "It is exciting not just to find a planet, but to find one as unusual as this one; it turns out to be the first planet discovered around a fast rotating star, and it's also the hottest star found with a planet," says Meta. "The computer needed more than a thousand hours to do all the calculations," continues Remco. The planet is given the prosaic name OGLE2-TR-L9b. "But amongst ourselves we call it ReMeFra-1, after Remco, Meta, and myself," says Francis. The planet was discovered by looking at the brightness variations of about 15 700 stars, which had been observed by the OGLE survey once or twice per night for about four years between 1997 and 2000. Because the data had been made public, they were a good test case for the students' algorithm, who showed that for one of stars observed, OGLE-TR-L9, the variations could be due to a transit -- the passage of a planet in front of its star. The team then used the GROND instrument on the 2.2 m telescope at ESO's La Silla Observatory to follow up the observations and find out more about the star and the planet. "But to make sure it was a planet and not a brown dwarf or a small star that was causing the brightness variations, we needed to resort to spectroscopy, and for this, we were glad we could use ESO's Very Large Telescope," says Snellen. The planet, which is about five times as massive as Jupiter, circles its host star in about 2.5 days. It lies at only three percent of the Earth-Sun distance from its star, making it very hot and much larger than normal planets. The spectroscopy also showed that the star is pretty hot -- almost 7000 degrees, or 1200 degrees hotter than the Sun. It is the hottest star with a planet ever discovered, and it is rotating very fast. The radial velocity method -- that was used to discover most extrasolar planets known -- is less efficient on stars with these characteristics. "This makes this discovery even more interesting," concludes Snellen.

2008-12-01

267

Changing Planet: Ocean Acidification  

NSDL National Science Digital Library

This video discusses the impact of higher amounts of carbon dioxide absorbed by the oceans on marine organisms and how they are adapting to the new environment. Changing Planet is produced in partnership with the National Science Foundation.

2011-03-04

268

The Extrasolar Planets Encyclopaedia  

NSDL National Science Digital Library

Jean Schneider, of the Observatoire de Paris, put together this no-nonsense site featuring current information on the "detection and study of extrasolar planets, including exobiology." Schneider's commitment to the subject is clear with the inclusion of detailed scientific and technical articles, a tutorial (by Arizona State University) on the detection of extrasolar planets, and a hyperlinked bibliography of some 200 scientific journal articles, books, and reports. A catalog of extrasolar planets (with links to the scientific articles describing them) features dozens of confirmed planets (or brown dwarfs) around main sequence stars or pulsars, in addition to disks and unconfirmed objects. Whether you are a dedicated amateur or pro (and read English or French), these pages are clearly designed and well worth the orbit.

269

Dwarf Planet Pluto  

NSDL National Science Digital Library

This site discusses Pluto's orbit, moon, surface, density, and explorations. There are creative videos and animations. There are also several photos of the far off dwarf planet accompanied by descriptions of each.

Hamilton, Calvin

2007-01-24

270

Learning Planet Sizes  

NSDL National Science Digital Library

This lesson plan is part of the Center for Educational Resources (CERES), a series of web-based astronomy lessons created by a team of master teachers, university faculty, and NASA researchers. In this activity, students use general size concepts to classify student height, object size, and planet size. They then build scale planet models based on their discoveries. This lesson contains expected outcomes for students, materials, background information, follow-up questions, extension activities, and assessment procedures.

Tuthill, George; Obbink, Kim

271

Planets' magnetic environments  

SciTech Connect

The magnetospheres of Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and comets and the heliomagnetosphere are examined. The orientations of the planetary spin and magnetic axes, the size of the magnetospheres, and the magnetic properties and the radio emissions of the planets are compared. Results from spacecraft studies of the planets are included. Plans for the Voyager 2 mission and its expected study of the Neptune magnetosphere are considered.

Lanzerotti, L.J.; Uberoi, C.

1989-02-01

272

Outer planet satellites  

SciTech Connect

Recent findings on the outer-planet satellites are presented, with special consideration given to data on the rheologic properties of ice on icy satellites, the satellite surfaces and exogenic processes, cratering on dead cratered satellites, volcanism, and the interiors of outer-planet satellites. Particular attention is given to the state of Titan's surface and the properties of Triton, Pluto, and Charon. 210 refs.

Schenk, P.M. (USAF, Geophysics Laboratory, Hanscom AFB, MA (United States))

1991-01-01

273

Evaporation of extrasolar planets  

NASA Astrophysics Data System (ADS)

This article presents a review on the observations and theoretical modeling of the evaporation of extrasolar planets. The observations and the resulting constraints on the upper atmosphere (thermosphere and exosphere) of the ``hot-Jupiters'' are described. The early observations of the first discovered transiting extrasolar planet, HD209458b, allowed the discovery that this planet has an extended atmosphere of escaping hydrogen. Subsequent observations showed the presence of oxygen and carbon at very high altitude. These observations give unique constraints on the escape rate and mechanism in the atmosphere of hot-Jupiters. The most recent Lyman-alpha HST observations of HD189733b and MgII observations of Wasp-12b allow for the first time a comparison of the evaporation from different planets in different environments. Models to quantify the escape rate from the measured occultation depths, and an energy diagram to describe the evaporation state of hot-Jupiters are presented. Using this diagram, it is shown that few already known planets like GJ876d or CoRot-7b could be remnants of formerly giant planets.

Lecavelier Des Etangs, A.

2010-12-01

274

Classifying Planets: Nature vs. Nurture  

NASA Astrophysics Data System (ADS)

The idea of a planet was so simple when we learned about the solar system in elementary school. Now students and professional s alike are faced with confusing array of definitions --- from "Brown Dwarfs” to "Super Jupiters", from "Super Earths” to "Terrestrial Planets", and from "Planets” to "Small, Sort-of Round Things That Aren't Really Planets". I will discuss how planets might be defined by how they formed, where they are found, or by the life they might support.

Beichman, Charles A.

2009-05-01

275

High Precision Lightcurves of A Mutual Event of Transneptunian Binary (79360) Sila-Nunam From Gemini Observatory  

NASA Astrophysics Data System (ADS)

Cold-classical Kuiper Belt binary (79360) Sila-Nunam is in the midst of a decade-long mutual event season in which its nearly equal-sized components occult and eclipse each other as viewed from Earth (Grundy et al. 2012 Icarus 220, 74-83). On 14 February 2013 UT, the Gemini Multi-Object Spectrograph (GMOS-N) camera at Gemini Observatory on Mauna Kea, Hawai'i imaged nearly an entire inferior event in which Nunam, the smaller of the two objects, eclipsed and occulted Sila. Alternating 200-second exposures in Sloan r' and i' filters continuously during the 9.3-hour event produced lightcurves containing information about sizes, colors, shapes, and albedo patterns on the system components. This mutual event is a rare opportunity to determine physical characteristics of a surface which has likely been unaltered since the time of Solar System formation. A. Verbiscer acknowledges support from NASA Planetary Astronomy. W. Grundy acknowledges support from NSF Planetary Astronomy.

Verbiscer, Anne J.; Grundy, W.; Benecchi, S.; Rabinowitz, D.; Skrutskie, M. F.

2013-10-01

276

The discovery of Eris, the largest known dwarf planet  

NSDL National Science Digital Library

A webpage about the discovery of Eris, the first known dwarf planet larger than Pluto. The discovery of Eris prompted the demotion of Pluto by the IAU, and the page includes images and information about the object.

Brown, Michael; Technology, California I.

277

Cationic Gemini surfactant at the air/water interface.  

PubMed

The surface properties and structures of a cationic Gemini surfactant with a rigid spacer, p-xylyl-bis(dimethyloctadecylammonium bromide) ([C(18)H(37)(CH(3))(2)N(+)CH(2)C(6)H(4)CH(2)N(+)(CH(3))(2)C(18)H(37)],2Br(-), abbreviated as 18-Ar-18,2Br(-1)), at the air/water interface were investigated. It is found that the surface pressure-molecular area isotherms observed at different temperatures do not exhibit a plateau region but display an unusual "kink" before collapse. The range of the corresponding minimum compressibility and maximum compressibility modulus indicates that the monolayer is in the liquid-expanded state. The monolayers were transferred onto mica and quartz plates by the Langmuir-Blodgett (LB) technique. The structures of monolayers at various surface pressures were studied by atomic force microscopy (AFM) and UV-vis spectroscopy, respectively. AFM measurements show that at lower surface pressures, unlike the structures of complex or hybrid films formed by Gemini amphiphiles with DNA, dye, or inorganic materials or the Langmuir film formed by the nonionic Gemini surfactant, in this case network-like labyrinthine interconnected ridges are formed. The formation of the structures can be interpreted in terms of the spinodal decomposition mechanism. With the increase of the surface pressure up to 35 mN/m, surface micelles dispersed in the network-like ridges gradually appear which might be caused by both the spinodal decomposition and dewetting. The UV-vis adsorption shows that over the whole range of surface pressures, the molecules form a J-aggregate in LB films, which implies that the spacers construct a pi-pi aromatic stacking. This pi-pi interaction between spacers and the van der Waals interaction between hydrophobic chains lead to the formation of both networks and micelles. The labyrinthine interconnected ridges are formed first because of the rapid evaporation of solvent during the spreading processes; with increasing surface pressure, some of the alkyl chains reorient from tilting to vertical, forming surface micelles dispersed in the network-like ridges due to the strong interaction among film molecules. PMID:17631889

Qibin, Chen; Xiaodong, Liang; Shaolei, Wang; Shouhong, Xu; Honglai, Liu; Ying, Hu

2007-07-12

278

Stellar Companions to Stars with Planets  

Microsoft Academic Search

A combination of high-resolution and wide-field imaging reveals two binary stars and one triple star system among the sample of the first 11 stars with planets detected by radial velocity variations. High-resolution speckle or adaptive optics (AO) data probe subarcsecond scales down to the diffraction limit of the Keck 10 m or the Lick 3 m, and direct images or

J. Patience; R. J. White; A. M. Ghez; C. McCabe; I. S. McLean; J. E. Larkin; L. Prato; Sungsoo S. Kim; J. P. Lloyd; M. C. Liu; J. R. Graham; B. A. Macintosh; D. T. Gavel; C. E. Max; B. J. Bauman; S. S. Olivier; P. Wizinowich; D. S. Acton

2002-01-01

279

Why 400 Years to Discover Countless Planets?  

NASA Astrophysics Data System (ADS)

In 1584, Dominican monk Giordano Bruno envisioned the stars as "countless suns with countless earths, all rotating around their suns." Searching for intellectual freedom, he fled his native Italy to Protestant Switzerland and Germany, but in 1600 the Roman Inquisition condemned him for heresy. He was burned at the stake. Fast-forwarding to 1995, the Swiss astronomers Michel Mayor and Didier Queloz announced the discovery of a planet orbiting a star similar to our sun (51 Pegasi). In 2010, 500 planets had been found orbiting 421 stars. On Feb 2, 2011, NASA announced 1200 planet candidates. It took 400 years for telescope technology to advance and for Copernicus, Galileo, Newton, Bradley, and Foucault to make major contributions, culminating in today's astrophysics with digital imaging and processing. Contrasting with Bruno, in 2010 Dominican Francisco Ayala, who had been president of the Sigma Xi and AAAS, won the 1.6M Templeton Prize for affirming life's spiritual dimension.

Carr, Paul H.

2011-04-01

280

The Gemini MCAO infrastructure: laser service enclosure and support structure  

NASA Astrophysics Data System (ADS)

The Laser Service Enclosure (LSE) is an environmentally controlled ISO 7 clean room designed to house, protect and provide environmental control for the Gemini South multi-conjugate adaptive optics laser system. The LSE is 8.0 meters long, 2.5 meters wide and 2.5 meters high with a mass of approximately 5,100 kg. The LSE shall reside on a new telescope Nasmyth platform named the Support Structure (SS). The SS is a three-dimensional beam and frame structure designed to support the LSE and laser system under all loading conditions. This paper will review the system requirements and describe the system hardware including optical, environmental, structural and operational issues as well as the anticipated impact the system will have on the current telescope performance.

Cavedoni, Charles P.; Bombino, S.; Sheehan, M.; Karewicz, S.; Hardash, S.; Perez, G.; Collins, P.; d'Orgeville, C.; Boccas, M.; Maltes, D.; Gausachs, G.; Rogers, R.

2008-08-01

281

New family of Gemini surfactants with glucosamide-based trisiloxane  

Microsoft Academic Search

The interfacial properties of a new family of glucosamide-based trisiloxane Gemini surfactants of the general formula (CH2OCH2)n(Me3SiOSiMeR1OSiMe3)2 (R1 = (CH2)3NR2(CH2)2NHCO(CHOH)4CH2OH; R2 = CH2CH(OH)CH2OCH2, n=0, 1,and2) were studied. Members of this family reduced the surface tension of water to approximately 21mN\\/m at concentration levels of 10?4mol\\/l and 10?5mol\\/l. The physicochemical parameters of these dimeric compounds were compared with those of the

Fu Han; Gaoyong Zhang

2004-01-01

282

Biological properties of arginine-based gemini cationic surfactants.  

PubMed

Biological properties of novel gemini (double-chain/double-head) cationic surfactants, Nalpha,Nomega-bis(Nalpha-acylarginine)alpha,omega-alkylendiamides, so-called bis(Args), are reported. The effect of both the alkyl (10 and 12 carbon atoms) and the spacer chain (from 2-10 methylene groups) of bis(Args) on their antimicrobial activity, acute toxicity on Daphnia magna and Photobacterium phosphoreum, and aerobic biodegradability is studied. These surfactants constitute a novel class of chemicals of low toxicity with excellent surface properties and considerable antimicrobial activity. The aquatic toxicity of these compounds is lower than that of the conventional Monoquats. As regards the biodegradation test, the molecules with a spacer chain < or =6 methylene groups can be considered as ready biodegradable. The increase of hydrophobicity in the bis(Args) is a negative structural parameter for their environmental behavior. PMID:12069315

Pérez, Lourdes; García, Maria Teresa; Ribosa, Isabel; Vinardell, Maria Pilar; Manresa, Angeles; Infante, Maria Rosa

2002-06-01

283

Monolayer behavior of asymmetrical ester-type tartaric gemini amphiphiles.  

PubMed

The ester-type asymmetrical tartaric gemini amphiphiles (C(m)-C(n), where m and n are the number of carbon atoms of hydrophobic alkanoyl group, m+n=28) bearing two carboxyl groups and two different alkanoyl groups were prepared from L-tartaric acid, and the pressure-area (?-A) isotherms for a series of asymmetrical tartaric gemini amphiphiles were studied.The ?-A isotherms of asymmetrical C(m)-C(n) monolayers were classified into two groups. Group 1: The asymmetry was small (n/m <1.55), and a phase transition of the monolayer from the liquid-expanded to the liquid condensed state, and a subsequent transition to solid phases were observed. Group 2: The asymmetry was large (n/m >1.8), and only liquid-expanded state of the monolayer film was observed. Based on the subphase temperature (T(sub)) dependence of monolayer static elasticity, es, the melting temperature (T(L)) of asymmetrical C(m)-C(n) monolayer was estimated to be T(L) = 31.7°C and 50.6°C for C??-C?? and C??-C??, respectively. Furthermore, assuming that asymmetrical C??-C?? can be viewed as an equimolar mixture of symmetrical 2C?? and 2C??, the temperature dependence of monolayers of 2C?? and 2C?? mixture at various ratios were also studied. As a result, all TL values of 2C14, C??-C?? and an equimolar mixture of 2C?? and 2C?? were almost the same. However, the variation of T(L) with the molar fraction of 2C?? (X(2C15)) was remarkably different from that of solid melting point T(m) with X(2C15). PMID:23728328

Kawase, Tokuzo; Saito, Isao; Oida, Tatsuo

2013-01-01

284

The Gemini South MCAO laser guide star facility: getting ready for first light  

NASA Astrophysics Data System (ADS)

The Gemini Observatory is in the final integration and test phase for its Multi-Conjugate Adaptive Optics (MCAO) project at the Gemini South 8-meter telescope atop Cerro Pachón, Chile. This paper presents an overview and status of the laser-side of the MCAO project in general and its Beam Transfer Optics (BTO), Laser Launch Telescope (LLT) and Safety Systems in particular. We review the commonalities and differences between the Gemini North Laser Guide Star (LGS) facility producing one LGS with a 10W-class laser, and its southern sibling producing five LGS with a 50W-class laser. We also highlight the modifications brought to the initial Gemini South LGS facility design based on lessons learned over 3 years of LGS operations in Hawaii. Finally, current integration and test results of the BTO and on-sky LLT performance are presented. Laser first light is expected in early 2009.

d'Orgeville, Céline; Daruich, Felipe; Arriagada, Gustavo; Bec, Matthieu; Boccas, Maxime; Bombino, Stacy; Carter, Chris; Cavedoni, Chas; Collao, Fabian; Collins, Paul; James, Eric; Karewicz, Stan; Lazo, Manuel; Maltes, Diego; Mouser, Ron; Perez, Gabriel; Rigaut, François; Rojas, Roberto; Sheehan, Mike; Trancho, Gelys; Vergara, Vicente; Vucina, Tomislav

2008-07-01

285

Search for extra-solar planets  

NASA Astrophysics Data System (ADS)

A number of different observational techniques are used today for the detection of planets beyond our solar system. Most of them are indirect methods, based on dynamical or photometric effects induced by the planet and measured on the parent star. The most successful technique so far has been the Doppler (radial-velocity) method, based on precise measurements of small variations in the radial velocity of the parent star. About one hundred extra-solar planets have been discovered by this technique. Other methods are based on astrometric measurements, direct imaging, photometry, interferometry and gravitational microlensing. Some of these techniques are already able to produce positive results, but many of them are future projects needing more advanced instrumentation. In this paper the most important techniques for extra-solar planet detection will be reviewed and their results summarized. In the second part, two different projects carried out at Mt John University Observatory, Lake Tekapo, New Zealand will be presented, both involved in planet hunting. One is the HERCULES radial-velocity programme and the other is the MOA microlensing project.

Skuljan, J.

2003-10-01

286

Chemistry of planet formation  

NASA Astrophysics Data System (ADS)

This thesis explores how the chemical environment in which planets develop influences planet formation. The total solid mass, gas/solid ratio, and specific ice inventory of protoplanetary disks can dramatically alter the planet's formation timescale, core/atmosphere mass ratio, and atmosphere composition. We present the results of three projects that probe the links between solar nebula composition and giant planet formation. The first project offers evidence that stars with planets exhibit statistically significant silicon and nickel enrichment over the general metal-rich population. To test whether this prediction is compatible with the core accretion theory of planet formation, we construct new numerical simulations of planet formation by core accretion that establish the timescale on which a planet forming at 5 AU reaches rapid gas accretion, t rga , as a function of solid surface density s solid : ( t rga /1 Myr) = (s solid /25.0 g cm -2 ) - 1.44 . This relation enables us to construct Monte Carlo simulations that predict the fraction of star-disk systems that form planets as a function of [Fe/H], [Si/Fe], disk mass, outer disk radius and disk lifetime. Our simulations reproduce both the known planet-metallicity correlation and the planet-silicon correlation reported in this paper. The simulations predict that 15% of Solar-type stars form Jupiter-mass planets, in agreement with 12% predicted from extrapolation of the observed planet frequency-semimajor axis distribution. Despite the success of our Monte Carlo simulation of the planet-silicon correlation at predicting the properties of extrasolar Jovian planets, there is still no in situ core accretion simulation that can successfully account for the formation of Saturn, Uranus or Neptune within the observed 2-3 Myr lifetimes of protoplanetary disks. Since solid accretion rate is directly proportional to the available planetesimal surface density, one way to speed up planet formation is to take a full inventory of all the solids present in the solar nebula. In Project 2 (Chapter 3) we combine a viscously evolving protostellar disk with a kinetic model of ice formation, which includes not just water but methane, ammonia, CO and 54 minor ices. We use this combined dynamical+chemical simulation to calculate the planetesimal composition and solid surface density in the solar nebula as a function of heliocentric distance and time. We find three effects that strongly favor giant planet formation: (1) a decretion flow that brings mass from the inner solar nebula to the giant planet-forming region, (2) recent lab results (Collings et al. 2004) showing that the ammonia and water ice lines should coincide, and (3) the presence of a substantial amount of methane ice in the trans-Saturnian region. Our results show higher solid surface densities than assumed in the core accretion models of Pollack et al. (1996) by a factor of 3-4 throughout the trans-Saturnian region. We also discuss the location of ice lines and their movement through the solar nebula, and provide new constraints on the possible initial disk configurations from gravitational stability arguments. Finally, we present a core accretion simulation of Saturn with a planet formation timescale of 3.37 Myr, consistent with observed protostellar disk lifetimes. The protostellar disk model underlying this simulation is also capable of forming Jupiter within 2.5 Myr. We observe a new manifestation of the core accretion theory, in which Saturn's solid core does not reach isolation mass, and argue that this paradigm should apply to Uranus and Neptune as well. The planet formation timescale is then governed primarily by the solid accretion rate instead of the gas contraction efficiency. Our model predicts a core mass of 44 M (+) for Saturn, heavier than inferred from observations by a factor of at least 2. We discuss possible mechanisms for reducing the core size without slowing down formation and comment on the similarity between our core- heavy Saturn model and the exoplanet HD 149026 b .

Robinson, Sarah Elaine

2008-02-01

287

Planet Formation and Migration  

NASA Astrophysics Data System (ADS)

The discovery of over 160 extrasolar planets, many with very unusual properties, has driven a renaissance in the study of planet formation. It is likely that Jovian and supra-Jovian planets formed at large distances, migrated towards their central stars, and yet somehow managed to stop short of plunging in. The growing theoretical and observational study of protostellar disks is allowing us to better probe the mechanism(s) of planet formation and migration through disk-gas interactions. In this talk, we explore new insights in mechanisms for determing planetary masses that arise from the presence of turbulence-free, so called dead-zones in protostellar disks. Such regions should be present on scales of up to 15 AU in most disks and should have profound effects on the migration of both terrestrial and Jovian planets - in effect - saving planetary systems. We also explore some obervational consequences of such ideas for observing programmes that can be implemented at the planned new large-scale ground-based facilities; TMT and SKA.

Pudritz, Ralph E.; Matsumura, S.

2006-06-01

288

Target of Opportunity Observing in Queue Mode at the Gemini North Observatory  

NASA Astrophysics Data System (ADS)

The Gemini Observatories primarily operate a multi-instrument queue, with observers selecting observations that are best suited to weather and seeing conditions. Queue operations give higher ranked programs a greater chance for completion than lower ranked programs requesting the same conditions and instrument configuration. Queue observing naturally lends itself to Target of Opportunity (ToO) support since the time required to switch between programs and instruments is very short, and the staff observer is trained to operate all the available instruments and modes. Gemini Observatory has supported pre-approved ToO programs since beginning queue operations, and has implemented a rapid (less than 15 minutes response time) ToO mode since 2005. The rapid response ToO mode has thus far been exclusively utilized by the Gemini community for optical and near-IR follow-up of Gamma Ray Bursts (GRBs), primarily discovered by the Swift satellite. We discuss the ToO implementation at Gemini Observatory including the ToO user interface and the procedures followed by observatory staff astronomers once a ToO trigger is received. We present the statistics of 4 years of rapid ToOs at Gemini North Observatory, and the advances in our understanding of GRBs, their host galaxies and the intergalactic medium that this important mode has enabled. Finally we discuss recent changes in both software and policy to improve standard and rapid ToO support at the Gemini Observatories. The Gemini Observatory is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Science and Technology Facilities Council (United Kingdom), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), Ministério da Ciìncia e Tecnologia (Brazil), and SECYT (Argentina)

Roth, Katherine; Price, P.; Gillies, K.; Walker, S.; Miller, B.

2009-01-01

289

California and Carnegie Planet Research  

NSDL National Science Digital Library

The California and Carnegie Planet Research website presents the University of California Berkeley and the Carnegie Institution of Washington's investigations of planets around other stars. In the Public link, users can find easily understandable details on the diversity of exoplanets and on planet detection techniques. Researchers can find more technical details in the Scientific Research Site including a detailed almanac of planets and data on extrasolar planets. The website features publications, employment information, and team members' résumés. The materials are riddled with outside links to help users find other great planet-related educational and research websites.

290

Living Planet Report 1999  

NSDL National Science Digital Library

The second edition of the World Wildlife Fund's (WWF) Living Planet Report (last discussed in the October 9, 1998 Scout Report) has been placed online. The report attempts to quantify the speed at which nature is disappearing from Earth and trace human pressures on the natural environment. The first part of the report, the Living Planet Index (LPI), measures natural wealth and how it has changed between 1970 and 1995. According to the WWF, the LPI declined by 30 percent in this period, indicating that the world has lost "30 per cent of its natural wealth in the space of one generation." The second part of the Living Planet Report examines six causes of global environmental change related to human consumption of renewable and non-renewable resources.Users may view an executive summary and highlights of the report or download the full text in .pdf.

1999-01-01

291

Characterizing extrasolar planets  

NASA Astrophysics Data System (ADS)

Transiting extrasolar planets provide the best current opportunities for characterizing the physical properties of extrasolar planets. In this review, I first describe the geometry of planetary transits, and methods for detecting and refining the observations of such transits. I derive the methods by which transit light curves and radial velocity data can be analyzed to yield estimates of the planetary radius, mass, and orbital parameters. I also show how visible-light and infrared spectroscopy can be valuable tools for understanding the composition, temperature, and dynamics of the atmospheres of transiting planets. Finally, I relate the outcome of a participatory lecture-hall exercise relating to one term in the Drake equation, namely the lifetime of technical civilizations.

Brown, Timothy M.

292

Commission 53: Extrasolar Planets  

NASA Astrophysics Data System (ADS)

Commission 53 was created at the 2006 Prague General Assembly (GA) of the IAU, in recognition of the outburst of astronomical progress in the field of extrasolar planet discovery, characterization, and theoretical work that has occurred since the discovery of the first planet in orbit around a solar-type star in 1995. Commission 53 is the logical successor to the IAU Working Group on Extrasolar Planets (WGESP), which ended its six years of existence in August 2006. The founding President of Commission 53 was Michael Mayor, in honor of his seminal contributions to this new field of astronomy. The current President is Alan Boss, the former chair of the WGESP. The current members of the Commission 53 (C53) Organizing Committee (OC) began their service in August 2009 at the conclusion of the Rio de Janeiro IAU GA.

Boss, Alan; Lecavelier des Etangs, Alain; Mayor, Michel; Bodenheimer, Peter; Collier-Cameron, Andrew; Kokubo, Eiichiro; Mardling, Rosemary; Minniti, Dante; Queloz, Didier

2012-04-01

293

Trojan planets in HD108874?  

NASA Astrophysics Data System (ADS)

Today there are about 190 extrasolar planets in 156 extrasolar systems confirmed. We have only observational evidence for planets from 7 (Gliese 876 d) earth masses up to several Jupiter masses; and up to now no planet with a mass comparable to the Earth was found. To ensure that an orbit of such a planet is stable in the so-called habitable zone around a host star in planetary systems with Jupiter-like planets we can have different confugurations: either a hot Jupiter (very close to the central star) or (and) a planet far enough not to perturb the motions of a planetary body in the habitable zone (which depends on the astrophysical parameters of the star). Besides the two former mentioned possibilites there may exist also stable orbits around a 'Jupiter' in this habitable zone: a planet as satelliteor - we cannot exclude it - a Trojan planet. For the first time in a multiplanetary system, namely in HD108872 (a sunlike star), we found that Trojan planets may exist in the 1:1 resonance with the inner Jupiter-like planet (with a semimajor axis of approximately 1AU). We investigate the region around the Lagrange points for a wide range of the orbital parameters of the two planets. It turned out that with the actually determined orbital elements of both planets (for HD108874c a=2.7AU) a small region around the Lagrange points may host earth-like planets in the habitable zone of this star.

Schwarz, R.; Dvorak, R.; Pilat-Lohinger, E.; Erdi, B.

294

Location of Planet X  

SciTech Connect

Observed positions of Uranus and Neptune along with residuals in right ascension and declination are used to constrain the location of a postulated tenth planet. The residuals are converted into residuals in ecliptic longitude and latitude. The results are then combined into seasonal normal points, producing average geocentric residuals spaced slightly more than a year apart that are assumed to represent the equivalent heliocentric average residuals for the observed oppositions. Such a planet is found to most likely reside in the region of Scorpius, with considerably less likelihood that it is in Taurus. 8 references.

Harrington, R.S.

1988-10-01

295

How giant planets cool  

NASA Astrophysics Data System (ADS)

Understanding how giant planets cool is key to the study of their interior structure, composition and hence formation. I will review how the observed luminosities of Jupiter, Saturn, Uranus and Neptune may be accounted for, mostly by convective transport of heat limited by the atmospheric lip, but with several complications (sedimentation of helium droplets, gradients of composition...). Conversely, I will show that the the cooling of strongly irradiated giant planets ("Pegasids") is limited by heat transport in a thick external radiative zone with a possibility of a significant dissipation of heat due to tides. In all cases, both radiative transport and atmospheric/interior dynamics play crucial roles and require further studies.

Guillot, T.

2006-12-01

296

Five New Extrasolar Planets  

NASA Astrophysics Data System (ADS)

We report multiple Doppler measurements of five nearby FGK main-sequence stars and subgiants obtained during the past 4-6 yr at the Keck Observatory. These stars, namely, HD 183263, HD 117207, HD 188015, HD 45350, and HD 99492, all exhibit coherent variations in their Doppler shifts consistent with a planet in Keplerian motion. The five new planets occupy known realms of planetary parameter space, including a wide range of orbital eccentricities, e=0-0.78, and semimajor axes, 0.1-3.8 AU, that provide further statistical information about the true distributions of various properties of planetary systems. One of the planets, HD 99492b, has a low minimum mass of 0.112MJup=36MEarth. Four of the five planets orbit beyond 1 AU. We describe two quantitative tests of the false alarm probability for Keplerian interpretations of measured velocities. The more robust of these involves Monte Carlo realizations of scrambled velocities as a proxy for noise. Keplerian orbital fits to that ``noise'' yield the distribution of ?2? to compare with ?2? from the original (unscrambled) velocities. We establish a 1% false alarm probability as the criterion for candidate planets. All five of these planet-bearing stars are metal-rich, with [Fe/H]>+0.27, reinforcing the strong correlation between planet occurrence and metallicity. From the full sample of 1330 stars monitored at Keck, Lick, and the Anglo-Australian Telescope, the shortest orbital period for any planet is 2.64 days, showing that shorter periods occur less frequently than 0.1% in the solar neighborhood. Photometric observations were acquired for four of the five host stars with an automatic telescope at Fairborn Observatory. The lack of brightness variations in phase with the radial velocities supports planetary-reflex motion as the cause of the velocity variations. No transits were observed, but their occurrence is not ruled out by our observations. Based on observations obtained at the W. M. Keck Observatory, which is operated jointly by the University of California and the California Institute of Technology. Keck time has been granted by both NASA and the University of California.

Marcy, Geoffrey W.; Butler, R. Paul; Vogt, Steven S.; Fischer, Debra A.; Henry, Gregory W.; Laughlin, Greg; Wright, Jason T.; Johnson, John A.

2005-01-01

297

LONG RANGE OUTWARD MIGRATION OF GIANT PLANETS, WITH APPLICATION TO FOMALHAUT b  

SciTech Connect

Recent observations of exoplanets by direct imaging reveal that giant planets orbit at a few dozens to more than a hundred AU from their central star. The question of the origin of these planets challenges the standard theories of planet formation. We propose a new way of obtaining such far planets, by outward migration of a pair of planets formed in the 10 AU region. Two giant planets in mean motion resonance in a common gap in the protoplanetary disk migrate outward, if the inner one is significantly more massive than the outer one. Using hydrodynamical simulations, we show that their semimajor axes can increase by almost 1 order of magnitude. In a flared disk, the pair of planets should reach an asymptotic radius. This mechanism could account for the presence of Fomalhaut b; then, a second, more massive planet, should be orbiting Fomalhaut at about 75 AU.

Crida, Aurelien [Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA (United Kingdom); Masset, Frederic [Laboratoire AIM-UMR 7158, CEA/CNRS/Universite Paris Diderot, IRFU/Service d'Astrophysique, CEA/Saclay, 91191 Gif-sur-Yvette Cedex (France); Morbidelli, Alessandro, E-mail: A.Crida@damtp.cam.ac.u [Laboratoire Cassiopee UMR 6202, Universite de Nice Sophia-antipolis/Observatoire de la Cote d'Azur/CNRS, B.P. 4229, 06304 Nice Cedex 4 (France)

2009-11-10

298

Looking for Planets in all the Right Places  

NASA Astrophysics Data System (ADS)

Gravitational lensing has the potential to discover planets in orbits of all sizes, orbiting both nearby and distant stars. Until recently, however, searches for planets via lensing have been conducted by programs best suited to finding only a subset of planetary lenses. During the past year several new approaches have been developed, including searches for small periodic signals near baseline, and monitoring nearby stars. By taking these approaches, we will extend our search for planets to *all* the right places, and will increase the discovery rate. In addition, the extended lensing searches will discover nearby planetary systems that can subsequently be observed using the full range of planet-study techniques, including transit and radial velocity studies as well as direct imaging. I will talk about the theory and also about preliminary results from our monitoring of the first predicted lensing event for evidence of planets orbiting the nearby dwarf star VB 10.

Di Stefano, Rosanne

2012-05-01

299

Planet Detection: The Kepler Mission  

NASA Astrophysics Data System (ADS)

The search for exoplanets is one of the hottest topics in astronomy and astrophysics in the twenty-first century, capturing the public's attention as well as that of the astronomical community. This nascent field was conceived in 1989 with the discovery of a candidate planetary companion to HD114762 [35] and was born in 1995 with the discovery of the first extrasolar planet 51 Peg-b [37] orbiting a main sequence star. As of March, 2011, over 500 exoplanets have been discovered* and 106 are known to transit or cross their host star, as viewed from Earth. Of these transiting planets, 15 have been announced by the Kepler Mission, which was launched into an Earth-trailing, heliocentric orbit in March, 2009 [1,4,6,15,18,20,22,31,32,34,36,43]. In addition, over 1200 candidate transiting planets have already been detected by Kepler [5], and vigorous follow-up observations are being conducted to vet these candidates. As the false-positive rate for Kepler is expected to be quite low [39], Kepler has effectively tripled the number of known exoplanets. Moreover, Kepler will provide an unprecedented data set in terms of photometric precision, duration, contiguity, and number of stars. Kepler's primary science objective is to determine the frequency of Earth-size planets transiting their Sun-like host stars in the habitable zone, that range of orbital distances for which liquid water would pool on the surface of a terrestrial planet such as Earth, Mars, or Venus. This daunting task demands an instrument capable of measuring the light output from each of over 100,000 stars simultaneously with an unprecedented photometric precision of 20 parts per million (ppm) at 6.5-h intervals. The large number of stars is required because the probability of the geometrical alignment of planetary orbits that permit observation of transits is the ratio of the size of the star to the size of the planetary orbit. For Earth-like planets in 1-astronomical unit (AU) orbits† about sun-like stars, only ˜0.5% will exhibit transits. By observing such a large number of stars, Kepler is guaranteed to produce a robust null result in the unhappy event that no Earth-size planets are detected in or near the habitable zone. Such a result would indicate that worlds like ours are extremely rare in the Milky Way galaxy and perhaps the cosmos, and that we might be solitary sojourners in the quest to answer the age-old question: "Are we alone?" Kepler is an audacious mission that places rigorous demands on the science pipeline used to process the ever-accumulating, large amount of data and to identify and characterize the minute planetary signatures hiding in the data haystack. Kepler observes over 160,000 stars simultaneously over a field of view (FOV) of 115 square degrees with a focal plane consisting of 42 charge-coupled devices‡ (CCDs), each of which images 2.75 square degrees of sky onto 2200×1024 pixels. The photometer, which contains the CCD array, reads out each CCD every 6.54 s [10,11] and co-adds the images for 29.4 min, called a long cadence (LC) interval. Due to storage and bandwidth constraints, only the pixels of interest, those that contain images of target stars, are saved onboard the solid-state recorder (SSR), which can store 66+ days of data. An average of 32 pixels per star is allowed for up to 170,000 stellar target definitions. In addition, a total of 512 targets are sampled at 58.85-s short cadence (SC) intervals, permitting further characterization of the planet-star systems for the brighter stars with a Kepler magnitude,* Kp, brighter than 12 (Kp < 12) stars via asteroseismology [17], and more precise transit timing. In addition to the stellar images, collateral data used for calibration (CAL) are also collected and stored on the SSR. For each of the 84 CCD readout channels these data include up to 4500 background sky pixels used to estimate and remove diffuse stellar background and zodiacal light; 1100 pixels containing masked smear measurements and another 1100 pixels containing virtual smear measurements used to remove art

Jenkins, Jon M.; Smith, Jeffrey C.; Tenenbaum, Peter; Twicken, Joseph D.; Van Cleve, Jeffrey

2012-03-01

300

Microlensing detection of extrasolar planets  

NASA Astrophysics Data System (ADS)

We review the method of exoplanetary microlensing with a focus on two-body planetary lensing systems. The physical properties of planetary systems can be successfully measured by means of a deep analysis of lightcurves and high-resolution imaging of planetary systems, countering the concern that microlensing cannot determine planetary masses and orbital radii. Ground-based observers have had success in diagnosing properties of multi-planet systems from a few events, but space-based observations will be much more powerful and statistically more complete. Since microlensing is most sensitive to exoplanets beyond the snow line, whose statistics, in turn, allow for testing current planetary formation and evolution theories, we investigate the retrieval of semi-major axis density by a microlensing space-based survey with realistic parameters. Making use of a published statistical method for projected exoplanets quantities (Brown 2011), we find that one year of such a survey might distinguish between simple power-law semi-major axis densities. We conclude by briefly reviewing ground-based results hinting at a high abundance of free-floating planets and describing the potential contribution of space-based missions to understanding the frequency and mass distribution of these intriguing objects, which could help unveil the formation processes of planetary systems.

Giannini, Emanuela; Lunine, Jonathan I.

2013-05-01

301

Microlensing detection of extrasolar planets.  

PubMed

We review the method of exoplanetary microlensing with a focus on two-body planetary lensing systems. The physical properties of planetary systems can be successfully measured by means of a deep analysis of lightcurves and high-resolution imaging of planetary systems, countering the concern that microlensing cannot determine planetary masses and orbital radii. Ground-based observers have had success in diagnosing properties of multi-planet systems from a few events, but space-based observations will be much more powerful and statistically more complete. Since microlensing is most sensitive to exoplanets beyond the snow line, whose statistics, in turn, allow for testing current planetary formation and evolution theories, we investigate the retrieval of semi-major axis density by a microlensing space-based survey with realistic parameters. Making use of a published statistical method for projected exoplanets quantities (Brown 2011), we find that one year of such a survey might distinguish between simple power-law semi-major axis densities. We conclude by briefly reviewing ground-based results hinting at a high abundance of free-floating planets and describing the potential contribution of space-based missions to understanding the frequency and mass distribution of these intriguing objects, which could help unveil the formation processes of planetary systems. PMID:23604071

Giannini, Emanuela; Lunine, Jonathan I

2013-04-19

302

Space based microlensing planet searches  

NASA Astrophysics Data System (ADS)

The discovery of extra-solar planets is arguably the most exciting development in astrophysics during the past 15 years, rivalled only by the detection of dark energy. Two projects unite the communities of exoplanet scientists and cosmologists: the proposed ESA M class mission EUCLID and the large space mission WFIRST, top ranked by the Astronomy 2010 Decadal Survey report. The later states that: "Space-based microlensing is the optimal approach to providing a true statistical census of planetary systems in the Galaxy, over a range of likely semi-major axes". They also add: "This census, combined with that made by the Kepler mission, will determine how common Earth-like planets are over a wide range of orbital parameters". We will present a status report of the results obtained by microlensing on exoplanets and the new objectives of the next generation of ground based wide field imager networks. We will finally discuss the fantastic prospect offered by space based microlensing at the horizon 2020-2025.

Beaulieu, Jean-Philippe; Tisserand, Patrick; Batista, Virginie

2013-04-01

303

Unique aggregation behavior of a carboxylate gemini surfactant with a long rigid spacer in aqueous solution.  

PubMed

A new gemini surfactant with a long and rigid spacer, O,O'-bis(sodium 2-dodecylcarboxylate)-p-dibenzenediol (referred to as C(12)?(2)C(12)), has been synthesized. Its aggregation in aqueous solution has been studied using static and dynamic light scattering measurements. The homologue O,O'-bis(sodium 2-dodecylcarboxylate)-p-benzenediol (C(12)?C(12)) whose spacer only contains a single phenyl group was also examined for comparison. Dynamic light scattering (DLS) revealed the unexpected existence of large aggregates in the solution of C(12)?(2)C(12). However, C(12)?C(12) showed rather normal aggregation behavior. Both the results of intrinsic viscosity and light scattering demonstrated a loose structure for the large aggregates of C(12)?(2)C(12). This behavior was attributed to an extending configuration of C(12)?(2)C(12) with the two alkyl tails stretching toward the solution due to the rigidity of the long spacer. The large network-like aggregate formation was an inevitable outcome of spontaneously reducing the energy of the system. Freeze-fracture transmission electron microscopy (FF-TEM) images and (1)H NMR measurements supported this speculation. Due to the columnar-like molecular geometry, the large network-like aggregates were directly transformed into rodlike micelles with increasing surfactant concentration. Depending on further micellar growth, the wormlike micelles were finally formed as confirmed by rheological measurements. PMID:23244594

Xie, Dan Hua; Zhao, Jianxi

2012-12-31

304

RADIO GALAXY 3C 230 OBSERVED WITH GEMINI LASER ADAPTIVE-OPTICS INTEGRAL-FIELD SPECTROSCOPY  

SciTech Connect

The Altair laser-guide-star adaptive optics facility combined with the near-infrared integral-field spectrometer on Gemini North have been employed to study the morphology and kinematics of 3C 230 at z = 1.5, the first such observations of a high-redshift radio galaxy. These suggest a bi-polar outflow spanning 0.''9 ({approx}16 kpc projected distance for a standard {Lambda} CDM cosmology) reaching a mean relative velocity of 235 km s{sup -1} in redshifted H{alpha} +[N II] and [S II] emission. Structure is resolved to 0.''1 (0.8 kpc), which is well correlated with optical images from the Hubble Space Telescope and Very Large Array radio maps obtained at similar spatial resolution. Line diagnostics suggest that over the 10{sup 7} yr to 10{sup 8} yr duration of its active galactic nucleus activity, gas has been ejected into bright turbulent lobes at rates comparable to star formation, although constituting perhaps only 1% of the baryonic mass in the galaxy.

Steinbring, Eric [Herzberg Institute of Astrophysics, National Research Council Canada, Victoria, BC V9E 2E7 (Canada)

2011-11-15

305

NEAR-INFRARED OBSERVATIONS OF GQ LUP b USING THE GEMINI INTEGRAL FIELD SPECTROGRAPH NIFS  

SciTech Connect

We present new JHK spectroscopy (R approx 5000) of GQ Lup b, acquired with the Near-Infrared Integral Field Spectrograph and the adaptive optics system ALTAIR at the Gemini North telescope. Angular differential imaging was used in the J and H bands to suppress the speckle noise from GQ Lup A; we show that this approach can provide improvements in signal-to-noise ratio (S/N) by a factor of 2-6 for companions located at subarcsecond separations. Based on high-quality observations and Global Astrometric lnterferometer for Astrophysics synthetic spectra, we estimate the companion effective temperature to T {sub eff} = 2400 +- 100 K, its gravity to log g = 4.0 +- 0.5, and its luminosity to log(L/L {sub sun}) = -2.47 +- 0.28. Comparisons with the predictions of the DUSTY evolutionary tracks allow us to constrain the mass of GQ Lup b to 8-60 M {sub Jup}, most likely in the brown dwarf regime. Compared with the spectra published by Seifahrt and collaborators, our spectra of GQ Lup b are significantly redder (by 15%-50%) and do not show important Pabeta emission. Our spectra are in excellent agreement with the lower S/N spectra previously published by McElwain and collaborators.

Lavigne, Jean-Francois; Doyon, Rene [Departement de physique and Observatoire du Mont Megantic, Universite de Montreal, C.P. 6128, Succ. Centre-Ville, Montreal, QC, H3C 3J7 (Canada); Lafreniere, David [Department of Astronomy and Astrophysics, University of Toronto, 50 Street George Street, Toronto, ON, M5S 3H4 (Canada); Marois, Christian [NRC Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC, V9E 2E7 (Canada); Barman, Travis, E-mail: lavigne@astro.umontreal.c [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States)

2009-10-20

306

GEOLogic: Terrestrial and Jovian Planets  

NSDL National Science Digital Library

In this two-part example, students are given clues about properties about the terrestrial and Jovian planets respectively and asked to match up the planet with the correct equatorial radius, mean orbital velocity, and period of rotation.

Guertin, Laura

307

NASA Reveals Most Unusual Planet  

NASA Video Gallery

In exploring the universe, NASA has uncovered one planet more unusual than all others. This 30 second video shows you which planet that is, and explains that NASA science helps us better understand this world without equal.

gsfcvideo

2010-07-01

308

Planet formation: Protoplanetary disk removal and rotational stability of planets  

NASA Astrophysics Data System (ADS)

There are many unsolved problems in the physics of planet formation and the evolution of their parent disk is expected to play an important role in resolving them. In part I of this thesis, I discuss the evolution of protoplanetary disks under the influence of viscous evolution, photoevaporation from the central source, and photo evaporation by external stars; and explore the consequences for planet formation. The discovery of hot jupiters orbiting at a few AU from their stars compliments earlier detections of massive planets on very small orbits. The short period orbits strongly suggest that planet migration has occurred, with the likely mechanism being tidal interactions between the planets and the gas disks out of which they formed. The newly discovered long period planets, together with the gas giant planets in our solar system, show that migration is either absent or rapidly halted in at least some systems. I propose a mechanism for halting type-II migration at several AU in a gas disk: the formation of a photoevaporation gap prevents planets outside the gap from migrating down to the star. The final planet location relative to the habitable zone is often used to discuss the planet habitability. But a planet in the habitable zone may experience large amplitude motion of its rotation axis, which may cause severe climate variations and have major consequences for the development of life. In part II of this thesis, I investigate the true polar wander (TPW) rotational stability of planets. I revisit the classic problem of the long-term rotational stability of planets in response to loading using a new, generalized theoretical development based on the fluid limit of viscoelastic Love number theory. Finally, I explore the time dependent (rather than the equilibrium fluid limit) rotational stability of planets by considering the example of an ice age Earth. I present a new treatment of the linearized Euler equations that govern rotation perturbations on a viscoelastic planet driven by surface loading.

Matsuyama, Isamu Manuel

2005-11-01

309

Accumulation of the Planets  

NASA Astrophysics Data System (ADS)

The purpose of this project is to increase understanding of planet forming processes that are likely to have occurred in the Solar System during its early evolution. This was accomplished by development of computer models that are compatible with the present state of the Solar System as well as with observational and theoretical data attained from astrophysical observations and theory.

Wetherill, George W.

2002-09-01

310

Planets for Man.  

National Technical Information Service (NTIS)

Planets for Man was written at the height of the space race, a few years before the first moon landing, when it was assumed that in the not-too- distant future human beings 'will be able to travel the vast distances to other stars.' The authors propose to...

I. Asimov S. Dole

2007-01-01

311

The Centers of Planets  

Microsoft Academic Search

Because it is impossible to penetrate to the centers of planets, scientists must probe with experiments and simulations. Three techniques have provided insights: diamond-anvil cells, shock-wave experiments and molecular simulations. Each tries to create tiny worlds in which matter is compressed to high pressures where extreme transformations take place. To date, these methods have shown that Neptune must be filled

Sandro Scandolo; Raymond Jeanloz

2003-01-01

312

Take a Planet Walk  

ERIC Educational Resources Information Center

|Physical models in the classroom "cannot be expected to represent the full-scale phenomenon with complete accuracy, not even in the limited set of characteristics being studied" (AAAS 1990). Therefore, by modifying a popular classroom activity called a "planet walk," teachers can explore upper elementary students' current understandings; create…

Schuster, Dwight

2008-01-01

313

Extrasolar Planets in the Classroom  

ERIC Educational Resources Information Center

|The field of extrasolar planets is still, in comparison with other astrophysical topics, in its infancy. There have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques. Here we present a simple laboratory experiment to show how planets are detected using the transit technique.…

George, Samuel J.

2011-01-01

314

Dynamics of disks with planets  

Microsoft Academic Search

We review several theories of origin and evolution of the recently discovered extrasolar planetary systems. The properties of these systems were unexpected. This motivated theorists to extend and revise many preexisting the- ories. Important extensions include migration of bodies and planetary eccentric- ity pumping by planet-planet interaction, and primordial disk-planet interaction. Progress in observational techniques might allow us to nd

Pawel Artymowicz

315

Looking for a habitable planet  

Microsoft Academic Search

Only very favorable combination of many physical parameters may provide the necessary con-ditions for unicellular organisms to evolve into multicellular animals. The main factors of the planet, that is critical for the evolution and existence of life, form a peculiar labyrinth with many impasses. Most important are mass and temperature conditions on the planet. The planet that meets RNA\\/ DNA

Leonid Ksanfomality

2010-01-01

316

Terrestrial Planets Accreted Dry  

NASA Astrophysics Data System (ADS)

Plate tectonics shaped the Earth, whereas the Moon is a dry and inactive desert. Mars probably came to rest within the first billion years of its history, and Venus, although internally very active, has a dry inferno for its surface. The strong gravity field of a large planet allows for an enormous amount of gravitational energy to be released, causing the outer part of the planetary body to melt (magma ocean), helps retain water on the planet, and increases the pressure gradient. The weak gravity field and anhydrous conditions prevailing on the Moon stabilized, on top of its magma ocean, a thick buoyant plagioclase lithosphere, which insulated the molten interior. On Earth, the buoyant hydrous phases (serpentines) produced by reactions between the terrestrial magma ocean and the wet impactors received from the outer Solar System isolated the magma and kept it molten for some few tens of million years. The elemental distributions and the range of condensation temperatures show that the planets from the inner Solar System accreted dry. The interior of planets that lost up to 95% of their K cannot contain much water. Foundering of their wet surface material softened the terrestrial mantle and set the scene for the onset of plate tectonics. This very same process may have removed all the water from the surface of Venus 500 My ago and added enough water to its mantle to make its internal dynamics very strong and keep the surface very young. Because of a radius smaller than that of the Earth, not enough water could be drawn into the Martian mantle before it was lost to space and Martian plate tectonics never began. The radius of a planet therefore is the key parameter controlling most of its evolutional features.

Albarede, F.; Blichert-Toft, J.

2007-12-01

317

Earthshine and Extrasolar Planets  

NASA Astrophysics Data System (ADS)

The search for life on extrasolar planets requires first that we find terrestrial-mass planets around nearby stars, and second that we determine habitability and search for signs of life. The Terrestrial Planet Finder missions, a Coronagraph (TPF-C) and an Interferometer (TPF-I in the US, also Darwin in Europe) are designed to carry out these tasks. This talk will focus on how we could determine habitability and search for signs of life with these missions. In the visible and near-infrared, TPF-C could measure O2, H2O, O3, Rayleigh scattering, and the red-edge reflection of land planet leaves; on an early-Earth twin it also could measure CO2 and CH4. In the mid-infrared, TPF-I/Darwin could measure CO2, O3, H2O, and temperature. To validate some of these expectations, we observed Earthshine spectra in the visible and near-infrared, and modeled these spectra with our line-by-line radiative transfer code. We find that the major gas and reflection components are present in the data, and that a simple model of the Earth is adequate to represent the data, within the observational uncertainties. We determined that the Earth appears to be habitable, and also shows signs of life. However to validate the time variable features, including the continent-ocean differences, the presence of weather patterns, the large-scale variability of cloud types and altitude, and the rotation period of the planet, we need to obtain a continuous time-series of observations covering multiple rotations; these observations could be carried out in the coming years, using, for example, a site at the South Pole.

Traub, W. A.; Kaltenegger, L.; Turnbull, M. C.; Jucks, K. W.

2006-05-01

318

Almost All of Kepler's Multiple-planet Candidates Are Planets  

NASA Astrophysics Data System (ADS)

We present a statistical analysis that demonstrates that the overwhelming majority of Kepler candidate multiple transiting systems (multis) indeed represent true, physically associated transiting planets. Binary stars provide the primary source of false positives among Kepler planet candidates, implying that false positives should be nearly randomly distributed among Kepler targets. In contrast, true transiting planets would appear clustered around a smaller number of Kepler targets if detectable planets tend to come in systems and/or if the orbital planes of planets encircling the same star are correlated. There are more than one hundred times as many Kepler planet candidates in multi-candidate systems as would be predicted from a random distribution of candidates, implying that the vast majority are true planets. Most of these multis are multiple-planet systems orbiting the Kepler target star, but there are likely cases where (1) the planetary system orbits a fainter star, and the planets are thus significantly larger than has been estimated, or (2) the planets orbit different stars within a binary/multiple star system. We use the low overall false-positive rate among Kepler multis, together with analysis of Kepler spacecraft and ground-based data, to validate the closely packed Kepler-33 planetary system, which orbits a star that has evolved somewhat off of the main sequence. Kepler-33 hosts five transiting planets, with periods ranging from 5.67 to 41 days.

Lissauer, Jack J.; Marcy, Geoffrey W.; Rowe, Jason F.; Bryson, Stephen T.; Adams, Elisabeth; Buchhave, Lars A.; Ciardi, David R.; Cochran, William D.; Fabrycky, Daniel C.; Ford, Eric B.; Fressin, Francois; Geary, John; Gilliland, Ronald L.; Holman, Matthew J.; Howell, Steve B.; Jenkins, Jon M.; Kinemuchi, Karen; Koch, David G.; Morehead, Robert C.; Ragozzine, Darin; Seader, Shawn E.; Tanenbaum, Peter G.; Torres, Guillermo; Twicken, Joseph D.

2012-05-01

319

RADARGRAMMETRY ON THREE PLANETS  

Microsoft Academic Search

Synthetic Aperture Radar (SAR) can provide useful images in situations where passive optical imaging cannot, either because the microwaves used can penetrate atmospheric clouds, because active imaging can \\

R. L. Kirk; E. Howington-Kraus

320

Examine the vast distances between planets in the solar system  

NSDL National Science Digital Library

This animation is designed to help middle and high school students conceptualize the enormous interplanetary distances in space. The introduction provides background information about the distances between planets and how long it would take modern spacecraft to travel between them. The animation, moving at a virtual 300 times the speed of light, takes students on a journey from the sun, through the nine planets, to just beyond Pluto. As each planet appears, it is labeled with its name and distance from the sun. Movie controls allow students to repeat, pause, or step through the animation, which can give students more time to analyze the images. Copyright 2005 Eisenhower National Clearinghouse

Education, Terc. C.; Littell, Mcdougal

2003-01-01

321

Cellular uptake of polyurethane nanocarriers mediated by gemini quaternary ammonium.  

PubMed

The effective passage of drug formulations into tumor cells is a key factor in the development of nanoscale delivery systems. However, rapid cellular uptake with reduced toxicity remains a great challenge for efficient and safe delivery. In this study, we first use gemini quaternary ammonium (GQA) as a cell internalization promoter to enhance the cellular uptake of drug nanocarriers. It is found that a twenty times faster cell internalization could be achieved by introducing GQA into biodegradable multiblock polyurethane nanomicelles, as confirmed by flow cytometry and confocal laser scanning microscopy (CLSM) studies. Meanwhile, an added methoxyl-poly(ethylene glycol) (mPEG) outer corona could protect these cationic micelles from cytotoxicity at high concentrations, as verified by methyl tetrazolium (MTT) assay. Moreover, GQA not only acts as an enhancer for rapid cellular entry, but also plays an important role in controlled self-assembly and high drug loading capacity. Our work offers a new understanding on the role of cationic surfactants; and provides a facile and economical approach for the design of versatile drug nanocarriers to achieve efficient delivery and good biocompatibility. PMID:21907404

Ding, Mingming; He, Xueling; Wang, Zhigao; Li, Jiehua; Tan, Hong; Deng, Hua; Fu, Qiang; Gu, Qun

2011-09-09

322

Oleic acid-based gemini surfactants with carboxylic acid headgroups.  

PubMed

Anionic gemini surfactants with carboxylic acid headgroups have been synthesized from oleic acid. The hydrocarbon chain is covalently bound to the terminal carbonyl group of oleic acid via an ester bond, and the carboxylic acid headgroups are introduced to the cis double bond of oleic acid via disuccinyl units. The surfactants exhibit pH-dependent protonation-deprotonation behavior in aqueous solutions. In alkaline solutions (pH 9 in the presence of 10 mmol dm(-3) NaCl as the background electrolyte), the surfactants can lower the surface tension as well as form molecular assemblies, even in the region of low surfactant concentrations. Under acidic (pH 3) or neutral (pH 6-7) conditions, the surfactants are intrinsically insoluble in aqueous media and form a monolayer at the air/water interface. In this study, we have investigated physicochemical properties such as the function of the hydrocarbon chain length by means of static surface tension, pyrene fluorescence, dynamic light scattering, surface pressure-area isotherms, and infrared external reflection measurements. PMID:21768742

Sakai, Kenichi; Umemoto, Naoki; Matsuda, Wataru; Takamatsu, Yuichiro; Matsumoto, Mutsuyoshi; Sakai, Hideki; Abe, Masahiko

2011-01-01

323

Anionic Gemini Surfactants:. Synthesis and Surface Active Properties  

NASA Astrophysics Data System (ADS)

New compounds bearing two phosphate groups and two long chain (dodecyl) were prepared by two-step reaction: (i) phosphorylation of dodecanol with pyrophosphoric acid, (ii) reaction of dodecyl phosphate with N(CH3)4OH and 1,6-dibromo hexane. The effect of reaction variables like time and molar ratio of reactants on yield has also been reported. The 1:2:0.5 molar ratio of reactants (dodecyl phosphate, N(CH3)4OH, and Br(CH2)6 Br, respectively) and 3 h duration resulted to give maximum yield of anionic gemini surfactants. The structure of synthesized surfactant was investigated by modern analytical techniques, viz. FT-IR, 1H NMR, 13C NMR. Amphipathic disodium phosphates were obtained by neutralization of free acids with sodium hydroxide and their surface active properties in aqueous solution were measured. These disodium phosphates possessed 77.3% anionic content and showed good water solubility. Foaming properties and wetting ability were also evaluated.

Shukla, Dipti; Tyagi, V. K.

324

Probing the Planet-Forming Region of T Tauri Stars in Chamaeleon  

NASA Astrophysics Data System (ADS)

By studying the inner, planet-forming regions of circumstellar disks around low-mass pre-main sequence stars we can refine theories of giant planet formation and develop timescales for the evolution of disks and their planets. Spitzer infrared observations of T Tauri stars in the Chamaeleon star-forming region have given us an unprecedented look at dust evolution in young objects. However, despite this ground breaking progress in studying the dust in young disks, the gas properties of the inner disk remain essentially unknown. Using the high-resolution of Phoenix, we propose to measure the 4.7 (micron) CO fundamental emission originating in the innermost disk regions of classical T Tauri stars in different stages of evolution with the objective of revealing the timescales of gas dissipation and its relationship to dust dissipation. With the combined results of Spitzer and Gemini, our theoretical analysis will unveil the state of the dust and gas in disks in which planets may already be forming and starting to open gaps.

Espaillat, Catherine; Calvet, Nuria; Bergin, Edwin; Hartmann, Lee; Hinkle, Kenneth

2007-02-01

325

Near-infrared spectroscopic search for the close orbiting planet HD 75289b  

NASA Astrophysics Data System (ADS)

We present a search for the near-infrared spectroscopic signature of the close orbiting extrasolar giant planet HD 75289b. We obtained ~230 spectra in the wavelength range 2.18-2.19 ?m using the Phoenix spectrograph at Gemini South. By considering the direct spectrum, derived from irradiated model atmospheres, we search for the absorption profile signature present in the combined star and planet light. Since the planetary spectrum is separated from the stellar spectrum at most phases, we apply a phase-dependent orbital model and tomographic techniques to search for absorption signatures. Because the absorption signature lies buried in the noise of a single exposure we apply a multiline deconvolution to the spectral lines available in order to boost the effective signal-to-noise ratio (S/N) of the data. The wavelength coverage of 80 Å is expected to contain ~100 planetary lines, enabling a mean line with S/N of 800 to be achieved after deconvolution. We are nevertheless unable to detect the presence of the planet in the data and carry out further simulations to show that broader wavelength coverage should enable a planet like HD 75289b to be detected with 99.9 per cent confidence. We investigate the sensitivity of our method and estimate detection tolerances for mismatches between observed and model planetary atmospheres.

Barnes, J. R.; Leigh, C. J.; Jones, H. R. A.; Barman, Travis S.; Pinfield, D. J.; Collier Cameron, A.; Jenkins, J. S.

2007-08-01

326

An Infrared Precision Radial Velocity Search for Earth-Mass Planets  

NASA Astrophysics Data System (ADS)

We discuss the scientific motivation and design of the Precision Radial Velocity Spectrograph (PRVS), a potential next generation near-infrared instrument for the Gemini Observatory. PRVS is a fiber-fed, white-pupil, cooled echelle (R=70,000) spectrograph working in the Y, J and H bands. Using a simultaneous arc-line calibration method, long-term instrumental radial velocity precisions of less than 1 m/s can be achieved. Through modelling and simulation of the fundamental Doppler information in the spectra of stars, considerations of intrinsic stellar stability, and the effects of telluric contamination, we conclude that the best place to search for earth-mass planets in the habitable zone using their radial velocity signatures is around mid- to late-M dwarf stars at wavelengths of 1-2 microns. Mock surveys show that PRVS can survey several hundred stars for planets in the range 1-10 earth-mass over a period of five years and provide an important test of planet formation models. We also compare the observing niche of PRVS with other techniques proposed to search for earth-mass planets.

Rayner, John; PRVS Team

2007-05-01

327

PREDICTING PLANETS IN KEPLER MULTI-PLANET SYSTEMS  

SciTech Connect

We investigate whether any multi-planet systems among Kepler candidates (2011 February release) can harbor additional terrestrial-mass planets or smaller bodies. We apply the packed planetary systems hypothesis that suggests all planetary systems are filled to capacity, and use a Hill stability criterion to identify eight two-planet systems with significant gaps between the innermost and outermost planets. For each of these systems, we perform long-term numerical integrations of 10{sup 7} years to investigate the stability of 4000-8000 test particles injected into the gaps. We map out stability regions in orbital parameter space, and therefore quantify the ranges of semimajor axes and eccentricities of stable particles. Strong mean-motion resonances can add additional regions of stability in otherwise unstable parameter space. We derive simple expressions for the extent of the stability regions, which is related to quantities such as the dynamical spacing {Delta}, the separation between two planets in units of their mutual Hill radii. Our results suggest that planets with separation {Delta} < 10 are unlikely to host extensive stability regions, and that about 95 out of a total of 115 two-planet systems in the Kepler sample may have sizeable stability regions. We predict that Kepler candidate systems including KOI 433, KOI 72/Kepler-10, KOI 555, KOI 1596, KOI 904, KOI 223, KOI 1590, and KOI 139 can harbor additional planets or low-mass bodies between the inner and outer detected planets. These predicted planets may be detected by future observations.

Fang, Julia; Margot, Jean-Luc [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)

2012-05-20

328

Exploring the Planets: Discovery  

NSDL National Science Digital Library

This site describes what early civilizations knew about our solar system and how astronomy developed over the centuries. The early theories describing the movements of the planets, development of the first telescopes, and discoveries of the planets Uranus, Neptune and Pluto are some of the topics addressed in Discovery. Here you will find the Pluto discovery plate, the photographic plate taken the day Pluto's position was discovered by Clyde Tombaugh. Other topics covered at this site include: the Renaissance with the ideas of Copernicus and Kepler; the age of the telescope, which traces its development; Galileo, who is credited with discovering the moons of Jupiter, phases of Venus, and the craters on the Moon; and planetary satellites.

329

Exploring the Planets: Jupiter  

NSDL National Science Digital Library

This site contains most of the up-to-date information known about the planet Jupiter, including mean distance from the Sun, length of year, rotation period, mean orbital velocity, inclination of axis, spacecraft encounters, diameter, and number of observed satellites. The Galilean satellites Callisto, Ganymede, Europa, and Io are shown here in their correct positions relative to the planet and the odd moon Amalthea is discussed. There is tabular data on several of the other major moons. There are many thumbnail photographs that can be enlarged, including a grand view of the red spot. The radiation and radio noise of Jupiter is discussed, along with its atmosphere as compared to Saturn. The Galileo mission is discussed and links are provided for more information.

330

From Pebbles to Planets  

NASA Astrophysics Data System (ADS)

Planets form in protoplanetary discs around young stars as dust and ice particles collide to form ever larger bodies. Particle concentration in the turbulent gas flow may be necessary to form the planetesimals which are the building blocks of both the terrestrial planets and the cores of the gas giants and the ice giants. The streaming instability, which feeds off the relative motion of gas and particles, is a powerful mechanism to create overdense particle filaments. These filaments contract under their own gravity to form planetesimals with a wide range of sizes. I will also discuss how the pebbles left over from the planetesimal formation stage can lead to rapid formation of the cores of gas giants, well within the protoplanetary disc life-time, even in wide orbits.

Johansen, Anders

2013-10-01

331

Planet Hunters. V. A Confirmed Jupiter-size Planet in the Habitable Zone and 42 Planet Candidates from the Kepler Archive Data  

NASA Astrophysics Data System (ADS)

We report the latest Planet Hunter results, including PH2 b, a Jupiter-size (R PL = 10.12 ± 0.56 R ?) planet orbiting in the habitable zone of a solar-type star. PH2 b was elevated from candidate status when a series of false-positive tests yielded a 99.9% confidence level that transit events detected around the star KIC 12735740 had a planetary origin. Planet Hunter volunteers have also discovered 42 new planet candidates in the Kepler public archive data, of which 33 have at least 3 transits recorded. Most of these transit candidates have orbital periods longer than 100 days and 20 are potentially located in the habitable zones of their host stars. Nine candidates were detected with only two transit events and the prospective periods are longer than 400 days. The photometric models suggest that these objects have radii that range between those of Neptune and Jupiter. These detections nearly double the number of gas-giant planet candidates orbiting at habitable-zone distances. We conducted spectroscopic observations for nine of the brighter targets to improve the stellar parameters and we obtained adaptive optics imaging for four of the stars to search for blended background or foreground stars that could confuse our photometric modeling. We present an iterative analysis method to derive the stellar and planet properties and uncertainties by combining the available spectroscopic parameters, stellar evolution models, and transiting light curve parameters, weighted by the measurement errors. Planet Hunters is a citizen science project that crowd sources the assessment of NASA Kepler light curves. The discovery of these 43 planet candidates demonstrates the success of citizen scientists at identifying planet candidates, even in longer period orbits with only two or three transit events. .

Wang, Ji; Fischer, Debra A.; Barclay, Thomas; Boyajian, Tabetha S.; Crepp, Justin R.; Schwamb, Megan E.; Lintott, Chris; Jek, Kian J.; Smith, Arfon M.; Parrish, Michael; Schawinski, Kevin; Schmitt, Joseph R.; Giguere, Matthew J.; Brewer, John M.; Lynn, Stuart; Simpson, Robert; Hoekstra, Abe J.; Jacobs, Thomas Lee; LaCourse, Daryll; Schwengeler, Hans Martin; Chopin, Mike; Herszkowicz, Rafal

2013-10-01

332

MASSES, RADII, AND CLOUD PROPERTIES OF THE HR 8799 PLANETS  

SciTech Connect

The near-infrared colors of the planets directly imaged around the A star HR 8799 are much redder than most field brown dwarfs of the same effective temperature. Previous theoretical studies of these objects have concluded that the atmospheres of planets b, c, and d are unusually cloudy or have unusual cloud properties. Some studies have also found that the inferred radii of some or all of the planets disagree with expectations of standard giant planet evolution models. Here, we compare the available data to the predictions of our own set of atmospheric and evolution models that have been extensively tested against observations of field L and T dwarfs, including the reddest L dwarfs. Unlike some previous studies, we require mutually consistent choices for effective temperature, gravity, cloud properties, and planetary radius. This procedure thus yields plausible values for the masses, effective temperatures, and cloud properties of all three planets. We find that the cloud properties of the HR 8799 planets are not unusual but rather follow previously recognized trends, including a gravity dependence on the temperature of the L to T spectral transition-some reasons for which we discuss. We find that the inferred mass of planet b is highly sensitive to whether or not we include the H- and the K-band spectrum in our analysis. Solutions for planets c and d are consistent with the generally accepted constraints on the age of the primary star and orbital dynamics. We also confirm that, like in L and T dwarfs and solar system giant planets, non-equilibrium chemistry driven by atmospheric mixing is also important for these objects. Given the preponderance of data suggesting that the L to T spectral type transition is gravity dependent, we present an exploratory evolution calculation that accounts for this effect. Finally we recompute the bolometric luminosity of all three planets.

Marley, Mark S. [NASA Ames Research Center, MS-245-3, Moffett Field, CA 94035 (United States); Saumon, Didier [Los Alamos National Laboratory, Mail Stop F663, Los Alamos, NM 87545 (United States); Cushing, Michael [Department of Physics and Astronomy, The University of Toledo, 2801 West Bancroft Street, Toledo, OH 43606 (United States); Ackerman, Andrew S. [NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Freedman, Richard, E-mail: Mark.S.Marley@NASA.gov, E-mail: dsaumon@lanl.gov, E-mail: michael.cushing@utoledo.edu, E-mail: andrew.ackerman@nasa.gov, E-mail: jfortney@ucolick.org, E-mail: freedman@darkstar.arc.nasa.gov [SETI Institute and NASA Ames Research Center, MS-245-3, Moffett Field, CA 94035 (United States)

2012-08-01

333

Ocean Planet: Sea Secrets  

NSDL National Science Digital Library

Unit from Smithsonian multidisciplinary ocean curriculum. Lesson plan focuses on ocean bottom features including continental shelf, deep ocean plain, and mid-ocean ridges. Students study the discovery and mapping of seafloor features, learn to read seafloor maps, then create a map of Atlantic seafloor features. Unit includes: background essay; teacher instructions; maps and forms for student activity; discussion questions; all online in PDF format. Resources include online version of Smithsonian Ocean Planet exhibition.

334

Changing Planet: Thawing Permafrost  

NSDL National Science Digital Library

This video explains the current status of permafrost - the frozen ground that covers the top of the world. Because of a warming atmosphere, permafrost has been thawing rapidly and impacting other Earth systems over the last three decades. There is additional cause for concern beyond the far north, because the carbon released from thawing permafrost could raise global temperatures even higher. Changing Planet is produced in partnership with the National Science Foundation.

2011-03-25

335

Sprites on other planets  

NASA Astrophysics Data System (ADS)

Lightning discharges have been observed or inferred in several planets in the solar system, and so it seems reasonable to expect that like on Earth, some form of accompanying transient luminous events (TLEs, e.g. sprites, halos, elves) will occur in the atmospheres of these planets. We present simple calculations of the necessary lightning induced charge-moment changes and possible atmospheric heights for the occurrence of sprites on Venus, Mars, Titan and the gas giants Jupiter and Saturn. The types of thunderstorms and the postulated locations of charge centers are based on published spacecraft data and cloud models. We calculated the values of the conventional breakdown field over a wide range of pressures and temperatures in each planet's atmosphere, based on the parameters for each composition given by Sentman (2004). Assuming that sprites occur below the base of the ionosphere and above the upper-most planetary cloud layer, we show that for reasonable amounts of charge, sprites can be formed in Venus, Jupiter and Saturn, but not in Mars or Titan. For Venus, an intracloud flash with a charge-moment change of 500 C km occurring between the two lower cloud layers (presumably separated by 5 km), a sprite can be triggered approximately at an altitude 90 km above ground, ~20 km above the tops of the upper most cloud layer. For Jupiter, the results suggest that for a charge of 1000C located 30 km below the 1-bar pressure level, a sprite can be ignited at an altitude approximately 100 km above the top visible ammonia cloud layer. The observation methodology for sprites on other planets by orbiting spacecraft is limb observations above the nocturnal hemisphere (Venus, Jupiter) or even nadir view when the lightning light is obscured in the deep atmosphere (Venus, Saturn). The emission lines for planetary sprites were studied in laboratory experiments with appropriate gas mixtures, and are presented in a separate talk.

Yair, Y.; Takahashi, Y.; Ebert, U.; Price, C. G.; Yaniv, R.; Dubrovin, D.; Nijdam, S.; van Veldhuizen, E.

2009-12-01

336

Plant for the Planet  

NSDL National Science Digital Library

This video describes the foundation Plant for the Planet, a foundation created by a 9-year-old German boy, Felix. This foundation has planted more than 500,000 trees in Germany, which he says help sequester carbon and reduce greenhouse gas emissions. The student rallies, first his community and then other children, to plant millions of trees to offset our energy-use emissions.

Change, Young V.

337

Map-a-Planet  

NSDL National Science Digital Library

Since the explosion of online maps and related technologies onto the Internet, it has been relatively easy to find maps of any part of the Earth. Finding detailed maps of the various planets and moons that share the universe with us can be a bit more tricky. Stepping in to fill that gap in online material is the Map-A-Planet site, created and maintained by the United States Geological Survey's Astrogeology Research Program. Visitors to the site will be able create (and download) customizable maps of planets such as Mars and Venus, along with prominent moons such as Callisto (the second largest moon of Jupiter) and Ganymede, which is Jupiter's largest moon. Visitors can also create various levels of maps, ranging from those that are quite basic all the way to those that incorporate more detailed datasets. While the site is certain to be of general interest to most individuals, it may be of particular value to science educators who wish to offer students a rather rich-textured view of these marvelous bodies.

338

The Dependence of Signal-To-Noise Ratio (S\\/N) Between Star Brightness and Background on the Filter Used in Images Taken by the Vulcan Photometric Planet Search Camera  

Microsoft Academic Search

The Vulcan Photometric Planet Search is the ground-based counterpart of Kepler Mission Proposal. The Kepler Proposal calls for the launch of telescope to look intently at a small patch of sky for four year. The mission is designed to look for extra-solar planets that transit sun-like stars. The Kepler Mission should be able to detect Earth-size planets. This goal requires

Jose Mena-Werth

1998-01-01

339

GEMINI: A Computer Program for Two and Three Dimensional Linear Static, and Seismic Structural Analysis, CDC 7600 Version.  

National Technical Information Service (NTIS)

GEMINI is a computer program developed at the Lawrence Livermore National Laboratory for the calculation of static and dynamic response of linear elastic structures by the finite element method. GEMINI has evolved from SAPIV, a program developed at U.C. B...

R. C. Murray

1984-01-01

340

Extreme optics and the search for Earth-like planets  

Microsoft Academic Search

In this paper I describe a new and exciting application of optimization technology. The problem is to design a space tele- scope capable of imaging Earth-like planets around nearby stars. Because of limitations inherent in the wave nature of light, the design problem is one of diraction control so as to provide the extremely high contrast needed to image a

Robert J. Vanderbei

2008-01-01

341

Fusion of gemini based cationic liposomes with cell membrane models: implications for their biological activity.  

PubMed

The interaction of neutral and anionic phospholipid liposomes, used as cell models, with cationic liposomes formulated with 1,2-dimyristoyl-sn-glicero-3-phosphocholine and stereomeric cationic gemini surfactants was investigated by differential scanning calorimetry, fluorescence experiments and dynamic laser light scattering. This study was aimed at rationalizing the different biological features shown by liposomes based on different gemini stereoisomers observed in previous investigations. In fact, to correlate the observed biological activity of liposomes with the molecular structure of their components is critical for a rational and systematic approach to the design of new carriers for drug delivery. The obtained results show that the different stereochemistry of the gemini surfactant controls the interaction and the extent of fusion with different cell models. PMID:23051652

Aleandri, Simone; Bombelli, Cecilia; Bonicelli, Maria Grazia; Bordi, Federico; Giansanti, Luisa; Mancini, Giovanna; Ierino, Marco; Sennato, Simona

2012-10-07

342

Adsorption and Aggregation behaviors of tetrasiloxane-tailed gemini surfactants with (EO)m spacers.  

PubMed

Adsorption and aggregation behaviors of novel tetrasiloxane-tailed gemini surfactants N,N'-ditetrasiloxane-N,N'-digluconamide oligo ethylene glycol diglycidyl (Si-m-Si, where m is the number of ethylene glycol of 1, 2, and 3) were investigasted using surface tension, bromophenol blue encapsulation, dynamic light scattering (DLS), and transmission electron microscope (TEM) methods. The static surface tension of the aqueous Si-m-Si solutions measured at the critical aggregate concentration (CAC) was observed to be lower than that of traditional hydrocarbon gemini surfactants. This suggests that these newly synthesized gemini surfactants are capable of forming a closely packed monolayer film at the air/aqueous solution interface. With a combination of DLS data, TEM measurements, and bromophenol blue entrapment studies, formations of vesicles in Si-m-Si solutions appear to occur at a concentration well above the CAC. Moreover, the size of vesicles depended on their m values. PMID:23438340

Guoyong, Wang; Wenshan, Qu; Zhiping, Du; Wanxu, Wang; Qiuxiao, Li

2013-03-06

343

Synthesis, characterization and comparative evaluation of phenoxy ring containing long chain gemini imidazolium and pyridinium amphiphiles.  

PubMed

Two series of phenoxy ring containing long chain imidazolium and pyridinium based gemini amphiphiles have been synthesized from renewable cardanol oil having different spacers (i. e. -S-(CH(2))(n)-S-, where n is 2, 3, 4 & 6). Critical micelle concentration (cmc) of these new gemini amphiphiles has been determined by conductivity method. Further, these new cationic amphiphiles have been evaluated for their DNA binding capability by agarose gel electrophoresis, ethidium bromide exclusion experiments and transmission electron microscopy (TEM). The cytotoxicity of these new amphiphiles have been evaluated by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Comparative studies of these phenoxy ring containing long chain gemini imidazolium amphiphiles and their pyridinium analogues depicted low cmc values of the later but greater DNA interaction capability and low cytotoxicity of the former series of amphiphiles. PMID:21676409

Bhadani, Avinash; Kataria, Hardeep; Singh, Sukhprit

2011-05-18

344

Generation of fluorocarbon and hydrocarbon hybrid gemini surfactants controlled by micellar miscibility.  

PubMed

Hybrid surfactants were generated through the simple mixing of fluorocarbon and hydrocarbon gemini surfactants in aqueous solutions at 25°C. Disulfide exchange between the disulfide in the spacer chain occurred in the mixed micelles. However, the generation of hybrid gemini surfactants was particularly inhibited by the addition of salt. The suppression of the electrostatic repulsion between the hydrophilic headgroups led to the close packing of the hydrophobic chains in the micelles, resulting in the increased immiscibility of the fluorocarbon and hydrocarbon surfactants. On the other hand, when fluorocarbon-fluorocarbon or hydrocarbon-hydrocarbon surfactants were mixed, equilibrium with a 1:2 ratio of symmetric and dissymmetric gemini surfactants was attained after incubation for 24 h. PMID:23357813

Asakawa, Tsuyoshi; Ozawa, Tadahiro; Ohta, Akio

2013-01-01

345

Reverse micellar extraction of bovine serum albumin - a comparison between the effects of gemini surfactant and its corresponding monomeric surfactant.  

PubMed

Gemini surfactant displayed distinct advantages over monomeric surfactant in the liquid-liquid reverse micellar extraction process. First, less amount of gemini surfactant than monomeric surfactant was needed for transferring almost complete bovine serum albumin (BSA) into organic phase from aqueous phase. Second, the loading capacity of gemini surfactant reverse micelle phase was much higher than that of the corresponding monomeric surfactant reverse micelle. Third, efficient backward extraction (75-92%) of BSA could be effected in a wide pH range from 4 to 9 with gemini surfactant reverse micelle while a pH of ca. 4.3 is prerequisite to the recovery of BSA from monomeric surfactant reverse micelle. So far, the reports about the effect of surfactant structure on protein extraction have been limited. This study indicates the important role of the spacer of gemini surfactant in protein extraction process and may provide more knowledge on how to optimise surfactant structure. PMID:23122163

Xiao, Jing; Cai, Juan; Guo, Xia

2012-09-20

346

The Interior Structure, Composition, and Evolution of Giant Planets  

NASA Astrophysics Data System (ADS)

We discuss our current understanding of the interior structure and thermal evolution of giant planets. This includes the gas giants, such as Jupiter and Saturn, that are primarily composed of hydrogen and helium, as well as the “ice giants,” such as Uranus and Neptune, which are primarily composed of elements heavier than H/He. The effect of different hydrogen equations of state (including new first-principles computations) on Jupiter’s core mass and heavy element distribution is detailed. This variety of the hydrogen equations of state translate into an uncertainty in Jupiter’s core mass of 18 M ? . For Uranus and Neptune we find deep envelope metallicities up to 0.95, perhaps indicating the existence of an eroded core, as also supported by their low luminosity. We discuss the results of simple cooling models of our solar system’s planets, and show that more complex thermal evolution models may be necessary to understand their cooling history. We review how measurements of the masses and radii of the nearly 50 transiting extrasolar giant planets are changing our understanding of giant planets. In particular a fraction of these planets appear to be larger than can be accommodated by standard models of planetary contraction. We review the proposed explanations for the radii of these planets. We also discuss very young giant planets, which are being directly imaged with ground- and space-based telescopes.

Fortney, Jonathan J.; Nettelmann, Nadine

2010-05-01

347

Structural and transfection properties of amine-substituted gemini surfactant-based nanoparticles  

SciTech Connect

Increases in DNA transfection efficiencies for non-viral vectors can be achieved through rational design of novel cationic building blocks. Based on previous results examining DNA condensation by polyamines, novel gemini surfactants have been designed that incorporate aza or imino substituents within the spacer group in order to increase interactions with DNA and potentially improve their DNA transfection ability. Transfection efficiencies and cell toxicity of gemini nanoparticles constructed from plasmid DNA, gemini surfactant, and a neutral lipid were measured in COS7 cells using a luciferase assay. Structural properties of nanoparticles were examined by using circular dichroism, particle size, zeta potential, and small-angle X-ray scattering (SAXS) measurements. The incorporation of aza and imino substituents within the spacer group was observed to enhance the transfection ability of gemini surfactants. Incorporation of an imino group in the structure of the 1,9-bis(dodecyl)-1,1,9,9-tetramethyl-5-imino-1,9-nonanediammonium dibromide surfactant (12-7NH-12) resulted in a statistically significant (p < 0.01) 9-fold increase in transfection compared to an unsubstituted gemini surfactant and a 3-fold increase compared to the corresponding aza-substituted compound. A pH-dependent transition in size and zeta potential was observed to occur at pH 5.5 for complexes formed from the 12-7NH-12 compound. SAXS results show weakly ordered structures and the presence of multiple phases. The incorporation of a pH-active imino group within the spacer of the gemini surfactant results in a significant increase in transfection efficiency that can be related to both pH-induced changes in nanoparticle structure and the formation of multiple phases that more readily allow for membrane fusion that may facilitate DNA release.

Wettig,S.; Badea, I.; Donkuru, M.; Verrall, R.; Foldvari, M.

2007-01-01

348

Gene Transfection in High Serum Levels: Case Studies with New Cholesterol Based Cationic Gemini Lipids  

PubMed Central

Background Six new cationic gemini lipids based on cholesterol possessing different positional combinations of hydroxyethyl (-CH2CH2OH) and oligo-oxyethylene -(CH2CH2O)n- moieties were synthesized. For comparison the corresponding monomeric lipid was also prepared. Each new cationic lipid was found to form stable, clear suspensions in aqueous media. Methodology/Principal Findings To understand the nature of the individual lipid aggregates, we have studied the aggregation properties using transmission electron microscopy (TEM), dynamic light scattering (DLS), zeta potential measurements and X-ray diffraction (XRD). We studied the lipid/DNA complex (lipoplex) formation and the release of the DNA from such lipoplexes using ethidium bromide. These gemini lipids in presence of a helper lipid, 1, 2-dioleoyl phophatidyl ethanol amine (DOPE) showed significant enhancements in the gene transfection compared to several commercially available transfection agents. Cholesterol based gemini having -CH2-CH2-OH groups at the head and one oxyethylene spacer was found to be the most effective lipid, which showed transfection activity even in presence of high serum levels (50%) greater than Effectene, one of the potent commercially available transfecting agents. Most of these geminis protected plasmid DNA remarkably against DNase I in serum, although the degree of stability was found to vary with their structural features. Conclusions/Significance -OH groups present on the cationic headgroups in combination with oxyethylene linkers on cholesterol based geminis, gave an optimized combination of new genera of gemini lipids possessing high transfection efficiency even in presence of very high percentage of serum. This property makes them preferential transfection reagents for possible in vivo studies.

Misra, Santosh K.; Biswas, Joydeep; Kondaiah, Paturu; Bhattacharya, Santanu

2013-01-01

349

Deep-depletion Hamamatsu CCDs for the Gemini multi-object spectrograph  

NASA Astrophysics Data System (ADS)

The instrumentation group of the Herzberg Institute of Astrophysics was commissioned by the Gemini Observatory to develop a new focal plane assembly for the Gemini Multi-Object Spectrograph with an array of three deep-depletion Hamamatsu CCDs. The main objective of the upgrade is to improve the sensitivity of the instrument in the red and nearinfrared wavelengths, with the additional benefits of reduced fringing, faster readout, and better performance in the "nod and shuffle" mode. We describe what we learned about these relatively new CCDs, including several problems encountered during testing, and report on the performance of the system.

Hardy, Tim; Hanna, Kevin; Szeto, Kei; Burley, Greg

2012-07-01

350

Influence of statistical sequential decay on isoscaling and symmetry energy coefficient in a gemini simulation  

SciTech Connect

Extensive calculations on isoscaling behavior with the sequential-decay model gemini are performed for the medium-to-heavy nuclei in the mass range A=60-120 at excitation energies up to 3 MeV/nucleon. The comparison between the products after the first-step decay and the ones after the entire-steps decay demonstrates that there exists a strong sequential decay effect on the final isoscaling parameters and the apparent temperature. Results show that the apparent symmetry energy coefficient {gamma}{sub app} does not reflect the initial symmetry energy coefficient C{sub sym} embedded in the mass calculation in the present gemini model.

Zhou, P. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100080 (China); Tian, W. D.; Ma, Y. G.; Cai, X. Z.; Fang, D. Q.; Wang, H. W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China)

2011-09-15

351

Conceptual design for a high-resolution infrared spectrograph for the 8-m Gemini telescopes  

NASA Astrophysics Data System (ADS)

The High-Resolution Near-InfraRed Spectrograph (HRNIRS) concept for the Gemini telescopes combines a seeing limited R ~ 70000 cross-dispersed mode and an MCAO-fed near diffraction-limited R ~ 30000 multi-object mode into a single compact instrument operating over the 1 - 5 ?m range. The HRNIRS concept was developed in response to proposals issued through the Aspen instrument process by Gemini. Here we review the science drivers and key functional requirements. We present a general overview of the instrument and estimate the limiting performance.

Hinkle, Kenneth H.; Eikenberry, Stephen; Joyce, Richard; Liang, Ming; Muller, Gary; Hileman, Ed; French, Jim; Ge, Jian; Packham, Chris; Julian, Roger; Armandroff, Taft; Gaughan, Neil; Sprayberry, David

2006-07-01

352

Systems engineering and performance modeling of the Gemini High-Resolution Near-Infrared Spectrograph (HRNIRS)  

NASA Astrophysics Data System (ADS)

The High-resolution Near-infrared Spectrograph (HRNIRS) concept for the Gemini telescopes combines a seeing-limited R ~ 7000 cross-dispersed mode and an MCAO-fed near diffraction-limited R ~ 20000 multi-object mode into a single compact instrument operating over the 0.9 - 5.5 ?m range. We describe the systems engineering and performance modeling aspects of this study, emphasizing simulations of high-precision radial verlocity measurements in the Gemini Cassegrain-focus instrument environment.

Eikenberry, Stephen; Hinkle, Kenneth; Joyce, Dick; Liang, Ming; Muller, Gary; Heileman, Ed; French, Jim; Ge, Jian; Packham, Chris; Julian, Roger; Gaughan, Neil; Sprayberry, David

2006-07-01

353

Planet X - ract or fiction  

SciTech Connect

The search for a possible tenth planet in our solar system is examined. The history of the discoveries of Uranus, Neptune, and Pluto are reviewed. Searches of the sky with telescopes and theoretical studies of the gravitational influences on the orbits of known objects in the solar system are discussed. Information obtained during the Pioneer 10 and 11 missions which could suggest the presence of an undiscovered planet and computer simulations of the possible orbit of a tenth planet are presented.

Anderson, J.

1988-08-01

354

Formation of Gas Giant Planets  

NASA Astrophysics Data System (ADS)

The observed physical properties and orbits of giant planets, models of their internal structure and observations of protoplanetary disks provide constraints on the formation of gas giant planets. The four largest planets in our Solar System contain considerable quantities of hydrogen and helium; these gasses could not have condensed into solid planetesimals within the protoplanetary disk. Jupiter and Saturn are mostly hydrogen and helium, but have larger percentages of heavier elements than does the Sun. Neptune and Uranus are primarily composed of elements heavier than helium. The transiting extrasolar planet HD 149026 b, which is slightly more massive than is Saturn, appears to have comparable amounts of light gases and heavy elements. The other observed transiting exoplanets are primarily hydrogen and helium, but may contain supersolar abundances of heavy elements. Spacecraft flybys and observations of satellite orbits provide estimates of the gravitational moments of the giant planets in our Solar System, which in turn provide information on the internal distribution of matter within Jupiter, Saturn, Uranus and Neptune. Atmospheric thermal structure and heat flow measurements constrain the interior temperatures of these planets. Extrasolar planets orbiting very close to their stars almost certainly formed at larger distances and migrated inwards as a consequence of gravitational interactions with their protoplanetary disks. The preponderance of evidence supports the core nucleated gas accretion model. According to this model, giant planets begin their growth by the accumulation of small solid bodies, as do terrestrial planets. However, unlike terrestrial planets, the giant planet cores grow massive enough to accumulate substantial amounts of gas before the protoplanetary disk dissipates. The primary question regarding the core nucleated growth model is under what conditions can planets develop cores sufficiently massive to accrete gas envelopes within the lifetimes of typical gaseous protoplanetary disks.

Lissauer, Jack J.; D'Angelo, Gennaro

2006-09-01

355

Starting a Planet Protectors Club  

ERIC Educational Resources Information Center

|If your mission is to teach children how to reduce, reuse, and recycle waste and create the next generation of Planet Protectors, perhaps leading a Planet Protectors Club is part of your future challenges. You don't have to be an expert in waste reduction and recycling to lead a a Planet Protectors Club. You don't even have to be a teacher. You…

US Environmental Protection Agency, 2007

2007-01-01

356

Transits of Extrasolar Planets and Analysis Methods  

NASA Astrophysics Data System (ADS)

Using Wittenberg's 10-inch refracting telescope housed in Elgar Weaver Observatory, and an ST-8XE CCD camera, the egress of the transit of planet HD209458 `b' was observed on the night of December 18^th, 2006. This transit occurs when the planet passes directly between its host star and the telescope on Earth, and the brightness of the star decreases by about 1.5%. The brightness of the stars is measured by the number of counts in pixels in images taken as 30 second exposures over a period of 64 minutes. Data analysis techniques using Diffraction Limited's MaxImDL^TM yield a standard deviation of less than .004 magnitudes using a sliding box averaging method. This means that a change in brightness can be measured of about .4% and much dimmer transits of other planets may be recorded from this telescope. Analysis methods using MathWork's MATLAB^ are being developed to gain more control over how pixels are combined to determine the brightness of stars and more effective modes of combining images.

Fritchman, Joseph

2007-10-01

357

An All Sky Extrasolar Planet Survey with New Generation Multiple Object Doppler Instruments at Sloan Telescope  

NASA Astrophysics Data System (ADS)

The All Sky Extrasolar Planet Survey (ASEPS) would use the Sloan 2.5-m wide field telescope and new generation multiple object high throughput Doppler instruments to undertake a large-scale visible and near-IR band Doppler survey of up to ˜ 250,000 relatively bright stars (generally V up to < 13 for the visible and J < 11 for the near IR) for extrasolar planets between 2008-2013. An extended survey continuing until ˜ 2020 could survey an additional ˜ 250,000 stars and obtain information on long-period planets from the earlier detected planet sample, possibly detecting many solar analogs. ASEPS aims to increase the number of extrasolar planets by nearly two orders of magnitude (up to ˜ 10,000 planets in the 12-year survey using all clear nights). This dramatic increase in the number of known planets would allow astronomers to study correlations among the diverse properties of extrasolar planets much more effectively than at present. Additionally, the large number of planet discoveries will enable the detection of rare planets that may have eluded previous planet searches, as well as transiting planets, and interacting multiple planet systems. In March-June 2006, a single full-scale multi-object W.M. Keck Exoplanet Tracker (Keck ET) with 60 object capability was commissioned and a trial planet survey of ˜ 420 V=8-12 solar type stars has been conducted at Sloan telescope. Since the 2006 August engineering run, the instrument performance (throughput, image quality, and Doppler precision) has been substantially improved. Additional stars are being searched for planets.

Ge, J.; van Eyken, J. C.; Mahadevan, S.; Wan, X.; Zhao, B.; Hariharan, A.; Guo, P.; Dewitt, C.; Cohen, R.; Warner, C.; Fleming, S. W.; Crepp, J.; Kane, S.; Leger, F.; Pan, K.; Ford, E.; Seager, S.; Agol, E.; Schneider, D.; Shaklan, S.

2007-06-01

358

Exploring the Planets: Uranus  

NSDL National Science Digital Library

Facts on this site about Uranus include mean distance from Sun, length of year, rotation period, mean orbital velocity, inclination of axis, average temperature (day and night), diameter, and number of observed satellites. Uranus' axis of rotation is tilted nearly 98 degrees, almost perpendicular to its orbit. Consequently, the seasons and days on Uranus are strange. At times, the north pole points toward the Sun. At other times the south pole does. This site offers information about and many photographs of the rings, satellites, and of the planet itself. There is also tabular data on the fifteen moons and links to more information.

359

Pulse of the Planet  

NSDL National Science Digital Library

Akin to a living creature, Earths land, air, oceans, ice, and life fit together into a complex, interlocking system. Space affords a unique vantage point from which to observe the daily, seasonal, and annual changes in Earths systems. Using data from advanced satellites, NASA visualizations portray a majestic, and sometimes violent, natural world and also capture the influences humans have on the planet. Over 80 NASA-related earth science animations created over the past 8 years implementing realtime and non-realtime techniques have been used on this visual journey. Tools used included IDL, Lightwave3D, Final Cut Pro, Performer, Vis5D, and custom software.

Kekesi, Alex; Snodgrass, Stuart; Shirah, Greg; Bridgman, Tom; Thomson, Joycelyn; Perkins, Lori

2002-03-05

360

Minor Planet Mariotti  

NASA Astrophysics Data System (ADS)

“Named in memory of Jean-Marie Mariotti (1955-1998), French astronomer, most recently in Garching at the European Southern Observatory. He led the pioneering project to establish optical interferometry with the new Very Large Telescope as a breakthrough new astronomical instrument for the next century. His interest was in the area of high angular resolution, and he was involved in interferometric projects both on the ground (e.g., FLUOR and VLTI) and in space (DARWIN). He hoped with these techniques to find low-mass companions, and ultimately planets outside our solar system. He had an extraordinarily effective mix of technical expertise and scientific eagerness."

1999-03-01

361

Polarimetry of Extrasolar Planets  

NASA Astrophysics Data System (ADS)

Polarimetry is a powerful technique for detecting directly the starlight that is scattered in a planetary atmosphere and, thus, possesses information on its geometry, chemistry, and thermodynamics. Recently, we have started a polarimetric survey of nearby planetary systems with hot Jupiters closely orbiting their host stars using the DiPol polarimeter at the KVA telescope and the TurPol polarimeter at the Nordic Optical Telescope, La Palma. Here we present our first results and discuss orbital parameters of the HD 189733 system and scattering properties of its planet.

Berdyugin, A.; Berdyugina, S.; Fluri, D.; Piirola, V.

2011-11-01

362

Realistic limitations of detecting planets around young active stars  

NASA Astrophysics Data System (ADS)

Current planet hunting methods using the radial velocity method are limited to observing middle-aged main-sequence stars where the signatures of stellar activity are much less than on young stars that have just arrived on the main-sequence. In this work we apply our knowledge from the surface imaging of these young stars to place realistic limitations on the possibility of detecting orbiting planets. In general we find that the magnitude of the stellar jitter is directly proportional to the stellar vsini. For G and K dwarfs, we find that it is possible, for models with high stellar activity and low stellar vsini, to be able to detect a 1 MJupiter mass planet within 50 epochs of observations and for the M dwarfs it is possible to detect a habitable zone Earth-like planet in 10s of observational epochs.

Jeffers, S. V.; Barnes, J. R.; Jones, H.; Pinfield, D.

2013-04-01

363

Probing the Extrasolar Planet Diversity with SEE-COAST  

NASA Astrophysics Data System (ADS)

SEE-COAST is a space mission concept designed for the study of physical and chemical characteristics of exoplanets. The science driver of SEE-COAST is the exploration of the planetary diversity, which has been unveiled in the past 15 years. Both spectral and polarimetric properties of the parent starlight reflected by the planets are analyzed to better constraint the atmosphere of planets. The SEE-COAST concept relies on a series of high contrast imaging techniques like coronagraphy, differential imaging and possibly wavefront control. The science objectives as well as the wavelength range (0.4-1.25 microns) are complementary to the future near-infrared ground-based coronagraphic instruments and to the exoplanet imaging capability of the JWST. We propose SEE-COAST as a relatively secure step to prepare the more ambitious characterization mission of Earth-like planets. The strategy of the mission is presented and the instrumental concept is briefly introduced.

Baudoz, P.; Boccaletti, A.; Schneider, J.; Galicher, R.; Tinetti, G.

2010-10-01

364

NASA'S TERRESTRIAL PLANET FINDER MISSION: THE SEARCH FOR HABITABLE PLANETS  

Microsoft Academic Search

The Terrestrial Planet Finder (TPF) is one of the major missions in the NASA Office of Space Science Origins Theme. The primary science objective of the TPF mission is to search for, detect, and characterize planetary systems beyond our own Solar System, including specifically Earth-like planets. This paper describes the current status of TPF as well as outlines the plans

Daniel R. Coulter

365

The Planet Venus  

NASA Astrophysics Data System (ADS)

This book is not so much for the space scientist looking for background material for research as it is for one interested in the history of planetary exploration. The first half (˜100 pps) is devoted to studies of Venus before the space age, starting at several hundred years BC. It is obvious from the multitude of detailed descriptions of observers' accounts that considerable library research went into this section. While sometimes tedious, this chronology of Venus research is punctuated with amusing facts. While many may know about the Velikovsky theory of the cometary origin of the planet, few may know that Lowell drew pictures of Cytherian canals similar to the canals of Mars or that Frederick the Great of Prussia proposed to name the (once suspected) satellite of Venus D'Alembert, after the mathematician. An equally amusing appendix shows the ups and downs of the rotation period of this planet with the invisible surface. Much attention is focused on early telescope observations, the ashen light, and transits of Venus. At the end of this half, one appreciates that Venus has played a fairly important role in history in the areas of religion, science, and technology.

Luhmann, Janet

366

Planets and Life  

NASA Astrophysics Data System (ADS)

Astrobiology involves the study of the origin and history of life on Earth, planets and moons where life may have arisen, and the search for extraterrestrial life. It combines the sciences of biology, chemistry, palaeontology, geology, planetary physics and astronomy. This textbook brings together world experts in each of these disciplines to provide the most comprehensive coverage of the field currently available. Topics cover the origin and evolution of life on Earth, the geological, physical and chemical conditions in which life might arise and the detection of extraterrestrial life on other planets and moons. The book also covers the history of our ideas on extraterrestrial life and the origin of life, as well as the ethical, philosophical and educational issues raised by astrobiology. Written to be accessible to students from diverse backgrounds, this text will be welcomed by advanced undergraduates and graduates who are taking astrobiology courses.• Compiled by world experts in their disciplines to create a truly comprehensive book • Accessible to students from a wide range of backgrounds • A welcome addition to this rapidly-growing field

Sullivan, Woodruff T., III; Baross, John

2001-12-01

367

Geologic mapping of tectonic planets  

Microsoft Academic Search

Geological analysis of planets typically begins with the construction of a geologic map of the planets’ surfaces using remote data sets. Geologic maps provide the basis for interpretations of geologic histories, which in turn provide critical relations for understanding the range of processes that contributed to the evolution. Because geologic mapping should ultimately lead to the discovery of the types

Vicki L. Hansen

2000-01-01

368

Ionospheres of the terrestrial planets  

Microsoft Academic Search

The theory and observations relating to the ionospheres of the terrestrial planets Venus, the earth and Mars are reviewed. Emphasis is placed on comparing the basic differences and similarities between the planetary ionospheres. The review covers the plasma and electric-magnetic field environments that surround the planets, the theory leading to the creation and transport of ionization in the ionspheres, the

R. W. Schunk; A. F. Nagy

1980-01-01

369

Toward Earth-Like Planets  

NASA Astrophysics Data System (ADS)

NASA’s Kepler mission has the goal of detecting transiting planets as small as the Earth, even some that might be habitable. Kepler was launched 2009. After transiting planet candidates are detected, the challenge will be to sort out the real planets from the stellar imposters masquerading as planets. The ultimate test is a spectroscopic orbit that confirms the planet’s mass. A key facility for this follow-up work will be HARPS-NEF, a collaboration between the Geneva Observatory and Harvard University to build a version of HARPS for a telescope in the North. Kepler stares at a single field of view in Cygnus and Lyra for the entire four-year mission, to allow the detection of planets with orbital periods as long as a year. As a result the systems discovered by Kepler will be relatively far away, faint, and difficult for follow-up observations. To complement Kepler we need an all-sky survey that can identify the nearest and brightest transiting systems. For the photometry to be good enough to push to smaller planets we need to get above the Earth’s atmosphere. TESS is a proposal for such a mission.

Latham, D. W.

2009-12-01

370

Get Me Off This Planet  

NSDL National Science Digital Library

The purpose of this lesson is to teach students how a spacecraft gets from the surface of the Earth to Mars. Students first investigate rockets and how they are able to get us into space. Finally, the nature of an orbit is discussed as well as how orbits enable us to get from planet to planet â specifically from Earth to Mars.

Integrated Teaching And Learning Program

371

Planet Migration in Planetesimal Disks  

Microsoft Academic Search

Planets embedded in a planetesimal disk will migrate as a result of angular momentum and energy conservation as the planets scatter the planetesimals that they encounter. A surprising variety of interesting and complex dynamics can arise from this apparently simple process. In this chapter, we review the basic characteristics of planetesimal-driven migration. We discuss how the structure of a planetary

H. F. Levison; A. Morbidelli; R. Gomes; D. Backman

2007-01-01

372

The Star, the Dwarf and the Planet  

NASA Astrophysics Data System (ADS)

Astronomers have detected a new faint companion to the star HD 3651, already known to host a planet. This companion, a brown dwarf, is the faintest known companion of an exoplanet host star imaged directly and one of the faintest T dwarfs detected in the Solar neighbourhood so far. The detection yields important information on the conditions under which planets form. "Such a system is an interesting example that might prove that planets and brown dwarfs can form around the same star", said Markus Mugrauer, lead author of the paper presenting the discovery. ESO PR Photo 39a/06 ESO PR Photo 39a/06 The Companion to HD 3651 HD 3651 is a star slightly less massive than the Sun, located 36 light-years away in the constellation Pisces (the "Fish"). For several years, it has been known to harbour a planet less massive than Saturn, sitting closer to its parent star than Mercury is from the Sun: the planet accomplishes a full orbit in 62 days. Mugrauer and his colleagues first spotted the faint companion in 2003 on images from the 3.8-m United Kingdom Infrared Telescope (UKIRT) in Hawaii. Observations in 2004 and 2006 using ESO's 3.6 m New Technology Telescope (NTT) at La Silla provided the crucial confirmation that the speck of light is not a spurious background star, but indeed a true companion. The newly found companion, HD 3651B, is 16 times further away from HD 3651 than Neptune is from the Sun. HD 3651B is the dimmest directly imaged companion of an exoplanet host star. Furthermore, as it is not detected on the photographic plates of the Palomar All Sky Survey, the companion must be even fainter in the visible spectral range than in the infrared, meaning it is a very cool low-mass sub-stellar object. Comparing its characteristics with theoretical models, the astronomers infer that the object has a mass between 20 and 60 Jupiter masses, and a temperature between 500 and 600 degrees Celsius. It is thus ten times colder and 300 000 less luminous than the Sun. These properties place it in the category of cool T-type brown dwarfs. ESO PR Photo 38b/06 ESO PR Photo 39b/06 The Relative Position of the Companion to HD 3651 "Due to their faintness even in the infrared, these cool T dwarfs are very difficult to find", said Mugrauer. "Only two other brown dwarfs with similar brightness are presently known. Their study will provide important insights into the atmospheric properties of cool sub-stellar objects." More than 170 stars are currently known to host exoplanets. In some cases, these stars were also found to have one or several stellar companions, showing that planet formation can also take place in a dynamically more complex environment than our own Solar System where planet formation occurred around an isolated single star. In 2001, Mugrauer and his colleagues started an observational programme to find out whether exoplanet host stars are single or married. In this programme, known exoplanet host stars are systematically imaged at two different epochs, at least several months apart. True companions can be distinguished from coincidental background objects as only they move together with the stars over time. With this effective search strategy several new companions of exoplanet host stars have been detected. Most of the detected companions are low-mass stars in the same evolutionary state as the Sun. In two cases, however, the astronomers found the companions to be white dwarfs, that is, stars at the end of their life. These intriguing systems bear evidence that planets can even survive the troubled last moments in the life of a nearby star. The planet host star HD 3651 is thus surrounded by two sub-stellar objects. The planet, HD 3651b, is very close, while the newly found brown dwarf companion revolves around the star 1500 times farther away than the planet. This system is the first imaged example that planets and brown dwarfs can form around the same star.

2006-10-01

373

Preparation of dicarboxylic acid-type gemini surfactant via Diels-Alder reaction & ozone oxidation.  

PubMed

We wish to report a novel preparation method for Gemsurf analogs as well as dicarboxylic acid-type Gemini surfactant from Diels-Alder adducts of 2-trimethylsilyloxy-1,3-butadiene, in which ozone oxidation is adopted to convert C=C double bond to dicarboxylic acid without any additional oxidant. PMID:23728332

Chau, Huynh N; Kawase, Tokuzo; Oida, Tatsuo

2013-01-01

374

The mode of the antifungal activity of gemini-pyridinium salt against yeast.  

PubMed

The gemini quaternary salt (gemini-QUAT) containing two pyridinium residues per molecule, 3,3'-(2,7-dioxaoctane) bis (1-decylpyridinium bromide) (3DOBP-4,10), exerted fungicidal activity against Saccharomyces cerevisiae accompanied by respiration inhibition and the cytoplasmic material leakage of ATP, magnesium, and potassium ions. We previously found that gemini-QUAT exerted bacterioclastic action against Escherichia coli by causing the rapid and abundant leakage of turbid materials from the cells. In addition, the first stage of the bacterioclastic action was the leakage of magnesium ions, outer membrane protein E, ATP, and lipopolysaccharides. Here, we investigated how the gemini-QUAT 3DOBP-4,10 exerts fungicidal action against S. cerevislae. The results showed that that > or = 0.4 microM 3DOBP-4,10 stopped respiration and that > or = 3.0, 1.0 and 1.0 microM caused the leakage of cytoplasmic components ATP, magnesium and potassium ions, respectively. Scanning and transmission electron micrographs showed a preserved cell wall structure, whereas intracellular organelles were destroyed in cells incubated with 3DOBP-4,10. We postulated that 3DOBP-4,10 exerts its fungicidal action against S. cerevisiae not through cell wall destruction and protein leakage, but rather by penetrating the cell wall and disrupting the membranes of organelles. PMID:19344094

Shirai, Akihiro; Sumitomo, Tomoko; Kurimoto, Mayuko; Maseda, Hideaki; Kourai, Hiroki

2009-03-01

375

Gemini Multi-Conjugate Adaptive Optics (GeMS) Laser Guide Star Facility Commissioning Results  

NASA Astrophysics Data System (ADS)

The engineering and science commissioning phase of the Gemini Multi-Conjugate Adaptive Optics System (Gemini MCAO a.k.a. GeMS) project was kicked off in January 2011 when the Gemini South Laser Guide Star Facility (GS LGSF) propagated its 50W laser on the sky above the summit of Cerro Pachón, Chile. With 3 deformable mirrors, 3 Natural Guide Stars (NGS) and 5 sodium Laser Guide Stars (LGS), GeMS will be the first facility-class MCAO capability to be offered for normal science observations world-wide starting in 2012. This presentation will focus on the LGSF-side of the project and provide an overview of the LGSF subsystems, their top-level specifications, design, integration with the telescope, and current on-sky performance. Subsystems of the GS LGSF include a diode-pumped solid-state 1.06+1.32 micron sum-frequency laser producing over 50W of output power at the sodium wavelength (589nm), Beam Transfer Optics (BTO) that transport the 50W beam up the telescope, split the beam five-ways and configure the five 10W beams for projection by the Laser Launch Telescope (LLT) located behind the Gemini South 8m telescope secondary mirror, and a variety of safety systems to ensure safe laser operations for observatory personnel and equipment, neighbor observatories, as well as passing aircrafts and satellites.

d'Orgeville, Celine

2011-09-01

376

Gemini\\/GMOS Search for Massive Binaries in the Ionizing Cluster of 30 Dor  

Microsoft Academic Search

If binaries are common among massive stars, it will have important consequences for the derivation of fundamental properties such as the cluster age, initial mass function, and dynamical mass. Making use of the multiplexing facilities of the Gemini Multi-Object Spectrograph, we were able to investigate the presence of binary stars within the ionizing cluster of 30 Doradus. From a seven-epoch

Guillermo Bosch; Elena Terlevich; Roberto Terlevich

2009-01-01

377

Exploración con GEMINI-GMOS del sistema de cúmulos globulares de NGC 5044  

NASA Astrophysics Data System (ADS)

We present preliminary results of the first photometric study of the globular cluster system associated to the elliptical galaxy NGC 5044, the dominant object in the homonymous group. These results are based on data recently (semester 2009A) obtained with the Multi Object Spectrograph GMOS at the Gemini South telescope. FULL TEXT IN SPANISH

Faifer, F. R.; Cellone, S. A.; Smith Castelli, A. V.; Bassino, L. P.; Forte, J. C.

378

Structure and order of DODAB bilayers modulated by dicationic gemini surfactants.  

PubMed

Cationic liposomes have been extensively studied from the experimental and theoretical standpoints, motivated both by their fundamental interest and by potential applications in drug delivery and gene therapy. However, a detailed understanding of the nature of interactions within mixed bilayers containing cationic gemini surfactants is still lacking. This work focuses on the structural and dynamic properties of DODAB membranes in the presence of dicationic gemini surfactants. A thermodynamic characterization of the phase transitions in the mixed systems has been carried out by differential scanning calorimetry, while insight into the molecular interactions in the bilayer has been provided by molecular dynamics. For this purpose, variations in the gemini spacer and tail length, as well as in the respective molar fraction, have been included in both experimental and simulation studies. The results indicate that the influence of cationic gemini surfactants upon the thermotropic behavior and degree of order of DODAB structures is controlled by a complex interplay between charge density, conformation and hydrophobic effects, for which a detailed rationale is provided. PMID:21720610

Almeida, João A S; Pinto, Sandra P R; Wang, Yujie; Marques, Eduardo F; Pais, Alberto A C C

2011-06-30

379

Formation of Planets around Pulsars  

NASA Astrophysics Data System (ADS)

Pulse arrival-time delays PSR 1257+ 12 suggest the existence of at least two planets in nearly circular orbits around it. In this paper we discuss different scenarios for the formation of planets in circular orbits around pulsars. Among other topics, we look in some detail at wind emission mechanisms that are particularly relevant to the process of evaporation of planets around pulsars and discuss their possible role in orbit circularization. We conclude that the formation of such planets may occur in a very late phase of low-mass X-ray binary (LMXB) or binary millisecond pulsar (BMP) evolution. Evaporation of the companion star in these phases supplies matter to a circumbinary "excretion" disk in which the physical conditions, similar to those appropriate for the BMP 1957+20 system, may allow the formation of planets like those observed in PSR 1257+12.

Banit, M.; Ruderman, M. A.; Shaham, J.; Applegate, J. H.

1993-10-01

380

Albedo of Irregular Satellites of the Giant Planets  

NASA Astrophysics Data System (ADS)

The outer solar system is filled with small bodies that hold some of the keys to understanding the formation and evolution of the giant planets and the Solar System itself. The Kuiper Belt, Centaurs and irregular satellites are considered to be from the same phase space of the solar system, although the exact connection remains unknown. We have performed a series of observations on the small bodies of the solar system with the goal of understanding their physical composition and characteristic. Using mid-infrared observations done with the Spitzer InfraRed Telescope Facility, together with groundbased visual observations, we have determined albedos and sizes for 21 jovian and 8 saturnian irregular satellites. We will also compare the result with recent mid-infrared results on main belt asteroids, trojans, centaurs and trans-Neptunian objects. Based on observations performed with Spitzer InfraRed Telescope Facility, Gemini Observatory, Keck Observatory and Subaru Observatory. This work has been supported by grants NASA/JPL-RSA1264797 and NASA/JPL1270738.

Grav, T.

2005-08-01

381

Planets and Life  

NASA Astrophysics Data System (ADS)

Foreword; Preface; Contributors; Prologue; Part I. History: 1. History of astrobiological ideas W. T. Sullivan and D. Carney; 2. From exobiology to astrobiology S. J. Dick; Part II. The Physical Stage: 3. Formation of Earth-like habitable planets D. E. Brownlee and M. Kress; 4. Planetary atmospheres and life D. Catling and J. F. Kasting; Part III. The Origin of Life on Earth: 5. Does 'life' have a definition? C.E. Cleland and C. F. Chyba; 6. Origin of life: crucial issues R. Shapiro; 7. Origin of proteins and nucleic acids A. Ricardo and S. A. Benner; 8. The roots of metabolism G.D. Cody and J. H. Scott; 9. Origin of cellular life D. W. Deamer; Part IV. Life on Earth: 10. Evolution: a defining feature of life J. A. Baross; 11. Evolution of metabolism and early microbial communities J. A. Leigh, D. A. Stahl and J. T. Staley; 12. The earliest records of life on Earth R. Buick; 13. The origin and diversification of eukaryotes M. L. Sogin, D. J. Patterson and A. McArthur; 14. Limits of carbon life on Earth and elsewhere J. A. Baross, J. Huber and M. Schrenk; 15. Life in ice J. W. Deming and H. Eicken; 16. The evolution and diversification of life S. Awramik and K. J. McNamara; 17. Mass extinctions P. D. Ward; Part V. Potentially Habitable Worlds: 18. Mars B. M. Jakosky, F. Westall and A. Brack; 19. Europa C. F. Chyba and C. B. Phillips; 20. Titan J. I. Lunine and B. Rizk; 21. Extrasolar planets P. Butler; Part VI. Searching for Extraterrestrial Life: 22. How to search for life on other worlds C. P. McKay; 23. Instruments and strategies for detecting extraterrestrial life P. G. Conrad; 24. Societial and ethical concerns M. S. Race; 25. Planetary protection J. D. Rummel; 26. Searching for extraterrestrial intelligence J. C. Tarter; 27. Alien biochemistries P. D. Ward and S. A. Benner; Part VII. Future of the Field: 28. Disciplinary and educational opportunities L. Wells, J. Armstrong and J. Huber; Epilogue C. F. Chyba; Appendixes: A. Units and usages; B. Planetary properties; C. The geological time scale S. Awramik and K. J. McNamara; D. Astrobiological destinations on planet Earth J. Harnmeijer; E. Micro*scope web tool D. J. Patterson and M. L. Sogin; Index.

Sullivan, Woodruff T., III; Baross, John

2007-09-01

382

Planet Classification: A Historical Perspective  

NASA Astrophysics Data System (ADS)

As philosopher George Santayana famously said, "those who cannot remember the past are condemned to repeat it." The professional astronomy community, as embodied in the IAU, now suffers from Santayana's malady. Ceres was expelled from the community of planets because it apparently was not a planet; yet, no working, scientifically reasonable definition of the word planet existed in the early nineteenth century and so no rational basis existed for excluding or including Ceres or, for that matter, Uranus or the soon-to-be-discovered Neptune from the family of planets. Instead, William Herschel disparaged Ceres as only an "asteroid," a term he invented specifically to separate Ceres and Pallas and Vesta from the true planets. Clearly, in Herschel's view, Ceres was not big enough, and apparently, to Herschel, size mattered. So how big is big enough and by what method was size put in place as the critical scientific metric for assessing planethood? Certainly, as members of the newly discovered asteroid belt, the newly identified asteroids were members of a previously unknown family of objects in the solar system. But why did that make these non-classically known objects asteroids but not planets rather than asteroids and planets? Uranus and Neptune were also members of a newly identified and previously unknown family of solar system objects that we now call "ice giants." On what basis were these two objects embraced as planets and why have these two non-classical objects become known as ice giants and planets rather than ice giants but not planets? Perhaps our scientific predecessors were too quick to render judgment, as they lacked the scientific context in which to understand the many new objects discovered during the years 1781 to 1846. Is that a lesson from the past that we might remember today?

Weintraub, David A.

2009-05-01

383

On-board calibration of the spectral response functions of the Advanced Baseline Imager's thermal IR channels by observation of the planet Mercury  

NASA Astrophysics Data System (ADS)

The Advanced Baseline Imager (ABI) will image Earth in 16 spectral channels, including 10 thermal IR (TIR) channels. The instantaneous field of view (IFOV) of each TIR detector element is (56 ?rad)2. The ABI has an onboard fullaperture blackbody, the Internal Calibration Target (ICT), used in conjunction with deep space looks to calibrate the ABI's TIR channels. The ICT is only observed over a small range of temperatures and at one specific pair of reflection angles from the ABI's two scan mirrors. The sunlit area on Mercury's surface underfills the IFOV's of the ABI's TIR channels, but has a much higher range of characteristic temperatures than the ICT, so its radiation is weighted more strongly toward shorter wavelengths. Comparison of a TIR channel's responses to the ICT and to Mercury provides a sensitive means to evaluate variations in spectral response functions among detector elements, across the ABI's field of regard, and among instruments on different satellites. Observations of Mercury can also verify co-registration among the ABI's atmospheric absorption channels that do not observe features on Earth's surface. The optimal conditions for viewing Mercury typically occur during one or two intervals of a few weeks each year when it traverses the ABI's FOR (-10.5o < declination < +10.5o) with an elongation angle from the Sun of at least 20.5o.

Bremer, James C.

2010-08-01

384

A Surface Rheological Study of a Glucosamide-Based Trisiloxane Gemini Surfactant at the Air\\/Water Interface  

Microsoft Academic Search

Surface dilational viscoelasticity of the glucosamide-based trisiloxane gemini surfactant as bulk concentration: (Solid) dilational modulus; (Open) phase angle. (Square) 0.1 Hz; (Circle) 0.2 Hz; (UpTriangle) 0.3 Hz; (DownTriangle) 0.4 Hz; (Diamond) 0.5 Hz.The dilational viscoelastic properties of a glucosamide-based trisiloxane gemini surfactant at the air\\/water interface were investigated. Aqueous solutions of the glucosamide-based trisiloxane gemini surfactant were spread onto a pendant drop and the dynamic

Fu Han; Pengli Wang; Jia Song; Yawen Zhou; Baocai Xu

2012-01-01

385

Solution properties and emulsification properties of amino Acid-based gemini surfactants derived from cysteine.  

PubMed

Amino acid-based anionic gemini surfactants (2CndiCys, where n represents an alkyl chain with a length of 10, 12, or 14 carbons and "di" and "Cys" indicate adipoyl and cysteine, respectively) were synthesized using the amino acid cysteine. Biodegradability, equilibrium surface tension, and dynamic light scattering were used to characterize the properties of gemini surfactants. Additionally, the effects of alkyl chain length, number of chains, and structure on these properties were evaluated by comparing previously reported gemini surfactants derived from cystine (2CnCys) and monomeric surfactants (CnCys). 2CndiCys shows relatively higher biodegradability than does CnCys and previously reported sugar-based gemini surfactants. Both critical micelle concentration (CMC) and surface tension decrease when alkyl chain length is increased from 10 to 12, while a further increase in chain length to 14 results in increased CMC and surface tension. This indicates that long-chain gemini surfactants have a decreased aggregation tendency due to the steric hindrance of the bulky spacer as well as premicelle formation at concentrations below the CMC and are poorly packed at the air/water interface. Formation of micelles (measuring 2 to 5 nm in solution) from 2CndiCys shows no dependence on alkyl chain length. Further, shaking the mixtures of aqueous 2CndiCys surfactant solutions and squalane results in the formation of oil-in-water type emulsions. The highly stable emulsions are formed using 2C12diCys or 2C14diCys solution and squalane in a 1:1 or 2:1 volume ratio. PMID:23985487

Yoshimura, Tomokazu; Sakato, Ayako; Esumi, Kunio

2013-01-01

386

Monopole planets and galaxies  

NASA Astrophysics Data System (ADS)

Spherical clusters of SU(2) Bogomol’nyi-Prasad-Sommerfield monopoles are investigated here. A large class of monopole solutions is found using an Abelian approximation, where the clusters are spherically symmetric, although exact solutions cannot have this symmetry precisely. Monopole clusters generalize the Bolognesi magnetic bag solution of the same charge, but they are always larger. Selected density profiles give structures analogous to planets of uniform density, and galaxies with a density decaying as the inverse square of the distance from the center. The Bolognesi bag itself has features analogous to a black hole, and this analogy between monopole clusters and astrophysical objects with or without black holes in their central region is developed further. It is also shown that certain exact, platonic monopoles of small charge have sizes and other features consistent with what is expected for magnetic bags.

Manton, N. S.

2012-02-01

387

Exploring the Planets: Saturn  

NSDL National Science Digital Library

Information on this site about Saturn includes mean distance from the Sun, length of a year, rotation period, mean orbital velocity, inclination of axis, diameter, and number of observed satellites. The view from Earth shows how the appearance changes depending on the relative position in orbit. Pioneer at Saturn is one of the first spacecraft views of Saturn and was taken by Pioneer 11 three days before its closest encounter, and in this photograph the moon Titan is seen to the upper left. The Voyager Encounters provide close-up views of the rings, showing their intricate structure such as gaps, a braided ring and the mysterious spokes. This site discusses the violent atmosphere and strong magnetic field of the planet and offers three sections and tabular information about the moons of Saturn. There is also information about future exploration, a large photo gallery and links to more resources.

388

Angry Red Planet  

NSDL National Science Digital Library

This mystery puts the reader in control, Mission Control, as he/she helps with a simulated flight to Mars. In this simulation, four "bionauts" are sealed into identical pods containing plants, animals and water. The goal is for them to survive for six months receiving no water, food or air from outside. The reader monitors the conditions in each pod, simulating Misson Control back on Earth. This story begins on the 34th day of the simulation, when the reader notices something wrong in one of the pods. The oxygen is getting low - why? Besides the usual Science Mystery themes (literacy, inquiry-based learning, problem-solving logic, inductive and deductive reasoning), "Angry Red Planet" puts your students hands-on with facts about respiration, ecosystems and ecological cycles, chemical and biochemical reactions, carbon dioxide poisoning, and the effects of stress on human physiology and psychology. They must learn how to read graphs and evaluate data to solve the mystery.

BEGIN:VCARD VERSION:2.1 FN:Ken Eklund N:Eklund;Ken ORG:WriterGuy REV:2005-04-06 END:VCARD

2000-12-15

389

Mission to planet earth  

SciTech Connect

Plans for environmental monitoring using remote-sensing satellites in the era of the International Space Station are reviewed. The role of international cooperation is stressed, considering the present Landsat, SPOT, and Marine Observation Satellite programs; ERS-1 and Topex/Poseidon; and plans for the Italian Lageos-2, the Indian Remote Sensing Satellite, and the Japanese Advanced Earth Observation Satellite. The NASA Mission to Planet Earth proposal calls for four polar-orbit and five GEO platforms (five NASA, two ESA, and two NASDA), to be in place by the year 2000, as well as dedicated spacecraft of the Earth System Explorer series in the 1990s. Payloads will monitor the geomagnetic field, atmospheric temperature and water vapor, O3 and aerosols, outgoing radiation, precipitation, sea-surface temperature, sea ice, ocean chlorophyll, surface winds, wave height, ocean circulation, snow cover, land use, vegetation, crops, volcanic activity, and the hydrologic cycle.

Baker, D.J.

1988-07-01

390

A "Thinking Journey" to the Planets Using Scientific Visualization Technologies: Implications to Astronomy Education.  

ERIC Educational Resources Information Center

|Presents a novel approach to teaching astronomy and planetary sciences centered on visual images and simulations of planetary objects. Focuses on the study of the moon and the planet Mars by means of observations, interpretation, and comparison to planet Earth. (Contains 22 references.) (Author/YDS)|

Yair, Yoav; Schur, Yaron; Mintz, Rachel

2003-01-01

391

In-situ Planet Formation: Implications for Planets near Resonances  

NASA Astrophysics Data System (ADS)

We investigate a very simple model of planet formation in which planets grow in-situ, without migration or any dissipative process. Quite remarkably, this model exhibits an asymmetric distribution of orbital periods around mean motion resonances, with a gap around the nominal resonance location and a pile-up wide of the resonance, qualitatively similar to that observed in the Kepler sample of multiple planet systems. This suggests that dissipation and migration may not be necessary to account for the resonant features seen in Kepler data.

Malhotra, Renu; Petrovich, C.; Tremaine, S.

2013-10-01

392

The Deuterium Test for Exo-Planet Candidates Detected Directly  

NASA Astrophysics Data System (ADS)

In the near future, direct images will be obtained for massive planets orbiting around other stars. Most likely, the first such objects detected directly will have masses near the proposed limit between brown dwarfs and planets, i.e., around 13 Jupiter masses, because the more massive planets are the brightest. Hence, it may be dubious in these first few cases, whether the detected object is a brown dwarf or a real planet. To solve this problem, one can perform the deuterium test, i.e., one can distinguish between a brown dwarf (defined as an object able to fuse all deuterium) and an real planet (defined as an object not being able to fuse any deuterium) by whether or not deuterium can be identified in a spectrum. Any such object, brown dwarf or planet, would have spectral type T, defined as those with strong methane lines in the infrared. We present a model spectrum with the CH3D line at ~ 4.5 ?m which can be obtained for such objects with CRIRES at the VLT.

Neuhäuser, Ralph; Seifahrt, Andreas; Hauschildt, Peter; Alves, Joao; Guenther, Eike

393

Meeting contribution: Bright lights on giant planets  

NASA Astrophysics Data System (ADS)

Prof Miller explained that his scientific background was in chemistry rather than astronomy, but that he had become involved with planetary science, and especially aurorae, through an interest in the chemical composition of planetary atmospheres. The various colours seen in aurorae were powerful probes of the chemical constituents of atmospheres, and the speaker illustrated this with an image of the aurora borealis of our own planet. The deep red emission seen at the highest celestial altitudes could be attributed to atomic oxygen, and likewise the brighter green emission below it. Towards the lower edge of the aurora, closest to the horizon, reddish-pink emission stemmed from molecular nitrogen.

Miller, S.

2007-04-01

394

Planet Hunters: the first two planet candidates identified by the public using the Kepler public archive data  

NASA Astrophysics Data System (ADS)

Planet Hunters is a new citizen science project designed to engage the public in an exoplanet search using NASA Kepler public release data. In the first month after launch, users identified two new planet candidates which survived our checks for false positives. The follow-up effort included analysis of Keck HIRES spectra of the host stars, analysis of pixel centroid offsets in the Kepler data and adaptive optics imaging at Keck using NIRC2. Spectral synthesis modelling coupled with stellar evolutionary models yields a stellar density distribution, which is used to model the transit orbit. The orbital periods of the planet candidates are 9.8844 ± 0.0087 d (KIC 10905746) and 49.7696 ± 0.000 39 d (KIC 6185331), and the modelled planet radii are 2.65 and 8.05 R?. The involvement of citizen scientists as part of Planet Hunters is therefore shown to be a valuable and reliable tool in exoplanet detection. This publication has been made possible by the participation of more than 40 000 volunteers in the Planet Hunters project. Their contributions are individually acknowledged at .

Fischer, Debra A.; Schwamb, Megan E.; Schawinski, Kevin; Lintott, Chris; Brewer, John; Giguere, Matt; Lynn, Stuart; Parrish, Michael; Sartori, Thibault; Simpson, Robert; Smith, Arfon; Spronck, Julien; Batalha, Natalie; Rowe, Jason; Jenkins, Jon; Bryson, Steve; Prsa, Andrej; Tenenbaum, Peter; Crepp, Justin; Morton, Tim; Howard, Andrew; Beleu, Michele; Kaplan, Zachary; Vannispen, Nick; Sharzer, Charlie; Defouw, Justin; Hajduk, Agnieszka; Neal, Joe P.; Nemec, Adam; Schuepbach, Nadine; Zimmermann, Valerij

2012-02-01

395

Extrasolar planets in the classroom  

NASA Astrophysics Data System (ADS)

The field of extrasolar planets is still, in comparison with other astrophysical topics, in its infancy. There have been about 300 or so extrasolar planets detected and their detection has been accomplished by various different techniques. Here we present a simple laboratory experiment to show how planets are detected using the transit technique. Following the simple analysis procedure describe we are able to determine the planetary radius to be 1.27 ± 0.20RJ which, within errors, agrees with the established value of 1.32 ± 0.25RJ.

George, Samuel J.

2011-07-01

396

Observing planet-disk interaction in debris disks  

NASA Astrophysics Data System (ADS)

Context. Debris disks are commonly considered to be a by-product of planet formation. Structures in debris disks induced by planet-disk interaction are promising to provide valuable constraints on the existence and properties of embedded planets. Aims: We investigate the observability of structures in debris disks induced by planet-disk interaction with future facilities in a systematic way. High-sensitivity, high angular resolution observations with large (sub-)mm interferometers and large space-based telescopes operating in the near- to mid-infrared wavelength range are considered. Methods: The observability of debris disks with the Atacama Large Millimeter/submillimeter Array (ALMA) is studied on the basis of a simple analytical disk model. Furthermore, N-body simulations are used to model the spatial dust distribution in debris disks under the influence of planet-disk interaction. From these simulations, images at optical scattered light to millimeter thermal re-emission are computed. Available information about the expected capabilities of ALMA and the James Webb Space Telescope (JWST) are used to investigate the observability of characteristic disk structures with these facilities through spatially resolved imaging. Results: Our simulations show that planet-disk interaction can result in prominent structures in the whole considered wavelength range. The exact result depends on the configuration of the planet-disk system and on the observing wavelength which provides the opportunity of detecting and characterizing extrasolar planets in a range of masses and radial distances from the star that is not accessible to other techniques. Facilities that will be available in the near future at both considered wavelength ranges are shown to provide the capabilities to spatially resolve and characterize structures in debris disks that arise because of planet-disk interaction. Limitations are revealed and suggestions for possible instrument setups and observing strategies are given. In particular, ALMA is limited by its sensitivity to surface brightness, which requires a trade-off between sensitivity and spatial resolution. Space-based mid-infrared observations will be able to detect and spatially resolve regions in debris disks even at a distance of several tens of AU from the star, where the emission from debris disks in this wavelength range is expected to be low. Conclusions: Both ALMA and the planned space-based near- to mid-infrared telescopes will provide unprecedented capabilities to study planet-disk interaction in debris disks. In particular, a combination of observations at both wavelengths will provide very strong constraints on the planetary/planetesimal systems.

Ertel, S.; Wolf, S.; Rodmann, J.

2012-08-01

397

78 FR 40541 - GDT Tek, Inc., Gemini Explorations, Inc., Genetic Vectors, Inc., and Global Gate Property Corp...  

Federal Register 2010, 2011, 2012, 2013

...Inc., Gemini Explorations, Inc., Genetic Vectors, Inc., and Global Gate Property...information concerning the securities of Genetic Vectors, Inc. because it has not filed...Filed 7-2-13; 4:15 pm] BILLING CODE...

2013-07-05

398

Earth: The Water Planet  

NASA Astrophysics Data System (ADS)

"We all live on this water planet which we have mistakenly chosen to call Earth" (Anon.) When viewed from outer space, the dominant feature of the earth's surface is the abundance of liquid water. Liquid water has been present at and near the earth's surface for most of its history, and has made it possible for life to develop, evolve and survive on the third rock from the Sun. In recent years it has also become clear that the earth's interior represents an important storehouse for water and that water in the deep earth exerts a major influence on the geochemical and geodynamic evolution of the planet. The largest near-surface water reservoir is the oceans, containing 13,400 x 1017 kg of H2O, or about 97.3% of all water at and near the earth's surface. The major geological reservoirs for water can be divided into the oceanic and continental crust, the upper and lower mantle, the transition zone and the core. The core has been estimated to contain up to 100 times the amount of water in the earth's oceans, in the form of hydrogen in high-pressure iron alloy (Williams and Hemley, 2001, Ann. Rev. Earth Planet. Sci., v. 29: 365-418). In the upper and lower mantle and the transition zone water is present mainly as trace and minor amounts (101 -" 104 ppm) in nominally anhydrous phases. Even though the concentrations are low, the absolute amount of water in these mantle reservoirs may be very large given their relative contributions to the total mass of the earth. Thus, the upper mantle is estimated to contain between 1,230 and 3,693 x 1017 kg of H2O, the transition zone between 4,481 -" 89,613 x 1017 kg of H2O, and the lower mantle between 34,200 and 68,500 x 1017 kg of H2O. Assuming even the most conservative estimates for the amount of water in these geologic reservoirs, the amount of water in the oceans and other near-surface reservoirs is dwarfed by that contained in the geologic reservoirs. The conventional hydrologic cycle describes the movement of water between the various near-surface reservoirs. Similarly, water moves between the geologic reservoirs to define a geohydrologic cycle, although the fluxes between reservoirs are poorly constrained. Perhaps the most important environment in which water moves from one geo-reservoir to another is in subduction zones, where water from the subducting oceanic slab (composed of oceanic crust and upper mantle material) is transferred to several reservoirs, including the oceans, continental crust, oceanic crust, upper and (possibly) lower mantle, and the transition zone. Approximately 1.01 x 1012 kg of H2O is subducted per year. Of this amount, 9 x 111 kg is returned to the oceans by updip flow. The remainder is transported to greater depths and incorporated into the various mantle reservoirs. The major environments in which water from geo-reservoirs is returned to near-surface reservoirs are arc volcanoes and the mid-ocean ridge hydrothermal systems. Approximately 0.35 to 1.05 x 1011 kg of H2O is transferred from the deep crust and upper mantle and returned to the atmosphere per annum from arc volcanoes, while 1.2 x 1011 kg of magmatic (mantle) H2O is returned to the oceans as a result of submarine volcanism. Fluxes between the other deep-earth reservoirs are model dependent and at present are poorly constrained.

Bodnar, R. J.; Azbej, T.; Becker, S.; Cannatelli, C.; Fall, A.; Severs, M.

2006-05-01

399

Multiple Planets Problems and Solutions in Astrometry  

Microsoft Academic Search

In early 2008, NASA asked the SIM project to conduct a double blind study to determine how well astrometry at the microarcsec level can detect Earth-like planets in the habitable zone in the environment of a multiple planet system. Astrometric planet detection looks for a periodic signature and confusion can result if two or more planets have orbital frequencies that

Michael Shao; C. Zhai; J. Catanzarite; T. Loredo; B. McArthur; F. Benedict

2009-01-01

400

How to Find a Habitable Planet  

Microsoft Academic Search

Over 400 extrasolar planets have now been discovered by ground-based methods, especially the radial velocity (RV) method. Most of these planets are much bigger than Earth, and only a handful of them are rocky planets that could conceivably harbor life. Within the next few years, we may be able to identify Earth-sized planets within the habitable zones around M stars

J. F. Kasting

2010-01-01

401

Chapter 24. Families of Minor Planets  

Microsoft Academic Search

This paper describes how the families of minor planets were discovered and how minor planets are classified into families and shows several evidences that at least some families were originated by collisions of minor planets. In fact for major families there are much more fainter minor planets than in other regions and when the families were discovered by Hirayama in

Yoshihide Kozai

1988-01-01

402

Planet-C: Venus Climate Orbiter mission of Japan  

Microsoft Academic Search

The Venus Climate Orbiter mission (PLANET-C), one of the future planetary missions of Japan, aims at understanding the atmospheric circulation of Venus. Meteorological information will be obtained by globally mapping clouds and minor constituents successively with four cameras at ultraviolet and infrared wavelengths, detecting lightning with a high-speed imager, and observing the vertical structure of the atmosphere with radio science

Masato Nakamura; Takeshi Imamura; Munetaka Ueno; Naomoto Iwagami; Takehiko Satoh; Shigeto Watanabe; Makoto Taguchi; Yukihiro Takahashi; Makoto Suzuki; Takumi Abe; George L. Hashimoto; Takeshi Sakanoi; Shoichi Okano; Yasumasa Kasaba; Jun Yoshida; Manabu Yamada; Nobuaki Ishii; Takahiro Yamada; Kazunori Uemizu; Tetsuya Fukuhara; Koh-Ichiro Oyama

2007-01-01

403

Visit to An Ocean Planet: Salinity and Deep Ocean Currents  

NSDL National Science Digital Library

This resource uses text, images, maps and a laboratory exercise to explain how differences in the temperature and salinity of ocean water cause the formation of deep-ocean currents. It is part of the Jet Propulsion Laboratory's "Ocean Surface Topography from Space" website. This material is also available on the "Visit to An Ocean Planet" CD-ROM.

404

Voyager to the Seventh Planet.  

ERIC Educational Resources Information Center

Presents recent findings obtained by the Voyager 2 mission on Uranus. Updates information on the planet's moons, rings, atmosphere, and magnetic field. Illustrations and diagrams of selected aspects of Uranus are included. (ML)

Gold, Michael

1986-01-01

405

Voyager to the Seventh Planet.  

ERIC Educational Resources Information Center

|Presents recent findings obtained by the Voyager 2 mission on Uranus. Updates information on the planet's moons, rings, atmosphere, and magnetic field. Illustrations and diagrams of selected aspects of Uranus are included. (ML)|

Gold, Michael

1986-01-01

406

Dictionary of Minor Planet Names  

NASA Astrophysics Data System (ADS)

Until recently, minor planet name citations were scattered in the astronomical literature, and the origin of many names remained obscure. IAU Commission 20 in 1988 established a study group to elucidate the meanings of asteroid names. Under the chairmanship of the author, some 20 scientists took part in the preparation of the names database. In addition to being of practical value for identification purposes, minor planet names also provide a most interesting historical insight into the work of astronomers.

Schmadel, Lutz D.

407

The Planet-Metallicity Correlation  

Microsoft Academic Search

We have recently carried out spectral synthesis modeling to determine Teff, logg, vsini, and [Fe\\/H] for 1040 FGK-type stars on the Keck, Lick, and Anglo-Australian Telescope planet search programs. This is the first time that a single, uniform spectroscopic analysis has been made for every star on a large Doppler planet search survey. We identify a subset of 850 stars

Debra A. Fischer; Jeff Valenti

2005-01-01

408

Habitability of Planets in Binaries  

Microsoft Academic Search

A survey of currently known extrasolar planets indicates that close to 20% of\\u000atheir hosting stars are members of binary systems. While the majority of these\\u000abinaries are wide (i.e., with separations between 250 and 6500 AU), the\\u000adetection of Jovian-type planets in the three binaries of Gamma Cephei\\u000a(separation of 18.5 AU), GL 86 (separation of 21 AU), and

Nader Haghighipour

2007-01-01

409

White dwarf planets from GAIA  

NASA Astrophysics Data System (ADS)

We investigate the potential of high-precision astrometry with GAIA for detection of giant planetary companions to nearby white dwarfs. If one considers that, to date, no confirmed planets around single white dwarfs are known, the results from GAIA will be crucial to study the late-stage evolution of planetary systems and to verify the possibility that 2nd-generation planets are formed.

Silvotti, Roberto; Sozzetti, Alessandro; Lattanzi, Mario

2010-11-01

410

A new view on planet formation  

NASA Astrophysics Data System (ADS)

The standard picture of planet formation posits that giant gas planets are over-grown rocky planets massive enough to attract enormous gas atmospheres. It has been shown recently that the opposite point of view is physically plausible: the rocky terrestrial planets are former giant planet embryos dried of their gas ``to the bone'' by the influences of the parent star. Here we provide a brief overview of this ``Tidal Downsizing'' hypothesis in the context of the Solar System structure.

Nayakshin, Sergei

2011-11-01

411

Gemini Spectroscopy of Supernovae from the Supernova Legacy Survey: Improving High-Redshift Supernova Selection and Classification  

NASA Astrophysics Data System (ADS)

We present new techniques for improving the efficiency of supernova (SN) classification at high redshift using 64 candidates observed at Gemini North and South during the first year of the Supernova Legacy Survey (SNLS). The SNLS is an ongoing 5 year project with the goal of measuring the equation of state of dark energy by discovering and following over 700 high-redshift SNe Ia using data from the Canada-France-Hawaii Telescope Legacy Survey. We achieve an improvement in the SN Ia spectroscopic confirmation rate: at Gemini 71% of candidates are now confirmed as SNe Ia, compared to 54% using the methods of previous surveys. This is despite the comparatively high redshift of this sample, in which the median SN Ia redshift is z=0.81 (0.155<=z<=1.01). These improvements were realized because we use the unprecedented color coverage and light curve sampling of the SNLS to predict whether a candidate is a SN Ia and to estimate its redshift, before obtaining a spectrum, using a new technique called the ``SN photo-z.'' In addition, we have improved techniques for galaxy subtraction and SN template ?2 fitting, allowing us to identify candidates even when they are only 15% as bright as the host galaxy. The largest impediment to SN identification is found to be host galaxy contamination of the spectrum-when the SN was at least as bright as the underlying host galaxy the target was identified more than 90% of the time. However, even SNe in bright host galaxies can be easily identified in good seeing conditions. When the image quality was better than 0.55", the candidate was identified 88% of the time. Over the 5 year course of the survey, using the selection techniques presented here, we will be able to add ~170 more confirmed SNe Ia than would be possible using previous methods. APC, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France. DSM/DAPNIA, CEA/Saclay, 91191 Gif-sur-Yvette Cedex, France.

Howell, D. A.; Sullivan, M.; Perrett, K.; Bronder, T. J.; Hook, I. M.; Astier, P.; Aubourg, E.; Balam, D.; Basa, S.; Carlberg, R. G.; Fabbro, S.; Fouchez, D.; Guy, J.; Lafoux, H.; Neill, J. D.; Pain, R.; Palanque-Delabrouille, N.; Pritchet, C. J.; Regnault, N.; Rich, J.; Taillet, R.; Knop, R.; McMahon, R. G.; Perlmutter, S.; Walton, N. A.

2005-12-01

412

Self-assembly of anionic gemini surfactant: fluorescence resonance energy transfer and simulation study.  

PubMed

The interaction of dyes with a sulfonated Gemini surfactant was investigated in aqueous solution using Förster resonance energy transfer with acridine orange (AO) as a donor and rhodamine B (RhB) as an acceptor. Surface tension results showed that AO and RhB have different effects on the self-assembly of the Gemini surfactant, with AO giving a higher critical micelle concentration (cmc) and lower surface tension, while the opposite was observed for RhB. Energy transfer from AO to RhB was observed in the presence of the surfactant, and the energy transfer efficiency initially improved with increased surfactant concentration but then decreased significantly when the surfactant reached a higher concentration due to the formation of larger aggregates, which increased the average distance between AO and RhB. Dynamic light scattering demonstrated the existence of these large aggregates. Moreover, simulations using dissipative particle dynamics supported the experimental results. PMID:23582023

Liu, Lijuan; Fei, Xuening; Zhu, Sen; Yu, Lu; Zhang, Baolian

2013-04-22

413

Design and current status of the reconstructor for Altair: the Gemini North adaptive optics system  

NASA Astrophysics Data System (ADS)

Altair is the facility Adaptive Optics (AO) system for the Gemini North Telescope on Mauna Kea, Hawaii. Designed to take advantage of the excellent natural seeing conditions that Gemini North will experience, Altair is also unique in that the Deformable Mirror (DM) is conjugate to a fixed altitude of 6.5 kilometers. Running at a control loop speed of at least one kHz, the reconstructor for this high order AO system is subject to a number of conditions that drove its design and implementation. Initial studies indicated that a single RISC CPU would be capable of performing the reconstruction for Altair, as opposed to the more common solution of multiple DSP processors. We present some of these conditions, the results of a throughput benchmark test that verified the choice of hardware, some components of the processing steps of the reconstructor and a summary of the current status of the project.

Saddlemyer, Leslie K.; Herriot, Glen; Veran, Jean-Pierre

2000-07-01

414

Mixed Micellization Behavior of Gemini and Conventional Surfactants: Influence of Spacer Length and Temperature  

Microsoft Academic Search

Mixed micellar behavior of gemini surfactant butanediyl-1,4-bis(dimethyldodecylammonium bromide) (12-4-12) with conventional surfactant tetradecyl trimethylammonium bromide (TTAB) has been studied in aqueous and in aqueous polyvinyl pyrrolidone (PVP) solutions at various temperatures (288.15, 298.15, 308.15 and 318.15 K) using conductometric method. The behavior of the mixed system has been analyzed in light of Rubingh's regular solution theory. The study indicates that the

T. S. Banipal; A. K. Sood; Jobanpreet Kaur

2012-01-01

415

Surface-Active Properties and Antimicrobial Study of Conventional Cationic and Synthesized Symmetrical Gemini Surfactants  

Microsoft Academic Search

Symmetrical gemini surfactants of cationic series ?,?-alkanediyl bis (dimethyl ammonium bromide) commonly referred as “m–s–m” have been synthesized. Spectral analysis was performed to confirm compound structures and purity. Conductivity and surface\\u000a tension measurements provide better understanding of the micellization process. Their self-assembly behavior in aqueous solution\\u000a is also discussed in detail. The antimicrobial efficacy was measured by bacterial and fungal

Ketan Kuperkar; Jigisha Modi; Keshav Patel

416

Determination of nanograms of proteins based on decreased resonance light scattering of zwitterionic gemini surfactant  

Microsoft Academic Search

A new high-sensitivity detection of protein assay at the nanogram level is proposed based on the decreased resonance light scattering (RLS) signals of zwitterionic gemini surfactant (phosphodiesters quaternary ammonium salt [PQAS]). It was found that PQAS self-assembled into nanometer-scale PQAS aggregates, which induced intense RLS signal in Britton–Robinson (BR) buffer solution (pH 10.5). Under the optimum conditions, the RLS intensity

Zhanguang Chen; Guoliang Liu; Maohuai Chen; Yurui Peng; Mingyao Wu

2009-01-01

417

Polymerizable anionic gemini surfactants: physicochemical properties in aqueous solution and polymerization behavior.  

PubMed

A novel polymerizable anionic gemini surfactant has been synthesized and the physicochemical properties in aqueous solution have been studied with a combination of various analytical techniques. The surfactant (PA12-2-12) contains two anionic monomeric parts linked with an ethylene spacer and polymerizable methacryloxy groups covalently bound to the terminal of the hydrocarbon chains. The static surface tension data suggest that, when compared with a conventional (non-polymerizable) anionic gemini surfactant (A12-2-12), (i) the interfacial adsorption of PA12-2-12 occurs more effectively from low surfactant concentrations, whereas (ii) a weak interaction of the polymerizable terminal groups with water molecules (and/or the steric hindrance of the polymerizable groups) plays a significant role in the subsequent molecular packing at the air/aqueous solution interface. The latter effect (as well as the electrostatic repulsion between the anionic headgroups) results in a relatively less packed monolayer film, overcoming the strong intermolecular attractive interaction that is frequently seen for gemini surfactant systems. In the region of low added electrolyte concentrations, PA12-2-12 spontaneously forms spherical micelles in aqueous solution, which is confirmed with the Corrin-Harkins analysis (critical micelle concentration (cmc) vs. total counter-ion concentration) and cryogenic transmission electron microscopy (cryo-TEM). The spherical micelles have been polymerized under UV light irradiation in the absence of added electrolytes. Cryo-TEM measurements confirm that no significant change in the original micelle morphology occurs during the polymerization. This offers a possibility that the polymerizable anionic gemini surfactant should be useful as nano-structural organic templates and/or interfacial stabilizers in aqueous solution. PMID:19584566

Sakai, Kenichi; Wada, Miyuki; Matsuda, Wataru; Tsuchiya, Koji; Takamatsu, Yuichiro; Tsubone, Kazuyuki; Endo, Takeshi; Torigoe, Kanjiro; Sakai, Hideki; Abe, Masahiko

2009-01-01

418

Three Lyalpha Emitters at z ~ 6: Early GMOS\\/Gemini Data from the GLARE Project  

Microsoft Academic Search

We report spectroscopic detection of three z~6 Lyalpha-emitting galaxies, in the vicinity of the Hubble Ultra Deep Field, from the early data of the Gemini Lyman Alpha at Reionisation Era (GLARE) project. Two objects, GLARE 3001 (z=5.79) and GLARE 3011 (z=5.94), are new detections and are fainter in z' (z'AB=26.37 and 27.15) than any Lyman break galaxy previously detected in

Elizabeth R. Stanway; Karl Glazebrook; Andrew J. Bunker; Roberto G. Abraham; Isobel Hook; James Rhoads; Patrick J. McCarthy; Brian Boyle; Matthew Colless; David Crampton; Warrick Couch; Inger Jørgensen; Sangeeta Malhotra; Rick Murowinski; Kathy Roth; Sandra Savaglio; Zlatan Tsvetanov

2004-01-01

419

Gemini Surfactant as a New “Green” Demulsifier for Treating Oilfield Emulsions  

Microsoft Academic Search

Surface tension and interfacial tension (IFT) were the key factors asso- ciated with the stability of crude oil emulsion. Investigation of interfacial tension behavior related with the demulsification of crude oil emulsions can have a great impact on the development of crude oil demulsification processes and products. This article presents the surface and interface behaviors of Gemini surfactants (12-2-12, (12)-2-(12),

Z. Huang; H. Lu; T. Zhang; R. Wang; D. Qing

2010-01-01

420

The Planet, the Galaxy and the Laser  

NASA Astrophysics Data System (ADS)

On the night of 21 July, ESO astronomer Yuri Beletsky took images of the night sky above Paranal, the 2600m high mountain in the Chilean Atacama Desert home to ESO's Very Large Telescope. The amazing images bear witness to the unique quality of the sky, revealing not only the Milky Way in all its splendour but also the planet Jupiter and the laser beam used at Yepun, one of the 8.2-m telescopes that make up this extraordinary facility. ESO PR Photo 33a/07 ESO PR Photo 33a/07 The Planet, the Galaxy and the Laser "The images are not composite", emphasises Yuri Beletsky. "The camera was being tracked on the stars, which can be easily noticed if you look at the telescope domes on the image (they look a little fuzzy). The colour of the laser beam on the first image actually looks pretty close to what one can see on the sky with the unaided eye." Most striking in the images is the wide band of stars called the Milky Way. Spanning more than 100 degrees in the first of these images, it shows the dust and stars that are part of our own Galaxy, a spiral galaxy containing about 100 billion stars. In the middle of this image, two bright objects are also seen. The brighter of the two is the planet Jupiter. The other is the bright star Antares. Another bright star, Alpha Centauri, one of the closest stellar neighbours to the Sun, is visible at the middle-left edge of the image. Three of the four domes that shelter the 8.2-m VLT's Unit Telescopes are visible on the first image. Streaming out of Yepun, Unit Telescope number 4, is the laser beam used to create an artificial star above Paranal, aiming directly at the centre of our own Galaxy. At the time the pictures were taken, astronomers were indeed using the SINFONI instrument (see ESO 21/04) to study the Galactic Centre, having a close look at the supermassive black hole that lurks in there. ESO PR Photo 32e/07 ESO PR Photo 33b/07 Shooting a Laser at the Galactic Centre With so many stars visible from the exceptional site of Paranal, one may wonder why it is necessary to create another, artificial, star? The answer lies in the very sophisticated instruments that are used on ESO's VLT. Some of them, such as NACO and SINFONI, make use of adaptive optics, a technique that allows astronomers to overcome the blurring effect of the atmosphere. This means that astronomers obtain images almost as good as if the whole telescope was placed in space, above Earth's atmosphere. Adaptive optics, however, requires a nearby reference star that has to be relatively bright, thereby limiting the area of the sky that can be surveyed. To surmount this limitation, astronomers now use at Paranal a powerful laser that creates an artificial star, where and when they need it (see ESO 07/06 and 27/07). Launching such a powerful laser from a telescope is state-of-the-art technology, whose set-up and operation is a continuous challenge. As seen from the images, this is, however, a technology that is now well mastered on Paranal. The images were obtained with a digital camera and 10-mm optics, mounted on a small equatorial mount, and are each the result of a single 5 minute exposure.

2007-08-01

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