scholarly journals The NASA EPOXI mission of opportunity to gather ultraprecise photometry of known transiting exoplanets

2008 ◽  
Vol 4 (S253) ◽  
pp. 301-307 ◽  
Author(s):  
Jessie L. Christiansen ◽  
David Charbonneau ◽  
Michael F. A'Hearn ◽  
Drake Deming ◽  
Matthew J. Holman ◽  
...  
Keyword(s):  
High Resolution ◽  
Light Curves ◽  
Extrasolar Planet ◽  
Deep Impact ◽  
System Parameters ◽  
Two Phases ◽  
Planetary Moons

AbstractThe NASA Discovery mission EPOXI, utilizing the Deep Impact flyby spacecraft, comprises two phases: EPOCh (Extrasolar Planet Observation and Characterization) and DIXI (Deep Impact eXtended Investigation). With EPOCh, we use the 30-cm high resolution visible imager to obtain ultraprecise photometric light curves of known transiting planet systems. We will analyze these data for evidence of additional planets, via transit timing variations or transits; for planetary moons or rings; for detection of secondary eclipses and the constraint of geometric planetary albedos; and for refinement of the system parameters. Over a period of four months, EPOCh observed four known transiting planet systems, with each system observed continuously for several weeks. Here we present an overview of EPOCh, including the spacecraft and science goals, and preliminary photometry results.

scholarly journals Optical Follow up Photometry of the Transiting Extrasolar Planet XO-2

2008 ◽  
Vol 4 (S253) ◽  
pp. 443-445
Author(s):  
Jose M. Fernandez ◽  
Matthew J. Holman ◽  
Joshua N. Winn
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Markov Chain ◽  
Markov Chain Monte Carlo ◽  
Light Curves ◽  
Extrasolar Planet ◽  
System Parameters

AbstractWe present three full z-band transit light curves for the extrasolar planet XO-2 obtained with KeplerCam and the FLWO 1.2m telescope. The system parameters were determined fitting the data to transit models using a Markov Chain Monte Carlo simulation (MCMC). The main results presented in this poster are revised values for the parameters Rp/Rs, a/Rs and b.

scholarly journals Hydrodynamic Models of Solar and Stellar Flares

1989 ◽  
Vol 104 (1) ◽  
pp. 289-298
Author(s):  
Giovanni Peres
Keyword(s):  
High Resolution ◽  
Light Curve ◽  
Solar Flares ◽  
Impulsive Phase ◽  
Light Curves ◽  
Physical Parameters ◽  
The Sun ◽  
Hydrodynamic Models ◽  
X Ray ◽  
Stellar Flares

AbstractThis paper discusses the hydrodynamic modeling of flaring plasma confined in magnetic loops and its objectives within the broader scope of flare physics. In particular, the Palermo-Harvard model is discussed along with its applications to the detailed fitting of X-ray light curves of solar flares and to the simulation of high-resolution Caxix spectra in the impulsive phase. These two approaches provide complementary constraints on the relevant features of solar flares. The extension to the stellar case, with the fitting of the light curve of an X-ray flare which occurred on Proxima Centauri, demonstrates the feasibility of using this kind of model for stars too. Although the stellar observations do not provide the wealth of details available for the Sun, and, therefore, constrain the model more loosely, there are strong motivations to pursue this line of research: the wider range of physical parameters in stellar flares and the possibility of studying further the solar-stellar connection.

scholarly journals Energetics of Hi-C EUV brightenings

2018 ◽  
Vol 615 ◽  
pp. A47 ◽  
Author(s):  
Srividya Subramanian ◽  
Vinay L. Kashyap ◽  
Durgesh Tripathi ◽  
Maria S. Madjarska ◽  
John G. Doyle
Keyword(s):  
High Resolution ◽  
Energy Loss ◽  
Extreme Ultraviolet ◽  
Thermal Structure ◽  
Emission Measure ◽  
Light Curves ◽  
Solar Dynamics Observatory ◽  
Differential Emission Measure ◽  
Dominant Mechanism ◽  
Solar Dynamics

We study the thermal structure and energetics of the point-like extreme ultraviolet (EUV) brightenings within a system of fan loops observed in the active region AR 11520. These brightenings were simultaneously observed on 2012 July 11 by the High-resolution Coronal (Hi-C) imager and the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). We identified 27 brightenings by automatically determining intensity enhancements in both Hi-C and AIA 193 Å light curves. The energetics of these brightenings were studied using the Differential Emission Measure (DEM) diagnostics. The DEM weighted temperatures of these transients are in the range log T(K) = 6.2−6.6 with radiative energies ≈1024−25 ergs and densities approximately equal to a few times 109 cm−3. To the best of our knowledge, these are the smallest brightenings in EUV ever detected. We used these results to determine the mechanism of energy loss in these brightenings. Our analysis reveals that the dominant mechanism of energy loss for all the identified brightenings is conduction rather than radiation.

scholarly journals A photometric and spectroscopic study of R Coronae Borealis stars in the LMC

1991 ◽  
Vol 148 ◽  
pp. 351-352
Author(s):  
W. A. Lawson ◽  
P. L. Cottrell ◽  
K. R. Pollard
Keyword(s):  
High Resolution ◽  
Spectroscopic Study ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Light Curves ◽  
Photometric Observations ◽  
R Coronae Borealis Stars

Over the last several years we have obtained photometric observations of the four suspected (W Men, HV 5637, HV 12671, HV 12842) R Coronae Borealis (RCB) stars in the Large Magellanic Cloud (LMC). Fourier analyses of the light curves has revealed some periodicity in HV 12842, where there appear to be at least two closely spaced periods of 55 and 60 d. High resolution spectra of HV 12842, obtained with the Ango-Australian Telescope (AAT), indicate that it has similar atmospheric properties to a number of warmer galactic RCB and hydrogen-deficient Carbon (HdC) stars, e.g. R CrB, RY Sgr and XX Cam.

scholarly journals A Photometric and Spectroscopic Study of Southern RV Tauri Stars

1993 ◽  
Vol 139 ◽  
pp. 216-216
Author(s):  
Karen Pollard ◽  
P.M. Kilmartin ◽  
A.C. Gilmore ◽  
P.L. Cottrell
Keyword(s):  
Shock Wave ◽  
High Resolution ◽  
Light Curve ◽  
Spectroscopic Study ◽  
Light Curves ◽  
Phase Lag ◽  
Line Formation ◽  
The Past ◽  
Medium Resolution ◽  
Colour Curve

AbstractA program to obtain photometric and spectroscopic (high and medium resolution) observations of a number of southern RV Tauri stars has been undertaken over the past two years at the Mount John University Observatory (MJUO). Eleven RV Tauri stars of both RVa (constant mean magnitude) and RVb (varying mean magnitude) photometric type have been chosen as well as normal and weak metal lined RV Tauri stars.Most program stars display the alternating deep and shallow semi-regular light variations as well as the light curve - colour curve phase lag characteristic of RV Tauri stars. Fourier analyses of the light curves have revealed the dominant periodicities (see figure 1) and allowed phasing of the spectroscopic observations.High resolution échelle spectra obtained of these stars around the Hα region display the complex emission and absorption structure of the Hα line at various phases. Metallic lines show emission and line doubling or ‘splitting’ - profiles characteristic of the shock wave that propagates through the line-formation regions of these stars during a pulsational cycle. Spectra at specific phases will be used in an abundance analysis of selected RV Tauri stars.

scholarly journals IUE Ultraviolet Spectra of the Interacting Binary U Cephei

1980 ◽  
Vol 88 ◽  
pp. 237-241
Author(s):  
Yoji Kondo ◽  
George E. McCluskey ◽  
Robert E. Stencel
Keyword(s):  
High Resolution ◽  
Ultraviolet Light ◽  
Stellar Evolution ◽  
Binary Systems ◽  
Light Curves ◽  
Close Binary ◽  
Eclipsing Binary ◽  
Ultraviolet Spectra ◽  
International Ultraviolet Explorer ◽  
Far Ultraviolet

The eclipsing binary U Cephei has proven to be of great interest in the study of stellar evolution in close binary systems. Batten (1974), Hall and Walter (1974), Rhombs and Fix (1976), Markworth (1977), and Olson (1978), among others, have recently reported on their intensive ground based studies of U Cephei. Kondo, McCluskey and Wu (1978) have investigated the ultraviolet light curves of U Cephei obtained with Astronomical Netherlands Satellite (ANS). Kondo, McCluskey and Stencel (1979) have discussed the International Ultraviolet Explorer (IUE) spectra of U Cephei. This paper discusses results incorporating additional IUE high resolution spectra of U Cephei obtained in both far-ultraviolet and mid-ultraviolet spectral regions.

scholarly journals Preliminary Results on HAT-P-4, TrES-3, XO-2, and GJ 436 from the NASA EPOXI Mission

2008 ◽  
Vol 4 (S253) ◽  
pp. 470-473 ◽  
Author(s):  
Sarah Ballard ◽  
David Charbonneau ◽  
Michael F. A'Hearn ◽  
Drake Deming ◽  
Matthew J. Holman ◽  
...  
Keyword(s):  
Time Series ◽  
Extrasolar Planet ◽  
Deep Impact ◽  
Preliminary Results ◽  
Science Investigation ◽  
Discovery Program ◽  
Exoplanet Systems

AbstractEPOXI (EPOCh + DIXI) is a NASA Discovery Program Mission of Opportunity using the Deep Impact flyby spacecraft. The EPOCh (Extrasolar Planet Observation and Characterization) Science Investigation will gather photometric time series of known transiting exoplanet systems from January through August 2008. Here we describe the steps in the photometric extraction of the time series and present preliminary results of the first four EPOCh targets.

scholarly journals Extrasolar planet detections with gravitational microlensing

2007 ◽  
Vol 3 (S249) ◽  
pp. 25-30
Author(s):  
Shude Mao ◽  
Eamonn Kerins ◽  
Nicholas J. Rattenbury
Keyword(s):  
Light Curve ◽  
Real Time ◽  
Extrasolar Planets ◽  
Light Curves ◽  
Extrasolar Planet ◽  
Galactic Centre ◽  
Wide Field ◽  
High Magnification ◽  
Gravitational Microlensing

AbstractMicrolensing light curves due to single stars are symmetric and typically last for a month. So far about 4000 microlensing events have been discovered in real-time, the vast majority toward the Galactic centre. The presence of planets around the primary lenses induces deviations in the usual light curve which lasts from hours (for an Earth-mass [M⊕] planet) to days (for a Jupiter-mass [Mj] planet). Currently the survey teams, OGLE and MOA, discover and announce microlensing events in real-time, and follow-up teams (together with the survey teams) monitor selected events intensively (usually with high magnification) in order to identify anomalies caused by planets. So far four extrasolar planets have been discovered using the microlensing technique, with half a dozen new planet candidates identified in 2007 (yet to be published). Future possibilities include a network of wide-field 2m-class telescopes from the ground (which can combine survey and follow-up in the same setup) and a 1m-class survey telescope from space.

scholarly journals A Precise Estimate of the Radius of HD 149026b

2008 ◽  
Vol 4 (S253) ◽  
pp. 466-469
Author(s):  
Philip Nutzman ◽  
David Charbonneau ◽  
Joshua N. Winn ◽  
Heather A. Knutson ◽  
Jonathan J. Fortney ◽  
...  
Keyword(s):  
Accurate Determination ◽  
Stellar Mass ◽  
Radius Ratio ◽  
Light Curves ◽  
Heavy Elements ◽  
Precise Estimate ◽  
Extrasolar Planet ◽  
Orbital Inclination ◽  
Limb Darkening

AbstractWe present Spitzer 8 μm transit observations of the extrasolar planet system HD 149026b. At this wavelength, transit light curves are weakly affected by stellar limb-darkening, allowing for a simpler and more accurate determination of planetary parameters. We measure a planet-star radius ratio of Rp/R∗=0.05158±0.00077, and in combination with ground-based data and independent constraints on the stellar mass and radius, we derive an orbital inclination of i = 85°.4+0°.9−0°.8 and a planet radius of 0.755 ± 0.040 RJ. These measurements further support models in which the planet is greatly enriched in heavy elements.

scholarly journals UBV Photometry of the Massive Eclipsing Binary TT Aur

2001 ◽  
Vol 18 (2) ◽  
pp. 151-157 ◽  
Author(s):  
S. Özdemir ◽  
H. Ak ◽  
M. Tanriver ◽  
H. Gülseçen ◽  
S. Gülseçen ◽  
...  
Keyword(s):  
Binary System ◽  
Primary Component ◽  
Light Curves ◽  
National Observatory ◽  
Simultaneous Solution ◽  
Primary Minimum ◽  
Circumstellar Material ◽  
System Parameters ◽  
Ubv Photometry ◽  
Excess Absorption

AbstractUBV observations of the massive binary system TT Aur were carried out mainly at theTurkish National Observatory (TUG). These observations, together with IUE spectra and times of eclipse minima collected from the literature, were used to study the system parameters.Simultaneous solution of the light curves by the Wilson-Devinney code allows a semi-detached configuration with a slightly larger Roche-lobe filling secondary. This picture is supported by other evidence. The shoulders of the primary minimum suggest some excess absorption, in keeping with circumstellar material in the form of a disk-like structure around the primary component. The deeper primary minimum in the U filter may indicate a hotter region on the secondary-facing hemisphere of the primary.The period variation of the system can also be related to the possible existence of a third component in a circular orbit around the system.An alternative detached representation is also considered using optimal curve-fitting techniques. We appeal for further observations to help resolve some outstanding issues in this interesting massive binary.

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