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Kepler Guest Observer Program

Cycle 3 (2011) Accepted Guest Observer Programs

Conny Aerts
Leuven University

Our goal is to establish the simultaneous detection of uniform period spacings and rotational frequency splittings of nonradial gravity mode oscillations in a sample of carefully selected bright (i.e., Vmag below 13) F-type pulsating main-sequence stars, which are representative of massive host stars of exoplanetary systems, with the Kepler satellite. This will allow to deduce if rotational mixing near the stellar core is the cause of deviations from period spacings and/or if other yet unknown mixing processes occur. Additionally, we will determine the internal angular momentum distribution from the stellar core to the surface for all stars with rotational splitting. We plan to use the novel method we recently developed after the first detection such period spacings of gravity modes of a main-sequence pulsator, based on 150 consecutive days of high-precision space photometry gathered with the CoRoT satellite (Degroote et al., 2010, Nature, 464, 259). The small deviation from the spacing uniformity of the star HD50230 allowed to deduce the occurrence of a chemically inhomogeneous zone adjacent to the stellar core of this star. The CoRoT data have a too short time base to allow the additional detection of rotational splitting of the gravity modes. This prevented us to deduce the internal angular momentum distribution inside the star despite the readiness of the methodology. We shall overcome this limitation with Kepler data for a sample of 72 F-type gravity mode pulsators discovered in the public Q1 Kepler data. This will provide a seismically calibrated law for the near-core mixing and angular momentum distribution in main sequence stars, thanks to their gravity modes which penetrate all the way from the core to the surface.

Roi Alonso
Laboratoire d'Astrophysique de Marseille

We plan to continue our research on one of the very few systems of a white dwarf with a M star eclipsing component that is accesible to Kepler FOV. Extending the observations through Cycle3 will allow us to 1) improve the precision on the orbital parameters, 2) study the anual evolution of the flare activity on the M companion and its dependance with the orbital phase, 3) study the evolution of magnetic active regions on any of the components, 4) improve the precision on the expected detection of a secondary eclipse, 5) gain valuable data on the O-C residuals of the 1040 eclipses/year that Kepler is able to obtain, that might allow the detection of small stellar companions and probably substellar, and 6) search for pulsations of the WD component.

Alexander Brown
University Of Colorado

Starspots on late-type stars are a direct manifestation of the photospheric emergence of strong dynamo-generated magnetic fields. We propose to extend our Cycle 1 and 2 projects of 30 minute cadence Kepler photometry, in which we are investigating how activity phenomena such as the growth, migration, and decay of starspots, differential rotation, activity cycles, and flaring operate on single and binary stars with a wide range of mass (and hence convection zone depth). We expect that such investigations will stimulate and enable theoretical studies of magnetic flux generation and transport processes in the regime of moderate to fast rotation, which any successful theory must be able to address. Our Kepler Cycle 1 data shows a rich variety of photometric variability including starspot rotational modulation, pulsations (both simple and very complex), flaring, and eclipses. Our proposed Cycle 3 sample of 219 active stars is based on GALEX Cycles 4 and 5 FUV and NUV imaging of the Kepler field. Accurate measurements of starspot longitudes and spot filling-factor maps can be obtained from the Kepler photometry using our newly-developed light-curve inversion methods that fully utilize the powerful diagnostic capabilities of Kepler time series data. We check results from our new inversion code, which -- given the high quality of the Kepler lightcurves -- can directly model the differential rotation, with results from our previous inversion codes. A full suite of supporting high resolution optical echelle spectroscopy is being obtained using the Hobby- Eberly, MMT, NOT, and Apache Point Observatory telescopes. These observations will provide accurate determinations of the stellar properties, such as effective temperature, surface gravity, and projected rotational velocity, and also which stars are spectroscopic binaries and measure their radial velocity curves. Supporting X-ray imaging will commence in 2011 with an approved XMM Large Project and ultraviolet spectroscopy of several Kepler targets will be proposed in the coming months. Our sample includes stars for which Doppler imaging, both conventional and magnetic, is feasible using current technology.

Timothy Brown
University Of Colorado

We propose to measure the spin-orbit alignment of the primary in low mass-ratio eclipsing binaries. Although spin-orbit alignment is a subject of intense study for transiting planetary systems, only a few measurements have been done so far for stellar eclipsing binaries. The angle between the star's spin axis and orbital angular momentum axis is a key piece of information in the study of stellar binary formation and evolution. Naively one would expect the three angular momentum axes, the self rotation of both stars and the orbital angular momentum, to be well aligned as they all originate from the angular momentum of the same primordial molecular cloud. However, this simple view could be misleading. Several processes have been proposed in the literature that result in misalignment. Moreover, misalignment for both stellar components was already identified for one system, out of only three for which the spin orbit angles were accurately measured. Our measurement technique was never applied before and requires the very high precision photometry provided by Kepler. Our proposal will significantly extend the science done by Kepler.

Rosanne Di Stefano
Smithsonian Institution/Smithsonian Astrophysical Observatory

Do white dwarfs host asteroid systems? To answer this question we propose that Kepler continue the first search for asteroids transiting a white dwarf. Kepler's unique photometric sensitivity will allow it to detect the passage of 100-km class objects against the small disk of a white dwarf. To achieve this goal, we propose to continue our AO2 program to conduct observations of 2 white dwarfs in Kepler's 1-minute cadence mode. Theoretical arguments, recent observations of metal-enriched white dwarf atmospheres, and detections of debris disks, suggest that white dwarfs may be orbited by large populations of asteroids. Data collected by Kepler may provide the most direct evidence that such populations exist. A second year of observations is essential to increase the chance of detecting transits and to significantly increase the science return from any AO2 detections. Public interest in this type of project is high, making it ideal for education and outreach.

Michael Fanelli
NASA Ames Research Center

We propose to monitor a set of the brightest galaxies located within the Kepler field of view, the Kepler Galaxy Survey. Our primary objective is to explore the photometric stability of galactic systems with Kepler's unique blend of high precision and continuous monitoring. With important exceptions, galaxies provide a population of quiescent, non-variable sources, which can be used to quantify the photometric stability and noise characteristics of the Kepler photometer. The proposed survey will be sensitive to both continuous variability, especially low-level variations from embedded active nuclei, and random episodic events, such as supernovae. Using a J-band flux limit, we propose to monitor 200 bright galaxies encompassing a range of morphologies located across the field-of-view. Given the Survey's source brightness and spatial distribution, these data will form the temporal baseline for extragalactic investigations with Kepler.

Peter Garnavich
University Of Notre Dame

The progenitors of type Ia supernovae remain a mystery despite their importance as fundamental distance indicators for cosmology. We still do not know if thermonuclear events come from single degenerate binary stars or binaries made from two white dwarfs. Recent models show that the secondary star in a single degenerate binary will cause bright shock emission in the first hours to days after the explosion while double degenerate explosions are expected to brighten monotonically. We propose to monitor about 100 galaxies at z<0.05 in the Kepler field to obtain very early observations of a couple of supernovae. No other experiment ---past, present, or presently planned--- can match the time resolution and continuous monitoring of the Kepler mission. This program is also sensitive to shock breakouts in core collapse supernovae which constrain the physics of the early explosion.

Douglas Gies
Georgia State University

Stellar companions are commonplace among more massive stars, and these companions probably are the repository of the angular momentum of the original natal cloud. In order for star formation processes to lead to very close binary stars (with orbital periods of a few days), a distant third star may be required to carry the bulk of the angular momentum. Our goal here is to search for such companions surrounding eclipsing pairs of intermediate-mass stars (of spectral types B, A, and F). We will use the remarkably accurate light curves from the Kepler Observatory of some 41 eclipsing binaries to measure carefully the times of the eclipses. We will search for companions by investigating periodic variations in the eclipse timings caused by the light travel time across the orbital displacement of the close binary. In favorable circumstances, we will detect companions as small as brown dwarf stars and/or massive planets. We began this program in Cycle 1, and preliminary results confirm the feasibility of the research plans. This continuing program will provide an observational legacy of the orbital, pulsational, and magnetic variations among stars with the best determined physical properties in the Kepler field of view.

John Gizis
University Of Delaware

We have computed models which predict that M dwarf radii can be inflated by the effects of magnetic fields on convection and which also predict pulsations on the main sequence, particulary during He 3 burning. We request rapid cadence observations of a select sample of M dwarfs with spots with Kepler to observe these pulsations. The results will provide new constraints on the fundamental properties of low-mass stars.

Jonathan Grindlay
Smithsonian Institution/Smithsonian Astrophysical Observatory

The Digital Access to a Sky Century at Harvard (DASCH) project has begun to digitize and analyze the scientific data contained in over half a million Harvard plates from the 1880s to the 1980s. Here we propose to obtain Kepler light curves for three classes of variable stars we have discovered in our analysis of 2000 digitized DASCH images with at least partial coverage of the Kepler field. The first class are 5 K giants which showed ~1 mag changes on timescales of 10-50 years. Our initial discovery (Tang et al. 2010) of 3 such variables near M44, all K2III, has now been expanded to 20 which show ~1 mag changes on timescales from 10 to 100 yrs. Their light curves do not match known types of variable stars, or any models for red giants, and their nature remains mysterious. Kepler light curves will allow us to study the short-term variability of the 5 stars included on the Kepler CCDs and measure their star spot activities and rotations. Using the tools of asteroseismology, the stellar parameters will also be estimated. The second group of variables we propose to monitor are 4 other long-term variables. The third group are 3 Chandra X-ray sources with positional matches to KIC stars which showed variability in their 100y DASCH light curves, 3 CVs and 6 flare variables bluer than K type found in DASCH.

Joyce Guzik
Los Alamos National Laboratory

The delta Scuti and gamma Doradus pulsating variables are main-sequence (core hydrogen-burning) stars with masses somewhat larger than the sun (1.2 to 2.5 solar masses). The lower-mass gamma Dor stars are pulsating in nonradial gravity modes with periods of near one day, whereas the delta Sct stars are radial and nonradial p-mode (acoustic mode) pulsators with periods of order two hours. Because of the near one-day periods of gamma Dor stars, it is very difficult to discover and monitor these variables from ground-based photometry or spectroscopy due to the 1 cycle/day alias. Hybrid gamma Dor/delta Sct stars are among the most interesting targets for asteroseismology because the two types of modes (pressure and gravity) probe different regions of the star and are sensitive to the details of the two different driving mechanisms. Because these driving mechanisms are somewhat mutually exclusive, hybrid stars exhibiting both types of pulsations are expected to exist only in a small overlapping region of temperature-luminosity space in the Hertzsprung-Russell diagram. However, Kepler Asteroseismic Science Consortium (KASC) Working Groups 4/10 (delta Sct/gamma Dor) have discovered that hybrid stars are surprisingly ubiquitous. In a study of 750 KASC A-F stars observed for up to four quarters, 47% show hybrid pulsations. Despite extensive study of this large sample during the past summer by the KASC WGs, no obvious frequency or amplitude correlations have emerged, and there seems to be no clear separation of gamma Dor and delta Sct pulsators in the HR diagram. The known driving mechanisms cannot explain the pulsation behavior. In our Cycle 1 Guest Observer program, targeting only 14 stars, five show clear hybrid behavior, and five more show gamma Dor pulsations. In addition, at least six stars showed some amplitude variability between Q2 and Q4 in the long-cadence data. We are awaiting data on an additional 187 targets from the Cycle 2 GO program, searching for more hybrids. Here we propose to take advantage of the Kepler unprecedented micromagnitude photometric precision and ideal cadence length for these pulsation periods to supplement the KASC sample for fainter stars, and perform longer-term monitoring to quantify and characterize amplitude or frequency spectrum variation. After Kepler, we will likely not have the opportunity in this generation of researchers to obtain such data (unless a European mission, Plato, competes successfully). We propose continued monitoring of the gamma Dor/delta Sct candidates discovered in Cycle 1, as well as continued monitoring of the Cycle 2 stars. In addition, we propose to observe 517 new targets to fill in the statistics for the magnitude 14-15 stars with Teff and log g appropriate for gamma Dor or delta Sct stars. Our aim with this set is to determine whether there is actually a magnitude cutoff for detecting variability as hinted at in the KASC analysis. Long-term monitoring of a large sample of these stars with the high-precision Kepler photometry is essential to help resolve the mysteries surrounding the theoretical model predictions and to realize the potential for asteroseismology of these stars.

Thomas Harrison
New Mexico State University

We will use NMSU facilities to obtain UBVRI light curves of a set of eclipsing binaries in the Kepler field of view to ascertain the limb darkening for the broad Kepler bandpass. As we show below, limb darkening strongly affects the values of physical parameters extracted from exoplanet transits. The Kepler bandpass is very broad, and therefore the derived, mean limb darkening cannot be easily predicted. This is especially true given that limb darkening for normal stars has been shown to be in error by +/- 10 to 20%. We have independently analyzed the Kepler public release data set to identify deep eclipsing binaries spanning the spectral type range A to K. We concentrate on systems with similar temperatures for both components. We will obtain ground-based, multi-wavelength light curves and simultaneously model them using a modified version of JKTEBOP to to derive the limb darkening. In this way, we will construct a data base of observationally determined limb darkening coefficients for the Kepler bandpass.

Thomas Harrison
New Mexico State University

We are requesting continued 30-minute cadence observations of 99 low-mass, main-sequence, detached, double-lined, eclipsing binaries in the Kepler field. These systems were identified from both Q0/Q1 Kepler data (Coughlin et al. 2010, AJ, in press), as well as our existing Kepler GO program. The Kepler observations we request, coupled with our ongoing ground-based multi-wavelength photometric and spectroscopic follow-up data, will allow us to more accurately measure the masses and radii of these stars, and test the theory that binary spin-up is the primary cause of inflated radii in low-mass stars observed to-date. We will detect relativistic photometric beaming in 15 of the systems, and apsidal motion due to general relativity in 27 of the systems, allowing us to independently measure the stellar masses via photometry. We will also be able to probe the internal density distribution of these stars via measurement of classical apsidal motion in many of the systems. Finally, we will also measure spot, and therefore magnetic, activity as a function of spectral type and binary rotation period, and track the temporal evolution thereof. The full year of observations is needed to have a sufficient temporal baseline for the apsidal motion and spot variability measurements, as well as to build enough signal to noise for a robust detection of the relativistic beaming effect.

Suzanne Hawley
University of Washington

Active G, K, and M dwarfs exhibit energetic outbursts caused by magnetic reconnection events, called flares, which occur over a large range of timescales and energies. While analysis of high cadence observations has shown that canonical (fast rise, exponential decay) flares can be represented by a T = 8,000 to 10,000 K blackbody component (Hawley & Fisher 1992, Hawley et al 2003), flares which exhibit highly complex light curves (characterized by > 15 additional sub-events) have been phenomenologically modeled as T = 16,000 to 20,000 K hotspots near the photosphere (Kowalski et al 2010b). Such hotspots require about 14x more heating of the photosphere than predicted by current radiative hydrodynamic (RHD) models, potentially indicating a new, significant gap in our understanding of flare physics. We propose to monitor 2 active G, 1 active K, and 3 active M dwarfs at short (1 minute) cadence for 6 months. These data will enable us to (a) determine when and how often light curve substructure forms during flares, as a function of total flare energy; and (b) ascertain whether the prevalence of this complex morphological structure changes with spectral type (G to K to M) and across the convective boundary in M dwarfs. This program will provide the first statistical assessment of whether flare-induced hotspots are a common byproduct of flares and whether there is a threshold flare energy required to trigger the phenomenon, hence constraining efforts to develop self-consistent models that accurately describe the physics of stellar flares.

Kenneth Hinkle

Long secondary period (LSP) variables are so named because they are late type giants with both a long period and shorter period pulsation. While approximately 25-30% of all pulsating AGB stars show LSP behavior there is no known physical cause for the longer period. LSP variables are the only form of stellar variability that is not understood. However, LSP variables are known to obey a period-luminosity (P-L) relation. This limits the possible causes to two causes: binarity and pulsation. Strong arguments can be made against both binarity and radial pulsation. The remaining possibility is non-radial pulsation. While the long period mode fits this violates current interior models.cWe obtained Kepler Cycle 2 time to look for higher order non-radial pulsation modes. While we have yet to see any Cycle 2 data, Cycle 0 and 1 data snippets suggest strongly that non-radial modes are present. Fourier analysis of the light curve should readily identify these modes. We proposed extending these observations to study the stability and power in the very low frequency modes. The techniques of asteroseismology will be applied. In the absence of non-radial pulsations, we will explore the detailed long term light curve to see if it agrees to high precision with models of ellipsoidal variations. Either the binary or the pulsation models allow interesting outcomes. The binary model involves near-planet sized companions with orbits evolved into a very specific configuration. The pulsation model is forbidden by present stellar interior models and will drive now understanding of stellar interior structure.

Kenneth Hinkle

The extraordinary galactic open cluster NGC 6791 falls in the Kepler field. NGC 6791 is ancient with an age of 8 Gyr, metal rich with [Fe/H]= +0.30, and one of the most massive open clusters known. We propose to obtain Kepler time series photometry for a sample of stars on the RGB/AGB of this cluster. From the population of the cluster and the stellar evolutionary time scales we know that a small fraction of the program objects are AGB stars but the only way to distinguish the RGB/AGB stars with certainty is to look at the interior structure. We will do this using Kepler data and the tools of asteroseismology. This will give us a text book perspective of how stellar interior structure changes up the RGB, to the giant clump, and then up the AGB for a set of stars of the same initial composition and near solar mass. Classification of the evolutionary status of the RGB/AGB stars will enable additional studies of stellar composition, mixing, and mass loss. This will produce a case study into the cycling of matter through cluster stars stars and back into the ISM. This project is being undertaken in collaboration with the Kepler Asteroseismic Science Consortium.

Jay Holberg
University Of Arizona

We propose to continue our efforts to determine the absolute photometric calibration of Kepler using relatively small samples of white dwarfs during Cycle 3. Since Cycle 1 we have been observing 8 DA white dwarfs to which were added 7 white dwarfs in Cycle 2. Our Cycle 1 data show, as expected, no short period or long term variations in any of our stars that are not associated with instrumental or spacecraft effects. We continue to study the spacecraft related modulations in the data.

Steve Howell

Cataclysmic variables provide the cleanest available natural laboratories to investigate the physical behaviour of accretion. The timing capabilities and sensitivity of Kepler are well matched to the timescales and amplitude of accretion variability in these sources. This combination provides an unprecedented opportunity to test and refine the paradigms of stellar accretion with high-precision, uniform data containing no diurnal or seasonal gaps. We propose a multi-faceted observational and modeling program that puts our current understanding of accretion to the test and has the potential to measure the spatial structure of model-dependent disk parameters. Kepler observations of cataclysmic variables will impact profoundly our understanding of accretion dynamics and the nature of astrophysical viscosity. Our proposed observations will provide an outstanding astrophysical legacy for the Kepler mission archive.

George Jacoby
Carnegie Institution of Washington

We will determine the fraction of planetary nebulae (PN) in the Kepler field that have central stars with close binary companions. Ground-based measurements of the binary rate of PN central stars is about 20% whereas the observational evidence based on a diverse set of arguments is that this fraction should be 50-80%. The observations are so challenging from the ground that we cannot say whether there is a conflict or not. Kepler's unique ability to measure small photometric variations will allow an accurate estimate of binary central stars for the PNe in the field of view. The question of binary frequency has wide-ranging consequences that impact stellar and galactic evolution.

Styliani Kafka
Carnegie Institution of Washington

Magnetic activity cycles comprise a fundamental parameter for testing and understanding magnetic activity, stellar dynamos and space weather around stars. Especially at a time where planetary searches reach their zenith, the understanding of long-term variations in stellar atmospheres weigh heavily in the long-term stability of stellar habitable zones and the preservation of biosignatures on the atmospheres of extrasolar earths. Our proposed Kepler observations aim at exploring long-term (multi-annual) variations in the stellar activity characteristics of K/M dwarfs in the Kepler field. Specifically, for the stars in our sample we will derive correlations between rotation, active region growth and decay, flare rate, flip-flop evolution activity cycles and stellar mass, using long-term Kepler light curves. In turn, this will provide fundamental input parameters for the study of stellar dynamos and the determination of the magnetic field action in stars with deep convection zones.

Steven Kawaler
Iowa State University

The subdwarf B (sdB) stars lie at the extreme blue end (Teff~25,000-35,000K) of the horizontal branch, and are the remnant cores of stars that have experienced the core helium flash while on the RGB. They have extremely thin (and inert) hydrogen shells surrounding a core undergoing helium fusion. How these stars form is currently unknown, though leading scenarios include mass transfer in a binary system. Single-star mechanisms have also been proposed and remain viable given the limitations of observables in these stars. We propose to continue Kepler observations of the unique hot blue star B4 in NGC 6791, one of only a handful of (sdB) stars known to exist in an old open cluster, and the only cluster sdB known to show photometric variability caused by binarity. Our goals are twofold - to observe short-period nonradial pulsations in this star, and to study longer period variations caused by its binarity. Asteroseismic probes of this star, coupled with the additional constraints of cluster membership and the properties of the binary system, should provide important clues about the formation mechanism of the sdB stars. At least 75% of sdB stars with Teff and log g similar to B4 show g-mode pulsations. B4 was selected for short-cadence observation for Cycle 2. If it is a pulsator, a second year of photometry will enable us to refine the pulsation periods, reach low-amplitude modes at levels (70ppm) seen in known Kepler sdB pulsators , and perhaps measure changes in the pulsations driven by evolution of the star. A pulsator in an open cluster of known metallicity and age will provide new and unique probes of the pulsation mechanism and interior of these stars. Given its faintness, the multiperiodic variations (45 to 90 minute periods) and the small amplitude of the pulsations, Kepler is the only instrument able to measure these oscillations to the degree of precision needed for asteroseismic analysis. Another year of SC data would allow us to look for smaller amplitude pulsations than one year alone might reveal, perhaps showing multiplet structure that can provide mode identification. This star is already known to be a low-amplitude (2%-9%) variable with a period of less than 1 day. Our second goal is to extend the high signal-to-noise light curve for analysis of the binary system. High-precision Kepler photometry, coupled with ground-based spectroscopy that we will obtain, can measure the orbital properties of the binary, the mass and radius of the companion, and the distance. With a second year of photometry of the binary light curve, we can begin to place interesting limits on a tertiary components through timing variations. Because this star is faint (Kepler magnitude Kp = 18.27), ground-based data have been insufficient to establish the nature of the known variability or determine the properties of the binary system. Ground-based data are insufficient to detect short-period variability from pulsations. Only an extended, uninterrupted time series can address these issues, and at present Kepler is the only instrument capable of providing the needed data. B4 is a uniquely valuable star: a (possibly) nonradially pulsating star, in a close binary system, within a cluster. The binary nature will allow mass and radius determination,and its presence in a cluster secures knowledge of its age, metallicity, and distance. With these known, asteroseismology will be tightly constrained.

Karen Kinemuchi
NASA Ames Research Center

RR Lyrae variable stars are pulsating stars that are useful objects in the study of Galactic structure and evolution, and stellar astrophysics. They are easily identifiable in photometric surveys with their distinctive light curve shapes. However, we focus our study on the Bailey c-type RR Lyrae stars (RRc), which are relatively shorter period and less numerous than the ab-type stars. The RRc stars are often confused with eclipsing binary stars via the light curves, and candidate stars are often hard to classify, even with good time-series sampling. We propose to look at four RRc stars discovered with the Q0/Q1 Kepler data that exhibit additional periodic and/or long term phenomena, unusual for this type of star. We will use Fourier decompositions techniques as well as a new automated stellar classification software to confirm the status of these RRc stars. We will also study the new long term phenomena with the additional quarters and identify the source(s). Coupled with the Kepler data, we will obtain ground based photometric and spectroscopic followup data.

Karen Kinemuchi
NASA Ames Research Center

The Kepler mission provides the deepest, complete, high precision photometry with uniform cadence of stars down to the confusion limit of Kp=21. Due to the short lifetime of this mission, it is crucial to use this resource now and take advantage of the unique catalog the spacecraft can obtain. Kepler does not record the whole field and only uses a finite number of masks to observe interesting targets. The precision of the relative photometry is at 4% accuracy at Kp=20. Pre-launch surveys have completeness down to 16-17th magnitude, but our new variable star catalog goes down to the confusion limit. Thus, our catalog will provide a large number of potentially interesting targets for Kepler to observe. This variable star catalog was constructed from the full frame images taken during the commissioning phase of Kepler, and we estimate over 265,000 faint variable stars in the field. Given Kepler's unique capabilities, this survey will provide a unique opportunity to find various variable stars such as eclipsing binaries, pulsators, rotators, and cataclysmic/eruptor stars. We propose a pilot study of 45 stars, all of which demonstrate the most interesting large amplitude variations, to begin this survey.

Jifeng Liu
Smithsonian Institution/Smithsonian Astrophysical Observatory

The Kepler mission, while designed for exoplanet search, has proved powerful in understanding the accretion disks around compact objects for its unique capability of continous monitoring with unprecedented photometric precision. Previous Kepler observations of symbiotics and Cataclysmic Variables have successfully probed the structures of the accretion flows around white dwarfs. Here we seek to probe the accretion flows around more compact neutron stars and black holes, a regime never been studied before. For this purpose, a sample of low-mass X-ray binary (LMXB) candidates in the Kepler field have been selected from the ROSAT All Sky Survey, and subsequent Chandra/ACIS observations have identified seven LMXBs with unique optical counterparts suitable for Kepler observations. The proposed Kepler continuous monitoring of these seven LMXBs, combined with daily and weekly Swift/XRT monitoring for two brightest LMXBs in X-ray, will probe the accretion disk structure, its evolution with accretion rate, and how the accretion flow proceeds inward.

Kenneth Mighell

We propose to monitor the 57 eclipsing binaries in Cycle 3 that we previously observed during our program Kepler GO Cycle 1 proposal 08-KEPLER08-0014 "A Calibration Study of Variable Stars in the Kepler Field". Our goal is to improve the modeling of eclipsing binaries based on long-cadence Kepler observations. At least 10% (6 of 57 systems) of our sample exhibit strong evidence of starspots and we seek to determine if and how those starspots have moved between Cycles 1 and 3. We seek to achieve period measurements with a precision of better than 0.00001 days (< 0.864 sec). This precision should allow us to determine small but significant period changes in contact binaries in our sample that would be due to mass flows from the secondary to the primary star. Observations spread Cycles 1 and 3 should allow us to determine if any subtle timing effects remain in the Kepler processing pipeling procedures that are due to seasonal effects. The non-contact systems will be used to calibrate our new period timing procedures.

Mike Montgomery
University of Texas

We propose to use the nonlinearities present in the light curves of large-amplitude Gamma Doradus variables to constrain the depth of their convection zones. The basis of this technique is the strong temeperature dependence of stellar convection zones: relatively small variations in the surface temperature due to pulsation can result in large changes in the size of the convection zone during a pulsation cycle, and this in turn introduces nonlinearities into the light curves. This technique has been successfully applied to pulsating white dwarf stars and should be straightforward to apply to the Gamma Doradus stars. In addition, we seek to monitor changes in the convection zones of these objects over multiple epochs. We therefore request continuing long-cadence observations for four such Gamma Doradus stars in the upcoming Kepler observing cycle. At present there are two competing proposed mechanisms concerning the source of mode driving based on completely different assumptions regarding the physics of convection in these objects; our analysis will help resolve this long-standing question. Finally, we note that our approach is one of only two techniques that can be used to measure the depth of the convection zone of a pulsating star, and it is the only one available for stars such as the Gamma Doradus variables which have only a handful of excited modes. As a result, this investigation will provide important data with which to test the results of hydrodynamical simulations of convection in this part of the HR diagram.

Richard Mushotzky

We propose continued long-cadence monitoring of 11 confirmed and 8 candidate AGN in the Kepler FOV. Kepler's unparalleled combination of high precision, good cadence, long duration and nearly uninterrupted coverage will provide AGN light curves that will be unsurpassed for many years to come. These will allow the first optical power spectral density functions capable of determining the form of the PSD and the first optical/x-ray cross-correlation functions to probe time scales below 1 day. Kepler's only limitation is that only a small number of AGN had been identified in its FOV; to rectify this we have identified 9 new AGN candidates in addition to our cycle 2 sample in order to accumulate the richest achievable data set while this unique instrument is still operating.

Robert Olling
University of Maryland

We propose to monitor about 400 small galaxies in Kepler's field of view for photometric variations at the millimagnitude (mmag) level to detect active galactic nuclei (AGN) at unprecedented low amplitude of variability or brightness. Since ~8% of galaxies are known AGNs (Sarajedini, 2008), we expect to find of order 32 normal AGN in our sample, but an unknown number of low amplitude AGN. The excellent photometric accuracy of Kepler makes it an ideal instrument to investigate the unexplored regime of very-low amplitude variability in AGN, on timescales from a year down to a week, or less. The technical goal of our proposal is to improve the long-term absolute photometry by a factor of several (10x is the photon-noise limit) so that we can push the limiting Eddington ratio even further into the unexplored region of AGN variability for low luminosity objects. Our current-best photometric stability is already better than 3 mmag for data extracted within a given quarter in the Kepler full-frame images.

Peter Papics
Leuven University

For a sample of 9 carefully selected B stars (based on the public Q1 data of non-KASC targets, see Debosscher et al., submitted to A&A) we will deduce the core overshooting parameter value from frequency and period spacings (see Degroote et al. 2010, Nature, 464, 259), and check if we can establish a relation between it and the stellar mass. Via the detection of rotational splitting (see Aerts et al. 2003, Science, 300, 1926) - which was not achieved yet from CoRoT data for B stars - we plan to check the internal rotational law of these carefully selected hot massive stars. To have a sufficient frequency resolution, we need at least one year of ong cadence data. We have guaranteed access at the 1.2 meter Mercator telescope on La Palma to take high resolution HERMES spectra for the brighter targets simultaneously with the Kepler observations during the entire season in 2011 and 2012 when the field is visible, and we plan to submit proposals for other spectrographs on larger telescopes to extend our coverage. The first spectroscopic measurements already confirmed that the targets are main-sequence stars of spectral type B, with various projected surface rotational velocity values.

Ruth Peterson
Lick Observatory

We propose 130 photometrically-selected targets with V < 17.3 within 14' of the center of the old, metal-rich open cluster NGC 6791 for Kepler 30-min long-cadence observations. Sixty-six of these were granted as targets to this program in Cycle 2. The goal is to detect eclipsing binaries suitable for determining the masses of the components, through future ground-based observations of radial velocities. Our targets are giants and subgiants, not main-sequence stars, in order to reduce confusion in the Kepler field and to provide feasible targets for spectroscopy. We need a large target sample to isolate favorable binaries, as some stars will be non-members, only half of the members will be in binaries, many of these will have merged, and only a few of those remaining are useful. Suitable binary systems should not be triple, and should include a giant and a main-sequence turnoff star so that both components can be detected spectroscopically. The components must not have previously exchanged or lost mass. Binary periods must be one to a few years, the orientation must be nearly edge-on, and the eccentricity will be finite but should not be large. Kepler is already looking at many targets near the cluster center, where proper motions provide membership information. We are including a number of these, many of which were granted as targets to this program in Cycle 2, and most of which are brighter giants for which we have membership information from a decade-long radial-velocity survey. But we also need to go to the outer regions of the cluster and to fainter stars, to increase the binary sample, mitigate against possible binary interactions at high cluster density and large stellar radii, and include a wider range of evolutionary stage. Consequently we are including many more targets, those relatively uncrowded stars that fall on the cluster color magnitude diagrams defined by the inner members. From this sample we expect to detect roughly a half-dozen binaries from which meaningful masses can be obtained. Follow-up ground-based high-resolution spectra will derive their parameters and confirm cluster membership, as well as define the primary velocity curve, the secondary velocity offset, and the system period. This should stringently constrain comparisons of observed color-magnitude diagrams to produce meaningful cluster parameters. Such constraints would have major significance for the derivation of age and metallicity from the broadband colors and integrated spectra of old elliptical galaxies, for which NGC 6791 is a critical resolved template.

Geraldine Peters
University Of Southern California

We propose a combination of high and low cadence Kepler observations of ten Algol-type binaries in the Kepler fields to study the physics of mass accretion in these interacting systems. Emphasis will be placed on long-term variability, especially the Double Periodic Phenomenon identified by Mennickent et al. (2003). Double Periodic Variables (DPVs) display cyclic photometric variations on the short time scales of their orbital periods and long cycles of hundreds of days. The cause for the long cycle is unknown, but it might be the result of the waxing and waning of an obscuring circumstellar (CS) disk about the mass gainer precipitated by critical rotation of the gainer. Variability in an identified hot accretion spot at the site of the gas stream impact (photosphere or disk) and its size and longitude on the time scale of the long period will be investigated. We will look for changes in possible accretion-induced photospheric pulsations that might help drive mass loss to a CS disk and study its depth dependence. We will also search for variable micro-flaring that might result from shocks due to a clumpy gas stream. Since the radiative energy from hot spots and disk mass loss at L3 can precipitate systemic mass loss, their existence influences the evolution of close binaries. We expect that a hot spot and micro-flaring will be visible only on the trailing hemisphere of the system. Pulsations should be global, but perhaps of an irregular nature on hemisphere experiencing the impact. Although we have a general understanding of how Algol systems are formed and their evolutionary state, little is known about the details of the mass accretion. We will investigate both short and long-term variability over many orbital cycles to identify unique light curve structure that will provide insight into the physics of mass transfer. The Kepler photometry will be analyzed with the latest version of the Wilson-Devinney light curve analysis program. The residual light will be analyzed using standard Fourier techniques. Frequencies found in the residuals will be interpreted with the aid of current asteroseismology software. The project addresses NASA¿s Strategic Subgoal 3D, Discover the origin, structure, evolution, and destiny of the universe, and search for Earth-like planets, as it will advance our understanding of the evolution of early-type close binary stars

Eric Sandquist
San Diego State University

Age is difficult to measure to extreme precision for stars other than the Sun. In the field being observed by Kepler, the open star clusters NGC 6791 and NGC 6819 offer the opportunity to test a variety of methods of age determination, including several capable of high precision. We propose to use Kepler to push the limits of age determination using weakly-interacting binary stars that contain evolved stars. Because mass and radius can be measured extremely precisely (to better than 1%) for such binaries and require minimal theoretical interpretation, we can make use of the rapid changes in size that begin when a star leaves the main sequence to constrain ages tightly. With a minimal investment of short-cadence observations, we demonstrate that we can push the age precision in both clusters to better than 7% via this method. These two open clusters are becoming extremely strong tests of stellar evolution theory, and will have an important influence well beyond stellar astrophysics.

David Soderblom
Space Telescope Science Institute

We have found solar-type stars (G and K stars on and near the main sequence) in the Kepler Q1 data release that exhibit dramatic flares, with energies at least ~100 to 1,000 times those seen in the largest solar flares. These flaring stars are worth examining in much greater detail, both to understand better the physics of flaring, and to understand why these particular stars exhibit this extraordinary behavior and what that may mean for the nearby environments of these stars. If they are, in fact, the youngest stars in the Kepler sample, then these flares are putting energies into their surrounding environments at a critical phase in planet formation. However, we believe for several reasons that these stars are not simply the youngest stars in the Kepler sample and are likely to be older stars. If that is true then we are witnessing solar-type stars exhibit behavior not ever seen before, and there are important implications. Our working hypothesis is that these stars show flares episodically. This proposal has been written to ensure continued observation of the flaring stars, to ensure access to those data, and to obtain one-minute cadence observations of a subset of the flaring stars in order to derive precise physical parameters for these extraordinary objects and to better study the flares themselves. That can then permit gaining a fuller understanding of the context of the extraordinary flaring behavior.

Ann Wehrle
Space Science Institute

We propose to double the time baseline of our approved Cycle 2 program to search for variability in four flat spectrum radio quasars (blazars) and one powerful radio galaxy, Cygnus A, on timescales comparable to the light crossing time of the accretion disk (AD) around the central supermassive black hole (SMBH) or the base of the relativistic jet. When the quasars are quiescent, a quasi-periodic light curve indicates an AD origin, and provides a way to estimate the mass of the SMBH. When the quasars are active, long-lived quasi-periodic oscillations (QPOs) are very probably from helical features in the jets; if several different short-lived QPOs are seen in one quasar, then the emission is probably coming from turbulence behind a shock. When we instead see aperiodic variations during a faint state, high and low frequency breaks in the power spectral density (PSD) yield the inner and outer edges of ADs, hence the BH mass. Breaks in the PSD could yield physical cales in the relativistic jet. Kepler is ideally suited to the necessary measurements by delivering highly stable photometry continuously on timescales from minutes to days. By adding a second year of data, we will: see more of the quasars' faint quiescent states, thus measuring the duration and occurrence rate of QPO-emitting blobs in the AD; use the better SNR in the PSD to improve our ability to detect the inner and outer edges of the AD; and reduce the error on the SMBH mass estimate by 30%. For bright states, we will observe: long-timescale QPO-producing helical features in the jet; short-timescale QPO-emitting blobs near shocks; for aperiodic signals, we could detect twice as large physical scales in the jet, and use the better SNR to reduce error bars on the smallest strong structures in the jet by 30%.

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