Had I special: The Astronomical Contributions of the Herschel Family

НазваниеHad I special: The Astronomical Contributions of the Herschel Family
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Potential Optical Counterparts to High Mass X-Ray and γ-Ray Binaries

Carl Mitchell1, M. V. McSwain1
1Lehigh University.

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We seek to identify optical counterparts to several previously discovered high mass X-ray binaries and γ-ray sources from the Liu et al. and Fermi first year catalogues. Observations were taken with the CTIO 0.9-meter telescope, operated by the SMARTS Consortium. Photometric data were taken in the Strömgren b and y filters, as well as a narrow-band Hα filter. We present color-color diagrams of y-Hα vs. b-y for each field, and candidates for optical counterparts were selected based on their excesses of Hα emission. We also present spectral energy distributions for select candidates. This work is supported by the NSF REU site grant PHY-0849416, NASA DPR No. NNX09AT67G, and Lehigh University. We also thank the SMARTS Consortium, Rachael Roettenbacher, Tina Aragona, and Amber Marsh.


Time-series, Multi-wavelength Monitoring Of The High Mass X-ray Binary 4U 2206+54

Jessica L. Bugno1, E. G. Hintz1, M. D. Joner1, C. D. Laney1
1Brigham Young University.

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The high mass X-ray binary 4U 2206+54 has been a very controversial system. Optical time-series observations of this system from West Mountain Observatory and the Orson Pratt Observatory were analyzed to determine a more accurate orbital period. The summers of 2008 and 2009 provided a total of 55 nights of observations in the Johnson V filter. The summer of 2010 provided 20 nights of observations in Johnson BVRI. We present our preliminary results as of October 1, 2010 as well as the error analysis for the data. We also acknowledge NSF grant AST-0618209 for data collected from the West Mountain 36” telescope.


Optical Monitoring Of Two High Mass X-ray Binary Systems: 4u 1907+09 And Ks 1947+300

Juan C. Payan1, E. G. Hintz2, M. D. Joner2
1Worcester Polytechnic Institute, 2Brigham Young University.

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Using the BYU West Mountain 0.9-m telescope we monitored two High Mass X-ray Binary systems during the summer of 2010. The optical counterpart for 4U 1907+09 is reported as an O9 Ia star with an orbital period of 8.38 days and a magnitude of V= 16.4. For KS 1947+300 we find a B0 Ve reported as the optical counterpart with an orbital period of 40.4 days and V=14.2. We felt these two targets provided a good test of the new telescope’s capabilities. Each target was observed every clear night from June to September in the broadband B, V, and I filter. We will report on the optical variability seen in both systems and its relation to the published periods. This work is supported by NSF grant AST-0618209.


Optical Monitoring Of Three High Mass X-ray Binary Systems: BD+53 2262, RX J2030.5+4751, And BD+49 3718

Nathaly Zurita1, E. G. Hintz1, E. Salway1, C. R. Porritt1
1Brigham Young University.

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Over the past four summers we have monitored a number of High Mass X-ray binary systems as part of our undergraduate research program, including our REU program. These systems have been primarily monitored using the 0.4-m telescope of the BYU Orson Pratt Observatory. The data set is a mixture of high density single night observing runs that cover many hours, along with long term night to night monitoring. In this poster we will present preliminary results for three systems we have monitored; BD+53 2262, RX J2030.5+4751, and BD+49 3718. We wish to acknowledge the support of a BYU ORCA MEGs grant which has provided support for this program.


CCD Photometry Of The Extreme Mass Ratio Binary, TYC 1404-1687-1

Danny R. Faulkner1, Ron Samec, Evan Figg, Bruce Oliver, Astronomy Program, Bob Jones University, Walter VanHamme, Florida Interational University
1University of South Carolina Lancaster.

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We report our photometric analysis of the variable, TYC 1404-1687-1 (GSC 1404 1687, Cancer). The images were taken in December, 2008, March 2009 with NURO and 16 January 2009 via remote observing with SARA North. The UBVRI CCD photometry shows that TYC 1404-1687-1 has a totally eclipsing W UMa light curve, yet it has a shallow amplitude (AV~0.4 mag.). We studied the possibility the low amplitude was due to the presence of a third component: we began our analysis with ~30% third light as determined from Binary Maker. Next, we performed a BVRI simultaneous WD synthetic light curve analysis. Surprisingly, we obtained two nearly identical sums of square solutions, one with a measurable but small third light component (0-2%) and another with no third light. We conclude that the solution does not require a third light.
Our period study yielded 9 new times of minimum light, two from ROTSEI curves, JD Hel Min= 2452721.4226 and 2452728.3972, and the others from our observations: HJD Min I = 2454848.8844 ±0.0014, 2454901.8924 ±0.0006, 2454902.6903 ±0.0014, 2454904.6790 ±0.0058, HJD Min II = 2454823.9678 ±0.0017, 2454827.9618 ±0.0005, 2454901.6927 ±0.0005. Using these, we calculated the first precision ephemeris for this system,
HJD Min I = 2454902.6912 ±0.0009 + 0.3985874 ±0.0000003 d*E.
UBVRCIC standard magnitudes were determined. We find that the comparison star (GSC 1404 0119) is a late G-type dwarf while the check star (GSC 1404 0587) is a mid F-type dwarf. The binary is an F0V contact binary. We also performed a number of solutions (a q-search) which minimized at a mass ratio near 0.2. Our WD solution gave a fill-out of 45%. No spots are needed in the solution. So we find that TYC 1404-1687-1 is among the once rare, but growing number, of low amplitude-extreme mass ratio, totally eclipsing binaries.


The Mass Transfer Rate Of A Nearly Semi-detached Eccentric Binary Star Systems

Colby Haggerty1, J. F. Sepinsky1
1University of Scranton.

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We calculate the instantaneous mass loss rate of a nearly-semi-detached donor star in an eccentric orbit about its companion by taking into account the varying size and shape of the donor’s Roche Lobe throughout the orbit. As in the circular case, we model the density of the stellar atmosphere as a decreasing exponential function of the instantaneous gravitational potential above the photosphere. At each point in the orbit, the equipotential surfaces corresponding to the stellar photosphere and the inner Lagrangian point need to be recalculated due to the changing distance between and relative orbital velocity of the two objects. By analyzing the shape of the potential in the vicinity of the inner Lagrangian point we can determine the effective cross-section of the flow out of the donor star’s effective Roche Lobe. Combining this with mass density and sound speed we determine the instantaneous mass loss rate through the inner Lagrangian point of the donor star at each point in the orbit. We show the functional form of this rate over the course of a single orbit for a wide variety of binary parameters. This orbit variable mass loss rate is vital to proper calculations of orbital evolution of mass transferring eccentric binary system.


Estimating the Fraction of Binaries Affecting the JMAPS Astrometry

Henrique R. Schmitt1, B. F. Lane2, R. B. Hindsley3
1NRL/CPI, 2C. S. Draper Laboratory, 3NRL.

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We estimate the fraction of stars that are binaries and have a large enough motion of the center of light relative to the center of mass of the system, larger than 1 mas, to significantly affect the astrometric accuracy of the Joint Milli-Arcsecond Pathfinder Survey (JMAPS). These calculations were done using information about the observed distribution of spectral types, the frequency of binary systems as a function of spectral type, their mass ratios and period distributions. We find that, for systems with periods smaller than 10 years, approximately 12 percent of the stars with I=2 mag will have a motion of the center of light relative to the center of mass larger than 1 mas, decreasing to less than 1 percent for stars with I=14 mag. We explore the effects of reddening, orbital eccentricity, and different distributions of spectral types, to these fractions. These results are compared with the fraction of binary stars detected by the Hipparcos satellite.


Exploring Possible Origins of an Improbable Binary Star in the Open Cluster NGC 6819 Through Dynamical Exchange Simulations

Thomas Finzell1, A. Geller2, N. Gosnell1, R. Mathieu1
1UW Madison, 2Northwestern University.

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We model the origin of the binary star system, NGC 6819-3002-a highly improbable star system that is likely the remnant of a dynamical encounter. The horizontal-branch primary star would have had a large enough radius while in it's giant phase to engulf the orbit of the secondary star, making it very unlikely that these two stars were born together. In order to explore the likelihood that the binary was created via a dynamical exchange interaction we use a scattering experiment algorithm to simulate encounters between a single star and binary system. We use this to investigate the possible initial parameters that could produce the currently observed properties of the system. We incorporate the scattering experiments within a genetic algorithm, which searches over the large parameter space and iteratively selects initial parameters that yield the observed binary. The genetic algorithm gives us the ability to confine the potential parameter space into one of a computationally manageable size. We then perform a more systematic search of the identified region of parameter space in order
to determine the multi-dimensional probability distribution of parameters that can produce
NGC 6819-3002. We then correlate that probability distribution with the distribution of binary and stellar parameters of NGC 6819 in order to determine the likelihood that such a dynamical interaction could have occurred. The result of this process shows that NGC 6819-3002 may indeed have originated through a dynamical exchange interaction. Applying this technique to additional stars and star systems in other clusters will allow us to constrain the impact of dynamical encounters on the formation of anomalous objects like NGC 6819-3002.
We gratefully acknowledge funding from the National Science Foundation under grant AST-0908082.


Comparisons Between SPH and Grid-Based Simulations of the Common Envelope Phase

Jean-Claude Passy1, C. L. Fryer2, S. Diehl2, O. De Marco3, M. Mac Low4, F. Herwig5, J. S. Oishi6
1American Museum of Natural History and University of Victoria, 2Los Alamos National Laboratory, 3Macquarie University, Australia, 4American Museum of Natural History, 5University of Victoria, Canada, 6Kavli Institute for Particle Astrophysics and Cosmology.

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The common envelope (CE) interaction between a giant star and a lower-mass companion provides a formation channel leading eventually to Type Ia supernovae, sdB stars and bipolar PNe. More broadly, it is an essential ingredient for any population synthesis study including binaries, e.g. cataclysmic variables. Occurring on a short time scale - typically between one and ten years, the CE interaction itself has so far never been observed with certainty but the existence of companions in close orbits around evolved stars, whose precursor's radius was larger than today's orbital separation, vouches for such interaction taking place frequently. Via a detailed study of the energetics and the use of stellar evolution models, we derived in our previous paper the efficiency α of the CE interaction from a carefully selected and statistically analyzed sample of systems thought to be outcomes of a CE interaction. We deduced the initial configuration of those systems using stellar models, and derived a possible inverse dependence of α with the companion to primary mass ratio. Here, we compare these predictions to numerical simulations with two different codes. Enzo is a 3D adaptive mesh refinement grid-based code. For our stellar problem we have modified the way gravity and boundary conditions are treated in this code. The SNSPH code is a 3D hydrodynamics SPH code using tree gravity. The results from both codes for different companion masses and different types of primary stars are consistent with each other. Those results include a resolution study of a 0.88 M red giant interacting with a 0.9, 0.6 and 0.3 M white dwarf, respectively. Those systems reach a final separation of 25, 18 and 10 R, respectively. In this contribution, we present and discuss those results and compare them to our predictions.
This research was funded by NSF grant 0607111.


The Colliding Stellar Winds of the Extreme Wolf-Rayet Binary CQ Cephei

Rosina Iping1, G. Sonneborn1, J. C. Bouret2
1NASA's GSFC, 2Laboratoire d'Astrophysique de Marseille, France.

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We present time-resolved observations of the Wolf-Rayet + O star Binary CQ Cephei using the FUSE satellite. We acquired a series of observations of CQ Cephei and determined the structure of the bow shock zone formed when the winds of the two hot stars collide. CQ Cephei has the shortest period of all the known W-R+O binaries. The W-R star is classified as a nitrogen-rich WN6 star and the companion as an O9 II-Ib star. The observations cover a significant part of the 1.64-day orbital period. We were able to study the wind interaction zone from phase-dependent spectral variations. Of particular importance in the FUSE wavelength range is the large number of emission lines of abundant elements with different ionization potentials, ranging from O VI, S IV, P V, C III, to N II. The S and P lines are important because these elements are produced only in SN explosions and are not enhanced by nuclear processes in the binary stars themselves. We present improved constraints on orbital parameters and on characteristics of the W-R star itself (wind momentum, mass-loss rate, and abundances).


Mass of the Black Hole in V4641 Sgr

Rachel K. D. MacDonald1, C. D. Bailyn1, A. G. Cantrell1
1Yale University.

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V4641 Sgr is a galactic microquasar, or x-ray binary, with a B9III star as secondary and an orbital period of 2.82 days. Although the secondary star is very bright (13th mag.), it is clear that the disk around the black hole also contributes to the optical emission. This makes the determination of the orbital inclination, and thus the mass of the compact object, uncertain. We present simultaneous spectroscopy and photometry from 2009 and 2010, taken at the SMARTS telescopes in Cerro Tololo, Chile, which enables us to determine the disk fraction of the optical emission. Once this disk fraction has been determined, a more definitive mass measurement for the black hole in the system will be possible.

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