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Very Wide Binaries
Robert Olling1, E. Shaya1
1Univ. Of Maryland.
We develop Bayesian statistical methods for discovering and assigning probabilities to physical stellar companions. The probabilities depend on similarities in ";corrected"; proper motion, parallax, and the phase-space density of field stars.
Very wide binaries with separations over 10,000 AU have recently been predicted to form during the dissolution process of low-mass star clusters. In this case, these wide systems would still carry information about the density and size of the star cluster in which they formed.
Alternatively, Galactic tides and weak interactions with passing stars peel off stars from such very wide binaries in less than 1/2 of a Hubble time. In the past, these systems have been used to rule in/out MACHOs or less compact dark (matter) objects.
Ours is the first all-sky survey to locate escaped companions that are still drifting along with each other, long after their binary bond has been broken. We test stars for companionship up to an apparent separation of ~8 parsec: 10 to 100 times wider than previous searches.
Among Hipparcos stars within 100 pc, we find about 260 systems with separations between 0.01 and 1 pc, and another 190 with separation from 1 to 8 parsec.
We find a number of previously unnoticed naked-eye companions, among which: Capella & 50 Per; Alioth, Megrez & Alcor; gamma & tau Cen; phi Eri & eta Hor; 62 & 63 Cnc; gamma & tau Per; zeta & delta Hya; beta01, beta02 & beta03 Tuc; 44 & 58 Oph and pi & rho Cep. At least 15 of our candidates are exoplanet host stars.
Standardization of Comparison Stars in the Fields of 10 High Mass X-ray Binaries
Eric G. Hintz1, M. D. Joner1
1Brigham Young Univ..
To support our current observing program to monitor High Mass X-ray Binary (HMXB) systems for optical variability, we calibrated a large sample of comparison stars in the fields of ten HMXB systems. This was done using the new BYU West Mountain 0.9-m telescope. Calibrations were done in the B, V, and I filter with Landolt standard fields. Two of our systems, 4U 1907+09 and KS 1947+300, had previously published magnitudes for the optical counterpart of each x-ray system. The eight remaining systems had no identified optical counterparts. These systems include: AXJ1844.8-0258, 4U 1850-03, 4U 1901+03, 4U 1908+075, XTE J1906+090, XTE J1908+094, IGR J19140+0951, and IGR 18410-0535. We will report on the calibrations for each field and an attempt to identify each optical counterpart. This work is supported by NSF grants AST-0618209. We also acknowledge support from a BYU ORCA MEG grant.
Potential Optical Counterparts to High Mass X-Ray and γ-Ray Binaries
Carl Mitchell1, M. V. McSwain1
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
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.
Photometry, Spectroscopy, And Doppler Tomography Of The Eclipsing LMXB EXO 0748-676 = UY Vol
Valerie J. Mikles1, R. I. Hynes1, E. D. Jones1
1Louisiana State University.
We present optical spectra and Doppler tomography of the low-mass X-ray binary EXO 0748-676 = UY Vol. UY Vol is an eclipsing X-ray binary hosting a neutron star. With a total of 65 spectra spread over 4 nights, we have complete phase coverage and construct trailed spectra and Doppler tomograms for thirteen lines and line blends. Although we were not able to detect fluorescent N III/C III emission from the irradiated secondary, we do detect S-wave emission of several He II lines and O II 5289A. Our analysis of the trailed spectra and tomograms allows us to constrain the origin of the line emission. UY Vol has spent the better part of the last two decades in a burst state, but since our spectroscopy, the source has entered a quiescent phase. The optical counterpart, originally ~17th mag has faded substantially to R~22 mag. We present a new light-curve of the source in its quiescent state.
This work is partially supported by the National Science Foundation under Grant No. AST-0908789 and by NASA/Louisiana Board of Regents grant NNX07AT62A/LEQSF(2007-10) Phase3-02.
New Low-Mass PMS Eclipsing Binaries In Orion
Maria Morales-Calderon1, J. R. Stauffer1, L. M. Rebull1
In Fall 2009, we conducted a large, multi-wavelength time-series photometric monitoring campaign of about a one square degree region of the Orion Nebula cluster (ONC). Our program produced light curves for 2000 Orion young stellar objects (YSOs), with data often in at least four bands (I, J, [3.6] and [4.5]). While our primary goal was to use these data to investigate the structure of the inner disk and time-variable accretion in YSOs with circumstellar disks, these data also provide a treasury of data on all types of pre-main-sequence (PMS) variability. Specifically, we identify nine stars in our FOV whose light curves show eclipse features. Four of these are the previously known ONC eclipsing binaries (EBs) and the other five systems are newly identified ONC PMS EB candidates - more than doubling what was known up to now. Here we present our current work to confirm these candidates.
Characterizing X-ray Point Source Populations in Nearby Galaxies
Tyler D. Desjardins1, R. E. Kilgard1, A. H. Prestwich2
1Wesleyan University, 2Harvard-Smithsonian Center for Astrophysics.
We present an analysis of Hubble Space Telescope ACS images of the nearby galaxies IC 10 and M 51 in which we determine the characteristics of optical sources that are coincident with X-ray point sources detected with the Chandra X-ray Observatory. For IC 10, we find optical counterparts for six sources consistent with B dwarf stars, with one of the sources likely coincident with an OB association. In M 51, there are twelve X-ray sources that have stellar counterparts with colors and magnitudes indicating O and B dwarfs as well as several early type supergiants. H-alpha images show several supernova remnants in M 51 that are coincident with X-ray point sources. We also present preliminary results on constructing discrete X-ray source luminosity functions segregated by class of optical counterpart.
The Chandra Galactic Bulge Survey
Robert I. Hynes1, P. G. Jonker2, C. G. Bassa3, A. Dieball4, S. Greiss5, T. J. Maccarone4, G. Nelemans6, D. Steeghs5, M. A. P. Torres2, C. T. Britt1, J. L. Clem1, L. Gossen1, J. E. Grindlay7, P. J. Groot6, L. Kuiper2, E. Kuulkers8, M. Mendez9, V. J. Mikles1, E. M. Ratti2, N. Rea10, L. van Haaften6, R. Wijnands11, J. J. M. in't Zand2
1Louisiana State Univ., 2SRON-Netherlands Institute for Space Research, Netherlands, 3University of Manchester, United Kingdom, 4University of Southampton, United Kingdom, 5University of Warwick, United Kingdom, 6Radboud University, Netherlands, 7Harvard-Smithsonian, CfA, 8ESA/ESAC, Spain, 9Groningen University, Netherlands, 10ICE, CSIC-IEEC, Spain, 11University of Amsterdam, Netherlands.
The Chandra Galactic Bulge Survey (CGBS) is a shallow but wide survey of two approximately 6x1 degree strips of the Galactic Bulge about a degree above and below the plane. The survey by design targets regions where extinction and crowding are manageable and optical counterparts are accessible to detailed follow-up. Our strategy is based on going deep enough to detect quiescent low-mass X-ray binaries (LMXBs), but no deeper in order to avoid an excess of cataclysmic variables (CVs), while covering a large area to maximize the numbers of recovered objects. The primary goals of the CGBS are to test predictions of binary evolutionary models through number counts and period distributions of detected sources, and to greatly expand the sample of LMXBs suitable for detailed optical follow-up including mass determination. We have recovered over a thousand X-ray sources most with optical counterparts, and expect these to be divided evenly between quiescent LMXBs, magnetic CVs, and R CVn stars, with smaller numbers of other source types. We are actively pursuing multiwavelength follow-up including searches for optical, infrared, and ultraviolet counterparts, measurement of variability, and optical spectroscopy. So far we have identified about ten candidate LMXBs and CVs and a few other unusual objects such as X-ray selected sdO and carbon stars, both likely products of binary evolution.
This work is supported by the National Science Foundation under Grant No. AST-0908789.
Chandra And Hst Studies Of The Prototype Ns X-ray Transient, Cen X-4
Samuel Park1, M. R. Garcia1
1Harvard - Smithsonian.
For nearly a century Black holes have been a hot topic, a physical singularity or simply a flawed, all be it brilliant, mathematical concept? Fundamental proof of the existence of black holes lies in the proof of the existence of their event horizons. One such proof lies in the comparison of the X-ray luminosities of black hole and neutron star X-ray transients however this proof assumes that both NS and BH transients continue to accrete at low Mdot during quiescence. Cen X-4 is the prototype NS X-ray transient, and this work is compared to A06020-00, the prototype BH X-ray Transient. As part of this comparison we obtained the first short-wavelength UV spectrum of Cen X-4 in 2004 with HST STIS and obtained simultaneous X-ray data with Chandra. Interestingly, the X-ray flux was found to decrease by a factor of three, while the UV was down by a factor of two. We report on our search for evidence for a disk in the UV and optical spectra, even at these very low Mdot levels. We have extracted the highest quality spectrum from the HST STIS and Chandra data, and compared Cen X -4 to A0620, searching for hints as to the accretion, emission mechanisms and ultimately the existence of their event horizons. This research as been jointly funded by the University of Southampton and the Harvard-Smithsonian center for astrophysics.
A Chandra Search for Low-mass Companions of Late B Stars in Tr 16
Nancy Remage Evans1, K. DeGioia-Eastwood2, M. Gagne3, L. Townsley4, S. Wolk1, Y. Naze5, P. Broos4, M. Corcoran6, L. Oskinova7, A. F. J. Moffat8, J. Wang1, N. Walborn9
1SAO, 2Northern Arizona University, 3West Chester University, 4Pennsylvania State University, 5Universite de Liege, Belgium, 6NASA's Goddard Space Flight Center, 7University of Potsdam, Germany, 8Universite de Montreal, Canada, 9Space Telescope Science Institute.
The cluster Tr 16 is included within the area of the large survey of the Carina region with Chandra (PI: Townsley). Stars later than B3 are not known to produce X-rays. On the other hand, low mass stars (later than mid-F spectral type) produce copious X-rays when they are young. We have developed a list of B3 to A0 stars in the young cluster Tr 16 which: 1.) are within 3' of Eta Car, 2.) have an appropriate V and B-V combination (including a range of +/- 0.1 in E(B-V), and 3.) have proper motions consistent with cluster membership. We have identified stars from this list which are X-ray sources on a 90 ksec Chandra image of Tr 16. Presumably the X-rays are produced by a low mass companion, at least in nearly all cases. This attribution is reinforced by the fact that the X-ray sources have higher median temperatures than O and early B sources. In addition, the spectral fits to 4 strongest sources produce temperatures typical of low-mass coronal sources. On this basis, 39% of the late B stars have low mass companions. Interpretation of this number depends on the completeness of the X-ray detections, however discussion of the low mass stars in Tr 16 indicates that stars which will be M stars on the main sequence are detected.
N. Evans acknowledges support from the Chandra X-ray Center NASA Contract NAS8-03060
LSI +61 303 And LS5039: More Mysteries Uncovered By Fermi
Richard Dubois1, Fermi LAT Collaboration
1SLAC National Accelerator Laboratory.
Results from the first two year of Fermi LAT (Large Area Telescope) observations of the bright sources LS I +61 303 and LS 5039, well observed binary systems at X-ray and TeV energies, have yielded new questions at GeV energies about their nature. These sources are proving to be surprising in terms of spectral behaviour and variability. The exponential cutoff seen in both sources is very reminiscent of the many pulsars Fermi has found, yet the orbital variability is not expected in that interpretation. In addition, LS I +61 303 has shown remarkable, abrupt changes in its flux levels and orbital modulation. In survey mode the LAT observes every point in the sky every 3 hours making it an ideal monitor for these systems.
Gamma-Ray Emission from Variable Galactic Radio Sources
Chris R. Shrader1, D. J. Macomb2
1NASA's GSFC, 2Boise State University.
We describe our ongoing program using data obtained with the Swift/BAT and the Fermi Large Area Telescope to search for hard-X-ray and gamma-ray emission from recently published surveys of galactic radio sources. Radio emission was established as a ubiquitous property of gamma ray sources prior to the launch of Fermi and subsequent examination of the composition of the 1451 source catalog of that mission further supports this idea. Known classes of galactic variable radio sources include high-mass X-ray binaries such as Cyg X-3 and LSI +61 303 which are already established gamma-ray emitters. Those objects are often transient in nature and they are often revealed through survey observations in the hard-X-ray band. Additional objects among this class may be revealed and establishing them as gamma-ray emitters would be of great interest. Other possible source classes include magnetars, RRATs (Rotating Radio Transients) and flare stars. Most interestingly, totally unexpected phenomena could also be revealed. We will describe our sample selection, data extraction and analysis methods and present results obtained to date.
Gamma-ray/x-ray Observations Of The Be-pulsar Binary 1a0535+262 During A Major Outburst
Angelo Varlotta1, G. Maier2, VERITAS
1Purdue University, 2Deutsches Elektronensynchrotron (DESY), Germany.
The detection of Cyg X-1, PSR B1259-63, LS 5039 and LS I +61 303 at TeV energies have established X-ray binaries as a new class of VHE gamma-ray emitters. In this work, we report results from gamma-ray and X-ray observations of 1A035+262 during a major outburst in December 2009. The TeV gamma-ray data were obtained with VERITAS (0.1-30 TeV). We also used public Fermi/LAT data to cover the GeV band (0.1-300 GeV). The X-ray data were obtained with the RXTE/PCA (2-60 keV) and Swift/XRT (0.3-10 keV). The observations provided a good coverage of the X-ray outburst, as well as the binary orbit. 1A0535+262 was not detected at TeV or GeV energies. This is consistent with the fact that the observed X-ray continuum can be described as the combination of blackbody and Comptonized emission from thermal electrons (presumably in the accretion disk and ";corona";) and that the source radiates little at radio wavelengths. The lack of non-thermal electrons distinguishes the source from those Be X-ray binaries (such as PSR B1259-63 and LS I +61 303) that have been detected at GeV-TeV energies. We discuss the implications of the results on theoretical models.
Career Paths, Professional Development, and STEM Diversity
The Astronomer's H-R diagram
Alberto Conti1, S. Lowe2, A. Accomazzi3, G. DiMilia3
1STScI, 2LCOGT, 3ADS.
Most people who've taken an astronomy course are familiar with the Hertzsprung-Russell diagram. It was developed to show the relationships between the temperature (or colour) of a star and its luminosity. Following this premise and an original idea by Stuart Lowe, we asked ourselves if american astronomer as a group have a ";Main Career Sequence"; in the space of Peer Reviewed papers and ";absolute"; Google index. Here we expand on Stuart's original idea examining several cuts in publication and Google parameter space with the help of proper ADS data
Career Outcomes for Astronomy Ph.D. Graduates of the University of Texas at Austin: The Next Generation
Harriet L. Dinerstein1
1Univ. of Texas, Austin.
Sixteen years ago I conducted a survey of the career trajectories and outcomes of 78 individuals who earned Ph.D.s from the Department of Astronomy at the University of Texas at Austin during the period 1984-1995 (Dinerstein, H. 1996, AAS, 189.0501). In the current poster I extend these statistics up to the present, adding 68 Ph.D. recipients from 1996-2010. This is a sufficiently large sample to search for secular trends such as possible changes in duration of the postdoctoral stage, redistribution of demographics among different kinds of long-term positions, and the emergence of new categories of astronomy-related employment. The picture is less discouraging than one might expect. As of 2010, about 75% of the Texas graduates 7 - 14 years past the Ph.D. are still doing astronomy, and most of those in non-astronomical careers left the field by choice (and often have had considerable success in their alternate careers). Of those 6 years or less past the Ph.D., 50% were in postdoctoral positions and less than 10% had left astronomy. Recent reconsiderations of the employment market (Metcalfe, T.S. 2008, PASP, 120, 229; Seth, A. 2009, Astro2010: The Astronomy and Astrophysics Decadal Survey, Position Paper No. 51) make the point that a typical astronomer who ultimately achieves a permanent position will have held two or three prior temporary positions; this was equally true three decades ago. There has been notable growth nationwide in the number of astronomers employed as faculty at small liberal arts colleges and other undergraduate-centered institutions, a trend that to some degree was anticipated by the University of Texas cohort, which included a number of students for whom this was their personal goal. In a world where job certainty is no longer so prevalent, motivated and resourceful astronomers are finding ways to remain active members of our community.
AstroBetter: A Blog and Wiki for Professional Astronomers
Kelle L. Cruz1, J. Lu2, J. Rigby3, E. Bressert4, T. Robitaille5, M. Huerta6, S. Dhital7
1Hunter College/CUNY & AMNH, 2Caltech, 3Greenbelt, MD, 4University of Exeter, United Kingdom, 5Harvard/CfA, 6Gentleman Scholar, 7Vanderbilt.
is a multi-contributor blog and wiki website designed for information sharing among professional astronomers. The goal of the site is to increase the productivity of astronomers by creating a centralized location for tips and tools of our multifaceted trade. Our content includes topics related to data reduction and analysis, general computing, writing papers and proposals, giving talks, teaching, career planning, productivity, organization, and diversity and equity in science and education. While we have several contributors, the site is intended to be community driven and we encourage everyone to publish to the wiki, submit guest posts, suggest post ideas, and to comment on blog entries. One of our primary goals is to consolidate and reduce the transient nature of the astronomy community's collective knowledge base by having an active wiki. Currently, the most common way to share astro-centric tools and tips that are not appropriate for a published paper, is to put them on an individual's website. However, the average astronomer's website will have at least four different addresses over the course of their career and only the site owner can edit the content. As a result, information on personal websites goes stale very quickly and dead links to such sites abound. It is our hope that community maintained wikis, such as the one hosted on AstroBetter, will gradually replace the personal website. In this poster we introduce the contributors to AstroBetter, show statistics about our current readership, give excerpts of some of our most popular posts and wiki entries, and show how anyone can add or edit content on the wiki. The goal of this poster is to spread the word about AstroBetter and increase our community of readers and wiki editors, because together, we can AstroBetter.
LGBT Workplace Issues for Astronomers
Laura E. Kay1, R. Danner2, K. Sellgren3, V. Dixon4, GLBTQastro
1Barnard College, 2Northrup Grumman Aerospace Systems, 3Ohio State University, 4Johns Hopkins Univ..
Federal Equal Employment Opportunity laws and regulations do not provide protection from discrimination on the basis of sexual orientation or gender identity or gender expression. Sexual minority astronomers (including lesbian, gay, bisexual and transgender people; LGBT) can face additional challenges at school and work. Studies show that LGBT students on many campuses report experiences of harassment. Cities, counties, and states may or may not have statutes to protect against such discrimination. There is wide variation in how states and insurance plans handle legal and medical issues for transgender people. Federal law does not acknowledge same-sex partners, including those legally married in the U.S. or in other countries. Immigration rules in the U.S. (and many other, but not all) countries do not recognize same-sex partners for visas, employment, etc. State `defense of marriage act' laws have been used to remove existing domestic partner benefits at some institutions, or benefits can disappear with a change in governor. LGBT astronomers who change schools, institutions, or countries during their career may experience significant differences in their legal, medical, and marital status.
Commitment to Broadening Participation at NOAO
Catharine D. Garmany1, D. Norman1
1National Optical Astronomy Observatory.
AURA and NOAO take seriously the importance of Broadening Participation in Astronomy. At the request of the AURA President, each of the AURA centers (NOAO, NSO, STSCI, Gemini) appointed a Diversity Advocates (DA). At NOAO this job is shared by Dara Norman and Katy Garmany, who were appointed by Dave Silva in Jan 2009. The DA’s are members of the AURA Committee on Workforce and Diversity (WDC), a designated subcommittee of the AURA Board of Directors. The role of this committee includes reviewing activities and plans on an AURA wide basis aimed at broadening the participation within AURA, and reviewing AURA wide policies on the workforce. At NOAO, the role of the DAs spans a number of departments and activities. They serve on observatory search committees, and offer suggestions on how NOAO job searches can reach the most diverse audience. The DA’s job is to insure that NOAO actively pursues every opportunity to increase diversity: to this end they are involved in outreach and educational activities that focus on workplace development and encourage inclusion of woman, minorities and persons with disabilities.
Current Results and Future Directions of the Pulsar Search Collaboratory
Sue Ann Heatherly1, R. Rosen1, M. McLaughlin2, D. Lorimer2
1NRAO, 2West Virginia University.
The Pulsar Search Collaboratory (PSC) is a joint partnership between the National Radio Astronomy Observatory (NRAO) and West Virginia University (WVU. The ultimate goal of the PSC is to interest students in science, technology, engineering, mathematics (STEM) fields by engaging them in conducting authentic scientific research—specifically the search for new pulsars.
Of the 33 schools in the original PSC program, 13 come from rural school districts; one third of these are from schools where over 50% participate in the Free/Reduced School Lunch program. We are reaching first generation college-goers. For students, the program succeeds in building confidence in students, rapport with the scientists involved in the project, and greater comfort with team-work. We see additional gains in girls, as they see themselves more as scientists after participating in the PSC program, which is an important predictor of success in STEM fields. The PSC has had several scientific successes as well. To date, PSC students have made two astronomical discoveries: a 4.8-s pulsar and bright radio burst of astrophysical origin, most likely from a sporadic neutron star.
We will report on the status of the project including new evaluation data. We will also describe PSC-West, an experiment to involve schools in Illinois and Wisconsin using primarily online tools for professional development of teachers and coaching of students. Knowledge gained through our efforts with PSC-West will assist the PSC team in scaling up the project.
The California-Arizona Minority Partnership for Astronomy Research and Education (CAMPARE): an Educational Experience for Undergraduates at the University of Arizona Alumni Association's Astronomy Camp.
Courtney Lemon1, D. McCarthy2, A. Rudolph1
1California State Polytechnic University, Pomona, 2University of Arizona.
The California-Arizona Minority Partnership for Astronomy Research and Education (CAMPARE) is an NSF-funded partnership between the Astronomy Program at Cal Poly Pomona (CPP) and the University of Arizona Steward Observatory designed to promote participation of underrepresented minorities (including women) in astronomy research and education. As part of the education component of the program, CPP undergraduate physics majors and minors are eligible to work as a counselor at the University of Arizona's Astronomy Camp, one of the premier astronomy outreach opportunities in the world. CAMPARE students have the opportunity to work in this learn-by-doing environment with a wide range of students to gain first hand experience of teaching astronomy to students of a wide variety of ages in highly structured educational setting. Cal Poly Pomona students who are interested in education, both formal and informal, work in a variety of camps, from Girl Scout camps to camps for advanced high school students, to further their understanding of what it means to be a professional in the field of education. The CAMPARE student who participated in this program during summer 2010 had the opportunity to work under Dr. Don McCarthy, camp director of University of Arizona's Astronomy Camps for 20 years, and observe the interpersonal relations between campers and staff that is so vital to the learning the students receive. Through these observations, the CAMPARE student was able to learn to gauge students' interest in the material, and experience real life teaching and learning scenarios in the informal education realm.
The Lowell Observatory Predoctoral Scholar Program
Lisa A. Prato1
Lowell Observatory is pleased to solicit applications for our Predoctoral Scholar Fellowship Program. Now beginning its fourth year, this program is designed to provide unique
research opportunities to graduate students in good standing, currently enrolled at Ph.D. granting institutions. Lowell staff research spans a wide range of topics, from astronomical instrumentation, to icy bodies in our solar system, to exoplanet science, to stellar populations and dwarf irregular galaxies. First light with the observatory's
new 4.2 meter Discovery Channel Telescope is expected in 2011, making this a particularly exciting time in our history. Student research is expected to lead to a thesis dissertation appropriate for graduation at the doctoral level at the student's home institution. Currently, five students are enrolled in our program; our first graduate completed the program in August, 2009. The Observatory provides competitive compensation and full benefits to student scholars. For more information, see http://www.lowell.edu/rsch/predoc.php and links therein.
Applications for Fall 2011 are due by May 1, 2011.
POCA Update: An NSF PAARE Project
Donald K. Walter1, S. D. Brittain2, J. L. Cash1, D. H. Hartmann2, S. B. Howell3, J. R. King2, M. D. Leising2, E. A. Mayo1, K. J. Mighell3, D. M. Smith, Jr.1
1South Carolina State Univ., 2Clemson University, 3National Optical Astronomy Observatory.
We report on the status of “A Partnership in Observational and Computational Astronomy (POCA)” under the NSF's ";Partnerships in Astronomy and Astrophysics Research and Education (PAARE)"; program. This partnership includes South Carolina State University (a Historically Black College/University), Clemson University (a Ph.D. granting institution) and the National Optical Astronomy Observatory. We have reached the midpoint of this 5-year award and discuss the successes, challenges and obstacles encountered to date. Included is a summary of our summer REU program, the POCA graduate fellowship program, faculty research capacity building, outreach activities, increased use of NSF facilities and shared resources. Additional POCA research presentations by the authors are described elsewhere in these proceedings. Support for this work was provided by the NSF PAARE program to South Carolina State University under award AST-0750814 as well as resources and support provided by Clemson University and the National Optical Astronomy Observatory.
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