118425143
DISCOVERY OF THE TRANSITING PLANET KEPLER-5b
We present 44 days of high duty cycle, ultra precise photometry of the 13th magnitude star Kepler-5 (KIC 8191672, T eff= 6300 K, log g= 4.1), which exhibits periodic transits with a depth of 0.7%. Detailed modeling of the transit is consistent with a planetary companion with an orbital period of 3.548460 ± 0.000032 days and a radius of 1.431+0.041 –0.052 R J. Follow-up radial velocity measurements with the Keck HIRES spectrograph on nine separate nights demonstrate that the planet is more than twice as massive as Jupiter with a mass of 2.114+0.056 –0.059 M J and a mean density of 0.894 ± 0.079 g cm–3.
15724697
The Hubble Deep Field South - STIS imaging
We present the imaging observations made with the Space Telescope Imaging Spectrograph (STIS) of the Hubble Deep Field South. The field was imaged in four bandpasses: a clear CCD bandpass for 156 ks, a long-pass filter for 22–25 ks pixel-1 typical exposure, a near-UV bandpass for 23 ks, and a far-UV bandpass for 52 ks. The clear, visible image is the deepest observation ever made in the UV-optical wavelength region, reaching a 10 σ AB magnitude of 29.4 for an object of area 0.2 arcsec2. The field contains QSO J2233-606, the target of the STIS spectroscopy, and extends 50'' × 50'' for the visible images, and 25'' × 25'' for the ultraviolet images. We present the images, catalog of objects, and galaxy counts obtained in the field.
9685561
Hubble Space Telescope and Ground-based Optical and Ultraviolet Observations of GRB 010222
We report on Hubble Space Telescope (HST) Wide Field Planetary Camera 2 optical and Space Telescope Imaging Spectrograph (STIS) near-ultraviolet MAMA observations and ground-based optical observations of GRB 010222, spanning 15 hr to 71 days. The observations are well described by a relativistic blast wave model with a hard electron energy distribution, p = 1.57, and a jet transition at t* = 0.93 days. These values are slightly larger than previously found as a result of a correction for the contribution from the host galaxy to the late-time ground-based observations and the larger temporal baseline provided by the HST observations. The host galaxy is found to contain a very compact core (size <025), which coincides with the position of the optical transient. The STIS near-ultraviolet MAMA observations allow for an investigation of the extinction properties along the line of sight to GRB 010222. We find that the far-ultraviolet curvature component c4 is rather large. In combination with the low optical extinction, AV = 0.110 mag, when compared with the hydrogen column inferred from X-ray observations, we suggest that this is evidence for dust destruction.
119288725
Observational detection of eclipses of J5 Amalthea by the Galilean satellites
Aims. We carried out observations of the small jovian satellite Amalthea (J5) as it was being eclipsed by the Galilean satellites near the 2009 equinox of Jupiter in order to apply the technique of mutual event photometry to the astrometric determination of this satellite’s position. Methods. The observations were carried out during the period 06/2009−09/2009 from the island of Maui, Hawaii and Siding Spring, Australia with the 2m Faulkes Telescopes North and South respectively. We observed in the near-infrared part of the spectrum using a PanStarrs-Z filter with Jupiter near the edge of the field in order to mitigate against the glare from the planet. Frames were acquired at rates >1/min during eclipse times predicted using recent JPL ephemerides for the satellites. Following subtraction of the sky background from these frames, differential aperture photometry was carried out on Amalthea and a nearby field star. Results. We have obtained three lightcurves which show a clear drop in the flux from Amalthea, indicating that an eclipse took place as predicted. These were model-fitted to yield best estimates of the time of maximum flux drop and the impact parameter. These are consistent with Amalthea’s ephemeris but indicate that Amalthea is slightly ahead of, and closer to Jupiter than, its predicted position by approximately half the ephemeris uncertainty in these directions. We argue that a ground-based campaign of higher-cadence photometry accurate at the 5% level or better during the next season of eclipses in 2014-15 should yield positions to within 0. �� 05 and affect a corresponding improvement in Amalthea’s ephemeris.
118530564
DISCOVERY OF A RED GIANT WITH SOLAR-LIKE OSCILLATIONS IN AN ECLIPSING BINARY SYSTEM FROM KEPLER SPACE-BASED PHOTOMETRY
Oscillating stars in binary systems are among the most interesting stellar laboratories, as these can provide information on the stellar parameters and stellar internal structures. Here we present a red giant with solar-like oscillations in an eclipsing binary observed with the NASA Kepler satellite. We compute stellar parameters of the red giant from spectra and the asteroseismic mass and radius from the oscillations. Although only one eclipse has been observed so far, we can already determine that the secondary is a main-sequence F star in an eccentric orbit with a semi-major axis larger than 0.5 AU and orbital period longer than 75 days.
119293956
The Kepler Asteroseismic Investigation: Scientific goals and first results
Kepler is a NASA mission designed to detect exoplanets and characterize the properties of exoplanetary systems. Kepler also includes an asteroseismic programme which is being conducted through the Kepler Asteroseismic Science Consortium (KASC), whose 400 members are organized into 13 working groups by type of variable star. So far data have been available from the first 7 month of the mission containing a total of 2937 targets observed at a 1-min cadence for periods between 10 days and 7 months. The goals of the asteroseismic part of the Kepler project is to perform detailed studies of stellar interiors. The first results of the asteroseismic analysis are orders of magnitude better than seen before, and this bodes well for how the future analysis of Kepler data for many types of stars will impact our general understanding of stellar structure and evolution (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
197476756
Stellar Proper Motions in the Galactic Bulge from deep HST ACS/WFC Photometry
We present stellar proper motions in the Galactic bulge from the Sagittarius Window Eclipsing Extrasolar Search (SWEEPS) project using ACS/WFC on HST. Proper motions are extracted for more than 180,000 objects, with >81,000 measured to accuracy better than 0.3 mas/yr in both coordinates. We report several results based on these measurements: 1. Kinematic separation of bulge from disk allows a sample of >15,000 bulge objects to be extracted based on >6-sigma detections of proper motion, with <0.2% contamination from the disk. This includes the first detection of a candidate bulge Blue Straggler population. 2. Armed with a photometric distance modulus on a star by star basis, and using the large number of stars with high-quality proper motion measurements to overcome intrinsic scatter, we dissect the kinematic properties of the bulge as a function of distance along the line of sight. This allows us to extract the stellar circular speed curve from proper motions alone, which we compare with the circular speed curve obtained from radial velocities. 3. We trace the variation of the {l,b} velocity ellipse as a function of depth. 4. Finally, we use the density-weighted {l,b} proper motion ellipse produced from the tracer stars to assess the kinematic membership of the sixteen transiting planet candidates discovered in the Sagittarius Window; the kinematic distribution of the planet candidates is consistent with that of the disk and bulge stellar populations.
1793441
Diagonal free field matrix correlators, global symmetries and giant gravitons
We obtain a basis of diagonal free field multi-matrix 2-point correlators in a theory with global symmetry group G. The operators fall into irreducible representations of G. This applies for gauge group U(N) at finite N. For composites made of n fundamental fields, this is expressed in terms of Clebsch-Gordan coefficients for the decomposition of the n-fold tensor products of the fundamental field representation in terms of G × Sn representations. We use this general construction in the case of the SL(2) sector of = 4 SYM. In this case, by using oscillator constructions, we reduce the computation of the relevant Clebsch-Gordans coupling infinite dimensional discrete series irreps of SL(2) to a problem in symmetric groups. Applying these constructions we write down gauge invariant operators with a Fock space structure similar to that arising in a large angular momentum limit of worldvolume excitations of giant gravitons. The Fock space structure emerges from Clebsch multiplicities of tensor products of symmetric group representations. We also give the action of the 1-loop dilatation operator of = 4 SYM on this basis of multi-matrix operators.
119282322
FLASH MIXING ON THE WHITE DWARF COOLING CURVE: SPECTROSCOPIC CONFIRMATION IN NGC 2808*
We present new Hubble Space Telescope far-UV spectroscopy of two dozen hot evolved stars in NGC 2808, a massive globular cluster with a large population of 'blue-hook' (BHk) stars. The BHk stars are found in ultraviolet color-magnitude diagrams of the most massive globular clusters, where they fall at luminosities immediately below the hot end of the horizontal branch (HB), in a region of the H-R diagram unexplained by canonical stellar evolution theory. Using new theoretical evolutionary and atmospheric models, we have shown that these subluminous HB stars are very likely the progeny of stars that undergo extensive internal mixing during a late He-core flash on the white dwarf cooling curve. This flash mixing leads to hotter temperatures and an enormous enhancement of the surface He and C abundances; these hotter temperatures, together with the decrease in H opacity shortward of the Lyman limit, make the BHk stars brighter in the extreme UV while appearing subluminous in the UV and optical. Our far-UV spectroscopy demonstrates that, relative to normal HB stars at the same color, the BHk stars of NGC 2808 are hotter and greatly enhanced in He and C, thus providing unambiguous evidence of flash mixing in the subluminous population.more » Although the C abundance in the BHk stars is orders of magnitude larger than that in the normal HB stars, the atmospheric C abundance in both the BHk and normal HB stars appears to be affected by gravitational settling. The abundance variations seen in Si and the Fe-peak elements also indicate that atmospheric diffusion is at play in our sample, with all of our hot subdwarfs at 25,000-50,000 K exhibiting large enhancements of the iron-peak elements. The hottest subdwarfs in our BHk sample may be pulsators, given that they fall in the temperature range of newly discovered pulsating subdwarfs in {omega} Cen. In addition to the normal hot HB and BHk stars, we also obtain spectra of five blue HB stars, a post-HB star, and three unclassified stars with unusually blue UV colors.« less
6330621
UVUDF: Ultraviolet Imaging of the Hubble Ultra Deep Field with Wide-Field Camera 3
We present an overview of a 90 orbit Hubble Space Telescope treasury program to obtain near-ultraviolet imaging of the Hubble Ultra Deep Field using the Wide Field Camera 3 UVIS detector with the F225W, F275W, and F336W filters. This survey is designed to: (1) investigate the episode of peak star formation activity in galaxies at 1 < z < 2.5; (2) probe the evolution of massive galaxies by resolving sub-galactic units (clumps); (3) examine the escape fraction of ionizing radiation from galaxies at z ~ 2-3; (4) greatly improve the reliability of photometric redshift estimates; and (5) measure the star formation rate efficiency of neutral atomic-dominated hydrogen gas at z ~ 1-3. In this overview paper, we describe the survey details and data reduction challenges, including both the necessity of specialized calibrations and the effects of charge transfer inefficiency. We provide a stark demonstration of the effects of charge transfer inefficiency on resultant data products, which when uncorrected, result in uncertain photometry, elongation of morphology in the readout direction, and loss of faint sources far from the readout. We agree with the STScI recommendation that future UVIS observations that require very sensitive measurements use the instrument's capability to add background light through a "post-flash." Preliminary results on number counts of UV-selected galaxies and morphology of galaxies at z ~ 1 are presented. We find that the number density of UV dropouts at redshifts 1.7, 2.1, and 2.7 is largely consistent with the number predicted by published luminosity functions. We also confirm that the image mosaics have sufficient sensitivity and resolution to support the analysis of the evolution of star-forming clumps, reaching 28-29th magnitude depth at 5σ in a 0."2 radius aperture depending on filter and observing epoch.
7096602
The Rapidly Rotating, Hydrogen-deficient, Hot Post-Asymptotic Giant Branch Star ZNG?1 in the Globular Cluster M5
We report observations of the hot post-asymptotic giant branch star ZNG 1 in the globular cluster M5 (NGC 5904) with the Far Ultraviolet Spectroscopic Explorer. From the resulting spectrum, we derive an effective temperature Teff = 44300 ± 300 K, a surface gravity log g = 4.3 ± 0.1, a rotational velocity v sin i = 170 ± 20 km s-1, and a luminosity log = 3.52 ± 0.04. The atmosphere is helium-rich (Y = 0.93), with enhanced carbon (2.6% by mass), nitrogen (0.51%), and oxygen (0.37%) abundances. The spectrum shows evidence of a wind with a terminal velocity near 1000 km s-1 and an expanding shell of carbon- and nitrogen-rich material around the star. The abundance pattern of ZNG 1 is suggestive of the "born-again" scenario, whereby a star on the white dwarf cooling curve undergoes a very late shell flash and returns to the asymptotic giant branch, but the star's rapid rotation is more easily explained by a previous interaction with a binary companion.