220 research outputs found

    An X-Ray Absorption Feature in the BL Lacertae Object H1426+428

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    We report the presence of an absorption feature in the X-ray spectrum of the BL Lacertae object H1426)428 (z \ 0.129). H1426)428 was observed at three separate epochs with BBXRT, ROSAT , and ASCA. In the BBXRT spectrum an absorption feature is clearly present at D0.66 keV, consistent with absorption by highly ionized oxygen. The phenomenological model that best describes the absorption feature is an inverted Gaussian with width km s~1. This feature is not present in the FWHM ( 43,000 ROSAT and ASCA data, both taken when the source Nux was fainter by a factor B2. Instead, these data show some evidence for absorption edge(s) at lower energies. These results are consistent with par- tially ionized, low-density gas surrounding the central engine of H1426)428. As a -rst approximation the X-ray continuum can be described with a power law with photon index !B 2. The BBXRT and ASCA data are better -tted with a convex (downward-curved) broken power law. The exact shape of the continuum depends on the assumed pro-le for the absorption feature. We show that, using a speci-c warm absorber to -t the data, there is no need for a continuum model more complex than a single power law. Subject headings: BL Lacertae objects: individual (H1426)428) E line: identi-cation E radiation mechanisms: nonthermal E X-rays: galaxie

    Effects of paternal high-fat diet and maternal rearing environment on the gut microbiota and behavior.

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    Exposing a male rat to an obesogenic high-fat diet (HFD) influences attractiveness to potential female mates, the subsequent interaction of female mates with infant offspring, and the development of stress-related behavioral and neural responses in offspring. To examine the stomach and fecal microbiome\u27s potential roles, fecal samples from 44 offspring and stomach samples from offspring and their fathers were collected and bacterial community composition was studied by 16 small subunit ribosomal RNA (16S rRNA) gene sequencing. Paternal diet (control, high-fat), maternal housing conditions (standard or semi-naturalistic housing), and maternal care (quality of nursing and other maternal behaviors) affected the within-subjects alpha-diversity of the offspring stomach and fecal microbiomes. We provide evidence from beta-diversity analyses that paternal diet and maternal behavior induced community-wide shifts to the adult offspring gut microbiome. Additionally, we show that paternal HFD significantly altered the adult offspring Firmicutes to Bacteroidetes ratio, an indicator of obesogenic potential in the gut microbiome. Additional machine-learning analyses indicated that microbial species driving these differences converged on Bifidobacterium pseudolongum. These results suggest that differences in early-life care induced by paternal diet and maternal care significantly influence the microbiota composition of offspring through the microbiota-gut-brain axis, having implications for adult stress reactivity

    ACCESS & LRG-BEASTS: a precise new optical transmission spectrum of the ultrahot Jupiter WASP-103b

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    We present a new ground-based optical transmission spectrum of the ultrahot Jupiter WASP-103b (Teq=2484T_{eq} = 2484K). Our transmission spectrum is the result of combining five new transits from the ACCESS survey and two new transits from the LRG-BEASTS survey with a reanalysis of three archival Gemini/GMOS transits and one VLT/FORS2 transit. Our combined 11-transit transmission spectrum covers a wavelength range of 3900--9450A with a median uncertainty in the transit depth of 148 parts-per-million, which is less than one atmospheric scale height of the planet. In our retrieval analysis of WASP-103b's combined optical and infrared transmission spectrum, we find strong evidence for unocculted bright regions (4.3σ4.3\sigma) and weak evidence for H2_2O (1.9σ1.9\sigma), HCN (1.7σ1.7\sigma), and TiO (2.1σ2.1\sigma), which could be responsible for WASP-103b's observed temperature inversion. Our optical transmission spectrum shows significant structure that is in excellent agreement with the extensively studied ultrahot Jupiter WASP-121b, for which the presence of VO has been inferred. For WASP-103b, we find that VO can only provide a reasonable fit to the data if its abundance is implausibly high and we do not account for stellar activity. Our results highlight the precision that can be achieved by ground-based observations and the impacts that stellar activity from F-type stars can have on the interpretation of exoplanet transmission spectra.Comment: 33 pages, 17 figures, 7 tables. Accepted for publication in A

    ACCESS: A Visual to Near-infrared Spectrum of the Hot Jupiter WASP-43b with Evidence of H2O\rm H_2O, but no evidence of Na or K

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    We present a new ground-based visual transmission spectrum of the hot Jupiter WASP-43b, obtained as part of the ACCESS Survey. The spectrum was derived from four transits observed between 2015 and 2018, with combined wavelength coverage between 5,300 \r{A}-9,000 \r{A} and an average photometric precision of 708 ppm in 230 \r{A} bins. We perform an atmospheric retrieval of our transmission spectrum combined with literature HST/WFC3 observations to search for the presence of clouds/hazes as well as Na, K, Hα\alpha, and H2O\rm H_2O planetary absorption and stellar spot contamination over a combined spectral range of 5,318 \r{A}-16,420 \r{A}. We do not detect a statistically significant presence of Na I or K I alkali lines, or Hα\alpha in the atmosphere of WASP-43b. We find that the observed transmission spectrum can be best explained by a combination of heterogeneities on the photosphere of the host star and a clear planetary atmosphere with H2O\rm H_2O. This model yields a log-evidence of 8.26±0.428.26\pm0.42 higher than a flat (featureless) spectrum. In particular, the observations marginally favor the presence of large, low-contrast spots over the four ACCESS transit epochs with an average covering fraction fhet=0.270.16+0.42f_\text{het} = 0.27^{+0.42}_{-0.16} and temperature contrast ΔT=132 K±132 K\Delta T = 132\text{ K} \pm 132\text{ K}. Within the planet's atmosphere, we recover a log H2O\rm H_2O volume mixing ratio of 2.781.47+1.38-2.78^{+1.38}_{-1.47}, which is consistent with previous H2O\rm H_2O abundance determinations for this planet.Comment: 27 pages, 18 figures, 7 tables. Accepted for publication in AJ. Updated affiliation

    ACCESS: An optical transmission spectrum of the high-gravity, hot Jupiter HAT-P-23b

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    We present a new ground-based visible transmission spectrum of the high-gravity, hot Jupiter HAT-P-23b, obtained as part of the ACCESS project. We derive the spectrum from five transits observed between 2016 and 2018, with combined wavelength coverage between 5200 {\AA} - 9269 {\AA} in 200 {\AA} bins, and with a median precision of 247 ppm per bin. HAT-P-23b's relatively high surface gravity (g ~ 30 m/s^2), combined with updated stellar and planetary parameters from Gaia DR2, gives a 5-scale-height signal of 384 ppm for a hydrogen-dominated atmosphere. Bayesian models favor a clear atmosphere for the planet with the tentative presence of TiO, after simultaneously modeling stellar contamination, using spots parameter constraints from photometry. If confirmed, HAT-P-23b would be the first example of a high-gravity gas giant with a clear atmosphere observed in transmission at optical/NIR wavelengths; therefore, we recommend expanding observations to the UV and IR to confirm our results and further characterize this planet. This result demonstrates how combining transmission spectroscopy of exoplanet atmospheres with long-term photometric monitoring of the host stars can help disentangle the exoplanet and stellar activity signals.Comment: 28 pages, 18 Figures, accepted for publication in AJ. arXiv admin note: text overlap with arXiv:1911.0335

    The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey

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    The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z=0.52), 102,100 new quasar spectra (median z=2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperature estimates for stars with T_eff<5000 K and in metallicity estimates for stars with [Fe/H]>-0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SDSS-III Sloan Extension for Galactic Understanding and Exploration-2 (SEGUE-2). The astrometry error introduced in the DR8 imaging catalogs has been corrected in the DR9 data products. The next data release for SDSS-III will be in Summer 2013, which will present the first data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) along with another year of data from BOSS, followed by the final SDSS-III data release in December 2014.Comment: 9 figures; 2 tables. Submitted to ApJS. DR9 is available at http://www.sdss3.org/dr

    The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III

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    The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly alpha forest, and a radial velocity search for planets around ~8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes five-band imaging of roughly 5200 deg^2 in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg^2, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent photometric recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars at both high and low Galactic latitudes. All the more than half a million stellar spectra obtained with the SDSS spectrograph have been reprocessed through an improved stellar parameters pipeline, which has better determination of metallicity for high metallicity stars.Comment: Astrophysical Journal Supplements, in press (minor updates from submitted version

    Heart rate reactivity is associated with future cognitive ability and cognitive change in a large community sample

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    The relationship between cardiovascular reactions to acute mental challenge in the laboratory and cognitive ability has received scant attention. The present study examined the association between reactivity and future cognitive ability. Heart rate and blood pressure reactions to a mental stress task were measured in 1647 participants comprising three distinct age cohorts. Cognitive ability was assessed using the Alice Heim-4 test of general intelligence and choice reaction time five and 12 years later. High heart rate reactivity was related to higher general intelligence scores and faster choice reaction times at both follow-ups. High heart rate reactivity was also associated with a smaller decline in cognitive ability between assessments. These associations were still evident following adjustment for a wide range of potentially confounding variables. The present results are consistent with the notion that high reactivity may not always be a maladaptive response and that low or blunted reactivity may also have negative corollaries
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