Now showing items 4929-4948 of 13758

    • Hózhó: Promoting sleep health among Navajo caregivers

      Russell, Maureen; Baldwin, Carol M; Quan, Stuart F; Univ Arizona, Coll Med (ELSEVIER INC, 2020-04)
      Objectives: This study explored the feasibility and acceptability of a sleep health education intervention for caregivers of children with developmental disabilities (DD). Design: This mixed-methods pilot study utilized repeated measures and caregiver interviews. Setting: The intervention occurred in the homes of caregivers who live on the Navajo Nation. Participants: Fifteen caregivers of children with DD aged from birth to 3 years old participated. Intervention: The intervention consisted of three 1-hour home-based sessions. Educational modules were tailored to specific sleep issues of the caregiver and their child(ren), as well as the unique environmental and cultural features of Navajo families. Measurements: Quantitative measures included a sleep habits questionnaire, pre- and postmeasures of learning, and the SF-12 HRQoL. Quantitative data were analyzed with frequencies and repeated measures analyses with p.05. Qualitative comments regarding facilitators and detractors to healthy sleep were transcribed verbatim and categorized into themes. Results: Caregiver sleep duration increased by 2 hours (5.8 +/- 1.8 to 7.8 +/- 1.9, p = .005). Caregivers also reported improved physical (45.0 +/- 8.2 to 52.8+8.7 p = .001) and mental HR-QoL (41.8 +/- 8.9 to 49.3 +/- 10.9, p = .002), and enhanced knowledge of sleep disorders (13.4 +/- 4.0 to 20.7 +/- 5.6) and healthy sleep habits (15.7 +/- 4.1 to 25.4 +/- 3.4 each p = .005). Many participants reported better sleep quality in their children with earlier bedtimes and less night waking. Conclusions: Findings suggest that this tailored sleep education programis a culturally responsive approach to promoting caregiver sleep health and HR-QoL, as well as the sleep health of their children. Caregivers credited improved sleep to the support they received during visits and text messaging. (C) 2019 National Sleep Foundation. Published by Elsevier Inc. All rights reserved.
    • HPV32-related Heck’s disease in a chronic graft-versus-host disease patient with long-term successful KTP laser treatment: A rare case report

      Nguyen, J.T.; Allen, C.T.; Dodge, J.T.; Van Doorslaer, K.; McBride, A.A.; Pavletic, S.Z.; Mays, J.W.; School of Animal and Comparative Biomedical Sciences, The University of Arizona (Blackwell Publishing Ltd, 2021)
      We recently identified and treated a rare case of oral focal epithelial hyperplasia (FEH) in an adult patient with chronic graft-vs-host disease. This is the first report linking KTP laser therapy to successful long-term treatment HPV32 FEH. © Published 2021. This article is a U.S. Government work and is in the public domain in the USA. Clinical Case Reports published by John Wiley & Sons Ltd.
    • HR 10: a main-sequence binary with circumstellar envelopes around both components

      Montesinos, B.; Eiroa, C.; Lillo-Box, J.; Rebollido, I.; Djupvik, A. A.; Absil, O.; Ertel, S.; Marion, L.; Kajava, J. J. E.; Redfield, S.; et al. (EDP SCIENCES S A, 2019-08-27)
      Context. This paper is framed within a large project devoted to studying the presence of circumstellar material around main sequence stars, and looking for exocometary events. The work concentrates on HR 10 (A2 IV/V), known for its conspicuous variability in the circumstellar narrow absorption features of Ca II K and other lines, so far interpreted as beta Pic-like phenomena, within the falling evaporating body scenario. Aims. The main goal of this paper is to carry out a thorough study of HR 10 to find the origin of the observed variability, determine the nature of the star, its absolute parameters, and evolutionary status. Methods. Interferometric near-infrared (NIR) observations, multi-epoch high-resolution optical spectra spanning a time baseline of more than 32 yr, and optical and NIR photometry, together with theoretical modelling, were used to tackle the above objectives. Results. Our results reveal that HR 10 is a binary. The narrow circumstellar absorption features superimposed on the photospheric Ca II K lines - and lines of other species - can be decomposed into two or more components, the two deep ones tracing the radial velocity of the individual stars, which implies that their origin cannot be ascribed to transient exocometary events, their variability being fully explained by the binarity of the object. There does not appear to be transient events associated with potential exocomets. Each individual star holds its own circumstellar shell and there are no traces of a circumbinary envelope. Finally, the combined use of the interferometric and radial velocity data leads to a complete spectrometric and orbital solution for the binary, the main parameters being: an orbital period of 747.6 days, eccentricities of the orbits around the centre of mass 0.25 (HR 10-A), 0.21 (HR 10-B) and a mass ratio of q = M-B/M-A = 0.72-0.84. The stars are slightly off the main sequence, the binary being similar to 530 Myr old.
    • The HR 4796A Debris System: Discovery of Extensive Exo-ring Dust Material

      Schneider, Glenn; Debes, John H.; Grady, Carol A.; Gáspár, András; Henning, Thomas; Hines, Dean C.; Kuchner, Marc J.; Perrin, Marshall; Wisniewski, J.; Univ Arizona, Steward Observ; et al. (IOP PUBLISHING LTD, 2018-01-22)
      The optically and IR-bright and starlight-scattering HR 4796A ringlike debris disk is one of the most-(and best-) studied exoplanetary debris systems. The presence of a yet-undetected planet has been inferred (or suggested) from the narrow width and inner/outer truncation radii of its r = 1.'' 05 (77 au) debris ring. We present new, highly sensitive Hubble Space Telescope (HST) visible-light images of the HR 4796A circumstellar debris system and its environment over a very wide range of stellocentric angles from 0.'' 32 (23 au) to approximate to 15 '' (1100 au). These very high-contrast images were obtained with the Space Telescope Imaging Spectrograph (STIS) using six-roll PSF template-subtracted coronagraphy suppressing the primary light of HR 4796A, with three image-plane occulters, and simultaneously subtracting the background light from its close angular proximity M2.5V companion. The resulting images unambiguously reveal the debris ring embedded within a much larger, morphologically complex, and biaxially asymmetric exo-ring scattering structure. These images at visible wavelengths are sensitive to and map the spatial distribution, brightness, and radial surface density of micron-size particles over 5 dex in surface brightness. These particles in the exo-ring environment may be unbound from the system and interacting with the local ISM. Herein, we present a new morphological and photometric view of the larger-than-prior-seen HR 4796A exoplanetary debris system with sensitivity to small particles at stellocentric distances an order of magnitude greater than has previously been observed.
    • HSP60/10 chaperonin systems are inhibited by a variety of approved drugs, natural products, and known bioactive molecules

      Stevens, Mckayla; Abdeen, Sanofar; Salim, Nilshad; Ray, Anne-Marie; Washburn, Alex; Chitre, Siddhi; Sivinski, Jared; Park, Yangshin; Hoang, Quyen Q; Chapman, Eli; et al. (PERGAMON-ELSEVIER SCIENCE LTD, 2019-05-01)
      All living organisms contain a unique class of molecular chaperones called 60 kDa heat shock proteins (HSP60 - also known as GroEL in bacteria). While some organisms contain more than one HSP60 or GroEL isoform, at least one isoform has always proven to be essential. Because of this, we have been investigating targeting HSP60 and GroEL chaperonin systems as an antibiotic strategy. Our initial studies focused on applying this antibiotic strategy for treating African sleeping sickness (caused by Trypanosoma brucei parasites) and drug-resistant bacterial infections (in particular Methicillin-resistant Staphylococcus aureus - MRSA). Intriguingly, during our studies we found that three known antibiotics - suramin, closantel, and rafoxanide - were potent inhibitors of bacterial GroEL and human HSP60 chaperonin systems. These findings prompted us to explore what other approved drugs, natural products, and known bioactive molecules might also inhibit HSP60 and GroEL chaperonin systems. Initial high-throughput screening of 3680 approved drugs, natural products, and known bioactives identified 161 hit inhibitors of the Escherichia coli GroEL chaperonin system (4.3% hit rate). From a purchased subset of 60 hits, 29 compounds (48%) re-confirmed as selective GroEL inhibitors in our assays, all of which were nearly equipotent against human HSP60. These findings illuminate the notion that targeting chaperonin systems might be a more common occurrence than we previously appreciated. Future studies are needed to determine if the in vivo modes of action of these approved drugs, natural products, and known bioactive molecules are related to GroEL and HSP60 inhibition.
    • Hsp90 depletion goes wild

      Siegal, Mark; Masel, Joanna; Center for Genomics and Systems Biology, Department of Biology, New York University, 12 Waverly Place, New York, NY 10003, USA; Department of Ecology and Evolutionary Biology, University of Arizona, 1041 E. Lowell St, Tucson, AZ 85721, USA (BioMed Central, 2012)
      Hsp90 reveals phenotypic variation in the laboratory, but is Hsp90 depletion important in the wild? Recent work from Chen and Wagner in BMC Evolutionary Biology has discovered a naturally occurring Drosophila allele that downregulates Hsp90, creating sensitivity to cryptic genetic variation. Laboratory studies suggest that the exact magnitude of Hsp90 downregulation is important. Extreme Hsp90 depletion might reactivate transposable elements and/or induce aneuploidy, in addition to revealing cryptic genetic variation.See research article webcite
    • HST Detection of Extended Neutral Hydrogen in a Massive Elliptical at z = 0.4

      Zahedy, Fakhri S.; Chen, Hsiao-Wen; Rauch, Michael; Zabludoff, Ann; Univ Arizona, Steward Observ (IOP PUBLISHING LTD, 2017-09-08)
      We report the first detection of extended neutral hydrogen (H I) gas in the interstellar medium (ISM) of a massive elliptical galaxy beyond z similar to 0. The observations utilize the doubly lensed images of QSO HE 0047-1756 at z(QSO) = 1.676 as absorption-line probes of the ISM in the massive (M-star approximate to 10(11) M-circle dot) elliptical lens at z = 0.408, detecting gas at projected distances of d = 3.3 and 4.6 kpc on opposite sides of the lens. Using the Space Telescope Imaging Spectrograph, we obtain UV absorption spectra of the lensed QSO and identify a prominent flux discontinuity and associated absorption features matching the Lyman series transitions at z = 0.408 in both sightlines. The H I column density is log N(H I)= 19.6-19.7 at both locations across the lens, comparable to what is seen in 21 cm images of nearby ellipticals. The H I gas kinematics are well-matched with the kinematics of the Fe II absorption complex revealed in ground-based echelle data, displaying a large velocity shear of approximate to 360 km s(-1) across the galaxy. We estimate an ISM Fe abundance of 0.3-0.4 solar at both locations. Including likely dust depletions increases the estimated Fe abundances to solar or supersolar, similar to those of the hot ISM and stars of nearby ellipticals. Assuming 100% covering fraction of this Fe-enriched gas, we infer a total Fe mass of M-cool(Fe) similar to (5-8) x 10(4) M-circle dot in the cool ISM of the massive elliptical lens, which is no more than 5% of the total Fe mass observed in the hot ISM.

      Fischer, Patrick D.; Knutson, Heather A.; Sing, David K.; Henry, Gregory W.; Williamson, Michael W.; Fortney, Jonathan J.; Burrows, Adam S.; Kataria, Tiffany; Nikolov, Nikolay; Showman, Adam P.; et al. (IOP PUBLISHING LTD, 2016-08-10)
      We present the. Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) optical transmission spectroscopy of the cool Saturn-mass exoplanet WASP-39b from 0.29-1.025 mu m, along with complementary transit observations from Spitzer IRAC at 3.6 and 4.5 mu m. The low density and large atmospheric pressure scale height of WASP-39b make it particularly amenable to atmospheric characterization using this technique. We detect a Rayleigh scattering slope as well as sodium and potassium absorption features; this is the first exoplanet in which both alkali features are clearly detected with the extended wings predicted by cloud-free atmosphere models. The full transmission spectrum is well matched by a clear H-2-dominated atmosphere, or one containing a weak contribution from haze, in good agreement with the preliminary reduction of these data presented in Sing et al.. WASP-39b is predicted to have a pressure-temperature profile comparable to that of HD 189733b and WASP-6b, making it one of the coolest transiting gas giants observed in our HST STIS survey. Despite this similarity, WASP-39b appears to be largely cloud-free, while the transmission spectra of HD 189733b and WASP-6b both indicate the presence of high altitude clouds or hazes. These observations further emphasize the surprising diversity of cloudy and cloud-free gas giant planets in short-period orbits and the corresponding challenges associated with developing predictive cloud models for these atmospheres.
    • The HST large programme on NGC 6752 – III. Detection of the peak of the white dwarf luminosity function

      Bedin, L R; Salaris, M; Anderson, J; Libralato, M; Apai, D; Nardiello, D; Rich, R M; Bellini, A; Dieball, A; Bergeron, P; et al. (OXFORD UNIV PRESS, 2019-07-17)
      We report on the white dwarf (WD) cooling sequence of the old globular cluster NGC 6752, which is chemically complex and hosts a blue horizontal branch. This is one of the last globular cluster WE) cooling sequences accessible to imaging by the Hubble Space Telescope. Our photometry and completeness tests show that we have reached the peak of the luminosity function of the WD cooling sequence, at a magnitude m(F606w) = 29.4 +/- 0.1, which is consistent with a formal age of similar to 14 Gyr. This age is also consistent with the age from fits to the main-sequence turn-off (13-14 Gyr), reinforcing our conclusion that we observe the expected accumulation of WDs along the cooling sequence.
    • The HST Large Programme on NGC 6752. I. Serendipitous discovery of a dwarf Galaxy in background

      Bedin, L R; Salaris, M; Rich, R M; Richer, H; Anderson, J; Bettoni, D; Nardiello, D; Milone, A P; Marino, A F; Libralato, M; et al. (OXFORD UNIV PRESS, 2019-01-10)
      As part of a large Hubble Space Telescope investigation aiming at reaching the faintest stars in the Galactic globular cluster NGC 6752, an Advanced Camera for Surveys/Wide Field Channel field was the subject of deep optical observations reaching magnitudes as faint as V ∼ 30. In this field, we report the discovery of Bedin I, a dwarf spheroidal galaxy too faint and too close to the core of NGC 6752 for detection in earlier surveys. As it is of broad interest to complete the census of galaxies in the local Universe, in this letter we provide the position of this new object along with preliminary assessments of its main parameters. Assuming the same reddening as for NGC 6752, we estimate a distance modulus of (m − M)0 = 29.70 ± 0.13 from the observed red giant branch, i.e. 8.7+0.5−0.7 Mpc, and size of ∼840 × 340 pc, about one-fifth the size of the Large Magellanic Cloud. A comparison of the observed colour–magnitude diagram with synthetic counterparts, which account for the galaxy distance modulus, reddening, and photometric errors, suggests the presence of an old (∼13 Gyr) and metal-poor ([Fe/H] ∼ −1.3) population. This object is most likely a relatively isolated satellite dwarf spheroidal galaxy of the nearby great spiral NGC 6744, or potentially the most distant isolated dwarf spheroidal known with a secure distance.
    • The HST Large Programme on NGC 6752 – II. Multiple populations at the bottom of the main sequence probed in NIR

      Milone, A P; Marino, A F; Bedin, L R; Anderson, J; Apai, D; Bellini, A; Dieball, A; Salaris, M; Libralato, M; Nardiello, D; et al. (OXFORD UNIV PRESS, 2019-04)
      Historically, multiple populations in globular clusters (GCs) have been mostly studied from ultraviolet and optical filters down to stars that are more massive than similar to 0.6,M-circle dot. Here, we exploit deep near-infrared (NIR) photometry from the Hubble Space Telescope to investigate multiple populations among M-dwarfs in the GC NGC 6752. We discovered that the three main populations (A, B, and C), previously observed in the brightest part of the colour-magnitude diagram (CMD), define three distinct sequences that run from the main-sequence (MS) knee towards the bottom of the MS (similar to 0.15 M-circle dot). These results, together with similar findings on NGC 2808, M 4, and omega Centauri, demonstrate that multiple sequences of M-dwarfs are common features of the CMDs of GCs. The three sequences of low-mass stars in NGC 6752 are consistent with stellar populations with different oxygen abundances. The range of [O/Fe] needed to reproduce the NIR CMD of NGC 6752 is similar to the oxygen spread inferred from high-resolution spectroscopy of red giant branch (RGB) stars. The relative numbers of stars in the three populations of M-dwarfs are similar to those derived among RGB and MS stars more massive than similar to 0.6 M-circle dot. As a consequence, the evidence that the properties of multiple populations do not depend on stellar mass is a constraint for the formation scenarios.
    • The HST large programme on omega Centauri - I. Multiple stellar populations at the bottom of the main sequence probed in NIR-Optical

      Milone, A. P.; Marino, A. F.; Bedin, L. R.; Anderson, J.; Apai, D.; Bellini, A.; Bergeron, P.; Burgasser, A. J.; Dotter, A.; Rees, J. M.; et al. (OXFORD UNIV PRESS, 2017-07)
      As part of a large investigation with Hubble Space Telescope to study the faintest stars within the globular cluster omega Centauri, in this work we present early results on the multiplicity of its main sequence (MS) stars, based on deep optical and near-infrared observations. By using appropriate colour-magnitude diagrams, we have identified, for the first time, the two main stellar Populations I and II along the entire MS, from the turn-off towards the hydrogen-burning limit. We have compared the observations with suitable synthetic spectra of MS stars and conclude that the two main sequences (MSs) are consistent with stellar populations with different metallicity, helium and light-element abundance. Specifically, MS-I corresponds to a metal-poor stellar population ([Fe/H] similar to -1.7) with Y similar to 0.25 and [O/Fe] similar to 0.30. The MS-II hosts helium-rich (Y similar to 0.37-0.40) stars with metallicity ranging from [Fe/H] similar to -1.7 to -1.4. Below the MS knee (m(F160W) similar to 19.5), our photometry reveals that each of the two main MSs hosts stellar subpopulations with different oxygen abundances, with very O-poor stars ([O/Fe] similar to -0.5) populating the MS-II. Such a complexity has never been observed in previous studies of M-dwarfs in globular clusters. A few months before the launch of the James Webb Space Telescope, these results demonstrate the power of optical and near-infrared photometry in the study of multiple stellar populations in globular clusters.
    • The HST Large Programme on ω Centauri. II. Internal Kinematics

      Bellini, Andrea; Libralato, Mattia; Bedin, Luigi R.; Milone, Antonino P.; van der Marel, Roeland P.; Anderson, Jay; Apai, Dániel; Burgasser, Adam J.; Marino, Anna F.; Rees, Jon M.; et al. (IOP PUBLISHING LTD, 2018-01-25)
      In this second installment of the series, we look at the internal kinematics of the multiple stellar populations of the globular cluster omega Centauri in one of the parallel Hubble Space Telescope (HST) fields, located at about 3.5 hal-flight radii from the center of the cluster. Thanks to the over 15 yr long baseline and the exquisite astrometric precision of the HST cameras, well-measured stars in our proper-motion catalog have errors as low as similar to 10 mu as yr(-1), and the catalog itself extends to near the hydrogen-burning limit of the cluster. We show that second-generation (2G) stars are significantly more radially anisotropic than first-generation (1G) stars. The latter are instead consistent with an isotropic velocity distribution. In addition, 1G stars have excess systemic rotation in the plane of the sky with respect to 2G stars. We show that the six populations below the main-sequence (MS) knee identified in our first paper are associated with the five main population groups recently isolated on the upper MS in the core of cluster. Furthermore, we find both 1G and 2G stars in the field to be far from being in energy equipartition, with eta(1G) = -0.007 +/- 0.026 for the former and eta(2G) = 0.074 +/- 0.029 for the latter, where eta is defined so that the velocity dispersion sigma(mu) scales with stellar mass as sigma(mu) proportional to m(-eta). The kinematical differences reported here can help constrain the formation mechanisms for the multiple stellar populations in omega Centauri and other globular clusters. We make our astro-photometric catalog publicly available.
    • The HST Large Programme on ω Centauri. III. Absolute Proper Motion

      Libralato, Mattia; Bellini, Andrea; Bedin, Luigi R.; Moreno, E.; Fernández-Trincado, José G.; Pichardo, B.; van der Marel, Roeland P.; Anderson, Jay; Apai, Dániel; Burgasser, Adam J.; et al. (IOP PUBLISHING LTD, 2018-02-09)
      In this paper, we report a new estimate of the absolute proper motion (PM) of the globular cluster NGC 5139 (omega Cen) as part of the HST large program GO-14118+ 14662. We analyzed a field 17 arcmin southwest of the center of omega Cen and computed PMs with epoch spans of similar to 15.1 years. We employed 45 background galaxies to link our relative PMs to an absolute reference-frame system. The absolute PM of the cluster in our field is (mu(alpha) cos delta, mu(delta))=(-3.341. 0.028, -6.557 +/- 0.043) mas yr(-1). Upon correction for the effects of viewing perspective and the known cluster rotation, this implies that for the cluster center of mass (mu(alpha) cos delta, mu(delta))=(-3.238. 0.028, -6.716 +/- 0.043) mas yr(-1). This measurement is direct and independent, has the highest random and systematic accuracy to date, and will provide an external verification for the upcoming Gaia Data Release 2. It also differs from most reported PMs for omega Cen in the literature by more than 5 sigma, but consistency checks compared to other recent catalogs yield excellent agreement. We computed the corresponding Galactocentric velocity, calculated the implied orbit of omega Cen in two different Galactic potentials, and compared these orbits to the orbits implied by one of the PM measurements available in the literature. We find a larger (by about 500 pc) perigalactic distance for omega Cen with our new PM measurement, suggesting a larger survival expectancy for the cluster in the Galaxy.
    • HST PanCET Program: A Cloudy Atmosphere for the Promising JWST Target WASP-101b

      Wakeford, H. R.; Stevenson, K. B.; Lewis, N. K.; Sing, D. K.; López-Morales, M.; Marley, M.; Kataria, T.; Mandell, A.; Ballester, G. E.; Barstow, J.; et al. (IOP PUBLISHING LTD, 2017-01-20)
      We present results from the first observations of the Hubble Space Telescope (HST) Panchromatic Comparative Exoplanet Treasury program for WASP-101b, a highly inflated hot Jupiter and one of the community targets proposed for the James Webb Space Telescope (JWST) Early Release Science (ERS) program. From a single HST Wide Field Camera 3 observation, we find that the near-infrared transmission spectrum of WASP-101b contains no significant H2O absorption features and we rule out a clear atmosphere at 13 sigma. Therefore, WASP-101b is not an optimum target for a JWST ERS program aimed at observing strong molecular transmission features. We compare WASP-101b to the well-studied and nearly identical hot Jupiter WASP-31b. These twin planets show similar temperature-pressure profiles and atmospheric features in the near-infrared. We suggest exoplanets in the same parameter space as WASP-101b and WASP-31b will also exhibit cloudy transmission spectral features. For future HST exoplanet studies, our analysis also suggests that a lower count limit needs to be exceeded per pixel on the detector in order to avoid unwanted instrumental systematics.
    • HST Proper Motions of NGC 147 and NGC 185: Orbital Histories and Tests of a Dynamically Coherent Andromeda Satellite Plane

      Sohn, Sangmo Tony; Patel, Ekta; Fardal, Mark A.; Besla, Gurtina; van der Marel, Roeland P.; Geha, Marla; Guhathakurta, Puragra; Univ Arizona, Dept Astron (IOP PUBLISHING LTD, 2020-09-21)
      We present the first proper-motion (PM) measurements for the dwarf elliptical galaxies NGC 147 and NGC 185, two satellite galaxies of M31, using multiepoch Hubble Space Telescope (HST) imaging data with time baselines of similar to 8 yr. For each galaxy, we take an error-weighted average of measurements from HST Advanced Camera for Surveys/WFC and Wide Field Camera 3/UVIS to determine the PMs. Our final results for the PMs are (mu(W),mu(N))(N147) = (-0.0232, 0.0378) (0.0143, 0.0146) mas yr(-1)for NGC 147 and (mu(W),mu(N))(N185) = (-0.0242, 0.0058) (0.0141, 0.0147) mas yr(-1)for NGC 185. The 2D direction of motion for NGC 147 about M31 is found to be aligned with its tidal tails. The 3D positions and velocities of both galaxies are transformed into a common M31-centric coordinate system to study the detailed orbital histories of the combined M31+NGC 147+NGC 185 system via numerical orbit integration. We find that NGC 147 (NGC 185) had its closest passage to M31 0.3-0.5 Gyr (greater than or similar to 1.6 Gyr) within the past 6 Gyr at distances of similar to 70 kpc (70-260 kpc). The pericentric times of NGC 147/NGC 185 correlate qualitatively well with the presence/absence of tidal tails seen around the galaxies. Our PMs show that the orbital poles of NGC 147, as well as NGC 185, albeit to a lesser degree, agree within the uncertainties with the normal of the Great Plane of Andromeda (GPoA). These are the first measurements of the 3D angular momentum vector of any satellite identified as original GPoA members. Our results strengthen the hypothesis that the GPoA may be a dynamically coherent entity. We revisit previous claims that NGC 147 and NGC 185 are binary galaxies and conclude that it is very unlikely that the two galaxies were ever gravitationally bound to each other.
    • An HST/STIS Optical Transmission Spectrum of Warm Neptune GJ 436b

      Lothringer, Joshua D.; Benneke, Björn; Crossfield, Ian J. M.; Henry, G.; Morley, Caroline V.; Dragomir, Diana; Barman, Travis S.; Knutson, Heather; Kempton, Eliza; Fortney, Jonathan J.; et al. (IOP PUBLISHING LTD, 2018-01-17)
      GJ 436b is a prime target for understanding warm Neptune exoplanet atmospheres and a target for multiple James Webb Space Telescope (JWST) Guaranteed Time Observation programs. Here, we report the first space-based optical transmission spectrum of the planet using two Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph (STIS) transit observations from 0.53 to 1.03 mu m. We find no evidence for alkali absorption features, nor evidence of a scattering slope longward of 0.53 mu m. The spectrum is indicative of moderate to high metallicity (similar to 100-1000x solar), while moderate-metallicity scenarios (similar to 100x. solar) require aerosol opacity. The optical spectrum also rules out some highly scattering haze models. We find an increase in transit depth around 0.8 mu m in the transmission spectra of three different sub-Jovian exoplanets (GJ 436b, HAT-P-26b, and GJ 1214b). While most of the data come from STIS, data from three other instruments may indicate this is not an instrumental effect. Only the transit spectrum of GJ 1214b is well fit by a model with stellar plages on the photosphere of the host star. Our photometric monitoring of the host star reveals a stellar rotation rate of 44.1 days and an activity cycle of 7.4 years. Intriguingly, GJ 436 does not become redder as it gets dimmer, which is expected if star spots were dominating the variability. These insights into the nature of the GJ 436 system help refine our expectations for future observations in the era of JWST, whose higher precision and broader wavelength coverage will shed light on the composition and structure of GJ 436b's atmosphere.
    • The Hubble PanCET program: an extensive search for metallic ions in the exosphere of GJ 436 b

      dos Santos, L. A.; Ehrenreich, D.; Bourrier, V.; Lecavelier des Etangs, A.; López-Morales, M.; Sing, D. K.; Ballester, G.; Ben-Jaffel, L.; Buchhave, L. A.; García Muñoz, A.; et al. (EDP SCIENCES S A, 2019-09-04)
      Context. The quiet M2.5 star GJ 436 hosts a warm Neptune that displays an extended atmosphere that dwarfs its own host star. Predictions of atmospheric escape in such planets state that H atoms escape from the upper atmosphere in a collisional regime and that the flow can drag heavier atoms to the upper atmosphere. It is unclear, however, what astrophysical mechanisms drive the process. Aims. Our objective is to leverage the extensive coverage of observations of the far-ultraviolet (FUV) spectrum of GJ 436 obtained with the Cosmic Origins Spectrograph (COS) to search for signals of metallic ions in the upper atmosphere of GJ 436 b, as well as study the activity-induced variability of the star. Methods. We analyzed flux time-series of species present in the FUV spectrum of GJ 436 and successfully performed geocoronal contamination removal in the COS Lyman-alpha profiles obtained near the Earth's night-side. Results. GJ 436 displays flaring events with a rate of similar to 10 d(-1). There is evidence for a possibly long-lived active region or longitude that modulates the FUV metallic lines of the star with amplitudes up to 20%. Despite the strong geocoronal contamination in the COS spectra, we detected in-transit excess absorption signals of similar to 50 and similar to 30% in the blue and red wings, respectively, of the Lyman-alpha line. We rule out a wide range of excess absorption levels in the metallic lines of the star during transit. Conclusions. The large atmospheric loss of GJ 436 b observed in Lyman-alpha transmission spectra is stable over the timescale of a few years, and the red wing signal supports the presence of a variable hydrogen absorption source besides the stable exosphere. The previously claimed in-transit absorption in the Si III line is likely an artifact resulting from the stellar magnetic cycle. The non-detection of metallic ions in absorption could indicate that the escape is not hydrodynamic or that the atmospheric mixing is not efficient in dragging metals high enough for sublimation to produce a detectable escape rate of ions to the exosphere.
    • Hubble PanCET: an isothermal day-side atmosphere for the bloated gas-giant HAT-P-32Ab

      Nikolov, N.; Sing, D. K.; Goyal, J.; Henry, G. W.; Wakeford, H. R.; Evans, T. M.; López-Morales, M.; García Muñoz, A.; Ben-Jaffel, L.; Sanz-Forcada, J.; et al. (OXFORD UNIV PRESS, 2018-02)
      We present a thermal emission spectrum of the bloated hot Jupiter HAT-P-32Ab from a single eclipse observation made in spatial scan mode with the Wide Field Camera 3 (WFC3) aboard the Hubble Space Telescope (HST). The spectrum covers the wavelength regime from 1.123 to 1.644 mu m which is binned into 14 eclipse depths measured to an averaged precision of 104 parts-per million. The spectrum is unaffected by a dilution from the close M-dwarf companion HAT-P-32B, which was fully resolved. We complemented our spectrum with literature results and performed a comparative forward and retrieval analysis with the 1D radiative-convective ATMO model. Assuming solar abundance of the planet atmosphere, we find that the measured spectrum can best be explained by the spectrum of a blackbody isothermal atmosphere with T-p = 1995 +/- 17 K, but can equally well be described by a spectrum with modest thermal inversion. The retrieved spectrum suggests emission from VO at the WFC3 wavelengths and no evidence of the 1.4 mu m water feature. The emission models with temperature profiles decreasing with height are rejected at a high confidence. An isothermal or inverted spectrum can imply a clear atmosphere with an absorber, a dusty cloud deck or a combination of both. We find that the planet can have continuum of values for the albedo and recirculation, ranging from high albedo and poor recirculation to low albedo and efficient recirculation. Optical spectroscopy of the planet's day-side or thermal emission phase curves can potentially resolve the current albedo with recirculation degeneracy.

      Jewitt, David; Agarwal, Jessica; Weaver, Harold; Mutchler, Max; Li, Jing; Larson, Stephen; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2016-09-06)
      Hubble Space Telescope observations of active asteroid 324P/La Sagra near perihelion show continued mass loss consistent with the sublimation of near-surface ice. Isophotes of the coma measured from a vantage point below the orbital plane are best matched by steady emission of particles having a nominal size. of. a similar to 100 mu m. The inferred rate of mass loss, dM(d)/dt similar to 0.2 kg s(-1), can be supplied by sublimation of water ice in thermal equilibrium with sunlight from an area as small as 930 m(2), corresponding to about 0.2% of the nucleus surface. Observations taken from a vantage point only 0.degrees 6. from the orbital plane of 324P set a limit to the velocity of ejection of dust in the direction perpendicular to the plane, V-perpendicular to < 1 m s(-1). Short-term photometric variations of the near-nucleus region, if related to rotation of the underlying nucleus, rule-out periods <= 3.8 hr and suggest that rotation probably does not play a central role in driving the observed mass loss. We estimate that, in the previous orbit, 324P lost about 4 x 10(7) kg in dust particles, corresponding to 6 x 10(-5) of the mass of a 550 m spherical nucleus of assumed density rho = 1000 kg m(-3). If continued, mass loss at this rate would limit the lifetime of 324P to similar to 1.6 x 10(4) orbits (about 10(5) years). To survive for the 100-400 Myr timescales corresponding to dynamical and collisional stability requires a duty cycle of 2 x 10(-4) <= f(d) <= 8 x 10(-4). Unless its time in orbit is overestimated by many orders of magnitude, 324P is revealed as a briefly active member of a vast population of otherwise dormant ice-containing asteroids.