8,424 research outputs found
Galaxy And Mass Assembly (GAMA) : ugrizYJHK Sersic luminosity functions and the cosmic spectral energy distribution by Hubble type
No full textWe report the morphological classification of 3727 galaxies from the Galaxy and Mass Assembly survey with Mr < −17.4 mag and in the redshift range 0.025 < z < 0.06 (2.1 × 105 Mpc3) into E, S0-Sa, SB0-SBa, Sab-Scd, SBab-SBcd, Sd-Irr and little blue spheroid classes. Approximately 70 per cent of galaxies in our sample are disc-dominated systems, with the remaining similar to ~30 per cent spheroid dominated. We establish the robustness of our classifications, and use them to derive morphological-type luminosity functions and luminosity densities in the ugrizYJHK passbands, improving on prior studies that split by global colour or light profile shape alone. We find that the total galaxy luminosity function is best described by a double-Schechter function while the constituent morphological-type luminosity functions are well described by a single-Schechter function. These data are also used to derive the star formation rate densities for each Hubble class, and the attenuated and unattenuated (corrected for dust) cosmic spectral energy distributions, i.e. the instantaneous energy production budget. While the observed optical/near-IR energy budget is dominated 58:42 by galaxies with a significant spheroidal component, the actual energy production rate is reversed, i.e. the combined disc-dominated populations generate similar to ~1.3 times as much energy as the spheroid-dominated populations. On the grandest scale, this implies that chemical evolution in the local Universe is currently largely confined to mid-type spiral classes like our Milky Way.Peer reviewe
Signature of Saturn's auroral cusp: Simultaneous Hubble Space Telescope FUV observations and upstream solar wind monitoring
No full textpeer reviewedModel simulations by Bunce et al. (2005a) have shown that direct precipitation of electrons in Saturn's dayside cusp regions is not capable of producing significant FUV aurora. Instead, they suggested the possibility that the FUV bright emissions sometimes observed near noon are associated with reconnection occurring at the dayside magnetopause, possibly pulsed, analogous to flux transfer events seen at the Earth. Pulsed reconnection at the low-latitude dayside magnetopause when the IMF is directed northward (antiparallel to Saturn's magnetic field lines) is expected to give rise to pulsed twin-vortical flows in the magnetosphere and hence to bipolar field-aligned currents centered in the vortical flows closing in ionospheric Pedersen current. In the case of southward IMF and high-latitude lobe reconnection the model predicts that the vortical flows are displaced poleward of the open-closed field line boundary with reversed field-aligned currents compared with the former case. During January 2004, a unique campaign took place during which magnetic field and plasma instruments on board the Cassini-Huygens spacecraft measured the in situ solar wind and embedded interplanetary magnetic field while the Hubble Space Telescope simultaneously observed the far ultraviolet aurora in Saturn's southern hemisphere. The IMF was highly structured during this interval. The electric potential at Cassini is estimated from solar wind magnetic field and velocity measurements for the case of low-latitude or lobe reconnection. We show that a dayside FUV signature of intense electron precipitation is found poleward of or along the main oval during a period of minor compression period when the dayside reconnection voltage is estimated to be ~30-100 kV. Overall, we find that the conceptual model of Bunce et al. (2005a) provides a good estimate of the UV brightness and power for the case of northward IMF but somewhat underestimates the power for the southward IMF case, except if the speed of the vortical flow is larger than its value in the nominal model
Laryngeal findings and acoustic changes in hubble-bubble smokers
No full textThe purpose of our investigation was to evaluate the laryngeal findings and acoustic changes in hubble-bubble smokers. A total of 42 subjects with history of hubble-bubble smoking were recruited for this study. A corresponding group with a history of cigarette smoking and controls were matched. All subjects underwent laryngeal video-endostroboscopic evaluation and acoustic analysis. In the hubble-bubble smoking group, 61.9percent were males. The average age was 30.02 ± 9.48 years and the average number of years of smoking was 8.09 ± 6.45 years. Three subjects had dysphonia at the time of examination. The incidence of benign lesions of the vocal folds in the hubble-bubble group was 21.5percent, with edema being the most common at 16.7percent followed by cyst at 4.8percent. The incidence of laryngeal findings was significantly higher in the hubble-bubble group compared to controls. In the cigarette-smoking group, the most common finding was vocal fold cyst in 14.8percent followed by polyps in 7.4percent, and edema, sulcus vocalis and granuloma. These findings were not significantly different from the hubble-bubble group except for the thick mucus, which was significantly higher in the latter. There were no significant changes in any of the acoustic parameters between hubble-bubble smokers and controls except for the VTI and MPT, which were significantly lower in the hubble-bubble group. In comparison with the cigarette-smoking group, hubble-bubble smokers had significantly higher Fundamental frequency and habitual pitch (p value 0.042 and 0.008, respectively). The laryngeal findings in hubble-bubble smokers are comparable to cigarette smokers. These laryngeal findings are not translated acoustically, as all the acoustic parameters are within normal range compared to controls. © 2010 Springer-Verlag.ALFAYEZ SF, 1988, TROP GEOGR MED, V40, P115; Al Mutairi SS, 2006, RESPIROLOGY, V11, P449, DOI 10.1111-j.1400-1843.2006.00873.x; Chaaya M, 2004, NICOTINE TOB RES, V6, P457, DOI 10.1080-14622200410001696628; Colton RH, 1996, UNDERSTANDING VOICE; Dore MP, 2008, DIGEST DIS SCI, V53, P2027, DOI 10.1007-s10620-007-0108-7; El-Hakim IE, 1999, INT J DERMATOL, V38, P108, DOI 10.1046-j.1365-4362.1999.00448.x; GILBERT HR, 1974, J PSYCHOLINGUIST RES, V3, P225, DOI 10.1007-BF01069239; Guimarães Isabel, 2005, Logoped Phoniatr Vocol, V30, P185, DOI 10.1080-14015430500294114; Guimaraes I, 2002, THESIS U LONDON; Kiter G, 2000, RESP MED, V94, P891, DOI 10.1053-rmed.2000.0859; LUBIN JH, 1992, INT J CANCER, V51, P390, DOI 10.1002-ijc.2910510310; MURPHY CH, 1987, OTOLARYNG HEAD NECK, V97, P376; Sajid Khan Mohammad, 1993, JPMA (Journal of the Pakistan Medical Association), V43, P179; SATALOFF RT, 1995, DIAGNOSIS TREATMENT, P247; Shafagoj YA, 2002, INT J CLIN PHARM TH, V40, P249; Shafagoj YA, 2002, SAUDI MED J, V23, P953; Shihadeh A, 2003, FOOD CHEM TOXICOL, V41, P143, DOI 10.1016-S0278-6915(02)00220-X; Singh N, 1989, J Assoc Physicians India, V37, P649; SORENSEN D, 1982, J COMMUN DISORD, V15, P135, DOI 10.1016-0021-9924(82)90027-2; Stemple J.C., 1995, CLIN VOICE PATHOLOGY; STOICHEFF ML, 1981, J SPEECH HEAR RES, V24, P437; SUKUMAR A, 1992, BIOL TRACE ELEM RES, V34, P99, DOI 10.1007-BF02783902; TAJADA JD, 1999, ACTA OTORRINOLARING, V50, P44; Varsano Shabtai, 2003, Harefuah, V142, P736; Vecerina-Volić S, 1997, Lijec Vjesn, V119, P1; Wiskirska-Woźnica Bozena, 2004, Przegl Lek, V61, P106822
hubble-bubble
No full texthubble-bubblea well-burnished cooking-stove sent out its heat, and on its top the tea-kettle sang a cheery song, in perfect harmony with the hubble-bubble of a boiler, its companion, ...PRINTED ITEM W. J. KIRWIN NOV 5 1964Not UsedNot usedWithdrawnChecked by Jordyn Hughes on Thu 21 May 201
IMF dependence of the open-closed field line boundary in Saturn's ionosphere, and its relation to the UV auroral oval observed by the Hubble Space Telescope
No full textWe study the dependence of Saturn's magnetospheric magnetic field structure on the interplanetary magnetic field (IMF), together with the corresponding variations of the open-closed field line boundary in the ionosphere. Specifically we investigate the interval from 8 to 30 January 2004, when UV images of Saturn's southern aurora were obtained by the Hubble Space Telescope (HST), and simultaneous interplanetary measurements were provided by the Cassini spacecraft located near the ecliptic ~0.2 AU upstream of Saturn and ~0.5 AU off the planet-Sun line towards dawn. Using the paraboloid model of Saturn's magnetosphere, we calculate the magnetospheric magnetic field structure for several values of the IMF vector representative of interplanetary compression regions. Variations in the magnetic structure lead to different shapes and areas of the open field line region in the ionosphere. Comparison with the HST auroral images shows that the area of the computed open flux region is generally comparable to that enclosed by the auroral oval, and sometimes agrees in detail with its poleward boundary, though more typically being displaced by a few degrees in the tailward direction
Hypervelocity impact in low earth orbit: finding subtle impactor signatures on the Hubble Space Telescope
No full textpublisher: Elsevier articletitle: Hypervelocity impact in low earth orbit: finding subtle impactor signatures on the Hubble Space Telescope journaltitle: Procedia Engineering articlelink: http://dx.doi.org/10.1016/j.proeng.2017.09.746 content_type: article copyright: © 2017 The Author(s). Published by Elsevier Ltd.© 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the 14th Hypervelocity Impact Symposium 2017. The file attached is the Published/publisher’s pdf version of the article.NHM Repositor
The Hubble Legacy Archive NICMOS grism data
No full textThe Hubble Legacy Archive (HLA) aims to create calibrated science data from the Hubble Space Telescope archive and make them accessible via user-friendly and Virtual Observatory (VO) compatible interfaces. It is a collaboration between the Space Telescope Science Institute (STScI), the Canadian Astronomy Data Centre (CADC) and the Space Telescope - European Coordinating Facility (ST-ECF). Data produced by the Hubble Space Telescope (HST) instruments with slitless spectroscopy modes are among the most difficult to extract and exploit. As part of the HLA project, the ST-ECF aims to provide calibrated spectra for objects observed with these HST slitless modes.
In this paper, we present the HLA NICMOS G141 grism spectra. We describe in detail the calibration, data reduction and spectrum extraction methods used to produce the extracted spectra. The quality of the extracted spectra and associated direct images is demonstrated through comparison with near-IR imaging catalogues and existing near-IR spectroscopy. The output data products and their associated metadata are publicly available (http://hla.stecf.org/) through a web form, as well as a VO-compatible interface that enables flexible querying of the archive of the 2470 NICMOS G141 spectra. In total, spectra of 1923 unique targets are included
Cosmic dust impacts on the Hubble Space Telescope
No full textExposure of the Hubble Space Telescope to space in low Earth orbit resulted in numerous hypervelocity impacts by cosmic dust (micrometeoroids) and anthropogenic particles (orbital debris) on the solar arrays and the radiator shield of the Wide Field and Planetary Camera 2, both subsequently returned to Earth. Solar cells preserve residues from smaller cosmic dust (and orbital debris) but give less reliable information from larger particles. Here, we present images and analyses from electron, ion and X-ray fluorescence microscopes for larger impact features (millimetre- to centimetre-scale) on the radiator shield. Validated by laboratory experiments, these allow interpretation of composition, probable origin and likely dimensions of the larger impactors. The majority (~90%) of impacts by grains greater than 50 μm in size were made by micrometeoroids, dominated by magnesium- and iron-rich silicates and iron sulfides, metallic iron-nickel and chromium-rich spinel similar to that in ordinary chondrite meteorites of asteroid origin. Our re-evaluation of the largest impact features shows substantially fewer large orbital debris impacts than reported by earlier authors. Mismatch to the NASA ORDEM and ESA MASTER models of particle populations in orbit may be partly due to model overestimation of orbital debris flux and underestimation of larger micrometeoroid numbers. This article is part of the theme issue ‘Dust in the Solar System and beyond’
A robust method for measuring the Hubble parameter
No full textWe obtain a robust, non-parametric, estimate of the Hubble constant from the linear diameters and rotation velocities of galaxies in the recent KLUN sample, calibrated using Cepheid distances to Hubble Space Telescope Key Project galaxies. There are two key features that make our analysis considerably more robust than previous work. First, the method is independent of the spatial distribution of galaxies and is insensitive to Malmquist bias. It may, therefore, be applied to more distant samples than so-called 'plateau' methods making it much less vulnerable to the impact of peculiar motions in the Local Supercluster. Secondly, we include information on the galaxy rotation velocities in a fully non-parametric manner: unlike the conventional TullyFisher relation we reconstruct a robust estimate of the cumulative distribution function of galaxy diameter at given rotation velocity, without requiring the assumption of, for example, a linear TullyFisher relation with symmetric Gaussian residuals
Estimating the Hubble constant on a base of observed values of the Hubble parameter H(z) in a model without expansion
No full textIn the model of low-energy quantum gravity by the author, the
ratio H(z)/(1 + z) should be equal to the Hubble constant. Here, the
weighted average value of the Hubble constant has been found using
29 observed values of the Hubble parameter H(z): ±σ0 =
(64.40 ± 5.95) km s−1 Mpc−1
- …
