A spectroscopic determination of singlet oxygen quantum yield of PPME in different solvents

Conference (2003)

Spectroscopic evidence for high-altitude Aurora at Jupiter from Galileo Extreme Ultraviolet Spectrometer and Hopkins Ultraviolet Telescope observations

in Icarus: International Journal of Solar System Studies (2001), 152(1), 151-171

The Galileo Extreme Ultraviolet Spectrometer (EUVS) and the Hopkins Ultraviolet Telescope (HUT) acquired UV spectra of Jupiter Aurora in the period from 1995 through 1997, The EUVS spectra spanned the ... [more ▼]

The Galileo Extreme Ultraviolet Spectrometer (EUVS) and the Hopkins Ultraviolet Telescope (HUT) acquired UV spectra of Jupiter Aurora in the period from 1995 through 1997, The EUVS spectra spanned the wavelength range 540-1280 Angstrom and the HUT spectra measured the extreme ultraviolet and far ultraviolet (EUV + FUV) wavelength range 830-1850 Angstrom. Both sets of spectra present evidence of high-altitude, optically thin H-2 band emissions from the exobase region, The analysis of the UV spectra with a two-stream electron transport model and a jovian model auroral atmosphere indicates that the primary electron flux is composed of both soft and hard electrons with characteristic energies in the soft electron energy range of 20-200 eV and the hard electron range of 5-100 keV, The soft electron flux causes enhanced EUV emission intensities below 1100 Angstrom. The soft electron flux may explain the high temperature of the upper atmosphere above the homopause as measured from Il: rovibrational temperatures in the IR. For the deep aurora, a high primary characteristic energy above 5 keV is known to be present. The Galileo Energetic Particle Detector (EPD) has measured the electron distribution functions for energies above 15 keV in the middle magnetosphere. The high-energy distribution functions can be modeled by a combination of Maxwellian and kappa distributions. However, the EUV (800-1200 Angstrom) portion of the HUT spectrum cannot be modeled with a single distribution of hard electrons as was possible in the past for the FUV (1200-1650 Angstrom) spectrum measured by itself, The combination of EUV and FUV spectral observations by HUT serves to identify the amount of soft electron flux relative to the hard primary flux required to produce the high-altitude aurora in the neighborhood of the exobase, (C) tool academic Press. [less ▲]

Spectroscopic follow-up of the colliding-wind binary WR140 during the 2009 January periastron passage

in Bulletin de la Societe Royale des Sciences de Liege (2011), 80

We present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in January 2009. This object is known as the archetype of colliding wind binaries and has a ... [more ▼]

We present the results from the spectroscopic follow-up of WR140 (WC7 + O4-5) during its last periastron passage in January 2009. This object is known as the archetype of colliding wind binaries and has a relatively large period (≃8 years) and eccentricity (≃0.9). We provide updated values for the orbital parameters, new estimates for the WR and O star masses and new constraints on the mass-loss rates. [less ▲]

Spectroscopic investigation of structure in octarellin (a de novo protein designed to adopt the alpha/beta-barrel packing)

in Protein Engineering (1991), 4(7), 745-9

We present here a spectroscopic structural characterization of octarellin, a recently reported de novo protein modelled on alpha/beta-barrel proteins [K. Goraj, A. Renard and J.A. Martial (1990) Protein ... [more ▼]

We present here a spectroscopic structural characterization of octarellin, a recently reported de novo protein modelled on alpha/beta-barrel proteins [K. Goraj, A. Renard and J.A. Martial (1990) Protein Engng, 3, 259-266]. Infrared and Raman spectra analyses of octarellin's secondary structure reveal the expected percentage of alpha-helices (30%) and a higher beta-sheet content (40%) than predicted from the design. When the Raman spectra obtained with octarellin and native triosephosphate isomerase (a natural alpha/beta-barrel) are compared, similar percentages of secondary structures are found. Thermal denaturation of octarellin monitored by CD confirms that its secondary structures are quite stable, whereas its native-like tertiary fold is not. Tyrosine residues, predicted to be partially hidden from solvent, are actually exposed as revealed by Raman and UV absorption spectra. We conclude that the attempted alpha/beta-barrel conformation in octarellin may be loosely packed. The criteria used to design octarellin are discussed and improvements suggested. [less ▲]

A spectroscopic investigation of the young open cluster IC 1805

in Rauw, Grégor; Nazé, Yaël; Blomme, R. (Eds.) et al Massive Stars and High-Energy Emission in OB Associations (2005, November 01)

We present the main results of a spectroscopic campaign devoted to the O-type stars in the young open cluster IC 1805. This study aims at the investigation of the multiplicity and the line profile ... [more ▼]

We present the main results of a spectroscopic campaign devoted to the O-type stars in the young open cluster IC 1805. This study aims at the investigation of the multiplicity and the line profile variability of its brightest massive members. We present new results concerning the line profile variability of He II 4686 and H-beta for HD 15570 and HD 15629. For these two stars, our radial velocity analysis does not reveal any variations compatible with a binary motion. We also significantly improve the orbital parameters of the long period binary HD 15558. For this latter system, we present for the first time evidence for the detection of the secondary, leading to spectral types of O5.5 and O7 respectively for the two components. [less ▲]

Spectroscopic mode identification for the beta Cephei star EN (16) Lacertae

in Astronomy and Astrophysics (2003), 399

We perform for the first time spectroscopic mode identification in the eclipsing binary beta Cephei star EN (16) Lac. This mode identification is based upon a time series of 942 line profiles of the He I ... [more ▼]

We perform for the first time spectroscopic mode identification in the eclipsing binary beta Cephei star EN (16) Lac. This mode identification is based upon a time series of 942 line profiles of the He I lambda lambda 6678 Åline in its spectrum. All three known frequencies f[SUB]1[/SUB], f,SUB>2,/SUB>, f[SUB]3[/SUB] of the star are present in the line-profile variations, but we failed to find additional modes. Using different identification methods we find conclusive evidence for the radial nature of the main mode and for the l=2, m=0 identification of the mode with frequency f[SUB]2[/SUB]. A unique identification of the third mode is not possible from the spectra, but we do derive that l[SUB]3[/SUB]<3. Fits to the amplitude and phase variability of the modes imply a rotation frequency between 0.1 and 0.4 c d[SUP]-1[/SUP]. The star's rotation axis is not aligned with the orbital axis. Based on observations gathered with the coudé spectrograph attached to the 2.0 m reflector telescope at Tautenburg Observatory. [less ▲]

Spectroscopic monitoring of 10 new northern slowly pulsating B star candidates discovered from the HIPPARCOS mission

in Astronomy and Astrophysics (2001), 379

A one-year follow-up campaign of high-resolution, high-signal-to-noise spectroscopy for 10 candidate slowly pulsating B stars, which were discovered from the HIPPARCOS astrometric mission, shows that all ... [more ▼]

A one-year follow-up campaign of high-resolution, high-signal-to-noise spectroscopy for 10 candidate slowly pulsating B stars, which were discovered from the HIPPARCOS astrometric mission, shows that all stars exhibit line-profile variability. From our data, and from the HIPPARCOS photometry, we conclude that all but one of the targets provide evidence of multiperiodicity, with periods of the order of days, confirming their pulsational nature. Thus they are confirmed slowly pulsating B stars. We summarize the pulsation periods and Q-values and select the most interesting targets for very-long-term follow-up observations with the goal of performing asteroseismology. Based on observations obtained at the Observatoire de Haute-Provence. [less ▲]

Spectroscopic monitoring of the Herbig Ae star HD 104237 - II. Non-radial pulsations, mode analysis and fundamental stellar parameters

in Astronomy and Astrophysics (in press)

Context. Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current ... [more ▼]

Context. Herbig Ae/Be stars are intermediate-mass pre-main sequence (PMS) stars showing signs of intense activity and strong stellar winds, whose origin is not yet understood in the frame of current theoretical models of stellar evolution for young stars. In addition, the evolutionary tracks of the earlier Herbig Ae stars cross the theoretical PMS instability strip located roughly in the same area of the HR diagram as the δ Scuti variables. Many of these stars exhibit pulsations of δ Scuti type. Aims. Understanding the internal structure of pulsating Herbig Ae stars based on asteroseismic studies will help constraining the origin of their tremendous activity, winds, and variability. It is therefore necessary to investigate the location of the PMS instability strip and of its boundaries, and to extend the sample of observed and studied pulsating Herbig Ae stars. The aim of this work was to carry out a thorough analysis of the line profile variations of the prototype Herbig Ae star HD104237 based on high-resolution spectroscopy and to redetermine precisely its fundamental parameters, which are the basic ingredients of a forthcoming asteroseismic modeling. Methods. HD104237 is a pulsating Herbig Ae star with eight detected frequencies based on the analysis of radial velocity variations. In this article, we reinvestigated an extensive high-resolution quasi-continuous spectroscopic data set in order to search for very faint indications of non-radial pulsations in the line profile by working on dynamical spectra of equivalent photospheric (LSD) profiles of HD104237. A 2D Fourier analysis (F2D) was performed of the entire profile and the temporal variation of the central depth of the line was studied with the time-series analysis tools Period04 and SigSpec. We present the results of these analysis including the mode identification corresponding to the detected dominant frequency, as well as a new determination of its fundamental stellar parameters. Results. The analysis of spectroscopic data set of April 22 - 25 obtained at SAAO in 1999 has confirmed the presence of multiple oscillation modes of low-degree ℓ in HD104237 and led to the first direct detection of a non-radial pulsation mode in this star: the dominant mode F1 was identified by the Fourier 2D method having a degree ℓ value comprised between 1 and 2, the symmetry of the pattern variation indicating an azimuthal order of ± 1. The detailed study of the fundamental stellar parameters has provided a Teff, log g, and iron abundance of 8550 ± 150 K, 3.9 ± 0.3, and −4.38 ± 0.19 (i.e. [Fe/H]= +0.16 ± 0.19 ), respectively. [less ▲]

Spectroscopic observations of pulsating stars

in Communications in Asteroseismology (2008), 157

During the past three decades, astronomers have been gathering extensive time series of high- precision spectroscopy of pulsating stars. In contrast to one-shot spectra, which provide the fundamental ... [more ▼]

During the past three decades, astronomers have been gathering extensive time series of high- precision spectroscopy of pulsating stars. In contrast to one-shot spectra, which provide the fundamental parameters, time-resolved spectroscopy offers a much broader variety of input for asteroseismology. The most important applications encompass the determination of the radial-velocity amplitudes and phases of the modes, the detection of modes that are invisible in photometry, the identification of the azimuthal orders through specialised methodology, the unravelling of pulsational and orbital motions, and, since a few years, the detection of solar-like oscillations in various types of stars. We discuss the input that spectroscopic time series can provide for asteroseismic modelling, for various types of pulsators. We end with some future prospects of how spectroscopy can help to push seismic applications beyond the present achievements. [less ▲]

Spectroscopic Properties of New IR Galaxies Detected in the European Large Area ISO Survey

in The Promise of the Herschel Space Observatory (2001, July 01)

We present preliminary results of multi-object spectroscopy of new mid-, and far-infrared selected galaxies detected in the European Large Area ISO Survey (ELAIS). The data have been obtained with the ... [more ▼]

We present preliminary results of multi-object spectroscopy of new mid-, and far-infrared selected galaxies detected in the European Large Area ISO Survey (ELAIS). The data have been obtained with the fibre spectrographs WYFFOS at the William Herschel Telescope (Observatorio del Roque de los Muchachos, ORM, Canary Islands) and Hydra at the WIYN Telescope (Kitt Peak Observatory, Arizona). The sample includes ISO sources detected at 7, 15 and 90 microns and radio sources from our deep VLA survey in the ELAIS areas. [less ▲]