A5026609033- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Gamma-ray bursts and supernovae
- Astrophysics and Star Formation Studies
- Astrophysical Phenomena and Observations
- Astro and Planetary Science
- Galaxies: Formation, Evolution, Phenomena
- Cardiac Imaging and Diagnostics
- Cardiovascular Function and Risk Factors
- Advanced MRI Techniques and Applications
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Astrophysics and Cosmic Phenomena
- Hemodynamic Monitoring and Therapy
- Adaptive optics and wavefront sensing
- Ultrasound Imaging and Elastography
- Vehicle Dynamics and Control Systems
- Geophysical and Geoelectrical Methods
- Geophysical Methods and Applications
- Space Exploration and Technology
- Atomic and Subatomic Physics Research
- Historical and Architectural Studies
- Advanced Frequency and Time Standards
- Space Science and Extraterrestrial Life
Virginia Tech
2022-2024
Västmanlands sjukhus Västerås
2019
Cerro Tololo Inter-American Observatory
1991-2011
Linköping University
2009
University of British Columbia
1993-1998
U.S. National Science Foundation
1993
Universities Space Research Association
1993
South African Radio Astronomy Observatory
1983-1985
Astronomical Observatory
1983
University of Washington
1982
We have obtained new observations of both secondary and tertiary spectrophotometric standards with the RC spectrographs CCD cameras on 1.5-m 4-m telescopes at CTIO in wavelength range 3300-7550 angstroms, as well UBV(RI)KC photometry for these stars. modified monochromatic fluxes published by Taylor (1984) according to calibration Vega provided Hayes (1985). also uned zero-point energy distribution stars matching their V synthetic magnitudes observed magnitudes. use adjusted order calculate...
Context. Quasar outflows are key players in the feedback processes that influence evolution of galaxies and intergalactic medium. The chemical abundance these provides crucial insights into their origin impact. Aims. We determine absolute abundances nitrogen sulfur physical conditions outflow seen quasar 3C298. Methods. analyzed archival spectral data from Hubble Space Telescope for measured ionic column densities absorption troughs compared results to photoionization predictions made with...
We present 13 spectra and 31 photometric observations covering the first 150 days of SN 1991bg in NGC 4374 (M 84). Although was a type Ia supernova displaying characteristic Si II absorption at 6150 A near maximum Fe emission lines late phases, it varied from well-defined norm for SNe several important respects. The peculiarities include faster declines B V light curves after maximum, distinct color evolution, very red - relatively faint peak luminosity, spectral short phase. narrow...
view Abstract Citations (61) References (10) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Gamma Cephei: Rotation or Planetary Companion? Walker, Gordon A. H. ; Bohlender, David Andrew R. Irwin, Alan W. Yang, Stephenson L. S. Larson, Ana In 1988 Cep was reported as a single-line, long-period spectroscopic binary with short-term periodic (P = 2.7 yr) residuals which might be caused by Jupiter-mass companion. Eleven years of data now give 2.52 yr (K 27 m/s)...
We present new FLAMES@VLT spectroscopic observations of 30 stars in the field Large Magellanic Cloud (LMC) stellar cluster NGC 1866. 1866 is one few young and massive globular clusters that close enough so its can be individually studied detail. Radial velocities have been used to separate belonging LMC field, same spectra derive chemical abundances for a variety elements, from [Fe/H] light (i.e. Na, O, Mg, etc.) heavy ones. The average iron abundance turns out [Fe/H]=−0.43 ± 0.01 dex (with...
Context. Quasar outflows play a significant role in the active galactic nucleus (AGN) feedback, impacting interstellar medium and potentially influencing galaxy evolution. Characterizing these is essential for understanding AGN-driven processes. Aims. We aim to analyze physical properties of mini-broad absorption line outflow quasar J1402+2330 using data from Dark Energy Spectroscopic Instrument (DESI) survey. seek measure location, energetics, potential impact on AGN feedback Methods. In...
Context. Quasar outflows play a significant role in the active galactic nucleus (AGN) feedback, impacting interstellar medium and potentially influencing galaxy evolution. Characterizing these is essential for understanding AGN-driven processes. Aims. We aim to analyze physical properties of mini-broad absorption line outflow quasar J1402+2330 using data from Dark Energy Spectroscopic Instrument (DESI) survey. seek measure outflow’s location, energetics, potential impact on AGN feedback...
Abstract Two moving string test targets have been developed and used to characterize ultrasound Doppler instrumentation. The characteristics investigated were sample volume size location. tests performed on a combined echo/Doppler instrument an annular array system. procedures can be carried out routinely in the clinical laboratory ensure that is working properly or as aid for correct interpretation of acquired data.
We have made a comprehensive transit search for exoplanets down to about 2 Earth radii in the HD 209458 system, based on nearly uninterrupted broadband optical photometry obtained with MOST (Microvariability and Oscillations of Stars) satellite, spanning 14 days 2004 44 2005. searched these data limb-darkened transits at periods other than that known giant planet, from 0.5 weeks. Monte Carlo statistical tests synthetic inserted allow us rule out additional close-in sizes ranging 0.20-0.36 RJ...
We present extensive spectroscopic time series observations of the multiperiodic, rapidly rotating, δ Scuti star τ Pegasi. Information about oscillations is contained within patterns line-profile variation star's blended absorption-line spectrum. introduce new technique Doppler deconvolution with which to extract these by modeling intrinsic stellar spectrum and broadening functions for each in series. Frequencies modes oscillation are identified from variations using Fourier-Doppler imaging...
We present infrared photometry of SN 1987A in the J, H, K, L, M, 10, and 20 micron filters through day 1352 since explosion Supernova. find that both optical mid-infrared magnitudes are slowly leveling out after their rapid decline brightness during epoch dust formation. The near colors (V-J, V-H, V- K> initially reddened formation around 500, but by days 900-1000, they began to evolve blue, perhaps due thinning dust. Optical spectra obtained 1150 show no evidence for a sudden drop...
CCD photometry of 9 RR Lyrae stars in the LMC globular cluster NGC 2210 suggests that true distance modulus is 18.42±0.10 mag, assuming |$\langle M_V\rangle_{\text {RR}}=0.60\enspace\text{and}\enspace E(B-V)=0.060$| for 2210. The implications this result on Cepheid scale are discussed. results demonstrate high-accuracy as faint 20 mag possible with a combination consisting camera and 1-m telescope.
ABSTRACT We analyse the VLT/UVES spectrum of quasar SDSS J143907.5-010616.7, retrieved from UVES Spectral Quasar Absorption Database. identify two outflow systems in spectrum: a mini broad absorption line (mini-BAL) system and narrow (NAL) system. measure ionic column densities mini-BAL ($v$ = −1550 km s−1) outflow, which has excited state troughs ${\rm Fe\, \rm {\small {ii}}}$. determine that electron number density $\log {n_e}=3.4^{+0.1}_{-0.1}$, based on ratios between ground abundances...
ABSTRACT We have identified a broad absorption line (BAL) outflow in the HST/STIS spectrum of quasar QSO B0254-3327B at velocity v = −3200 km s−1. The has troughs from ions such as Ne viii, Na ix, Si xii, and v. also report first detection S xiv troughs, implying very high ionization. Via measurement ionic column densities, photoionization analysis, determination electron number density outflow, we found kinetic luminosity system to be up ∼1 per cent quasar’s Eddington luminosity, or ∼5...
Abstract We observed the Seyfert 1 galaxy Mrk 817 during an intensive multiwavelength reverberation mapping campaign for 16 months. Here, we examine behavior of narrow UV absorption lines seen in Hubble Space Telescope/Cosmic Origins Spectrograph spectra, both and other epochs extending over 14 yr. conclude that, while outflow system (at −3750 km s −1 with FWHM = 177 ) responds to variations continuum as modified by X-ray obscurer, its total column density (log N H 19.5 <mml:math...
A detailed resistivity survey was made at the Roman Town of Wroxeter to investigate performance a recently introduced mobile multiplexing system. Measurements were with six twin-array separations (0.25 m 1.5 m), and Wenner double -dipole arrays. The resulting area plots are discussed compared existing fluxgate gradiometer data. data sets also: (i) used create stacked pseudo-sections in X Y directions; (ii) combined using various weightings composite images. overall results show that making...
ABSTRACT In the Hubble Space Telescope/Cosmic Origins Spectrograph spectrum of Seyfert 1 galaxy 2MASX J14292507+4518318, we have identified a narrow absorption line outflow system with velocity −151 km s−1. This exhibits troughs from resonance states ions like C iv, N v, S and Si ii, as well excited ii* ii*. Our investigation involved measuring ionic column densities conducting photoionization analysis. These allow total density to be estimated log NH = 19.84 cm−2, its ionization parameter...
Using high-quality spectra obtained with the hydrogren fluoride technique at Canada-France-Hawaii 3.6-meter telescope and Dominion Astrophysical Observatory 1.22-meter telescope, we have detected a low-amplitude periodicity in both radial velocity chromospheric emission of Beta Geminorum. In addition, long-term change (time scale > 12 years) thi star's which is reminiscent solar-type magnetic cycles believed present giants similar spectral type. The radial-velocity variations can be fitted...
We present the analysis of absorption troughs six outflows observed in quasar SDSS J1130+0411 ($z \approx 3.98$) with radial velocities ranging from $-2400$ to $-15,400$ km s$^{-1}$. These spectra were taken Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph over rest frame wavelength range $1135-1890$ \r{A}. In main outflow system ($v -3200$ s$^{-1}$), we identify Fe II several II* as well Si troughs, which use determine electron number density $\log n_e = 2.6_{-0.7}^{+0.8}$...
The stellar spectra obtained in our precise velocity program include the Ca II infrared triplet line at lambda-8662. Changes core flux of this line, quantified with Delta-EW8662 index, reflect changes chromospheric activity. In 12 years observations for 61 Cygni A, we detect a solar-type cycle 7.22 and rotational period 36.21 days which confirm earlier results based on H K lines. stability derived rotation over suggests that regions activity are either long-lived or formed within...
The main aim of this experiment is to provide a complete census old (t > 10 Gyr, RR Lyrae, type II Cepheids, red horizontal branch), intermediate age (red clump, Miras) and young (classical Cepheids) stellar tracers across the Galactic Bulge. To fully exploit unique photometric quality LSST images, we plan perform Shallow minisurvey (ugrizy, -20 < l 20 deg, -15 b deg) Deep (izy, -3 3 deg). former one aimed at constraining 3D structure galactic Bulge four quadrants, in particular,...
Context: The study of quasar outflows is essential in understanding the connection between active galactic nuclei (AGN) and their host galaxies. We analyze VLT/UVES spectrum SDSS J0932+0840 identify several narrow broad outflow components absorption, with multiple ionization species including Fe II, which puts it among a rare class known as FeLoBALs. Aims: one to determine its physical characteristics by determining total hydrogen column density, parameter number density. Through these...
The study of quasar outflows is essential for understanding the connection between active galactic nuclei (AGN) and their host galaxies. We analyzed VLT/UVES spectrum SDSS J0932+0840 identified several narrow broad outflow components in absorption, with multiple ionization species including Fe II . This places it among rare class known as iron low-ionization absorption line (FeLoBALs). studied one to determine its physical characteristics by determining total hydrogen column density,...