A5077884597- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- History and Developments in Astronomy
- Calibration and Measurement Techniques
- Solar and Space Plasma Dynamics
- Spectroscopy and Laser Applications
- Impact of Light on Environment and Health
- Adaptive optics and wavefront sensing
- Atomic and Molecular Physics
- Phase Equilibria and Thermodynamics
- Cosmology and Gravitation Theories
- Atmospheric and Environmental Gas Dynamics
- Space Exploration and Technology
- Spreadsheets and End-User Computing
- Scientific Measurement and Uncertainty Evaluation
- Atmospheric Ozone and Climate
- Pulsars and Gravitational Waves Research
- Optical Coatings and Gratings
York University
2005-2024
University of Hawaii System
2007
National Academies of Sciences, Engineering, and Medicine
2007
Canada–France–Hawaii Telescope
2007
Keele University
1999-2005
Association of Universities For Research In Astronomy
1999-2004
Universidad Nacional Autónoma de México
2003
University of Arizona
2003
Krirk University
1997
University of Alabama
1994
view Abstract Citations (709) References (101) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The chemistry of galaxies. I. nature giant extragalactic H II regions. McCall, M. L. ; Rybski, P. Shields, G. A. emission properties presently derived from spectrophotometric observations 99 regions in 20 spiral and irregular galaxies form a one-parameter sequence, the oxygen abundance is found to be underlying physical determinant spectrum region. ionizing...
view Abstract Citations (248) References (108) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Oxygen Abundances in Diffuse Ellipticals and the Metallicity-Luminosity Relations for Dwarf Galaxies Richer, Michael G. ; McCall, Marshall L. We have obtained spectroscopy of planetary nebulae dwarf irregular galaxy NGC 6822 diffuse elliptical galaxies 185 205. also introduced a new metallicity- luminosity relation based upon more homogeneous treatment distances...
The influence of shifts in effective wavelengths on ratios total to selective extinction is examined, primarily determine how evaluate the Galactic extragalactic bodies a way that minimizes systematic errors. In process, new procedure developed for evaluating or any source filter from index reddening. amount dust along sightline quantified by optical depth at 1 μm, which has advantage being roughly equal numerically E(B-V). can be derived iteratively color excess using an appropriate...
view Abstract Citations (279) References (50) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The type I supernova 1981b in NGC 4536 : the first 100 days. Branch, D. ; Lacy, C. H. McCall, M. L. Sutherland, P. G. Uomoto, A. Wheeler, J. Wills, B. High-quality optical spectra of Type from time maximum light to 116 days later are presented. This is compared photometrically with 1972e 5253, and two found be very similar. Synthetic based on resonance scattering...
view Abstract Citations (228) References (64) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The type II SN 1979c in M 100 and the distance to Virgo cluster. Branch, D. ; Falk, S. W. McCall, M. L. Rybski, P. Uomoto, A. K. Wills, B. J. Intensity calibrated optical spectrophotometric observations of supernova M100 were obtained between April 22, 1979 November 24, 1979. time development spectrum appears typical for events, except perhaps that H-alpha feature...
We identify a sample of 14 planetary nebulae in the nearby starburst disc galaxy NGC 253, using broad- and narrow-band imaging. A simple model stellar dust layers shows that nebula magnitudes are not statistically affected much by extinction. The luminosity function is fitted with models accounting for dust, which leads to distance 253 μ0= 27.62+0.16−0.26 mag (d= 3.34+0.26−0.38 Mpc). This new estimate found be agreement few existing estimates this when they all set common Large Magellanic...
In order to recognize environmental effects on the evolution of dwarf galaxies in clusters galaxies, it is first necessary quantify properties objects that have evolved relative isolation. With oxygen abundance as gauge metallicity, two key diagnostics irregular field are reexamined: metallicity-luminosity relationship and metallicity–gas fraction relationship. Gas fractions evaluated from masses luminous components only, i.e., constituents nucleogenetic pool. Results new optical...
The Magellanic Clouds and Leo I present several problems when they are interpreted as systems that have been permanently bound to the Milky Way since formation together in Big Bang. large angular momentum of relative exceptionally radial velocity suggest these satellites should be considered wider context whole Local Group. We use observational constraints recently measured proper motions, distances, velocities satellites. also previous estimates star history Way, an age universe about 15...
Distances and near-infrared luminosities of the brightest galaxies in Local Volume have been re-evaluated order to gain a fully homogeneous collection data for elucidating framework Sheet its relevance Group evolution. It is demonstrated that both geometrically dynamically distinct from Supercluster evolution were probably interconnected. The inclined by 8° with respect Supercluster, dispersion giant members about mid-plane only 230 kpc. A 'Council Giants' radius 3.75 Mpc encompasses Group,...
Deep wide-field CCD images in the optical and near-infrared have been acquired for 14 of 16 known or suspected members IC 342/Maffei Group galaxies, one closest groups to Milky Way, probably group M31. Because their low Galactic latitude, all galaxies are heavily extinguished, myriads foreground stars superimposed. A sophisticated algorithm built around DAOPHOT has developed which successfully removes stars, making possible comprehensive morphological photometric studies. The cleaned reveal...
We present optical spectroscopy of Hii regions in the Local Group galaxy IC 10 and UBVR photometry foreground stars three fields towards this galaxy. From these data, we find that reddening due to Milky Way is . contains considerable internal dust, which qualitatively explains variety values found by studies its different stellar populations. Based upon our reddening, has intrinsic photometric properties like those a blue compact dwarf galaxy, not irregular. This result consistent with much...
The galactic extinction of a heavily reddened spiral galaxy can be gauged from observations the Balmer decrement constituent giant H II regions and measurements annular-averaged I column densities. Application technique to IC 342 (l = 138.2^deg^, b + 10.6^deg^) reveals that A_B_ 3.05 +/- 0.25. Thus, this is nearly as luminous Milky Way only 1.9 times farther away M31. gravitational acceleration M31 by between 15% 25% due Way. It appears should regarded dynamically member quartet galaxies...
A sample of 34 dwarf irregular galaxies (dIs) in the Local Volume, most nearer than 5 Mpc, has been imaged near-infrared (NIR) J and Ks at Canada-France-Hawaii Telescope (CFHT) Hawaii Observatorio Astronómico Nacional Sierra San Pedro Mártir, Mexico. Absolute magnitudes range from -14 to -18. In CFHT images, stars brighter M ∼ -7.5 were resolved. We show that resolved component comprises more 50% light star formation bursts within last 3 Gyr. cases, population down = represents less 5% total...
view Abstract Citations (64) References (54) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Origin of Broad Emission Lines in the Extragalactic Giant H II Region NGC 2363 Roy, Jean-Rene ; Aube, Martin McCall, Marshall L. Dufour, R. J. High signal-to-noise long-slit spectra have been obtained giant region located dwarf SBm galaxy 2366. A discovery low-intensity broad spectral components (FWHM ~40 or 2400 km s^-1^) bright nebular lines Hα, Hβ, and [O III)...
view Abstract Citations (78) References (24) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Interpretation of the maximum light spectrum a type I supernova. Branch, D. ; Buta, R. Falk, S. W. Lccall, M. Sutherland, P. G. Uomoto, A. Wheeler, J. C. Wills, B. A synthetic consisting Ca II, Si S Mg II and O resonance scattering lines superposed on continuum represents high-quality optical 1981 Type supernova in NGC 4538 at light. Together with photospheres LTE...
The impact of the cluster environment on evolution dwarf galaxies is investigated by comparing properties a sample irregular (dI's) in Virgo Cluster with control nearby ("field") dI's having oxygen abundances derived from [O III] λ4363 measurements and measured distances resolved stellar constituents. Spectroscopic data are obtained for H II regions 11 distributed central outer cluster. To ensure that homogeneous manner, field computed using bright-line method compared directly λ4363, where...
The recent compilation of atomic data by Mendoza (1983) has been used to construct three-level atom formulae for the emission coefficients [N II], [O I], III], [Ne [S and [Ar III] as a function temperature density. Equations determining II] densities temperatures are presented also. generally predict ratios within 5 per cent five-level calculations, so should be considerable value analyses gaseous nebulae spectra.
Lines with P Cygni profiles produced by resonance scattering in an expanding atmosphere non-circular isophotes should show a linear polarization excess of that the continuum. Thus, spectropolarimetry offers means testing spherical symmetry supernovae and assessing reliability Baade method distances without invoking assumptions about introduced intervening dust.
Recent studies of the near-infrared (NIR) properties dwarf irregular galaxies (dIs) and blue compact dwarfs (BCDs) have provided improved estimates for NIR luminosity old stellar populations in these galaxies. These can be used to derive gas fractions, thereby evaluate how BCDs evolved with respect dIs. Oxygen abundances been derived four Virgo Cluster from a run at Gemini-North 2003. Combining new published values, we study correlations among metallicity, Ks luminosity, mass, baryonic...
A sample of 16 blue compact dwarf galaxies (BCDs) in the Virgo Cluster has been imaged near-infrared (NIR) J and Ks on 2.1 m telescope at Observatorio Astronómico Nacional Sierra San Pedro Mártir Mexico. Isophotes as faint μJ = 24 mag arcsec-2 μ 23 have reached most targets. Surface brightness profiles can be fitted across whole range radii by sum two components: a hyperbolic secant (sech) function, which is known to fit light irregular (dIs), Gaussian component, quantifies starburst near...
We present chemical abundances for planetary nebulae and H II regions in the Local Group dwarf irregular galaxy NGC 6822 based on spectroscopy obtained at Canada-France-Hawaii Telescope using Multi-Object Spectrograph. From these similar data compiled from literature Magellanic Clouds, Sextans A, B, Leo we consider origin evolution of stellar progenitors bright galaxies. On average, oxygen abundance observed galaxies coincides with that measured ISM, indicating that, general, irregulars...
We present chemical abundances for planetary nebulae in M32, NGC 185, and 205 based upon spectroscopy obtained at the Canada-France-Hawaii Telescope using Multi-Object Spectrograph. From these similar data compiled from literature other Local Group galaxies, we consider origin evolution of stellar progenitors bright galaxies where star formation ceased long ago. The ratio neon to oxygen is either identical that measured interstellar medium star-forming dwarf or most changed by a few percent,...
Star-forming dwarfs are studied to elucidate the physical underpinnings of their fundamental plane. It is confirmed that residuals in Tully-Fisher relation correlated with surface brightness, but even after accommodating brightness dependence through dwarf plane, absolute magnitude far larger than expected from observational errors. Rather, a more plane identified which connects potential HI line width and brightness. Residuals correlate axis ratio way can be accommodated by recognizing...
view Abstract Citations (49) References (102) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Portrait of a Novel Nova: V1500 Cygni Lance, Catherine M. ; McCall, Marshall L. Uomoto, Alan K. A comprehensive study Nova 1975 is presented. All previous work carefully reviewed to arrive at self-consistent set fundamental physical properties for the system. These data are then combined with old and new observations derive models ejecta remnant possible explanation...