A5001856551- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Spectroscopy and Laser Applications
- Radio Astronomy Observations and Technology
- Adaptive optics and wavefront sensing
- Astro and Planetary Science
- Scientific Research and Discoveries
- Phase Equilibria and Thermodynamics
- Geophysics and Gravity Measurements
- Satellite Image Processing and Photogrammetry
- Atmospheric Ozone and Climate
- Calibration and Measurement Techniques
- CCD and CMOS Imaging Sensors
- Magnetic confinement fusion research
- Computational Physics and Python Applications
- Superconducting Materials and Applications
- Advanced Optical Sensing Technologies
- Photocathodes and Microchannel Plates
- Structural Analysis of Composite Materials
New Mexico State University
2014-2024
Netherlands Institute for Radio Astronomy
2010
Ruhr University Bochum
2010
Osservatorio astronomico di Bologna
2010
Johns Hopkins University
2008
U.S. National Science Foundation
1997-2002
Kitt Peak National Observatory
1993-2002
Association of Universities For Research In Astronomy
1997-2002
University of California, Berkeley
1990-1991
Institute for Advanced Study
1988
Diffuse ionized gas (DIG) is prevalent in star-forming galaxies. Using a sample of 365 nearly face-on galaxies observed by Mapping Nearby Galaxies at APO, we demonstrate how DIG impacts the measurements emission-line ratios, hence interpretation diagnostic diagrams and gas-phase metallicity measurements. At fixed metallicity, DIG-dominated low ΣHα regions display enhanced [S ii]/Hα, [N [O ii]/Hβ i]/Hα. The gradients these line ratios are determined ΣHα. In ratio diagrams, contamination moves...
The Legacy ExtraGalactic UV Survey (LEGUS) is a Cycle 21 Treasury program on the Hubble Space Telescope aimed at investigation of star formation and its relation with galactic environment in nearby galaxies, from scales individual stars to those ∼kiloparsec-size clustered structures. Five-band imaging near-ultraviolet I band Wide-Field Camera 3 (WFC3), plus parallel optical Advanced for Surveys (ACS), being collected selected pointings 50 galaxies within local 12 Mpc. filters used...
We have undertaken a deep, wide-field H i imaging survey of M31, reaching maximum resolution about 50 pc and 2 km s−1 across 95 × 48 kpc region. The mass brightness sensitivity at 100 for 25 wide spectral feature is 1500 M☉ 0.28 K. Our study reveals ubiquitous self-opacity features, discernible in the first instance as filamentary local minima images peak temperature. Local are organized into complexes more than length particularly associated with leading edge spiral arm features. Just...
We introduce a new, very deep neutral hydrogen (HI) survey being performed with the Westerbork Synthesis Radio Telescope (WSRT). The Hydrogen Accretion in LOcal GAlaxieS (HALOGAS) Survey is producing an archive of some most sensitive HI observations available, on angular scales which are useful for studying faint, diffuse gas and around nearby galaxies. data used to perform careful modeling galaxies, characterizing their content, morphology, kinematics, primary goal revealing global...
We test cosmological models of structure formation using the rotation curve nearest spiral galaxy, M31, determined a recent deep, full-disk 21-cm imaging survey smoothed to 466 pc resolution. fit tilted ring model HI data from 8 37 kpc. The disk M31 warps 25 kpc outwards and becomes more inclined with respect our line sight. Newtonian dynamics without dark matter halo provide very poor derived warp model. In framework modified dynamic however is well fitted by gravitational potential traced...
We report the large effort which is producing comprehensive high-level young star cluster (YSC) catalogues for a significant fraction of galaxies observed with Legacy ExtraGalactic UV Survey (LEGUS) Hubble treasury program. present methodology developed to extract positions, verify their genuine nature, produce multiband photometry (from NUV NIR), and derive physical properties via spectral energy distribution fitting analyses. use nearby spiral galaxy NGC628 as test case demonstrating...
We present the first part of observations made for Continuum Halos in Nearby Galaxies, an EVLA Survey (CHANG-ES) project. The aim CHANG-ES project is to study and characterize nature radio halos, their prevalence as well magnetic fields, cosmic rays illuminating these fields. This paper reports with compact D configuration Karl G. Jansky Very Large Array (VLA) sample 35 nearby edge-on galaxies CHANG-ES. With new wide bandwidth capabilities VLA, unprecedented sensitivity was achieved all...
We report the discovery of a new dwarf spheroidal satellite M31, Andromeda IX, based on resolved stellar photometry from Sloan Digital Sky Survey (SDSS). Using both SDSS and public archival data we have estimated its distance other physical properties, compared these to properties previously known companion, V, also observed by SDSS. IX is lowest surface brightness galaxy found date (mu_{V} ~ 26.8 mag arcsec^-2), at estimate position tip IX's red giant branch, (m - M)_{0} 24.5 (805 kpc),...
We present an investigation of the relationship between giant molecular cloud (GMC) properties and associated stellar clusters in nearby flocculent galaxy NGC 7793. combine star cluster catalogue from HST LEGUS (Legacy ExtraGalactic UV Survey) programme with 15 pc resolution ALMA CO(2–1) observations. find a strong spatial correlation young GMCs such that all still GMC are younger than 11 Myr display median age 2 Myr. The distribution increases gradually as cluster–GMC distance increases,...
The vertical halo scale height is a crucial parameter to understand the transport of cosmic-ray electrons (CRE) and their energy loss mechanisms in spiral galaxies. Until now, radio could only be determined for few edge-on galaxies because missing sensitivity at high resolution. We developed sophisticated method determination With this we heights radial lengths sample 13 from CHANG-ES continuum survey two frequency bands. average value are 1.1 +/- 0.3kpc C-band 1.4 0.7kpc L-band. From...
Context. The magnetic field in spiral galaxies is known to have a large-scale structure along the galactic disk and observed as X-shaped halo of some galaxies. While can be well explained by dynamo action, 3-dimensional its physical nature still unclear. Aims. As first steps towards understanding fields, we want clarify whether wide-spread pattern halos these fields are just turbulent ordered compression or shear (anisotropic fields), regular structure. Methods. analysis Faraday rotation...
We present a systematic study of the extraplanar gas (EPG) in sample 15 nearby late-type galaxies at intermediate inclinations using publicly available, deep interferometric H I data from Hydrogen Accretion LOcal GAlaxieS (HALOGAS) survey. For each system we masked emission coming regularly rotating disc and used synthetic datacubes to model leftover “anomalous” flux. Our consists smooth, axisymmetric thick component described by three structural four kinematical parameters, which are fit...
We present the star cluster catalogs for 17 dwarf and irregular galaxies in $HST$ Treasury Program "Legacy ExtraGalactic UV Survey" (LEGUS). Cluster identification photometry this subsample are similar to that of entire LEGUS sample, but special methods were developed provide robust with accurate fluxes due low statistics. The colors ages largely consistent two widely used aperture corrections, a significant fraction clusters more compact than average training cluster. However, ensemble...
CHANG-ES (Continuum Halos in Nearby Galaxies—an EVLA Survey) is an ambitious project to target 35 nearby disk galaxies that are edge-on the line of sight. The orientation permits both and halo regions be studied. observations were initially at 1.5 GHz (L-band) 6.0 (C-band) a variety VLA array configurations, all four Stokes parameters, which allowed for spatially resolved images total intensity plus polarization. inclusion polarization unique galaxy survey reveals galaxies’ magnetic fields....
We present Hα images of five edge-on galaxies: NGC 891, 4631, 4244, 3003, and UGC 9242. also analyze [S II] λλ6717, 6731 [O III] λ5007 4631. For several these galaxies, are the most sensitive to date. ionized gas content, with particular attention diffuse (DIG). The DIG layer in 891 is traced out at least 5 kpc from midplane, confirming an earlier spectroscopic detection. four galaxies contributes 40%-50% total luminosity, similar contribution face-on but 80%-90%. This likely due higher dust...
We report the results of a spectroscopic investigation diffuse ionized gas (DIG) in M33, M81, and M51. All three galaxies have enhanced [S II]/Hα [N ratios DIG compared to H II regions, agreement with predictions photoionization models. The all also has [O III]/Hβ equal or greater than that neighboring regions. II]/[N II] ratio does not vary Hα surface brightness is similar both regions DIG. tentatively detected He I λ5876 line bright near NGC 604, indicating contribution from O7 hotter...
view Abstract Citations (114) References (54) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Diffuse Ionized Gas in the Spiral Galaxy M31 Walterbos, Rene A. M. ; Braun, Robert We present a study of diffuse ionized gas (DIG, or WIM for warm medium) nearby spiral M31, based on CCD imagery Hα and [S II] emission lines. find that DIG contributes 40% observed total luminosity, at least 20% after correction extinction. This fraction is constant across disk M31....
We have developed a robust, automated method, hereafter designated HIIphot, which enables accurate photometric characterization of H II regions while permitting genuine adaptivity to irregular source morphology. HIIphot utilizes object recognition techniques make first guess at the shapes all sources and then allows for departure from such idealized "seeds" through an iterative growing procedure. Photometric corrections spatially coincident diffuse emission are derived low-order surface fit...
In the quest to understand how star formation occurs and propagates in low-metallicity environment of Small Magellanic Cloud (SMC), we acquired deep F555W (∼V) F814W (∼I) Hubble Space Telescope ACS images young massive star-forming region NGC 346. These their photometric analysis provide us with a snapshot history region. We find evidence for extending from ≈10 Gyr past until ≈150 Myr field SMC. The youngest stellar population (∼3 ± 1 Myr) is associated 346 cluster. It includes rich...
We present a study of the diffuse ionized gas (DIG) in three Sculptor group galaxies: NGC 55, 253, and 300. The is based on narrow band imagery Hα + [N II](6548+6583 A) [S II] (6717+6731 A). find that DIG contributes 33 to 58% total luminosity these galaxies, or 30 54% after correcting for scattered light. 300 has higher fractional than other galaxies our sample, but it not clear whether this significant difference an effect high inclination galaxies. emission, averaged over optical extent...