A5089090678- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Astronomy and Astrophysical Research
- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Geophysics and Gravity Measurements
- History and Developments in Astronomy
- Atmospheric Ozone and Climate
- Astrophysics and Cosmic Phenomena
- Molecular Spectroscopy and Structure
- Space Exploration and Technology
- High-pressure geophysics and materials
- Spectroscopy and Laser Applications
- Adaptive optics and wavefront sensing
- Pulsars and Gravitational Waves Research
- Geomagnetism and Paleomagnetism Studies
- Mechanics and Biomechanics Studies
- Calibration and Measurement Techniques
- Scientific Measurement and Uncertainty Evaluation
- Advanced MRI Techniques and Applications
- Atomic and Molecular Physics
Search for Extraterrestrial Intelligence
2011-2023
University of Arizona
2000-2003
Kitt Peak National Observatory
2003
Ames Research Center
1999-2001
Jet Propulsion Laboratory
1997-1998
Stanford University
1994-1995
We have obtained images of the Trapezium Cluster (140'' × 140''; 0.3 pc pc) with Hubble Space Telescope Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). Combining these data new ground-based K-band spectra (R = 800) existing spectral types photometry, we constructed an H-R diagram used it other arguments to infer masses ages. To allow comparison results our previous studies IC 348 ρ Oph, first use models D'Antona & Mazzitelli. With models, distributions ages comparable samples...
view Abstract Citations (184) References (57) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Discovery of Hot Stars near the Galactic Center Thermal Radio Filaments Cotera, Angela S. ; Erickson, Edwin F. Colgan, Sean W. J. Simpson, Janet P. Allen, David A. Burton, Michael G. We report discovery a highly unusual cluster stars at GO.121+0.017 Arched (thermal) Filaments, ∼10' northeast center. H (1.65 μm) and K' (2.1 images are used to estimate distance...
We present a catalog of 9017 X-ray sources identified in Chandra observations 2°× 08 field around the Galactic center. This enlarges number known region by factor 2.5. The incorporates all ACIS-I as 2007 August, which total 2.25 Ms exposure. At distance to center (8 kpc), we are sensitive with luminosities 4 × 1032 erg s−1 (0.5–8.0 keV; 90% confidence) over an area 1 deg2, and up order magnitude more deepest exposure (1.0 Ms) Sgr A*. positions 60% our accurate <1 '' (95% confidence), 20%...
Our HST/NICMOS Pa survey of the Galactic center (GC) provides a uniform, panoramic, high-resolution map stars and ionized diffuse gas in central 416 arcmin^2 Galaxy. This was carried out with 144 HST orbits using two narrow-band filters at 1.87 1.90 micron NICMOS Camera 3. In this paper, we describe detail data reduction mosaicking procedures followed, including background level matching astrometric corrections. We have detected ~570,000 near-IR sources are able to quantify photometric...
We present new identifications of infrared counterparts to the population hard X-ray sources near Galactic center detected by Chandra Observatory. have confirmed 16 massive stellar population, including nitrogen-type (WN) and carbon-type (WC) Wolf-Rayet stars, O supergiants. For majority these sources, photometry is consistent with thermal emission from plasma having temperatures in range kT=1-8 keV or non-thermal power-law indices -1<gamma<3, luminosities Lx~1e32-1e34 erg/s. Several...
We have recently carried out the first wide-field hydrogen Paschen-alpha line imaging survey of Galactic Center (GC), using NICMOS instrument aboard Hubble Space Telescope. The maps a region 2253 pc^2 around central supermassive black hole (Sgr A*) in 1.87 and 1.90 Micron narrow bands with spatial resolution 0.01 pc at distance 8 kpc. Here we present an overview observations, data reduction, preliminary results, potential scientific implications, as well description rationale design survey....
ABSTRACT We report the discovery of 19 hot, evolved, massive stars near Galactic center region (GCR). These objects were selected for spectroscopy owing to their detection as strong sources Paschen-α (Pα) emission-line excess, following a narrowband imaging survey central 0.°65 × 0.°25 ( l , b ) around Sgr A* with Hubble Space Telescope . Discoveries include six carbon-type (WC) and five nitrogen-type (WN) Wolf–Rayet stars, O supergiants, two B supergiants. Two supergiants have X-ray...
We present Hubble Space Telescope near-infrared camera and multiobject spectrometer observations of the reflection nebulosity associated with T Tauri star HH 30. The images show scattered-light pattern characteristic a highly inclined, optically thick disk prominent dust lane whose width decreases increasing wavelength. reflected exhibits lateral asymmetry in upper lobe on opposite side to that reported previously published Wide Field Planetary Camera 2 images. radiation transfer model most...
The Arches cluster is an extraordinarily compact massive star with a core radius of about 10'' (~0.4 pc) and consisting more than 150 O candidates initial stellar masses greater 20 M☉ near G0.12-0.02. X-ray observations the radio Arc Galactic center at l ~ 02, which contains cluster, have been carried out Advanced CCD Imaging Spectrometer (ACIS) on board Chandra X-Ray Observatory. We report detection two sources from embedded within bath diffuse emission extending beyond edge to least 90'' ×...
We have obtained Spitzer IRAC observations of the central 2:0 ; 1:4 ($280 200 pc) Galaxy at 3.6Y 8.0 m.A point-source catalog 1,065,565 objects is presented.The includes magnitudes for point sources 3.6, 4.5, 5.8, and m, as well JHK s photometry from Two Micron All Sky Survey (2MASS).The confusion limited with average limits 12.4, 12.1, 11.7, 11.2 mag [3.6], [4.5], [5.8], [8.0], respectively.We find that are spatially variable because stellar surface density, background brightness level,...
We present results from our spectroscopic study, using the Infrared Spectrograph (IRS) onboard Spitzer Space Telescope, designed to identify massive young stellar objects (YSOs) in Galactic Center (GC). Our sample of 107 YSO candidates was selected based on IRAC colors high spatial resolution, sensitivity Spitzer/IRAC images Central Molecular Zone (CMZ), which spans central ~300 pc region Milky Way Galaxy. obtained IRS spectra over 5um 35um both high- and low-resolution modules....
Using near-infrared imaging and spectroscopy, we discuss the discovery of six emission-line sources within ~20 pc Sgr A West but outside central parsec. The objects are coincident with stars seen in J, H, K' images; all have Brγ (2.166 μm) emission, several also He I (2.058 2.112/3 μm), some II (2.189 emission lines. Comparison H- K-band spectra newly discovered recently published infrared spectral atlases optically classified suggests that most these similar to massive transition (e.g.,...
We present a survey of Spitzer Space Telescope/IRAC observations the central 2 × 1.5 degrees (265 200 pc) Galaxy at 3-8 μm. These data represent highest spatial resolution and sensitivity large-scale map made to date Galactic Center (GC) mid-infrared wavelengths. The IRAC provide census optically obscured stellar sources as well detailed highly filamentary structure in interstellar medium. diffuse emission is dominated by PAH from small grains star-forming regions. Dark clouds displaying...
We present 49 new candidate debris disks that were detected around nearby stars with the Spitzer Space Telescope using Multiband Imaging Photometer (MIPS) at 24 μm (MIPS24) and 70 (MIPS70). The survey sample was composed of within 25 pc Sun not previously observed by any other MIPS survey. Only V < 9 selected, corresponding to spectral types earlier than M0. MIPS24 integration times chosen detect stellar photosphere 10σ levels or better. MIPS70 observations designed excess infrared emission...
We present diffraction-limited 2-25 micron images obtained with the W. M. Keck 10-m telescopes that spatially resolve cool source, IRS 21, one of a small group enigmatic objects in central parsec our Galaxy have eluded classification. Modeled as Gaussian, azimuthally-averaged intensity profile 21 has half-width half-maximum (HWHM) size 650+/-80 AU at 2.2 microns and an average HWHM 1600+/-200 mid-infrared wavelengths. These large apparent sizes imply extended distribution dust. The color map...
We present Spitzer IRS spectra (R ~600, 10 - 38 micron) of positions in the Galactic Center (GC), all at same longitude and spanning plus/minus 0.3 degrees latitude. Our include Arches Cluster, Arched Filaments, regions near Quintuplet ``Bubble'' lying along line-of-sight as molecular cloud G0.11-0.11, diffuse interstellar gas higher latitudes. From measurements [O IV], [Ne II], III], [Si [S [Fe H_2 S(0), S(1), S(2) lines we determine excitation ionic abundance ratios. The Ne/H S/H ratios...
We present new extinction maps and high-resolution Paschen alpha images of G-0.02-0.07, a complex compact HII regions located adjacent to the M-0.02-0.07 giant molecular cloud, 6 parsecs in projection from center Galaxy. These regions, which lie just outside boundary Sgr A East supernova remnant, represent one most recent episodes star formation central The 1.87 micron extinctions A, B C are almost identical, approximately 1.5 magnitudes. Region D, contrast, has peak 2.3 Adopting Nishiyama...
We report on the discovery of a luminous blue variable (LBV) lying ≈7 pc in projection from Quintuplet cluster. This source, which we call LBV G0.120 − 0.048, was selected for spectroscopy owing to its detection as strong source Paschen-α (Pα) excess recent narrowband imaging survey Galactic center region with Hubble Space Telescope/Near-Infrared Camera and Multi-Object Spectrometer. The K-band spectrum is similar that Pistol Star other known LBVs. new previously cataloged photometric star,...
Outside of the known star clusters in Galactic Centre, a large number evolved massive stars have been detected; but their origins remain uncertain. We present spectroscopic study eight such stars, based on new Gemini Near-Infrared Spectrograph (GNIRS) and Near-IR Integral Field (NIFS) near-infrared observations. This work has led to discovery O If+ star. compare reddening-corrected J − K versus diagram for our with ones Arches cluster use stellar evolutionary tracks constrain ages masses....
The Galactic Center contains some of the most extreme conditions for star formation in our Galaxy as well many other phenomena that are unique to this region. Given relative proximity Center, we able study details physical processes a level is simply not yet possible more distant galaxies, yielding an otherwise inaccessible view nuclear region galaxy. We recently carried out targeted imaging survey mid-infrared bright portions at 25 and 37 $\mu$m using FORCAST instrument on SOFIA. This was...
We present J (1.2 microns) H (1-6 K' (2.11 and Br(gamma) (2.166 images from four large regions within the central 40 pc of Galaxy. Localized variations in extinction, as determined by observations stellar population, are examined using median H-K' color a function position each region. As value derived extinction stars is dependent upon intrinsic magnitude assumed type, J-H vs. diagrams first used to investigate distribution types regions. find that there distinct OB contrary earlier...
The G333 giant molecular cloud contains a few star clusters and H II regions, plus number of condensations currently forming stars. We have mapped 13 these sources with the appearance young stellar objects (YSOs) Spitzer Infrared Spectrograph in SL, SH, LH modules (5-36 micron). use spectra available photometry images to characterize YSOs. spectral energy distributions (SEDs) all peak between 35 110 micron, thereby showing their age. are divided into two groups: YSOs associated extended...
Abstract The current paradigm of Galactic Center (GC) gas motions and star formation envisions sequential in streams as they pass near the supermassive black hole Sgr A*. This is based on relative positions dense molecular clouds, very young star-forming region B2, much older C, several Myr old Arches Quintuplet Clusters. Because B1 found with B2 a common envelope far-infrared emission, two sources are thought to be physically related, even though there indicators significantly greater age...
The Galactic center H II region, G0.18-0.04, also known as the "Sickle," is located where nonthermal "Arc" crosses plane. Sickle appears to be ionized edge of a dense molecular cloud. source ionization has been ascribed both interaction cloud with magnetic field Arc and hot stars in adjacent cluster, AFGL 2004, "Quintuplet Cluster." This paper addresses relative locations stars, gas, sources gas excitation dust heating.
Abstract Sgr B1 is a luminous H ii region in the Galactic center immediately next to massive star-forming giant molecular cloud B2 and apparently connected it from their similar radial velocities. In 2018 we showed SOFIA FIFI-LS observations of [O iii ] 52 88 μ m lines that there no central exciting star cluster ionizing stars must be widely spread throughout region. Here present i 146 [C 158 formed surrounding photodissociation regions (PDRs). We find these correlate neither with each other...