Search Publications
The Spitzer View of Low-Metallicity Star Formation. II. Mrk 996, a Blue Compact Dwarf Galaxy with an Extremely Dense Nucleus
Hunt, Leslie K.; Thuan, Trinh X.; Izotov, Yuri I.
We present new Spitzer, UKIRT, and MMT observations of the blue compact dwarf galaxy (BCD) Mrk 996, with an oxygen abundance of 12 + log (O/H) = 8.0. This galaxy possesses an extraordinarily dense nuclear star-forming region, with a central density of ~106 cm-3, a very red color J - K = 1.8, broad- and narrow-line components,…
The Very Soft X-Ray Spectrum of the Double Pulsar System J0737-3039
Camilo, F.; Rea, N.; Possenti, A. +5 more
We present the results of an 80 ks Chandra ACIS-S observation of the double pulsar system J0737-3039. Furthermore, we report on spectral, spatial and timing analysis of the combined X-ray observations performed so far for this system. Fitting a total of ~1100 photons, we show that the X-ray spectrum of the J0737-3039 system is very soft, and not s…
The Structure of Active Merger Remnant NGC 6240 from IRAC Observations
Fazio, Giovanni G.; Wang, Zhong; Karovska, Margarita +1 more
NGC 6240 is a rare object in the local universe: an active merger remnant viewed at the point of merging where two active galactic nuclei are visible. We present IRAC data of this object, providing high-sensitivity maps of the stellar and PAH distribution in this complicated system. We use photometry to analyze the variation in these distributions…
Short-Lived Absorptive Type III-like Microwave Bursts as a Signature of Fragmented Electron Injections
Chen, Bin; Yan, Yihua
In this paper, we devote ourselves to interpreting the short-lived absorptive type III-like microwave bursts in the 2006 December 13 flare event observed with high temporal and spectral resolutions (8 ms and 10 MHz) by the Chinese Solar Broadband Radio Spectrometer (SBRS/Huairou) at 2.6-3.8 GHz. In the decimeter-centimeter wavelength range, we fir…
Measuring Stellar Radial Velocities with a Dispersed Fixed-Delay Interferometer
Ge, Jian; Mahadevan, Suvrath; Fleming, Scott W. +5 more
We demonstrate the ability to measure precise stellar barycentric radial velocities with the dispersed fixed-delay interferometer technique using the Exoplanet Tracker (ET), an instrument primarily designed for precision differential Doppler velocity measurements using this technique. Our barycentric radial velocities, derived from observations ta…
The Funnel Geometry of Open Flux Tubes in the Low Solar Corona Constrained by O VI and Ne VIII Outflow
Lie-Svendsen, Øystein; Esser, Ruth; Byhring, Hanne S.
We carry out model calculations to show that observed outflow velocities of order 7-10 km s-1 of C IV and O VI ions, and 15-20 km s-1 of Ne VIII ions, are not only consistent with models of the solar wind from coronal holes but also place unique constraints on the degree of flow tube expansion as well as the location of the e…
Analysis of the FUSE Spectrum of the Hot, Evolved Star GD 605
Chayer, P.; Fontaine, G.; Wesemael, F. +2 more
We present an analysis of the atmospheric properties of the evolved, hydrogen-rich object GD 605 using FUSE, IUE, and optical spectra in conjunction with non-LTE (NLTE) model atmospheres and synthetic spectra. We also present an analysis of the interstellar medium along the line of sight toward this star. Our effective temperature determination re…
Cosmic Ray Transport and Production in the Galaxy: A Stochastic Propagation Simulation Approach
Zhang, Ming; Connell, J. J.; Rassoul, Hamid +1 more
Galactic cosmic-ray composition reflects the effects of nuclear interactions during propagation through the interstellar medium. In order to use measurements to determine the source of cosmic rays, one needs a model to deconvolute the propagation effect. This paper presents a new numerical method to solve cosmic-ray diffusive transport equations w…
EA01A/B: High-Resolution H I Imaging of an Interacting Pair of Poststarburst (E+A) Galaxies
Dejonghe, Herwig; De Rijcke, Sven; Buyle, Pieter
We present high spatial resolution 21 cm H I observations of EA01A and EA01B, a pair of interacting poststarburst, or E+A, galaxies at z = 0.0746. Based on optical HST/WFPC2 images, both galaxies are known to display disturbed morphologies. They also appear to be linked by a bridge of stars. Previous H I observations by Chang et al. in 2001 had al…
Nonthermal Electron Measurements in Solar Flares with Hinode EIS
Landi, Enrico; Feldman, Uri; Ralchenko, Yuri
The spectral range of the Hinode EIS (EUV Imaging Spectrometer) instrument is 170-211 Å and 245-291 Å lines emitted by low-energy levels in highly ionized Mn, Fe, Co, and Ni, as well as the very energetic 1s2s3S1-1s2p3P2 transition in Fe XXV, appear in the EIS range. In this paper, we investigate the use…