Search Publications
Time-dependent ejection velocity model for the outflow of Hen 3-1475
Velázquez, P. F.; Raga, A. C.; Riera, A.
We present 2D axisymmetric and 3D numerical simulations of the proto-planetary nebula
Impulsive and Gradual Nonthermal Emissions in an X-Class Flare
Qiu, Jiong; Gary, Dale E.; Lee, Jeongwoo
In this paper we present a comprehensive case study of an X-class flare observed on 2001 April 6. The flare consists of two episodes, the first characterized by impulsive spiky bursts and the second by gradual smooth emission at hard X-ray and microwave wavelengths. Emissions in the two episodes are regarded as the impulsive and gradual components…
Ulysses Observations of the Magnetic Connectivity between Coronal Mass Ejections and the Sun
Crooker, N. U.; Riley, Pete; Gosling, J. T.
We have investigated the magnetic connectivity of coronal mass ejections (CMEs) to the Sun using Ulysses observations of suprathermal electrons at various distances between 1 and 5.2 AU. Drawing on ideas concerning the eruption and evolution of CMEs, we had anticipated that there might be a tendency for CMEs to contain progressively more open fiel…
XMM-Newton Spectroscopy of Four Bright Ultraluminous X-Ray Sources in the Antennae Galaxies (NGC 4038/4039)
Zezas, A.; Miller, J. M.; Fabbiano, G. +1 more
We report the results of spectral fits to four bright ultraluminous X-ray sources (ULXs) in the Antennae galaxies (NGC 4038/4039) observed for 41 ks with XMM-Newton. Although emission regions are not resolved as well as in prior Chandra observations, at least four ULXs (X-11, X-16, X-37, and X-44 in the Zezas and Fabbiano scheme) are sufficiently …
Astrometric Discovery of GJ 164B
Henry, Todd; Benedict, G. Fritz; Pravdo, Steven H. +1 more
We discovered a low-mass companion to the M dwarf GJ 164 with the CCD-based imaging system of the Stellar Planet Survey astrometric program. The existence of GJ 164B was confirmed with Hubble Space Telescope NICMOS imaging observations. A high-dispersion spectral observation in V sets a lower limit of Δm>2.2 mag between the two components of th…
12C/13C Ratio in Planetary Nebulae from the IUE Archives
Ferland, G. J.; Rubin, R. H.; Chollet, E. E. +1 more
We investigated the abundance ratio of 12C/13C in planetary nebulae by examining emission lines arising from C III 2s2p3Po2,1,0-->2s21S0. Spectra were retrieved from the International Ultraviolet Explorer archives, and multiple spectra of the same object wer…
The Nature of Radio Continuum Emission in the Dwarf Starburst Galaxy NGC 625
Cannon, John M.; Skillman, Evan D.
We present new multifrequency radio continuum imaging of the dwarf starburst galaxy NGC 625 obtained with the Very Large Array. Data at 20, 6, and 3.6 cm reveal global continuum emission dominated by free-free emission, with only mild synchrotron components. Each of the major H II regions is detected; the individual spectral indices are thermal fo…
The Nature of SN 1961V
Chu, You-Hua; Gruendl, Robert A.; Stockdale, Christopher J. +3 more
The nature of SN 1961V has been uncertain. Its peculiar optical light curve and slow expansion velocity are similar to those of superoutbursts of luminous blue variables (LBVs), but its nonthermal radio spectral index and declining radio luminosity are consistent with decades-old supernovae (SNe). We have obtained Hubble Space Telescope STIS image…
An L0 dwarf companion in the brown dwarf desert, at 30 AU
Martín, E. L.; Ségransan, D.; Udry, S. +8 more
We present the discovery of an L0 companion to the nearby M1.5 dwarf G 239-25, at a projected distance of 31 AU. It is the faintest companion discovered so far in our adaptive optics survey of all known M dwarfs within 12 pc, and it lies at the stellar/substellar limit. Given the assumed age of the primary star, the companion is likely an extremel…
CIRPASS near-infrared integral-field spectroscopy of massive star clusters in the starburst galaxy NGC 1140
O'Connell, R. W.; Gallagher, J. S.; Smith, L. J. +6 more
We analyse near-infrared integral field spectroscopy of the central starburst region of NGC 1140, obtained at the Gemini-South telescope equipped with CIRPASS. Our ~1.45-1.67µm wavelength coverage includes the bright [FeII]λ 1.64-µm emission line, as well as high-order Brackett (hydrogen) lines. While strong [FeII] emission, thought to…