Search Publications
A Tale of Three Mysterious Spectral Features in Carbon-rich Evolved Stars: The 21 µm, 30 µm, and “Unidentified Infrared” Emission Features
Li, Aigen; Jiang, B. W.; Mishra, Ajay
The mysterious “21 µm” emission feature seen almost exclusively in the short-lived protoplanetary nebula (PPN) phase of stellar evolution remains unidentified since its discovery two decades ago. This feature is always accompanied by the equally mysterious, unidentified “30 µm” feature and the so-called “unidentified infrared” (UIR) fe…
A possible mechanism of the enhancement and maintenance of the shear magnetic field component in the current sheet of the Earth's magnetotail
Malova, H. V.; Zelenyi, L. M.; Malykhin, A. Yu. +1 more
The influence of the shear magnetic field component, which is directed along the electric current in the current sheet (CS) of the Earth's magnetotail and enhanced near the neutral plane of the CS, on the nonadiabatic dynamics of ions interacting with the CS is studied. The results of simulation of the nonadiabatic ion motion in the prescribed mag…
Re-evaluation of the Neutron Emission from the Solar Flare of 2005 September 7, Detected by the Solar Neutron Telescope at Sierra Negra
Watanabe, K.; Matsubara, Y.; Muraki, Y. +9 more
The X17.0 solar flare of 2005 September 7 released high-energy neutrons that were detected by the Solar Neutron Telescope (SNT) at Sierra Negra, Mexico. In three separate and independent studies of this solar neutron event, several of its unique characteristics were studied; in particular, a power-law energy spectra was estimated. In this paper, w…
Kinetic structures of quasi-perpendicular shocks in global particle-in-cell simulations
Henri, Pierre; Khotyaintsev, Yuri; Johlander, Andreas +5 more
We carried out global Particle-in-Cell simulations of the interaction between the solar wind and a magnetosphere to study the kinetic collisionless physics in super-critical quasi-perpendicular shocks. After an initial simulation transient, a collisionless bow shock forms as a result of the interaction of the solar wind and a planet magnetic dipol…
A consistent spectral model of WR 136 and its associated bubble NGC 6888
Morisset, C.; Mesa-Delgado, A.; Peña, M. +1 more
We analyse whether a stellar atmosphere model computed with the code CMFGEN provides an optimal description of the stellar observations of WR 136 and simultaneously reproduces the nebular observations of NGC 6888, such as the ionization degree, which is modelled with the PYCLOUDY code. All the observational material available (far- and near-UV and…
Chandra identification of two AGN discovered by INTEGRAL
Rahoui, Farid; Bodaghee, Arash; Tomsick, John A. +5 more
Here, we report on observations of two hard X-ray sources that were originally discovered with the INTEGRAL satellite: IGR J04059+5416 and IGR J08297-4250. We use the Chandra X-ray Observatory to localize the sources and then archival near-IR images to identify the counterparts. Both sources have counterparts in the catalogue of extended 2 Micron …
Mid-infrared spectroscopy of the Andromeda galaxy
Barmby, P.; Smith, D. A.; Fazio, G. G. +6 more
We present Spitzer/Infrared Spectrograph (IRS) 5-21 µm spectroscopic maps towards 12 regions in the Andromeda galaxy (M31). These regions include the nucleus, bulge, an active region in the star-forming ring and nine other regions chosen to cover a range of mid-to-far-infrared colours. In line with previous results, polycyclic aromatic hydro…
Calibrating the α parameter of convective efficiency using observed stellar properties
Wang, L.; Zhao, G.; Grupp, F. +3 more
Context. Synthetic model atmosphere calculations are still the most commonly used tool when determining precise stellar parameters and stellar chemical compositions. Besides three-dimensional models that consistently solve for hydrodynamic processes, one-dimensional models that use an approximation for convective energy transport play the major ro…
The HIFI spectral survey of AFGL 2591 (CHESS). III. Chemical structure of the protostellar envelope
van der Tak, F. F. S.; van der Wiel, M. H. D.; Semenov, D. A. +2 more
Aims: The aim of this work is to understand the richness of chemical species observed in the isolated high-mass envelope of AFGL 2591, a prototypical object for studying massive star formation.
Methods: Based on HIFI and JCMT data, the molecular abundances of species found in the protostellar envelope of AFGL 2591 were derived with a Mon…
Hubble Space Telescope ultraviolet spectroscopy of the hottest known helium-rich pre-white dwarf KPD 0005+5106
Rauch, T.; Werner, K.
We present a model-atmosphere analysis of the ultraviolet echelle spectra of KPD 0005+5106 taken with the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope. The star is the hottest known pre-white dwarf (Teff = 200 000 ± 20 000 K, log g= 6.7 ± 0.3 (cm/s2)). Its atmosphere is composed of helium with trace …