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Regions of massive star formation offer some of the best and most easily-observed examples of radiation hydrodynamics. Boundaries where fully-ionized H II regions transition to neutral/molecular photodissociation regions (PDRs) are of…

Astrophysics of Galaxies · Physics 2015-06-15 P. Hartigan , J. Palmer , L. I. Cleeves

We discuss the interstellar absorption from many atomic and molecular species seen in high-resolution $HST$/STIS UV and high-S/N optical spectra of the moderately reddened B3-5~V star HD~62542. This remarkable sight line exhibits both very…

Astrophysics of Galaxies · Physics 2020-07-08 Daniel E. Welty , Paule Sonnentrucker , Theodore P. Snow , Donald G. York

Six high-resolution (\lambda/\Delta\lambda ~ 3000) far-UV (\lambda\lambda = 910-1210 \AA) spectra of the magnetic cataclysmic variable AM Herculis were acquired in 1996 November during the flight of the ORFEUS-SPAS II mission. AM Her was in…

Astrophysics · Physics 2009-10-30 Christopher W. Mauche , John C. Raymond

We report superfluorescent (SF) emission in electrically pumped InGaN/InGaN QW lasers with saturable absorber. In particular, we observe a superlinear growth of the peak power of SF pulses with increasing amplitude of injected current…

We present the first detection of molecular hydrogen (H_2) UV absorption profiles on the line of sight to the LMC. The star LH 10:3120 in the LMC was measured with the ORFEUS telescope and the Tuebingen echelle spectrograph during the space…

Astrophysics · Physics 2007-05-23 K. S. de Boer , P. Richter , D. J. Bomans , A. Heithausen , J. Koornneef

FU Orionis-type stars form a small class of variable Young Stellar Objects, defined by an optical outburst of 5-6 mag followed by gradual fading on a timescale of decades. Since the phenomenon is connected to the circumstellar medium the…

Astrophysics · Physics 2009-11-10 A. Kóspál , P. Ábrahám , Sz. Csizmadia

A new molecular hydrogen cloud is found in the sub-damped Ly-alpha absorber [log N(HI)=19.88+/-0.05] at the redshift z=1.15 toward the bright quasar HE0515-4414 (zem = 1.71). More than 30 absorption features in the Lyman band system of H2…

Astrophysics · Physics 2009-11-10 D. Reimers , R. Baade , R. Quast , S. A. Levshakov

Context: Molecular hydrogen (H2) is the most abundant molecule in the circumstellar (CS) environments of young stars, and is a key element in giant planet formation. The measurement of the H2 content provides the most direct probe of the…

Astrophysics · Physics 2009-11-13 C. Martin-Zaidi , E. F. van Dishoeck , J. -C. Augereau , P. -O. Lagage , E. Pantin

Context: To follow the early evolution of stars we need to understand how young stars accrete and eject mass. It is generally assumed that the FU Orionis phenomenon is related to the variations in the disk accretion, but many questions…

We present predictions for the fluorescent Lyman-alpha emission signature arising from photoionized, optically thick structures in Smoothed Particle Hydrodynamic (SPH) cosmological simulations of a Lambda-CDM universe using a Monte Carlo…

Cosmology and Nongalactic Astrophysics · Physics 2010-01-15 Juna A. Kollmeier , Zheng Zheng , Romeel Davé , Andrew Gould , Neal Katz , Jordi Miralda-Escudé , David H. Weinberg

We present low resolution near-infrared spectroscopy of an unbiased sample of 24 ultraluminous infrared galaxies (ULIRGs), selected from samples previously observed spectroscopically in the mid-infrared with the Infrared Space Observatory…

Astrophysics · Physics 2009-11-11 H. Dannerbauer , D. Rigopoulou , D. Lutz , R. Genzel , E. Sturm , A. F. M. Moorwood

Measurements of molecular hydrogen (H_2) column densities are presented for the first six rotational levels (J=0 to 5) for 73 extragalactic targets observed with FUSE. All of these have a final signal-to-noise ratio larger than \snlimit,…

Astrophysics · Physics 2009-11-11 B. P. Wakker

We use one-dimensional radiative transfer simulations to study the evolution of H_2 gas-phase (H^- catalyzed) formation and photo-dissociation regions in the primordial universe. We find a new positive feedback mechanism capable of…

Astrophysics · Physics 2009-10-31 Massimo Ricotti , Nickolay Y. Gnedin , J. Michael Shull

In the light of the recent results of the stellar interferometry, we examine the nature of the extra molecular layer outside the photosphere of red super- giant stars, so far studied mostly with the use of the infrared spectra. Although the…

Astrophysics · Physics 2009-11-11 Takashi Tsuji

We report infrared spectroscopy of the unusual eclipsing pre-main sequence object KH 15D, obtained using NIRSPEC on Keck II. During eclipse, observations using low spectral resolution (1000) reveal the presence of prominent molecular…

Astrophysics · Physics 2009-11-10 Drake Deming , David Charbonneau , Joseph Harrington

We have discovered 12 new molecular hydrogen emission-line objects (MHOs) in the vicinity of the candidate massive young stellar object Mol 121, in addition to five that were previously known. H2 2.12-micron/H2 2.25-micron flux ratios…

Astrophysics of Galaxies · Physics 2015-06-12 G. Wolf-Chase , K. Arvidsson , M. Smutko , R. Sherman

We present a multi-epoch infrared photometric study of the intermediate-mass star forming region G173.58+2.45. Photometric observations are obtained using the near-infrared $JHKL'M'$ filters and narrow-band filters centered at the…

Astrophysics · Physics 2014-10-13 Watson P. Varricatt , Christopher J. Davis , Andrew J. Adamson

Probing the growth of structure from the epoch of hydrogen recombination to the formation of the first stars and galaxies is one of the most important uncharted areas of observational cosmology. Far-IR spectroscopy covering $\lambda$…

Multi-wavelength ultraviolet (UV) observations by the IRIS satellite in active region NOAA 12529 have recently pointed out the presence of long-lasting brightenings, akin to UV bursts, and simultaneous plasma ejections occurring in the…

Solar and Stellar Astrophysics · Physics 2018-12-19 Salvo L. Guglielmino , Peter R. Young , Francesca Zuccarello

We have calculated the radiation field, dust grain temperatures, and far infrared emissivity of numerical models of turbulent molecular clouds. When compared to a uniform cloud of the same mean optical depth, most of the volume inside the…

Astrophysics · Physics 2009-11-10 Thomas Bethell , Ellen Zweibel , Fabian Heitsch , J. S. Mathis