Search Publications
Structure and Dynamics of the Accretion Process and Wind in TW Hya
Strader, Jay; Cranmer, S. R.; Smith, Graeme H. +3 more
Time-domain spectroscopy of the classical accreting T Tauri star, TW Hya, covering a decade and spanning the far UV to the near-infrared spectral regions can identify the radiation sources, the atmospheric structure produced by accretion, and properties of the stellar wind. On timescales from days to years, substantial changes occur in emission li…
A quiescent galaxy at the position of the long GRB 050219A
Covino, S.; Pian, E.; D'Elia, V. +25 more
Context. Long-duration gamma-ray bursts (LGRBs) are produced by the collapse of very massive stars. Because of the short life time of their progenitors, LGRBs pinpoint star-forming galaxies. Recent studies demonstrate that LGRBs populate all types of star-forming galaxies from sub-luminous, blue compact dwarfs to luminous infrared galaxies.
A…
The Heating of Mid-infrared Dust in the Nearby Galaxy M33: A Testbed for Tracing Galaxy Evolution
Calzetti, Daniela; Boquien, Médéric; van der Werf, Paul +10 more
Infrared emission is an invaluable tool for quantifying star formation in galaxies. Because the 8 µm polycyclic aromatic hydrocarbon (PAH) emission has been found to correlate with other well-known star formation tracers, it has widely been used as a star formation rate (SFR) tracer. There are, however, studies that challenge the accuracy an…
Quiescent Reconnection Rate Between Emerging Active Regions and Preexisting Field, with Associated Heating: NOAA AR 11112
Longcope, Dana W.; McKenzie, David E.; Yoshimura, Keiji +1 more
When magnetic flux emerges from beneath the photosphere, it displaces the preexisting field in the corona, and a current sheet generally forms at the boundary between the old and new magnetic domains. Reconnection in the current sheet relaxes this highly stressed configuration to a lower energy state. This scenario is most familiar and most often …
Ionizing stellar population in the disc of NGC 3310 - I. The impact of a minor merger on galaxy evolution
Pérez-Montero, E.; Sánchez, S. F.; Díaz, A. I. +2 more
Numerical simulations of minor mergers predict little enhancement in the global star formation activity. However, it is still unclear the impact they have on the chemical state of the whole galaxy and on the mass build-up in the galaxy bulge and disc. We present a two-dimensional analysis of NCG 3310, currently undergoing an intense starburst like…
Metal Distributions out to 0.5 r 180 in the Intracluster Medium of Four Galaxy Groups Observed with Suzaku
Sato, Kosuke; Matsushita, Kyoko; Sasaki, Toru
We studied the distributions of metal abundances and metal-mass-to-light ratios in the intracluster medium (ICM) of four galaxy groups, MKW 4, HCG 62, the NGC 1550 group, and the NGC 5044 group, out to ~0.5 r 180 observed with Suzaku. The iron abundance decreases with radius and is about 0.2-0.4 solar beyond 0.1 r 180. At a g…
Wind collisions in three massive stars of Cygnus OB2
Nazé, Yaël; Rauw, Gregor; Cazorla, Constantin
Aims: We wish to study the origin of the X-ray emission of three massive stars in the Cyg OB2 association: Cyg OB2 #5, Cyg OB2 #8A, and Cyg OB2 #12.
Methods: To this aim, dedicated X-ray observations from XMM-Newton and Swift are used, as well as archival ROSAT and Suzaku data.
Results: Our results on Cyg OB2 #8A improve the phase c…
High-speed photospheric material flow observed at the polarity inversion line of a δ-type sunspot producing an X5.4 flare on 2012 March 7
Shimizu, Toshifumi; Lites, Bruce W.; Bamba, Yumi
Solar flares abruptly release the free energy stored as a non-potential magnetic field in the corona and may be accompanied by eruptions of the coronal plasma. Formation of a non-potential magnetic field and the mechanisms for triggering the onset of flares are still poorly understood. In particular, photospheric dynamics observed near those polar…
Automatic detection of impact craters on Mars using a modified adaboosting method
Jin, Shuanggen; Zhang, Tengyu
The accurate recognition of impact craters is important to analyze and understand the relative dating of Martian surface. Since manually identifying small craters in a deluge of high-resolution Martian images is a tremendous task, a robust automatic detection algorithm of the crater is needed, but subject to lots of uncertainties and low successfu…
Developing a self-consistent description of Titan's upper atmosphere without hydrodynamic escape
Bougher, Stephen W.; Hunter Waite, J.; Bell, Jared M. +4 more
In this study, we develop a best fit description of Titan's upper atmosphere between 500 km and 1500 km, using a one-dimensional (1-D) version of the three-dimensional (3-D) Titan Global Ionosphere-Thermosphere Model. For this modeling, we use constraints from several lower atmospheric Cassini-Huygens investigations and validate our simulation res…