Search Publications
Formation of Dust in the Ejecta of Type Ia Supernovae
Nomoto, Ken'ichi; Maeda, Keiichi; Tanaka, Masaomi +3 more
We investigate the formation of dust grains in the ejecta of Type Ia supernovae (SNe Ia), adopting the carbon-deflagration W7 model. In the calculations of dust formation, we apply the nucleation and grain growth theory and consider the two extreme cases of the formation of CO and SiO molecules: complete formation and no formation. The results of …
Near-ultraviolet Excess in Slowly Accreting T Tauri Stars: Limits Imposed by Chromospheric Emission
Edwards, Suzan; Brown, Alexander; France, Kevin +20 more
Young stars surrounded by disks with very low mass accretion rates are likely in the final stages of inner disk evolution and therefore particularly interesting to study. We present ultraviolet (UV) observations of the ~5-9 Myr old stars RECX-1 and RECX-11, obtained with the Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph on t…
The minimal solar activity in 2008-2009 and its implications for long-term climate modeling
Schrijver, C. J.; Mewaldt, R. A.; Woods, T. N. +1 more
Variations in the total solar irradiance (TSI) associated with solar activity have been argued to influence the Earth's climate system, in particular when solar activity deviates from the average for a substantial period. One such example is the 17th Century Maunder Minimum during which sunspot numbers were extremely low, as Earth experienced the …
Quasi-stellar Object Selection Algorithm Using Time Variability and Machine Learning: Selection of 1620 Quasi-stellar Object Candidates from MACHO Large Magellanic Cloud Database
Trichas, Markos; Alcock, Charles; Kim, Dae-Won +3 more
We present a new quasi-stellar object (QSO) selection algorithm using a Support Vector Machine, a supervised classification method, on a set of extracted time series features including period, amplitude, color, and autocorrelation value. We train a model that separates QSOs from variable stars, non-variable stars, and microlensing events using 58 …
Solar Source and Heliospheric Consequences of the 2010 April 3 Coronal Mass Ejection: A Comprehensive View
Bale, Stuart D.; Liu, Ying; Luhmann, Janet G. +1 more
We study the solar source and heliospheric consequences of the 2010 April 3 coronal mass ejection (CME) in the frame of the Sun-Earth connection using observations from a fleet of spacecraft. The CME is accompanied by a B7.4 long-duration flare, dramatic coronal dimming, and EUV waves. It causes significant heliospheric consequences and space weat…
Radio Emission of the Quiet Sun and Active Regions (Invited Review)
Shibasaki, K.; Alissandrakis, C. E.; Pohjolainen, S.
Solar radio emission provides valuable information on the structure and dynamics of the solar atmosphere above the temperature minimum. We review the background and most recent observational and theoretical results on the quiet Sun and active region studies, covering the entire radio range from millimeter to decameter wavelengths. We examine small…
The outburst and nature of two young eruptive stars in the North America/Pelican Nebula Complex
Pál, A.; Ábrahám, P.; Kóspál, Á. +8 more
Context. The sudden optical brightening of two young stellar objects, HBC 722 and VSX J205126.1+440523, located in the North America/Pelican Nebula Complex, was announced in August 2010. Early photometric and spectroscopic observations of these objects indicated that they may belong to the FUor or EXor class of young eruptive stars. The eruptions …
Carina OB Stars: X-ray Signatures of Wind Shocks and Magnetic Fields
Corcoran, Michael F.; Walborn, Nolan R.; Moffat, Anthony F. J. +10 more
The Chandra Carina Complex contains 200 known O- and B-type stars. The Chandra survey detected 68 of the 70 O stars and 61 of 127 known B0-B3 stars. We have assembled a publicly available optical/X-ray database to identify OB stars that depart from the canonical L X/L bol relation or whose average X-ray temperatures exceed 1 …
The near-infrared broad emission line region of active galactic nuclei - II. The 1-µm continuum
Elvis, Martin; Karovska, Margarita; Korista, Kirk T. +3 more
We use quasi-simultaneous near-infrared (near-IR) and optical spectroscopy from four observing runs to study the continuum around 1 µm in 23 well-known broad emission line active galactic nuclei (AGN). We show that, after correcting the optical spectra for host galaxy light, the AGN continuum around this wavelength can be approximated by the…
The SWELLS survey - II. Breaking the disc-halo degeneracy in the spiral galaxy gravitational lens SDSS J2141-0001
Treu, Tommaso; Marshall, Philip J.; Holden, Bradford P. +6 more
The degeneracy among the disc, bulge and halo contributions to galaxy rotation curves prevents an understanding of the distribution of baryons and dark matter in disc galaxies. In an attempt to break this degeneracy, we present an analysis of the strong gravitational lens SDSS J2141-0001, discovered as part of the Sloan Lens ACS survey. The lens g…