Search Publications
Phase-resolved Infrared Spectroscopy and Photometry of V1500 Cygni, and a Search for Similar Old Classical Novae
Harrison, Thomas E.; Lyke, James E.; Campbell, Randy D.
We present phase-resolved near-infrared photometry and spectroscopy of the classical nova (CN) V1500 Cyg to explore whether cyclotron emission is present in this system. While the spectroscopy do not indicate the presence of discrete cyclotron harmonic emission, the light curves suggest that a sizable fraction of its near-infrared fluxes are due t…
Star formation, structure, and formation mechanism of cometary globules: near-infrared observations of CG 1 and CG 2
Haikala, L. K.; Mäkelä, M. M.
Context. Cometary globule (CG) 1 and CG 2 are "classic" cometary globules in the Gum Nebula. They have compact heads and long dusty tails that point away from the centre of the Gum Nebula.
Aims: We study the structure of CG 1 and CG 2 and the star formation in them to find clues to the CG formation mechanism. The two possible CG formation mec…
Active galactic nuclei behind the SMC selected from radio and X-ray surveys
Pietsch, W.; Haberl, F.; Filipović, M. D. +8 more
Context. The XMM-Newton survey of the Small Magellanic Cloud (SMC) revealed 3053 X-ray sources with the majority expected to be active galactic nuclei (AGN) behind the SMC. However, the high stellar density in this field often does not allow assigning unique optical counterparts and hinders source classification. On the other hand, the association…
Colour gradients of high-redshift early-type galaxies from hydrodynamical monolithic models
Matteucci, F.; Napolitano, N. R.; Tortora, C. +2 more
We analyse the evolution of colour gradients predicted by the hydrodynamical models of early-type galaxies (ETGs) in Pipino et al., which reproduce fairly well the chemical abundance pattern and the metallicity gradients of local ETGs. We convert the star formation (SF) and metal content into colours by means of stellar population synthetic model …
The geo-effectiveness of interplanetary small-scale magnetic fluxropes
Moldwin, M. B.; Zhang, X. -Y.; Cartwright, M.
The geo-effectiveness of Interplanetary small-scale magnetic flux ropes (ISMFRs) are studied using multiple satellites (ACE, WIND, Geotail, Cluster, THEMIS, and geosynchronous spacecraft) and ground magnetometers. We identified 16 ISMFR events during 2007-2008 that had in situ observations of the near-Earth upstream solar wind in addition to obser…
The distribution of warm gas in the G327.3-0.6 massive star-forming region
van Dishoeck, E. F.; Güsten, R.; van der Tak, F. +3 more
Aims: Most studies of high-mass star formation focus on massive and/or luminous clumps, but the physical properties of their larger scale environment are poorly known. In this work, we aim at characterising the effects of clustered star formation and feedback of massive stars on the surrounding medium by studying the distribution of warm gas …
Highly Ionized Fe-K Absorption Line from Cygnus X-1 in the High/Soft State Observed with Suzaku
Done, C.; Gandhi, P.; Yamada, S. +7 more
We present observations of a transient He-like Fe Kα absorption line in Suzaku observations of the black hole binary Cygnus X-1 on 2011 October 5 near superior conjunction during the high/soft state, which enable us to map the full evolution from the start to the end of the episodic accretion phenomena or dips for the first time. We model the X-ra…
The Size, Structure, and Ionization of the Broad-line Region in NGC 3227
Devereux, Nick
Hubble Space Telescope spectroscopy of the Seyfert 1.5 galaxy, NGC 3227, confirms previous reports that the broad Hα emission line flux is time variable, decreasing by a modest ~11% between 1999 and 2000 in response to a corresponding ~37% decrease in the underlying continuum. Modeling the gas distribution responsible for the broad Hα, Hβ, and Hγ …
Silicon isotopic abundance toward evolved stars and its application for presolar grains
de Gregorio-Monsalvo, I.; Testi, L.; Gray, M. D. +8 more
Aims: Galactic chemical evolution (GCE) is important for understanding the composition of the present-day interstellar medium (ISM) and of our solar system. In this paper, we aim to track the GCE by using the 29Si/30Si ratios in evolved stars and tentatively relate this to presolar grain composition.
Methods: We use…
Titan's Xanadu region: Geomorphology and formation scenario
Lunine, Jonathan I.; Mitri, Giuseppe; Langhans, Migrjam
Based on comprehensive mapping of the region, the recent theories of Xanadu's origin are examined and a chronology of geologic processes is proposed. The geologic history of Titan's Xanadu region is different from that of the other surface units on Saturn's moon. A previously proposed origin of western Xanadu from a giant impact in the early histo…