Search Publications
A Comparison of the Chemical Composition of Main-sequence and Giant Stars in the Open Cluster NCC 752
Lum, Michael G.; Boesgaard, Ann Merchant
The chemical composition of stars in open clusters provides the best information on the chemical evolution of stars via comparison of main-sequence stars with evolved giants. This is a case study of the abundances in the dwarfs and giants in the old open cluster NGC 752. It is also a pilot program for automated abundance determinations, including …
Global Energetics of Solar Flares. VII. Aerodynamic Drag in Coronal Mass Ejections
Gopalswamy, Nat; Aschwanden, Markus J.
The free energy that is dissipated in a magnetic reconnection process of a solar flare, generally accompanied by a coronal mass ejection (CME), has been considered as the ultimate energy source of the global energy budget of solar flares in previous statistical studies. Here we explore the effects of the aerodynamic drag force on CMEs, which suppl…
Direct Observation of the Broad Line Region in X-Rays during the Low State of NGC 4051
Miller, Jon M.; Behar, Ehud; Peretz, Uria
NGC 4051 is one of the most variable and X-ray bright Seyfert galaxies. During 2009, NGC 4051 was caught at its lowest state ever observed by XMM-Newton. The low source continuum emission allows a clear measurement of the He-like emission lines of {{{N}}}+5 and O+6. The exceptionally high intercombination line flux is a direc…
Constraining Stellar Parameters and Atmospheric Dynamics of the Carbon AGB star V Oph
Ohnaka, Keiichi; Carpenter, Kenneth G.; Rau, Gioia +2 more
Molecules and dust produced by the atmospheres of cool evolved stars contribute to a significant amount of the total material found in the interstellar medium. To understand the mechanism behind the mass loss of these stars, it is of pivotal importance to investigate the structure and dynamics of their atmospheres. Our goal is to verify if the ext…
The Weakening Outburst of the Young Eruptive Star V582 Aur
Cseh, B.; Kriskovics, L.; Pál, A. +17 more
V582 Aur is a pre-main-sequence FU Orionis type eruptive star, which entered a brightness minimum in 2016 March due to changes in the line-of-sight extinction. Here, we present and analyze new optical B, V, R C , and I C band multiepoch observations and new near-infrared J, H, and K S band photometric measurem…
A Statistical Study of the Magnetic Imprints of X-class Solar Flares
Ding, Mingde; Guo, Yang; Zhang, Yining +3 more
Magnetic imprints, the rapid and irreversible evolution of photospheric magnetic fields as feedback from flares in the corona, have been confirmed by many previous studies. These studies showed that the horizontal field will permanently increase at the polarity inversion line (PIL) after eruptions, indicating that a more horizontal geometry of the…
ALMA Observations of the Molecular Gas in the Elliptical Galaxy NGC 3557
Espada, Daniel; Cepa, Jordi; Vila-Vilaro, Baltasar +3 more
We present the results of CO interferometric observations of the southern elliptical galaxy NGC 3557 with ALMA. We have detected both the CO(1-0) emission line and a relatively strong continuum at 3 mm. The continuum shows a flat-spectrum central unresolved source (at our angular resolution of 0.″7) and two jets, associated with the larger-scale e…
Asymptotic Giant Branch Stars in the Nearby Dwarf Galaxy Leo P
van Loon, J. Th.; Zijlstra, A. A.; Skillman, E. D. +7 more
We have conducted a highly sensitive census of the evolved-star population in the metal-poor dwarf galaxy Leo P and detected four asymptotic giant branch (AGB) star candidates. Leo P is one of the best examples of a nearby analog of high-redshift galaxies because of its primitive metal content (2% of the solar value), proximity, and isolated natur…
High-velocity Bullets from V Hydrae, an Asymptotic Giant Branch Star in Transition: Ejection History and Spatio-kinematic Modeling
Sahai, R.; Morris, M. R.; Scibelli, S.
The carbon star V Hydrae (V Hya) provides new insight into the nature of the launching mechanism of jet-like outflows that are believed to be the cause of the poorly understood transition phase of asymptotic giant branch stars into aspherical planetary nebulae. V Hya has been shown to periodically eject collimated gas blobs at high velocities (“bu…
Investigating Early-type Galaxy Evolution with a Multiwavelength Approach. III. Insights from SPH Simulations with Chemophotometric Implementation
Mazzei, Paola; Rampazzo, Roberto; Marino, Antonietta +3 more
We are exploring galaxy evolution in low-density environments exploiting smooth particle hydrodynamic simulations, including chemophotometric implementation. From a large grid of simulations of galaxy encounters and mergers starting from triaxial halos of gas and dark matter, we single out the simulations matching the global properties of our targ…