Search Publications
Hypervelocity Stars from a Supermassive Black Hole-Intermediate-mass Black Hole Binary
Tagawa, Hiromichi; Rossi, Elena Maria; Fragione, Giacomo +4 more
In this paper we consider a scenario in which the currently observed hypervelocity stars in our Galaxy have been ejected from the Galactic center as a result of dynamical interactions with an intermediate-mass black hole (IMBH) orbiting the central supermassive black hole (SMBH). By performing three-body scattering experiments, we calculate the di…
The sdA problem - III. New extremely low-mass white dwarfs and their precursors from Gaia astrometry
Kepler, S. O.; Bell, Keaton J.; Pelisoli, Ingrid +1 more
The physical nature of the sdA stars - cool hydrogen-rich objects with spectroscopic surface gravities intermediate between main-sequence and canonical-mass white dwarfs - has been elusive since they were found in Sloan Digital Sky Survey Data Release 12 spectra. The population is likely dominated by metal-poor A/F stars in the halo with overestim…
Properties of Magnetic Reconnection and FTEs on the Dayside Magnetopause With and Without Positive IMF Bx Component During Southward IMF
Kilpua, E. K. J.; Fear, R. C.; Palmroth, M. +11 more
This paper describes properties and behavior of magnetic reconnection and flux transfer events (FTEs) on the dayside magnetopause using the global hybrid-Vlasov code Vlasiator. We investigate two simulation runs with and without a sunward (positive) Bx component of the interplanetary magnetic field (IMF) when the IMF is southward. The r…
The Quintuplet Cluster: Extended Structure and Tidal Radius
Rui, Nicholas Z.; Hosek, Matthew W., Jr.; Lu, Jessica R. +4 more
The Quintuplet star cluster is one of only three known young (<10 Myr) massive (M > 104 M ⊙) clusters within ∼100 pc of the Galactic center (GC). In order to explore star cluster formation and evolution in this extreme environment, we analyze the Quintuplet’s dynamical structure. Using the HST WFC3-IR instrument, we tak…
Mass function and dynamical study of the open clusters Berkeley 24 and Czernik 27 using ground based imaging and Gaia astrometry
Bisht, D.; Yadav, R. K. S.; Fynbo, J. P. U. +3 more
We present a UBVI photometric study of the open clusters Berkeley 24 (Be 24) and Czernik 27 (Cz 27). The radii of the clusters are determined as 2{^'.}7 and 2{^'.}3 for Be 24 and Cz 27, respectively. We use the Gaia Data Release 2 (GDR2) catalogue to estimate the mean proper motions for the clusters. We found the mean proper …
Source Imaging of a Moving Type IV Solar Radio Burst and Its Role in Tracking Coronal Mass Ejection from the Inner to the Outer Corona
Chen, Yao; Feng, Shiwei; Vasanth, V. +5 more
Source imaging of solar radio bursts can be used to track energetic electrons and associated magnetic structures. Here we present a combined analysis of data at different wavelengths for an eruption associated with a moving type IV (t-IVm) radio burst. In the inner corona, the sources are correlated with a hot and twisted eruptive EUV structure, w…
Study of CS, SiO, and SiS abundances in carbon star envelopes: assessing their role as gas-phase precursors of dust
Cernicharo, J.; Agúndez, M.; Massalkhi, S.
Aims: We aim to determine the abundances of CS, SiO, and SiS in a large sample of carbon star envelopes covering a wide range of mass loss rates to investigate the potential role that these molecules could play in the formation of dust in the surroundings of the central AGB star.
Methods: We surveyed a sample of 25 carbon-rich AGB stars …
The Dust and Molecular Gas in the Brightest Cluster Galaxy in MACS 1931.8-2635
Donahue, Megan; Frye, Brenda; Liu, Hauyu Baobab +6 more
We present new Atacama Large Millimeter Array observations of the molecular gas and far-infrared continuum around the brightest cluster galaxy (BCG) in the cool-core cluster MACS 1931.8-2635. Our observations reveal (1.9 ± 0.3) × 1010 M ⊙ of molecular gas, on par with the largest known reservoirs of cold gas in a cluster core…
Spectroscopic detection of multiple populations in the ∼2 Gyr old cluster Hodge 6 in the LMC
Martocchia, S.; Dalessandro, E.; Salaris, M. +8 more
We report the spectroscopic discovery of abundance spreads (i.e. multiple populations) in the ∼2 Gyr old cluster in the LMC, Hodge 6. We use low-resolution VLT FORS2 spectra of 15 member stars in the cluster to measure their CN and CH band strengths at ≃3883 and 4300 Å, respectively, as well as [C/Fe] and [N/Fe] abundances. We find a subpopulation…
Thermal emission from bow shocks. I. 2D hydrodynamic models of the Bubble Nebula
Green, Samuel; Mackey, Jonathan; Haworth, Thomas J. +2 more
The Bubble Nebula (or NGC 7635) is a parsec-scale seemingly spherical wind-blown bubble around the relatively unevolved O star BD+60°2522. The young dynamical age of the nebula and significant space velocity of the star suggest that the Bubble Nebula might be a bow shock. We ran 2D hydrodynamic simulations to model the interaction of the wind of t…