Search Publications
A quantitative study of O stars in NGC 2244 and the Monoceros OB2 association
Martins, F.; Hillier, D. J.; Rauw, G. +1 more
Aims: Our goal is to determine the stellar and wind properties of seven O stars in the cluster NGC 2244 and three O stars in the OB association Mon OB2. These properties give us insight into the mass loss rates of O stars. They allow us to both check the validity of rotational mixing in massive stars and to better understand the effects of th…
The Progenitor of the Type Ia Supernova that Created SNR 0519-69.0 in the Large Magellanic Cloud
Schaefer, Bradley E.; Pagnotta, Ashley; Edwards, Zachary I.
Models for the progenitor systems of Type Ia supernovae can be divided into double-degenerate systems, which contain two white dwarfs, and single-degenerate systems, which contain one white dwarf plus one companion star (either a red giant, a subgiant, or a >1.16 M ⊙ main-sequence star). The white dwarf is destroyed in the supernova …
The evolution of the star formation activity per halo mass up to redshift ~1.6 as seen by Herschel
Finoguenov, A.; Berta, S.; Magnelli, B. +40 more
Aims: Star formation in massive galaxies is quenched at some point during hierarchical mass assembly. To understand where and when the quenching processes takes place, we study the evolution of the total star formation rate per unit total halo mass (Σ(SFR)/M) in three different mass scales: low mass halos (field galaxies), groups, and cluster…
Measuring the Abundance of Sub-kilometer-sized Kuiper Belt Objects Using Stellar Occultations
Livio, Mario; Nelan, Edmund P.; Gal-Yam, Avishay +6 more
We present here the analysis of about 19,500 new star hours of low ecliptic latitude observations (|b| <= 20°) obtained by the Hubble Space Telescope's Fine Guidance Sensors over a time span of more than nine years, which is in addition to the ~12, 000 star hours previously analyzed by Schlichting et al. Our search for stellar occultations by s…
Systematic Investigation of Solar Modulation of Galactic Protons for Solar Cycle 23 Using a Monte Carlo Approach with Particle Drift Effects and Latitudinal Dependence
Boella, G.; Gervasi, M.; Grandi, D. +8 more
A propagation model of galactic cosmic protons through the heliosphere was implemented using a two-dimensional Monte Carlo approach to determine the differential intensities of protons during solar cycle 23. The model includes the effects due to the variation of solar activity during the propagation of cosmic rays from the boundary of the heliopau…
Swift Follow-up Observations of Candidate Gravitational-wave Transient Events
Liu, Y.; Lee, H. M.; Foley, S. +815 more
We present the first multi-wavelength follow-up observations of two candidate gravitational-wave (GW) transient events recorded by LIGO and Virgo in their 2009-2010 science run. The events were selected with low latency by the network of GW detectors (within less than 10 minutes) and their candidate sky locations were observed by the Swift observa…
TNOs are cool: A survey of the trans-Neptunian region. V. Physical characterization of 18 Plutinos using Herschel-PACS observations
Fornasier, S.; Hartogh, P.; Pál, A. +18 more
Context. The Herschel open time key programme TNOs are Cool: A survey of the trans-Neptunian region aims to derive physical and thermal properties for a set of ~140 Centaurs and trans-Neptunian objects (TNOs), including resonant, classical, detached and scattered disk objects. One goal of the project is to determine albedo and size distributions f…
Galaxy Disks Do Not Need to Survive in the ΛCDM Paradigm: The Galaxy Merger Rate Out to z ~ 1.5 from Morpho-kinematic Data
Flores, H.; Hammer, F.; Puech, M. +5 more
About two-thirds of present-day, large galaxies are spirals such as the Milky Way or Andromeda, but the way their thin rotating disks formed remains uncertain. Observations have revealed that half of their progenitors, six billion years ago, had peculiar morphologies and/or kinematics, which exclude them from the Hubble sequence. Major mergers, i.…
Triggered star formation in the inner filament of Centaurus A
Mutchler, Max; Whitmore, Bradley C.; Shabala, Stanislav S. +7 more
We present recent Hubble Space Telescope observations of the inner filament of Centaurus A, using the new Wide Field Camera 3 (WFC3) F225W, F657N and F814W filters. We find a young stellar population near the south-west tip of the filament. Combining the WFC3 data set with archival Advanced Camera for Surveys (ACS) F606W observations, we are able …
Multi-wavelength Observations of the Radio Magnetar PSR J1622-4950 and Discovery of Its Possibly Associated Supernova Remnant
Esposito, Paolo; Rea, Nanda; Drake, Jeremy J. +29 more
We present multi-wavelength observations of the radio magnetar PSR J1622-4950 and its environment. Observations of PSR J1622-4950 with Chandra (in 2007 and 2009) and XMM (in 2011) show that the X-ray flux of PSR J1622-4950 has decreased by a factor of ~50 over 3.7 years, decaying exponentially with a characteristic time of τ = 360 ± 11 days. This …