Search Publications
Deciphering the Activity and Quiescence of High-redshift Cluster Environments: ALMA Observations of Cl J1449+0856 at z = 2
Finoguenov, A.; Cimatti, A.; Daddi, E. +13 more
We present Atacama Large Millimeter/submillimeter Array observations of the 870 µm continuum and CO(4-3) line emission in the core of the galaxy cluster Cl J1449+0856 at z = 2, a near-IR-selected, X-ray-detected system in the mass range of typical progenitors of today’s massive clusters. The 870 µm map reveals six F 870µm
The infant bow shock: a new frontier at a weak activity comet
Simon Wedlund, Cyril; Nilsson, Hans; Goetz, Charlotte +6 more
The bow shock is the first boundary the solar wind encounters as it approaches planets or comets. The Rosetta spacecraft was able to observe the formation of a bow shock by following comet 67P/Churyumov-Gerasimenko toward the Sun, through perihelion, and back outward again. The spacecraft crossed the newly formed bow shock several times during two…
Two-phase Heating in Flaring Loops
Qiu, Jiong; Longcope, Dana W.; Zhu, Chunming
We analyze and model a C5.7 two-ribbon solar flare observed by the Solar Dynamics Observatory, Hinode, and GOES on 2011 December 26. The flare is made of many loops formed and heated successively over one and half hours, and their footpoints are brightened in the UV 1600 Å before enhanced soft X-ray and EUV missions are observed in flare loops. As…
A Data-constrained Model for Coronal Mass Ejections Using the Graduated Cylindrical Shell Method
Singh, T.; Yalim, M. S.; Pogorelov, N. V.
Coronal mass ejections (CMEs) are major drivers of extreme space weather conditions, as this is a matter of serious concern for our modern technologically dependent society. The development of numerical approaches that would simulate CME generation and propagation through the interplanetary space is an important step toward our capability to predi…
The completeness-corrected rate of stellar encounters with the Sun from the first Gaia data release
Bailer-Jones, C. A. L.
I report on close encounters of stars to the Sun found in the first Gaia data release (GDR1). Combining Gaia astrometry with radial velocities of around 320 000 stars drawn from various catalogues, I integrate orbits in a Galactic potential to identify those stars which pass within a few parsecs. Such encounters could influence the solar system, f…
Fast point spread function modeling with deep learning
Herbel, Jörg; Amara, Adam; Refregier, Alexandre +2 more
Modeling the Point Spread Function (PSF) of wide-field surveys is vital for many astrophysical applications and cosmological probes including weak gravitational lensing. The PSF smears the image of any recorded object and therefore needs to be taken into account when inferring properties of galaxies from astronomical images. In the case of cosmic …
O/H-N/O: the curious case of NGC 4670
Kumari, Nimisha; James, Bethan L.; Irwin, Mike J. +2 more
We use integral field spectroscopic (IFS) observations from Gemini Multi-Object Spectrograph North (GMOS-N) of a group of four H II regions and the surrounding gas in the central region of the blue compact dwarf (BCD) galaxy NGC 4670. At spatial scales of ∼9 pc, we map the spatial distribution of a variety of physical properties of the ionized gas…
HD 89345: a bright oscillating star hosting a transiting warm Saturn-sized planet observed by K2
Deeg, H.; Fridlund, M.; García, R. A. +40 more
We report the discovery and characterization of HD 89345b (K2-234b; EPIC 248777106b), a Saturn-sized planet orbiting a slightly evolved star. HD 89345 is a bright star (V = 9.3 mag) observed by the K2 mission with 1 min time sampling. It exhibits solar-like oscillations. We conducted asteroseismology to determine the parameters of the star, findin…
The part and the whole: voids, supervoids, and their ISW imprint
Kovács, András
The integrated Sachs-Wolfe (ISW) imprint of extreme structures in the cosmic web probes the dynamical nature of dark energy. Looking through typical cosmic voids, no anomalous signal has been reported. On the contrary, supervoids, associated with large-scale fluctuations in the gravitational potential, have shown potentially disturbing excess sign…
A rapid occultation event in NGC 3227
Turner, T. J.; Kraemer, S.; Reeves, J. N. +3 more
NGC 3227 exhibits rapid flux and spectral variability in the X-ray band. To understand this behaviour, we conducted a coordinated observing campaign using 320 ks of XMM-Newton exposures together with 160 ks of overlapping NuSTAR observations, spanning a month. Here, we present a rapid variability event that occurs toward the end of the campaign. T…