Search Publications
Constraining the distance to the North Polar Spur with Gaia DR2
Alves, João; Speagle, Joshua S.; Zucker, Catherine +3 more
The North Polar Spur (NPS) is one of the largest structures observed in the Milky Way in both the radio and soft X-rays. While several predictions have been made regarding the origin of the NPS, modelling the structure is difficult without precise distance constraints. In this paper, we determine accurate distances to the southern terminus of the …
New insight into the stellar mass function of Galactic globular clusters
Hilker, M.; Baumgardt, H.; Sollima, A. +2 more
We present the results of the analysis of deep photometric data of 32 Galactic globular clusters. We analysed 69 parallel field images observed with the Wide Field Channel of the Advanced Camera for Surveys of the Hubble Space Telescope which complemented the already available photometry from the globular cluster treasury project covering the cent…
EXTraS discovery of an X-ray superflare from an L dwarf
Stelzer, Beate; Esposito, Paolo; Tiengo, Andrea +13 more
We present the first detection of an X-ray flare from an ultracool dwarf of spectral class L. The event was identified in the EXTraS database of XMM-Newton variable sources, and its optical counterpart, J0331-27, was found through a cross-match with the Dark Energy Survey Year 3 release. Next to an earlier four-photon detection of Kelu-1, J0331-27…
X-ray properties of dust-obscured galaxies with broad optical/UV emission lines
Brandt, William N.; Garmire, Gordon P.; Zou, Fan +4 more
Dust-obscured galaxies (DOGs) with extreme infrared luminosities may represent a key phase in the co-evolution of galaxies and supermassive black holes. We select 12 DOGs at 0.3 ≲ z ≲ 1.0 with broad Mg II or H β emission lines and investigate their X-ray properties utilizing snapshot observations (~3 ks per source) with Chandra. By assuming that t…
Quiet, Discrete Auroral Arcs: Acceleration Mechanisms
Marghitu, O.; Karlsson, T.; Song, Y. +4 more
The theory of the acceleration of auroral particles is reviewed, focusing on developments in the last 15 years. We discuss elementary plasma physics processes leading to acceleration of electrons to energies compatible with emission observed for quiet, discrete auroral arcs, defined as arcs that have time scales of minutes or more and spatial scal…
Dynamical Masses of Young Stars. II. Young Taurus Binaries Hubble 4, FF Tau, and HP Tau/G3
Rizzuto, Aaron C.; Dupuy, Trent J.; Ireland, Michael J. +1 more
One of the most effective ways to test stellar evolutionary models is to measure dynamical masses for binary systems at a range of temperatures. In this paper, we present orbits of three young K+M binary systems in Taurus (Hubble 4, FF Tau, and HP Tau/G3) with very long baseline interferometry parallaxes. We obtained precision astrometry with Keck…
An ionized accretion disc wind in Hercules X-1
Fabian, A. C.; Reynolds, C. S.; Pinto, C. +3 more
Hercules X-1 is one of the best-studied highly magnetized neutron star X-ray binaries with a wealth of archival data. We present the discovery of an ionized wind in its X-ray spectrum when the source is in the high state. The wind detection is statistically significant in most of the XMM-Newton observations, with velocities ranging from 200 to 100…
NGTS and WASP photometric recovery of a single-transit candidate from TESS
Hellier, Coel; Jackman, James A. G.; Wheatley, Peter J. +26 more
The Transiting Exoplanet Survey Satellite (TESS) produces a large number of single-transit event candidates, since the mission monitors most stars for only ∼27 d. Such candidates correspond to long-period planets or eclipsing binaries. Using the TESS Sector 1 full-frame images, we identified a 7750 ppm single-transit event with a duration of 7 h a…
Galaxy spin direction distribution in HST and SDSS show similar large-scale asymmetry
Shamir, Lior
Several recent observations using large data sets of galaxies showed non-random distribution of the spin directions of spiral galaxies, even when the galaxies are too far from each other to have gravitational interaction. Here, a data set of$\sim8.7\cdot10^3$spiral galaxies imaged byHubble Space Telescope(HST) is used to test and profile a possibl…
MCMCI: A code to fully characterise an exoplanetary system
Bonfanti, A.; Gillon, M.
Context. Useful information can be retrieved by analysing the transit light curve of a planet-hosting star or induced radial velocity oscillations. However, inferring the physical parameters of the planet, such as mass, size, and semi-major axis, requires preliminary knowledge of some parameters of the host star, especially its mass or radius, whi…