Search Publications
Detecting periodic oscillations in astronomy data: revisiting wavelet analysis with coloured and white noise
Xu, Chang
The intrinsic random variability of an astronomical source hampers the detection of possible periodicities that we are interested in. We find that a simple first-order autoregressive [AR(1)] process gives a poor fit to the power decay in the observed spectrum for astrophysical sources and geodetic observations. Thus, appropriate background noise m…
Proper motions of five OB stars with candidate dusty bow shocks in the Carina Nebula
Smith, Nathan; Bally, John; Reiter, Megan +1 more
We constrain the proper motions of five OB stars associated with candidate stellar wind bow shocks in the Carina Nebula using Hubble Space Telescope ACS imaging over 9-10 yr baselines. These proper motions allow us to directly compare each star's motion to the orientation of its candidate bow shock. Although these stars are saturated in our imagin…
X-ray-selected broad absorption line quasi-stellar objects
Esquej, P.; Streblyanska, A.; Ebrero, J. +11 more
We study a sample of six X-ray-selected broad absorption line (BAL) quasi-stellar objects (QSOs) from the XMM-Newton Wide Angle Survey. All six objects are classified as BALQSOs using the classic balnicity index, and together they form the largest sample of X-ray-selected BALQSOs. We find evidence for absorption in the X-ray spectra of all six obj…
Two years of solar wind and pickup ion measurements at comet 67P/Churyumov-Gerasimenko
Glassmeier, K. -H.; Nilsson, H.; Eriksson, A. +8 more
The Ion and Electron Sensor (IES) as well as other members of the Rosetta Plasma Consortium (RPC) on board the Rosetta spacecraft (S/C) measured the characteristics of the solar wind almost continuously since its arrival at 67P/Churyumov-Gerasimenko (CG) in 2014 August. An important process at a comet is the so-called pickup process in which a new…
An eLIMA model for the 67 s X-ray periodicity in CAL 83
Meintjes, P. J.; Odendaal, A.
Supersoft X-ray sources (SSSs) are characterized by their low effective temperatures and high X-ray luminosities. The soft X-ray emission can be explained by hydrogen nuclear burning on the surface of a white dwarf (WD) accreting at an extremely high rate. A peculiar ∼67 s periodicity (P67) was previously discovered in the XMM-Newton li…
Young star clusters in circumnuclear starburst rings
Ho, Luis C.; de Grijs, Richard; Anders, Peter +2 more
We analyse the cluster luminosity functions (CLFs) of the youngest star clusters in two galaxies exhibiting prominent circumnuclear starburst rings. We focus specifically on NGC 1512 and NGC 6951, for which we have access to Hα data that allow us to unambiguously identify the youngest sample clusters. To place our results on a firm statistical foo…
Deconstructing a galaxy: colour distributions of point sources in Messier 83
Barmby, P.; Kiar, A. K.; Hidalgo, A.
What do we see when we look at a nearby, well-resolved galaxy? Thousands of individual sources are detected in multiband imaging observations of even a fraction of a nearby galaxy, and characterizing those sources is a complex process. This work analyses a ten-band photometric catalogue of nearly 70 000 point sources in a 7.3 square arcmin region …
Observations of V0332+53 during the 2015 outburst using Fermi/GBM, MAXI, Swift and INTEGRAL
Rodi, James; Cherry, Michael L.; Baum, Zachary A.
We present the light curves, spectra and hardness-intensity diagram (HID) of the high-mass X-ray binary V0332+53 using Fermi/GBM, MAXI, Swift/BAT and INTEGRAL through its 2015 Type II outburst. We observe characteristic features in the X-ray emission (2-50 keV) due to periastron passages, the dynamical time-scale of the accretion disc, and changes…
Reconstructing the cosmic Horseshoe gravitational lens using the singular perturbative approach.
Alard, C.
The reconstruction of the cosmic horseshoe gravitational lens using the perturbative method reveals the presence of significant third-order terms. The presence of these higher order terms is apparent in the numerical expansion of the perturbative fields in Fourier series. The expansion of the fields at order 2 produces a higher value of the chi-sq…
The dusty silhouette jet HH 1019 in the Carina Nebula
Smith, Nathan; Bally, John; Reiter, Megan +1 more
We report the discovery in Hubble Space Telescope (HST) images of the new Herbig-Haro jet, HH 1019, located near the Tr 14 cluster in the Carina Nebula. Like other HH jets in the region, this bipolar collimated flow emerges from the head of a dark dust pillar. However, HH 1019 is unique because - unlike all other HH jets known to date - it is iden…