Search Publications
The multi-outburst activity of the magnetar in Westerlund I
Campana, S.; Tiengo, A.; Götz, D. +17 more
After two major outbursts in 2006 and 2011, on 2017 May 16 the magnetar CXOU J164710.2-455216, hosted within the massive star cluster Westerlund I, emitted a short (∼20 ms) burst, which marked the onset of a new active phase. We started a long-term monitoring campaign with Swift (45 observations), Chandra (five observations), and NuSTAR (four obse…
On the diagnostic power of FIR/sub-mm SED fitting in massive galactic molecular clumps
Pitts, Rebecca L.; Barnes, Peter J.; Varosi, Frank
We used far-infrared (FIR) and sub-millimetre continuum data from Herschel and the Atacama Pathfinder EXperiment (APEX) to fit pixel-by-pixel modified Planck spectral energy distributions to prestellar and protostellar clumps in the Census of High- and Medium-mass Protostars (CHaMP) (280° < ℓ < 300°, -4° < b < +2°). We present maps of …
Field-Aligned Structures of the Poloidal-Mode ULF Wave Electric Field: Phase Relationship Implications
Zong, Q. G.; Ren, Jie; Zhou, X. Z. +2 more
Spacecraft observations within recent decades have demonstrated that ultralow frequency (ULF) waves play an important role in the dynamics of Earth's magnetosphere through drift and/or drift-bounce resonance with different particle species. The phase relationship between resonant particles and waves can help us understand the wave-particle interac…
Swift X-ray and UV observations of SDSS J141118.31+481257.6 during its first ever recorded superoutburst
Maccarone, T. J.; Rivera Sandoval, L. E.
SDSS J141118.31+481257.6 is an ultracompact white dwarf binary (or AM CVn system) with an orbital period of 46 min. We analyse ∼23 ks of X-ray and ultraviolet (UV) data taken with the Neil Gehrels Swift Observatory during its first ever recorded outbursts. The events took place 13 yr after the system was discovered. We detected three events in our…
Asymmetric Distribution of Weak Photospheric Magnetic Field Values
Mursula, Kalevi; Virtanen, Ilpo; Getachew, Tibebu
We use the synoptic maps of the photospheric magnetic field observed at Wilcox Solar Observatory, Mount Wilson Observatory, Kitt Peak, SOHO/MDI, SOLIS/VSM, and SDO/HMI to study the distribution of weak photospheric magnetic field values in 1974-2018. We fit the histogram distribution of weak field values for each synoptic map of the six data sets …
Measuring the Obscuring Column of a Disk Megamaser AGN in a Nearby Merger
Comastri, A.; Brusa, M.; Civano, F. +5 more
Active galactic nuclei (AGNs) hosting disk water megamasers are well known to be obscured by large amounts of gas, likely due to the presence along the line of sight of an almost edge-on disky structure orbiting the supermassive black hole. Correcting for the high obscuration is crucial to infer parameters intrinsic to the source, like its luminos…
Small-scale chemical abundance analysis in a blue compact dwarf galaxy SBS 1415+437
Kumari, Nimisha; Aloisi, Alessandra; James, Bethan L. +1 more
We use integral field spectroscopic (IFS) observations from Gemini Multi-Object Spectrograph-North (GMOS-N) to analyse the ionized gas in the principal star-forming region in the blue compact dwarf galaxy SBS 1415+437. The IFS data enable us to map the weak auroral line [O III] λ4363 at a spatial scale of ∼6.5 pc across a region of ∼143 × 143 pc
Microlens mass determination for Gaia's predicted photometric events
Evans, N. W.; Belokurov, V.; Zhang, Z. H. +2 more
We used Gaia Data Release 2 to search for upcoming photometric microlensing events, identifying two candidates with high amplification. In the case of candidate 1, a spectrum of the lens (l1) confirms it is a usdM3 subdwarf with mass ≈0.11M⊙, while the event reaches maximum amplification of 20^{+20}_{-10} mmag on 2019 November 3 (±1d). …
The extended main-sequence turn-off of the Milky Way open cluster Collinder 347
Piatti, Andrés E.; Bonatto, Charles
We made use of the Gaia DR2 archive to comprehensively study the Milky Way open cluster Collinder 347, known until now as a very young object of solar metal content. However, the G versus GBP - GRP colour-magnitude diagram (CMD) of bonafide probable cluster members, selected on the basis of individual stellar proper motions, …
Photometric and Spectral Observations of the W UMa Stars NSVS 4161544 and 1SWASP J034501.24+493659.9. GAIA Challenges
Kjurkchieva, Diana; Popov, Velimir A.; Stateva, Ivanka +1 more
Photometric and spectral observations of the W UMa binaries NSVS 4161544 and 1SWASP J034501.24+493659.9 with periods of around 8 hr are presented. The simultaneous light-curve and radial-velocity-curve solutions revealed that the two targets have over-contact configurations, and their components undergo partial eclipses. The derived parameters of …