Search Publications
SOFIA mid-infrared observations of Supernova 1987A in 2016 - forward shocks and possible dust re-formation in the post-shocked region
Matsuura, Mikako; Barlow, M. J.; Meixner, Margaret +10 more
The equatorial ring of Supernova (SN) 1987A has been exposed to forward shocks from the SN blast wave, and it has been suggested that these forward shocks have been causing ongoing destruction of dust in the ring. We obtained Stratospheric Observatory For Infrared Astronomy The Faint Object InfraRed CAmera for the SOFIA Telescope (FORCAST) 11.1, 1…
NGTS-7Ab: an ultrashort-period brown dwarf transiting a tidally locked and active M dwarf
Jackman, James A. G.; Wheatley, Peter J.; Moyano, Maximiliano +36 more
We present the discovery of NGTS-7Ab, a high-mass brown dwarf transiting an M dwarf with a period of 16.2 h, discovered as part of the Next Generation Transit Survey (NGTS). This is the shortest period transiting brown dwarf around a main or pre-main sequence star to date. The M star host (NGTS-7A) has an age of roughly 55 Myr and is in a state of…
Yule-Simpson's paradox in Galactic Archaeology
Guiglion, G.; Anders, F.; Chiappini, C. +7 more
Simpson's paradox, or Yule-Simpson effect, arises when a trend appears in different subsets of data but disappears or reverses when these subsets are combined. We describe here seven cases of this phenomenon for chemo-kinematical relations believed to constrain the Milky Way disc formation and evolution. We show that interpreting trends in relatio…
ASKAP detection of periodic and elliptically polarized radio pulses from UV Ceti
Kaplan, David L.; Lenc, Emil; Phillips, Chris +9 more
Active M dwarfs are known to produce bursty radio emission, and multiwavelength studies have shown that solar-like magnetic activity occurs in these stars. However, coherent bursts from active M dwarfs have often been difficult to interpret in the solar activity paradigm. We present Australian Square Array Pathfinder (ASKAP) observations of UV Cet…
The chemical composition of HIP 34407/HIP 34426 and other twin-star comoving pairs
Lambert, D. L.; Endl, M.; Meléndez, J. +4 more
We conducted a high-precision elemental abundance analysis of the twin-star comoving pair HIP 34407/HIP 34426. With mean error of 0.013 dex in the differential abundances (Δ[X/H]), a significant difference was found: HIP 34407 is more metal rich than HIP 34426. The elemental abundance differences correlate strongly with condensation temperature, w…
The diverse galaxy counts in the environment of high-redshift massive black holes in Horizon-AGN
Somerville, Rachel S.; Volonteri, Marta; Habouzit, Mélanie +4 more
High-redshift quasars are believed to reside in highly biased regions of the Universe, where black hole growth is sustained by an enhanced number of mergers and by being at the intersection of filaments bringing fresh gas. This assumption should be supported by an enhancement of the number counts of galaxies in the field of view of quasars. While …
The power spectrum of the Lyman-α Forest at z < 0.5
Hennawi, Joseph F.; Tripp, Todd M.; Prochaska, J. Xavier +7 more
We present new measurements of the flux power-spectrum P(k) of the z < 0.5 H I Lyman-α Forest spanning scales k ∼ 0.001-0.1 s km^{-1}. These results were derived from 65 far-ultraviolet quasar spectra (resolution R ∼ 18 000) observed with the Cosmic Origin Spectrograph (COS) on board the Hubble Space Telescope. The analysis required careful mas…
The nuclear environment of the NLS1 Mrk 335: Obscuration of the X-ray line emission by a variable outflow
Harrison, F. A.; Schartel, N.; Santos-Lleó, M. +12 more
We present XMM-Newton, NuSTAR, Swift, and Hubble Space Telescope observations of the Narrow-line Seyfert 1 galaxy Mrk 335 in a protracted low state in 2018 and 2019. The X-ray flux is at the lowest level so far observed, and the extremely low continuum flux reveals a host of soft X-ray emission lines from photoionized gas. The simultaneous UV flux…
The structure of the Mg II broad line emitting region in Type 1 AGNs
Popović, Luka Č.; Kovačević-Dojčinović, Jelena; Marčeta-Mandić, Sladjana
We investigate the structure of the Mg II broad line emission region in a sample of 284 Type 1 active galactic nuclei (AGNs), through comparing the kinematical parameters of the broad Mg II and broad Hβ lines. We found that the Mg II emitting region has more complex kinematics than the Hβ one. It seems that the Mg II broad line originates from two…
Benchmark ages for the Gaia benchmark stars
Feltzing, Sofia; Lindegren, Lennart; Sahlholdt, Christian L. +1 more
In the era of large-scale surveys of stars in the Milky Way, stellar ages are crucial for studying the evolution of the Galaxy. But determining ages of field stars is notoriously difficult; therefore, we attempt to determine benchmark ages for the extensively studied Gaia benchmark stars which can be used for validation purposes. By searching the …