Search Publications
Characterization and formation of on-disk spicules in the Ca II K and Mg II k spectral lines
Joshi, Jayant; Rouppe van der Voort, Luc; Henriques, Vasco M. J. +1 more
We characterize, for the first time, type-II spicules in Ca II K 3934 Å using the CHROMIS instrument at the Swedish 1 m Solar Telescope. We find that their line formation is dominated by opacity shifts with the K3 minimum best representing the velocity of the spicules. The K2 features are either suppressed by the Doppler-shif…
New Millimeter CO Observations of the Gas-rich Debris Disks 49 Cet and HD 32297
Pascucci, Ilaria; Hughes, A. Meredith; Moór, Attila +7 more
Previous observations revealed the existence of CO gas at nearly protoplanetary level in several dust-rich debris disks around young A-type stars. Here we used the Atacama Large Millimeter/submillimeter Array (ALMA) 7 m Array to measure 13CO and C18O emission toward two debris disks, 49 Cet and HD 32297, and detected similarl…
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…
A Jovian planet in an eccentric 11.5 day orbit around HD 1397 discovered by TESS
Bouchy, F.; Stassun, K.; Winn, J. N. +49 more
The Transiting Exoplanet Survey Satellite TESS has begun a new age of exoplanet discoveries around bright host stars. We present the discovery of HD 1397b (TOI-120.01), a giant planet in an 11.54-day eccentric orbit around a bright (V = 7.9) G-type subgiant. We estimate both host star and planetary parameters consistently using EXOFASTv2 based on …
Properties of Slow Magnetoacoustic Oscillations of Solar Coronal Loops by Multi-instrumental Observations
Moon, Y. -J.; Nakariakov, V. M.; Kumar, P. +3 more
Rapidly decaying oscillations of the thermal emission detected in the decay phase of solar and stellar flares are usually interpreted as standing or sloshing (reflecting) slow magnetoacoustic oscillations. We determine the scalings of the oscillation periods, damping times, and amplitudes with the temperature, considering both standing and sloshin…
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…
Chemical and kinematic structure of extremely high-velocity molecular jets in the Serpens Main star-forming region
Hull, Charles L. H.; Le Gouellec, Valentin J. M.; van Dishoeck, Ewine F. +3 more
Context. Outflows are one of the first signposts of ongoing star formation. The fastest molecular component of protostellar outflows, extremely high-velocity (EHV) molecular jets, are still puzzling since they are seen only rarely. As they originate deep inside the embedded protostar-disk system, they provide vital information about the outflow-la…
A deep groundwater origin for recurring slope lineae on Mars
Heggy, Essam; Abotalib, Abotalib Z.
The recurring slope lineae on Mars have been hypothesized to originate from snow melting, deliquescence, dry flow or shallow groundwater. Except for the dry flow origin, these hypotheses imply the presence of surficial or near-surface volatiles, placing the exploration and characterization of potential habitable environments within the reach of ex…
Kinetic Turbulence in Astrophysical Plasmas: Waves and/or Structures?
Chen, Christopher H. K.; Grošelj, Daniel; Mallet, Alfred +3 more
The question of the relative importance of coherent structures and waves has for a long time attracted a great deal of interest in astrophysical plasma turbulence research, with a more recent focus on kinetic scale dynamics. Here we utilize high-resolution observational and simulation data to investigate the nature of waves and structures emerging…