Search Publications
SUMER Measurement of the Fe X 3p43d 4D5/2,7/2 Energy Difference
Landi, E.; Li, W.; Hutton, R. +1 more
Recent studies have shown that magnetic fields in the solar corona are strong enough to significantly mix the two 3p43d 4D5/2,7/2 levels in Cl-like Fe X. This mixing gives rise to a magnetically induced transition (MIT) component in the bright Fe X 257.3 Å line, commonly observed by current instrumentation, that ca…
WR 72: a born-again planetary nebula with hydrogen-poor knots
Gvaramadze, V. V.; Gräfener, G.; Langer, N. +1 more
We report the discovery of a handful of optical hydrogen-poor (H-poor) knots in the central part of an extended infrared nebula centred on the [WO1] star WR 72, obtained by spectroscopic and imaging observations with the Southern African Large Telescope (SALT). Wide-field Infrared Survey Explorer (WISE) images of the nebula show that it is compose…
Uncovering the Primary X-Ray Emission and Possible Starburst Component in the Polarized NLS1 Mrk 1239
Komossa, S.; Gallo, Luigi C.; Grupe, Dirk +2 more
X-ray observations of the unique NLS1 galaxy Mrk 1239 spanning 18 yr are presented. Data from XMM-Newton, Suzaku, Swift, and NuSTAR are combined to obtain a broadband, multi-epoch view of the source. There is spectral variability in the 3-10 keV band over the 18 yr. An analysis of the NuSTAR and Suzaku lightcurves also suggests rapid variability i…
The PAU Survey: background light estimation with deep learning techniques
Carretero, J.; Castander, F. J.; García-Bellido, J. +17 more
In any imaging survey, measuring accurately the astronomical background light is crucial to obtain good photometry. This paper introduces BKGNET, a deep neural network to predict the background and its associated error. BKGNET has been developed for data from the Physics of the Accelerating Universe Survey (PAUS), an imaging survey using a 40 narr…
EUV-dependence of Venusian dayside ionopause altitude: VEX and PVO observations
Futaana, Yoshifumi; Fraenz, Markus; Wei, Yong +6 more
Average Radial Structures of Gas Convection in the Solar Granulation
Shimizu, T.; Oba, T.; Iida, Y.
Gas convection is observed in the solar photosphere as granulation, I.e., having highly time-dependent cellular patterns, consisting of numerous bright cells called granules and dark surrounding channels called intergranular lanes. Many efforts have been made to characterize the granulation, which may be used as an energy source for various types …
Herschel Observations of Disks around Late-type Stars
Gizis, John E.; Plavchan, Peter; Matrá, Luca +9 more
A set of twenty late-type (K5-M5) stars were observed with the Herschel Space Observatory at 100 and 160 microns with the goal of searching for far-infrared excesses indicative of the presence of circumstellar disks. Out of this sample, four stars (TYC 7443-1102-1, TYC 9340-437-1, GJ 784 and GJ 707) have infrared excesses above their stellar photo…
Variable stars in the Sh 2-170 H II region
Matsunaga, N.; Sharma, Saurabh; Sinha, Tirthendu +7 more
We present multi-epoch deep (∼20 mag) Ic-band photometric monitoring of the Sh 2-170 star-forming region to understand the variability properties of pre-main-sequence (PMS) stars. We report identification of 47 periodic and 24 non-periodic variable stars with periods and amplitudes ranging from ∼4 h to 18 d and from ∼0.1 to 2.0 mag, res…
The large amplitude X-ray variability in NGC 7589: possible evidence for accretion mode transition
Liu, Zhu; Yuan, Weimin; Liu, He-Yang +2 more
We report the discovery of large amplitude X-ray variability in the low-luminosity active galactic nucleus NGC 7589, and present possible observational evidence for accretion mode transition in this source. Long-term X-ray flux variations by a factor of more than 50 are found using X-ray data obtained by Swift/X-Ray Telescope and XMM-Newton over 1…
Low Water Outgassing from (24) Themis and (65) Cybele: 3.1 µm Near-IR Spectral Implications
Valtchanov, I.; Fornasier, S.; Küppers, M. +9 more
Asteroids (24) Themis and (65) Cybele have an absorption feature at 3.1 µm reported to be directly linked to surface water ice. We searched for water vapor escaping from these asteroids with the Herschel Space Observatory Heterodyne Instrument for the Far Infrared. While no H2O line emission was detected, we obtain sensitive 3σ wa…