Search Publications
USuRPER: Unit-sphere representation periodogram for full spectra
Zucker, S.; Binnenfeld, A.; Shahaf, S.
We introduce an extension of the periodogram concept to time-resolved spectroscopy. USuRPER, the unit-sphere representation periodogram, is a novel technique that opens new horizons in the analysis of astronomical spectra. It can be used to detect a wide range of periodic variability of the spectrum shape. Essentially, the technique is based on re…
Synoptic solar observations of the Solar Flare Telescope focusing on space weather
Sakurai, Takashi; Hanaoka, Yoichiro; Morita, Satoshi +2 more
The solar group at the National Astronomical Observatory of Japan is conducting synoptic solar observation with the Solar Flare Telescope. While it is a part of a long-term solar monitoring, contributing to the study of solar dynamo governing solar activity cycles, it is also an attempt at contributing to space weather research. The observations i…
Spectroscopic Studies of 30 Short-period Cataclysmic Variable Stars and Remarks on the Evolution and Population of Similar Objects
Thorstensen, John R.
We present spectroscopy and orbital periods Porb for 30 apparently nonmagnetic cataclysmic binaries with periods below ∼3 hr, nearly all of which are dwarf novae, mostly of the SU Ursae Majoris subclass. We then turn to the evidence supporting the prediction that short-period dwarf novae evolve toward longer periods after passing throug…
The Fundamental Plane of cluster spheroidal galaxies at z ∼ 1.3: evidence for mass-dependent evolution
Marchesini, D.; Annunziatella, M.; Gargiulo, A. +2 more
We present spectroscopic observations obtained at the Large Binocular Telescope in the field of the cluster XLSSJ0223-0436 at z = 1.22. We confirm 12 spheroids cluster members and determine stellar velocity dispersion for 7 of them. We combine these data with those in the literature for clusters RXJ0848+4453 at z = 1.27 (8 galaxies) and XMMJ2235-2…
Low-energy electron emission at the separation of gold-platinum surfaces induced by galactic cosmic rays on board LISA Pathfinder
Grimani, Catia; Villani, Mattia; Fabi, Michele +1 more
Galactic cosmic rays and solar energetic particles will induce spurious Coulomb forces on free-falling, gold-platinum test-masses on board the future interferometers for low-frequency gravitational wave detection in space. The European Space Agency mission LISA Pathfinder (LPF) was aimed to test the performance of instruments that will be placed o…
The Spatially Resolved Bipolar Nebula of Sakurai's Object. II. Mapping the Planetary Nebula Expansion
Matheson, Thomas; Hinkle, Kenneth H.; Joyce, Richard R. +2 more
Observations of the ejecta from the final flash (FF) of helium shell burning in Sakurai's Object (V4334 Sgr) are presented for 2015-2019, a period ∼20-24 yr after discovery. Adaptive optics images at Ks trace the expanding debris. While most of the ejecta mass is in ∼200 K dust, a small fraction, ∼0.4%, of the dust mass is at ∼760 K. Th…
Streaming classification of variable stars
Protopapas, P.; Zorich, L.; Pichara, K.
In the last years, automatic classification of variable stars has received substantial attention. Using machine learning techniques for this task has proven to be quite useful. Typically, machine learning classifiers used for this task require to have a fixed training set, and the training process is performed offline. Upcoming surveys such as the…
Simultaneous detection of an intrinsic absorber and a compact jet emission in the X-ray binary IGR J17091-3624 during a hard accretion state
Díaz Trigo, M.; Miller-Jones, J. C. A.; Migliari, S. +1 more
We present a detailed analysis of three XMM-Newton observations of the black hole low-mass X-ray binary IGR J17091-3624 taken during its 2016 outburst. Radio observations obtained with the Australia Telescope Compact Array indicate the presence of a compact jet during all observations. From the best X-ray data fit results, we concluded that the ob…
Rhea's subsurface probed by the Cassini radiometer: Insights into its thermal, structural, and compositional properties
Lellouch, E.; Le Gall, A.; Leyrat, C. +3 more
During its 13.5 years of operation around the Saturn system, the microwave radiometer incorporated in the Cassini RADAR observed Rhea at 2.2 cm during 9 flybys, with resolutions up to a tenth of Rhea's radius. We compare the antenna temperatures measured by this instrument to simulated data generated with the combination of thermal, radiative tran…
X-ray variability analysis of a large series of XMM-Newton +NuSTAR observations of NGC 3227
Turner, T. J.; Reeves, J. N.; Braito, V. +2 more
We present a series of X-ray variability results from a long XMM-Newton + NuSTAR campaign on the bright, variable AGN NGC 3227. We present an analysis of the light curves, showing that the source displays typically softer-when-brighter behaviour, although also undergoes significant spectral hardening during one observation which we interpret as du…