Search Publications
The Central Star of NGC 2346 as a Clue to Binary Evolution through the Common Envelope Phase
Bianchi, L.; Manteiga, M.; Gómez-Muñoz, M. A. +2 more
We present an analysis of the binary central star of the planetary nebula NGC 2346 based on archival data from the International Ultraviolet Explorer, and new low- and high-resolution optical spectra (3700-7300 Å). By including in the spectral analysis the contribution of both stellar and nebular continuum, we reconciled long-time discrepant UV an…
Search for Evolutionary Changes in the Periods of Cepheids: V1033 Cyg, a Classical Cepheid at the First Crossing of the Instability Strip
Lemasle, B.; Berdnikov, L. N.; Kniazev, A. Yu. +9 more
For the classical Cepheid V1033 Cyg we have constructed an O—C diagram spanning a time interval of 117 years. The O—C diagram has the shape of a parabola, which has made it possible to determine for the first time the quadratic light elements and to calculate the rate of evolutionary increase in the period dP/dt = 18.19 (±0.08) syr-1, i…
A slowly expanding torus associated with the candidate LBV MGE 042.0787+00.5084
Bordiu, Cristobal; Rizzo, J. Ricardo; Ritacco, Alessia
The luminous blue variable (LBV) phase is a poorly understood stage in the evolution of high-mass stars, characterized by its brevity and instability. The surroundings of LBV stars are excellent test beds to study their dense stellar winds and eruptive mass-loss events. Aiming to improve our knowledge of the LBV phase, we observed the J = 1 → 0 an…
Kelvin-Helmholtz Waves Magnetic Curvature and Vorticity: Four-Spacecraft Cluster Observations
Kieokaew, Rungployphan; Foullon, Claire
[1] Magnetopause Kelvin-Helmholtz (KH) waves are rich in complex magnetic and flow structures which are key to understand the role of these waves in facilitating the solar wind plasma transport into the Earth's magnetosphere. Four spacecraft in tetrahedral configuration provide the tools necessary for characterizing in situ magnetic geometry and v…
Variables in the Southern Polar Region Evryscope 2016 Data Set
Trifonov, Trifon; Law, Nicholas M.; Fors, Octavi +6 more
The regions around the celestial poles offer the ability to find and characterize long-term variables from ground-based observatories. We used multi-year Evryscope data to search for high-amplitude (≈5% or greater) variable objects among 160,000 bright stars (mv < 14.5) near the South Celestial Pole. We developed a machine-learning-b…
Edge-on Galaxies in the Hubble Ultra Deep Field
Savchenko, S. S.; Reshetnikov, V. P.; Usachev, P. A.
We have produced a sample of 58 edge-on spiral galaxies at redshifts z 1 selected in the Hubble Ultra Deep Field. For all galaxies we have analyzed the 2D brightness distributions in the V 606 and i 775 filters and measured the radial ( h r ) and vertical ( h z ) exponential scale lengths of the bright…
Climatology of CH4, HCN and C2H2 in Titan's upper atmosphere from Cassini/VIMS observations
Funke, Bernd; Filacchione, Gianrico; García-Comas, Maya +7 more
The Visual and Infrared Mapping Spectrometer (VIMS) measurements of non-Local Thermodinamic Equilibrium (non-LTE) emissions of CH4, HCN and C2H2 in the near-infrared represent a dataset with unique coverage to study Titan's upper atmosphere in the altitude range from 500 to 1000 km. This region is the key to a bett…
Multiwavelength study of the G345.5+1.5 region
Zavagno, A.; Hervías-Caimapo, C.; Bronfman, L. +4 more
Context. The star formation process requires the dust and gas present in the Milky Way to self-assemble into dense reservoirs of neutral material where the new generation of stars will emerge. Star-forming regions are usually studied in the context of Galactic surveys, but dedicated observations are sometimes needed when the study reaches beyond t…
Evidence for a TDE origin of the radio transient Cygnus A-2
Reynolds, C. S.; Rowlinson, A.; Siemiginowska, A. +3 more
In 2015, a radio transient named Cygnus A-2 was discovered in Cygnus A with the Very Large Array. Because of its radio brightness (νFν ≈ 6 × 1039 erg s-1), this transient likely represents a secondary black hole in orbit around the active galactic nucleus. Using Chandra ACIS observations from 2015 to 2017, we have …
Difference of source regions between fast and slow coronal mass ejections
Filippov, B.
Coronal mass ejections (CMEs) are tightly related to filament eruptions and usually are their continuation in the upper solar corona. It is common practice to divide all observed CMEs into fast and slow ones. Fast CMEs usually follow eruptive events in active regions near big sunspot groups and associated with major solar flares. Slow CMEs are mor…