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Discovery of a radio transient in M81
Gandhi, P.; Miller-Jones, J. C. A.; Fender, R. P. +9 more
We report the discovery of a radio transient in the spiral galaxy M81. The transient was detected in early 2015 as part of a two-year survey of M81 made up of 12 epochs using the Karl G. Jansky Very Large Array. While undetected on 2014 September 12, the source was first detected on 2015 January 2, from which point it remained visible at an approx…
Multiband Study of a Bidirectional Jet Occurred in the Upper Chromosphere
Reeves, Katharine K.; Ni, Lei; Lin, Jun +3 more
We present a study of a jet observed by the Solar Dynamics Observatory (SDO) and the Interface Region Imaging Spectrograph (IRIS), which provide high spatial-temporal resolution observational data of (extreme) ultraviolet images, spectra, and magnetograms. The jet was observed in multiple bands of AIA and manifested clear bidirectional flows in IR…
Direct detection anomalies in light of G A I A data
Buckley, Matthew R.; Mohlabeng, Gopolang; Murphy, Christopher W.
Measurements from the GAIA satellite have greatly increased our knowledge of the dark matter velocity distributions in the Solar neighborhood. There is evidence for multiple cold structures nearby, including a high-velocity stream counterrotating relative to the Sun. This stream could significantly alter the spectrum of recoil energies and increas…
The beamed jet and quasar core of the distant blazar 4C 71.07
Lähteenmäki, A.; Giroletti, M.; Villata, M. +61 more
The object 4C 71.07 is a high-redshift blazar whose spectral energy distribution shows a prominent big blue bump and a strong Compton dominance. We present the results of a 2-yr multiwavelength campaign led by the Whole Earth Blazar Telescope (WEBT) to study both the quasar core and the beamed jet of this source. The WEBT data are complemented by …
Quiescent X-ray variability in the neutron star Be/X-ray transient GRO J1750-27
Degenaar, N.; Wijnands, R.; Kaper, L. +5 more
The Be/X-ray transient GRO J1750-27 exhibited a type-II (giant) outburst in 2015. After the source transited to quiescence, we triggered our multi-year Chandra monitoring programme to study its quiescent behaviour. The programme was designed to follow the cooling of a potentially heated neutron-star crust due to accretion of matter during the prec…
Two's company, three's a crowd: SALT reveals the likely triple nature of the nucleus of the extreme abundance discrepancy factor planetary nebula Sp 3
Miszalski, Brent; Manick, Rajeev; Rauch, Thomas +3 more
The substantial number of binary central stars of planetary nebulae (CSPNe) now known (∼50) has revealed a strong connection between binarity and some morphological features including jets and low-ionisation structures. However, some morphological features and asymmetries might be too complex or subtle to ascribe to binary interactions alone. In t…
Sub-Eddington Supermassive Black Hole Activity in Fornax Early-type Galaxies
Treu, Tommaso; Ferrarese, Laura; Gallo, Elena +6 more
We characterize the incidence and intensity of low-level supermassive black hole activity within the Fornax cluster, through X-ray observations of the nuclei of 29 quiescent early-type galaxies. Using the Chandra X-ray Telescope, we target 17 galaxies from the Hubble Space Telescope Fornax Cluster Survey, down to a uniform (3σ) limiting X-ray lumi…
AGILE, Fermi, Swift, and GASP/WEBT multi-wavelength observations of the high-redshift blazar 4C +71.07 in outburst
Lähteenmäki, A.; Longo, F.; Morselli, A. +56 more
Context. The flat-spectrum radio quasar 4C +71.07 is a high-redshift (z = 2.172), γ-loud blazar whose optical emission is dominated by thermal radiation from the accretion disc.
Aims: 4C +71.07 has been detected in outburst twice by the AGILE γ-ray satellite during the period from the end of October to mid-November 2015, when it reached a γ-r…
Spot evolution in the eclipsing binary CoRoT 105895502
Schmitt, J. H. M. M.; Czesla, S.; Wichmann, R. +1 more
Stellar activity is ubiquitous in late-type stars. The special geometry of eclipsing binary systems is particularly advantageous to study the stellar surfaces and activity. We present a detailed study of the 145 d CoRoT light curve of the short-period (2.17 d) eclipsing binary CoRoT 105895502. By means of light-curve modeling with Nightfall, we de…
Estimation of Arrival Time of Coronal Mass Ejections in the Vicinity of the Earth Using SOlar and Heliospheric Observatory and Solar TErrestrial RElations Observatory Observations
Ravishankar, Anitha; Michałek, Grzegorz
The arrival time of coronal mass ejections (CMEs) in the vicinity of the Earth is one of the most important parameters in determining space weather. We have used a new approach to predicting this parameter. First, in our study, we have introduced a new definition of the speed of ejection. It can be considered as the maximum speed that the CME achi…