Search Publications
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…
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 …
Primeval very low-mass stars and brown dwarfs - VII. The discovery of the first wide M + L extreme subdwarf binary
Zhang, ZengHua
I present the discovery of the first wide M + L extreme subdwarf binary system Gaia J0452-36AB. The binary is located at a distance of 137.27 ^{+0.68}_{-0.67} pc with a projected separation of 15828 ± 78 au. I classified Gaia J0452-36AB as esdM1 and esdL0 subdwarfs, respectively. Gaia J0452-36AB have typical halo kinematics, metallicity of [Fe/H] …
On the ion-neutral coupling in cometary comae
Eriksson, Anders I.; Vigren, Erik
In a cometary coma, the ion-neutral decoupling distance, sometimes referred to as the ion exobase or collisionopause, can be defined as the cometocentric distance, rin, where ions, initially moving with the neutral outgassing speed, have a probability of 1/e of not colliding with neutrals on their subsequent journey radially outwards. W…
The exceptional X-ray evolution of SN 1996cr in high resolution
Bauer, F. E.; Brandt, W. N.; Quirola-Vásquez, J. +4 more
We present X-ray spectra spanning 18 yr of evolution for SN 1996cr, one of the five nearest SNe detected in the modern era. Chandra HETG exposures in 2000, 2004, and 2009 allow us to resolve spectrally the velocity profiles of Ne, Mg, Si, S, and Fe emission lines and monitor their evolution as tracers of the ejecta-circumstellar medium interaction…
Towards observing reverberating and superefficient pulsar wind nebulae
Coti Zelati, Francesco; Torres, Diego F.; Lin, Tingting
In a recent work, we numerically studied the radiative properties of the reverberation phase of pulsar wind nebulae (PWNe), i.e. when the reverse shock created by the supernova explosion travels back towards the pulsar, compressing the wind bubble. We focused on several well-characterized PWNe and used them as examples for introducing the concept …
Empirical method of proper element calculation and identification of asteroid families
Vinogradova, T. A.
A search for asteroid families was carried out with the use of a proper element set comprising 649 050 asteroid orbits. Proper elements were calculated by the empirical method. This method uses distributions of orbital elements to calculate secular perturbations. There are two types of secular perturbations: the classical perturbations and the Lid…
A cold stellar stream in Pegasus
Perottoni, Hélio D.; Rocha-Pinto, Helio J.; Newberg, Heidi Jo +3 more
We report the serendipitous discovery of a stellar stream in the constellation Pegasus in the south Galactic hemisphere. The stellar stream was detected using the SDSS Data Release 14 by means of a matched filter in the colour-magnitude diagram that is optimized for a stellar population that is 8 Gyr old with [Fe/H] = -0.46 dex, and located at hel…
A low-mass triple system with a wide L/T transition brown dwarf component: NLTT 51469AB/SDSS 2131-0119
Rebolo, R.; Béjar, V. J. S.; Zapatero Osorio, M. R. +6 more
We demonstrate that the previously identified L/T transition brown dwarf SDSS J213154.43-011939.3 (SDSS 2131-0119) is a widely separated (82{^''.}3, ∼3830 au) common proper motion companion to the low-mass star NLTT 51469, which we reveal to be a close binary itself, separated by 0{^''.}64 ± 0{^''.}01 (∼30 au). We …
A radio structure resolved at the deca-parsec scale in the radio-quiet quasar PDS 456 with an extremely powerful X-ray outflow
Zhang, Zhongli; Paragi, Zsolt; Yang, Jun +5 more
Active galactic nuclei (AGNs) accreting at rates close to the Eddington limit can host radiatively driven mildly relativistic outflows. Some of these X-ray absorbing but powerful outflows can produce strong shocks, resulting in a significant non-thermal emission. This outflow-driven radio emission might be detectable in the radio-quiet quasar PDS …