Search Publications
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…
Variable stars in Palomar 13; an evaporating globular cluster
Arellano Ferro, A.; Muneer, S.; Giridhar, Sunetra +3 more
We present new CCD VI photometry of the distant globular cluster Pal 13. Fourier decomposition of the light curves of the three cluster member RRab stars lead to estimations of [Fe/H] = -1.65, and a distance of 23.67 ± 0.57 kpc. Light and colour near minimum phases for RRab stars leads to an estimate of E(B - V) = 0.104 ± 0.001. A V /(V - I) colou…
Recovering saturated images for high dynamic kernel-phase analysis. Application to the determination of dynamical masses for the system Gl 494AB
Beuzit, J. -L.; Laugier, R.; Martinache, F. +3 more
Kernel-phase observables extracted from mid- to high-Strehl images are proving to be a powerful tool to probe within a few angular resolution elements of point sources. The attainable contrast is limited, however, by the dynamic range of the imaging sensors. The Fourier interpretation of images with pixels exposed beyond the saturation has so far …
Circumstellar envelopes of semi-regular long-period variables: mass-loss rate estimates and general model fitting of the molecular gas
Alcolea, J.; Santander-García, M.; Bujarrabal, V. +4 more
Aims: We aim to study the main properties of a volume-limited unbiased sample of well-characterized semi-regular variables (SRs) in order to clarify important issues that need to be further explained, such as the formation of axially symmetric planetary nebulae (PNe) from spherical circumstellar envelopes (CSEs), which takes place during the …
NuSTAR Observations of the Unidentified INTEGRAL Sources: Constraints on the Galactic Population of HMXBs
Mori, Kaya; Hare, Jeremy; Stern, Daniel +3 more
The NuSTAR Legacy program titled Unidentified INTEGRAL Sources targeted faint hard X-ray sources revealed by INTEGRAL in the Galactic plane in order to provide conclusive identification of their nature and insights on the population of faint hard X-ray sources. The NuSTAR and Swift X-Ray Telescope observations obtained in 2015-2017 contributed to …
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] …