Search Publications
Earth through the looking glass: how frequently are we detected by other civilizations through photometric microlensing?
Robin, A. C.; Awiphan, S.; Kerins, E. +5 more
Microlensing is proving to be one of the best techniques to detect distant, low-mass planets around the most common stars in the Galaxy. In principle, Earth's microlensing signal could offer the chance for other technological civilizations to find the Earth across Galactic distances. We consider the photometric microlensing signal of Earth to othe…
Comparing reflection and absorption models for the soft X-ray variability in the NLS1 AGN UGC 11763
Jiang, Jiachen; Gallo, Luigi C.; Grupe, Dirk +1 more
We present a spectral analysis of two XMM-Newton observations of the narrow-line Seyfert 1 galaxy UGC 11763. UGC 11763 shows very different soft X-ray spectral shapes in the two observations separated by 12 yr. Three spectral models are considered to explain the multi-epoch X-ray variability of UGC 11763, one based on the relativistic disc reflect…
On the physical size of the Milky Way globular cluster NGC 7089 (M2)
Piatti, Andrés E.
We study the outer regions of the Milky Way globular cluster NGC 7089 based on new Dark Energy Camera observations. The resulting background-cleaned stellar density profile reveals the existence of an extended envelope. We confirm previous results that cluster stars are found out up to ~1° from the cluster's centre, which is nearly three times the…
Dependence of the eruptive filaments dynamics on their length
Filippov, B.
We analyse numerically a model of eruption of a thin flux rope with the endpoints frozen in the photosphere. The flux rope is assumed to maintain a shape of partial current-carrying torus staying initially in equilibrium in the external dipolar magnetic field. There is an unstable equilibrium point, which can be reached by slow evolution of the sy…
Improving the solar wind density model used in processing of spacecraft ranging observations
Pavlov, Dmitry; Aksim, Dan
Solar wind plasma as a cause of radio signal delay plays an important role in solar and planetary science. Early experiments studying the distribution of electrons near the Sun from spacecraft ranging measurements were designed so that the radio signal was passing close to the Sun. At present, processing of spacecraft tracking observations serves …
Hubble Space Telescope Captures UGC 12591: bulge/disc properties, star formation and 'missing baryons' census in a very massive and fast-spinning hybrid galaxy
Mukherjee, Dipanjan; Mirakhor, Mohammad; Dhiwar, Suraj +4 more
We present Hubble Space Telescope (HST) observations of the nearby, massive, highly rotating hybrid galaxy UGC 12591, along with observations in the UV to FIRbands. HST data in V, I, and H bands is used to disentangle the structural components. Surface photometry shows a dominance of the bulge over the disc with an H-band B/D ratio of $69{{\,\rm p…
Broad-band spectral analysis of LMXB 2S 0921-63 with Suzaku
Jain, Chetana; Dutta, Anjan; Sharma, Prince
We present the broad-band spectral analysis of the low-mass X-ray binary 2S 0921-63 by using the Suzaku archival data covering the orbital phase between 0.31 and 1.16 during four close observations. It is the first time that a broad-band spectral analysis of 2S 0921-63 has been done up to 25 keV. The 0.5-10 keV XIS count rate varied between ~1 and…
On the validity of the spectroscopic age indicators [Y/Mg], [Y/Al], [Y/Si], [Y/Ca], and [Y/Ti] for giant stars
Abuchaim, Yuri; Kerber, Leandro; Katime Santrich, Orlando J. +1 more
The abundance ratios [Y/Mg], [Y/Al], [Y/Si], [Y/Ca], and [Y/Ti] have been suggested as chemical clocks for solar-metallicity dwarf stars in the field as well as for giant stars in open clusters. To verify this last hypothesis, we derive these abundances ratios of 50 giant stars belonging to seven open clusters. To calculate the abundances, we anal…
Companion mass limits for 17 binary systems obtained with binary differential imaging and MagAO/Clio
Weinberger, Alycia J.; Close, Laird M.; Males, Jared R. +4 more
Improving direct detection capability close to the star through improved star subtraction and post-processing techniques is vital for discovering new low-mass companions and characterizing known ones at longer wavelengths. We present results of 17 binary star systems observed with the Magellan adaptive optics system (MagAO) and the Clio infrared c…
A multiwavelength study of the flat-spectrum radio quasar NVSS J141922-083830 covering four flaring episodes
Stalin, C. S.; Kniazev, A.; Buckley, D. A. H. +9 more
We present multiwavelength observations and a model for flat-spectrum radio quasar (FSRQ) NVSS J141922-083830, originally classified as a blazar candidate of unknown type (BCU II object) in the Third Fermi-LAT AGN Catalog. Relatively bright flares (>3 magnitudes) were observed on 2015 February 21 (MJD 57074) and 2018 September 8 (MJD 58369) in …