Search Publications
The multi-epoch X-ray tale of I Zwicky 1 outflows
Brandt, W. N.; Costantini, E.; Mehdipour, M. +3 more
The narrow-line Seyfert 1 galaxy $\rm I\,\,Zwicky\, 1$ shows a unique and complex system of ionized gas in outflow, which consists of an ultra-fast wind and a two-component warm absorber. In the last two decades, XMM-Newton monitored the source multiple times enabling the study of the long-term variability of the various outflows. Plasma in photoi…
Galaxy luminosity functions at redshifts 0.6-1.2 in the Chandra Deep Field South
Page, M. J.; Breeveld, A. A.; Sharma, M.
We present the rest-frame ultraviolet (UV) galaxy luminosity function (LF) and luminosity density (LD) measurements in the far-UV (1500 Å) wavelength, in the redshift range $z$ = 0.6-1.2. The UV LF is derived using XMM-Newton Optical Monitor (XMM-OM), UV (1600-4000 Å) observations of the Chandra Deep Field South, over an area of 396 arcmin2
The light-curve intrinsic variability in 47 Kepler contact binary stars
Debski, B.
This work studies the significance of light-curve intrinsic variability in the numerical modelling of contact binaries. Using synthetic light curves, we show that the starspot-based intrinsic variability increases the apparent mass ratio by $\Delta q=5{{\ \rm per\ cent}}$. For systems with orbital period P > 0.3 d, the effects of intrinsic vari…
On the physical nature of the Wilson-Bappu effect: revising the gravity and temperature dependence
Schröder, K. -P.; Jack, D.; Rosas-Portilla, F.
We present a sample of 32 stars of spectral types G and K and luminosity classes I-V, with moderate activity levels, covering four orders of magnitude of surface gravity and a representative range of effective temperature. For each star we obtained high signal-to-noise ratio (S/N) spectra from the Telescopio Internacional de Guanajuato Robótico-Es…
Characterizing spatial variations of PAH emission in the reflection nebula NGC 1333
Peeters, E.; Wolfire, M.; Knight, C. +1 more
Infrared emission features at 3.3, 6.2, 7.7, 8.6, and 11.2 µm, attributed to polycyclic aromatic hydrocarbons (PAHs), show variations in relative intensity, shape, and peak position. These variations depend on the physical conditions of the photodissociation region (PDR) in which strong PAH emission arises but their relationship has yet to be full…
A measurement of stellar surface gravity hidden in radial velocity differences of comoving stars
Slone, Oren; Cantiello, Matteo; Perets, Hagai B. +2 more
The gravitational redshift induced by stellar surface gravity is notoriously difficult to measure for non-degenerate stars, since its amplitude is small in comparison with the typical Doppler shift induced by stellar radial velocity. In this study, we make use of the large observational data set of the Gaia mission to achieve a significant reducti…
Hen 3-860: new southern eclipsing symbiotic star observed in the outburst
Merc, J.; Gális, R.; Wolf, M. +3 more
Brightening of Hen 3-860, previously classified as an Hα emitter, was detected by the All-Sky Automated Survey for Supernovae (ASAS-SN) survey at the end of the year 2016. We have obtained the first spectroscopic observations of the transient and supplemented them with photometric data from the Digital Access to a Sky Century at Harvard (DASCH) ar…
Searching for young runaways across the sky
Stassun, Keivan G.; Kounkel, Marina; Leigh, Nathan +1 more
We present a catalogue of 3354 candidate young stars within 500 pc that appear to have been ejected from their parent associations with relative speeds of >5 km s-1. These candidates have been homogeneously selected through performing a 2D spherical traceback of previously identified pre-main-sequence candidates to various star-formi…
K2-99 revisited: a non-inflated warm Jupiter, and a temperate giant planet on a 522-d orbit around a subgiant
Fridlund, M.; Guenther, E. W.; García, R. A. +29 more
We report new photometric and spectroscopic observations of the K2-99 planetary system. Asteroseismic analysis of the short-cadence light curve from K2's Campaign 17 allows us to refine the stellar properties. We find K2-99 to be significantly smaller than previously thought, with R⋆ = 2.55 ± 0.02 R⊙. The new light curve also…
Discovery of two bright high-redshift gravitationally lensed quasars revealed by Gaia
McMahon, Richard G.; Auger, Matthew W.; Anguita, Timo +4 more
We present the discovery and preliminary characterisation of two high-redshift gravitationally lensed quasar systems in Gaia Data Release 2 (DR2). Candidates with multiple close-separation Gaia detections and quasar-like colours in WISE, Pan-STARRS, and DES are selected for follow-up spectroscopy with the New Technology Telescope. We confirm DES J…