Search Publications
Frequency of Planets in Binaries
Bonavita, Mariangela; Desidera, Silvano
The frequency of planets in binaries is an important issue in the field of extrasolar planet studies because of its relevance in the estimation of the global planet population of our galaxy and the clues it can give to our understanding of planet formation and evolution. Multiple stars have often been excluded from exoplanet searches, especially t…
The UV Perspective of Low-Mass Star Formation
France, Kevin; Schneider, P. Christian; Günther, H. Moritz
The formation of low-mass (M★≲2M⊙) stars in molecular clouds involves accretion disks and jets, which are of broad astrophysical interest. Accreting stars represent the closest examples of these phenomena. Star and planet formation are also intimately connected, setting the starting point for planetary systems like our own. The ultraviolet (UV) sp…
Massive Star Formation in the Ultraviolet Observed with the Hubble Space Telescope
Leitherer, Claus
Spectroscopic observations of a massive star formation in the ultraviolet and their interpretation are reviewed. After a brief historical retrospective, two well-studied resolved star clusters and the surrounding H II regions are introduced: NGC 2070 in the Large Magellanic Cloud and NGC 604 in M33. These regions serve as a training set for studie…
Unraveling the Physics of Quasar Jets: Optical Polarimetry and Implications for the X-ray Emission Process
Perlman, Eric S.; Clautice, Devon; Avachat, Sayali +4 more
Since the launch of Chandra twenty years ago, one of the greatest mysteries surrounding Quasar Jets is the production mechanism for their extremely high X-ray luminosity. Two mechanisms have been proposed. In the first view, the X-ray emission is inverse-Comptonized CMB photons. This view requires a jet that is highly relativistic (bulk Lorentz fa…
Short-Term X-ray Variability during Different Activity Phases of Blazars S5 0716+714 and PKS 2155-304
Pal, Main; Kushwaha, Pankaj
We explored the statistical properties of short-term X-ray variability using long-exposure XMM-Newton data during high X-ray variability phases of blazars S5 0716+714 and PKS 2155-304. In general, the hardness ratio shows correlated variations with the source flux state (count rate), but in a few cases, mainly the bright phases, the trend is compl…
Gaia DR2 Distances to Planetary Nebulae
Manteiga, Minia; Dafonte, Carlos; Manchado, Arturo +2 more
The aim of this work is to examine distances to planetary nebulae (PNe) together with other properties that were derived from them, using the astrometry of Gaia Data Release 2 (DR2). We were able to identify 1571 objects classified as PNe, for which we assumed distances calculated following a Bayesian statistical approach. From those objects, we s…
First Results from a Panchromatic HST/WFC3 Imaging Study of the Young, Rapidly Evolving Planetary Nebulae NGC 7027 and NGC 6302
Frank, Adam; Balick, Bruce; Kastner, Joel H. +3 more
We present the first results from comprehensive, near-UV-to-near-IR Hubble Space Telescope Wide Field Camera 3 (WFC3) emission-line imaging studies of two young planetary nebulae (PNe), NGC 7027 and NGC 6302. These two objects represent key sources for purposes of understanding PNe shaping processes. Both nebulae feature axisymmetric and point-sym…
X-ray Flux and Spectral Variability of Blazar H 2356-309
Gaur, Haritma; Wani, Kiran A.
We present the results of timing and spectral analysis of the blazar H 2356-309 using XMM-Newton observations. This blazar is observed during 13 June 2005–24 December 2013 in total nine observations. Five of the observations show moderate flux variability with amplitude 1.7–2.2%. We search for the intra-day variability timescales in these five lig…
On the Age of Galactic Bulge CSPNe: Too Young and Complicated?
Parker, Quentin A.; Lykou, Foteini; Zijlstra, Albert
We present preliminary results of our study of a small sample of planetary nebulae in the Galactic Bulge for which high-angular resolution Hubble Space Telescope imaging is available. From this and from archival spectroscopy, we were able to calculate temperatures and luminosities for their central stars. These were then correlated to up-to-date e…