Search Publications
Episodic mass loss in binary evolution to the Wolf-Rayet phase: Keck and HST proper motions of RY Scuti's nebula
Filippenko, Alexei V.; Smith, Nathan; Gehrz, Robert D. +4 more
Binary mass transfer via -Roche lobe overflow (RLOF) is a key channel for producing stripped-envelope Wolf-Rayet (WR) stars and may be critical to account for Type Ib/c supernova progenitors. RY Scuti is an extremely rare example of a massive binary star caught in this brief but important phase. Its unusual toroidal nebula indicates equatorial mas…
Chandra X-ray spectroscopy of the very early O supergiant HD 93129A: constraints on wind shocks and the mass-loss rate
Leutenegger, Maurice A.; Cohen, David H.; Sundqvist, Jon O. +5 more
We present an analysis of both the resolved X-ray emission-line profiles and the broad-band X-ray spectrum of the O2 If* star HD 93129A, measured with the Chandra High Energy Transmission Grating Spectrometer (HETGS). This star is among the earliest and most massive stars in the Galaxy, and provides a test of the embedded wind-shock scenario in a …
Quiescent X-ray variability from the neutron star transient Aql X-1
Wijnands, R.; Miller, J. M.; Homan, J. +2 more
A number of studies have revealed variability from neutron star low-mass X-ray binaries during quiescence. Such variability is not well characterized, or understood, but may be a common property that has been missed due to lack of multiple observations. One such source where variability has been observed is Aql X-1. Here, we analyse 14 Chandra and…
Herschel/HerMES: the X-ray-infrared correlation for star-forming galaxies at z∼1
Pérez-Fournon, I.; Rodighiero, G.; Ivison, R. J. +36 more
For the first time, we investigate the X-ray/infrared (IR) correlation for star-forming galaxies (SFGs) at z∼ 1, using SPIRE submm data from the recently launched Herschel Space Observatory and deep X-ray data from the 2-Ms Chandra Deep Field-North survey. We examine the X-ray/IR correlation in the soft X-ray (SX; 0.5-2 keV) and hard X-ray (HX; 2-…
The CoRoT star 105288363: strong cycle-to-cycle changes of the Blazhko modulation
Poretti, E.; Szabó, R.; Kolenberg, K. +4 more
We present an analysis of the COnvection, ROtation and planetary Transits (CoRoT) star 105288363, a new Blazhko RR Lyrae star of type RRab (f0= 1.7623 d-1), observed with the CoRoT spacecraft during the second long run in the direction of the Galactic Centre (LRc02, time-base 145 d). The CoRoT data are characterized by an exc…
Interaction between the intergalactic medium and central radio source in the NGC 4261 group of galaxies
Zezas, A.; Wolter, A.; Giacintucci, S. +4 more
Using observations from the Chandra and XMM-Newton X-ray observatories, we examine the interaction between the intragroup medium and central radio source in the nearby NGC 4261 galaxy group. We confirm the presence of cavities associated with the radio lobes and estimate their enthalpy to be ∼2.4 × 1058 erg. The mechanical power output …
On the anomalous secular increase of the eccentricity of the orbit of the Moon
Iorio, L.
A recent analysis of a Lunar Laser Ranging (LLR) data record spanning 38.7 yr revealed an anomalous increase of the eccentricity e of the lunar orbit amounting to ? yr-1. The present-day models of the dissipative phenomena occurring in the interiors of both the Earth and the Moon are not able to explain it. In this paper, we examine sev…
The effects of dust on the optical and infrared evolution of SN 2004et
Welch, D. L.; Barlow, M. J.; Clayton, Geoffrey C. +8 more
We present an analysis of multi-epoch observations of the Type II-P supernova SN 2004et. New and archival optical spectra of SN 2004et are used to study the evolution of the Hα and [O I] 6300-Å line profiles between days 259 and 646. Mid-infrared imaging with Michelle on Gemini-North and with all three instruments of the Spitzer Space Telescope wa…
The basal chromospheric Mg II h+k flux of evolved stars: probing the energy dissipation of giant chromospheres
Pérez Martínez, M. Isabel; Schröder, K. -P.; Cuntz, M.
Of a total of 177 cool G, K and M giants and supergiants, we measured the Mg II h+k line emission of extended chromospheres in high-resolution (LWR) International Ultraviolet Explorer (IUE) spectra by using the IUE final data archive at the Space Telescope Science Institute (STScI) and derived the respective stellar surface fluxes. They represent …
The expansion proper motions of the planetary nebula NGC 6302 from Hubble Space Telescope imaging
Walsh, J. R.; Zijlstra, A. A.; Szyszka, C.
Planetary nebulae expand on time-scales of 103- 104 yr. For nearby objects, their expansion can be detected within years to decades. The pattern of expansion probes the internal velocity field and provides clues to the nebula ejection mechanism. In the case of non-symmetric nebulae, and bipolar nebulae in particular, it can a…