Search Publications
Physical properties of fullerene-containing Galactic planetary nebulae
Otsuka, Masaaki; Peeters, E.; Bernard-Salas, J. +2 more
We searched the Spitzer Space Telescope data archive for Galactic planetary nebulae (PNe), which show the characteristic 17.4 and 18.9 µm features due to C60, also known as buckminsterfullerene. Out of 338 objects with Spitzer/Infrared Spectrograph data, we found eleven C60-containing PNe, six of which (Hen2-68, IC2501,…
The planetary nebula Abell 48 and its [WN] nucleus
Frew, David J.; Stupar, M.; Parker, Q. A. +6 more
We have conducted a detailed multi-wavelength study of the peculiar nebula Abell 48 and its central star. We classify the nucleus as a helium-rich, hydrogen-deficient star of type [WN4-5]. The evidence for either a massive WN or a low-mass [WN] interpretation is critically examined, and we firmly conclude that Abell 48 is a planetary nebula (PN) a…
The debris disc of solar analogue τ Ceti: Herschel observations and dynamical simulations of the proposed multiplanet system
Heras, A. M.; Fridlund, M.; Blommaert, J. A. D. L. +16 more
τ Ceti is a nearby, mature G-type star very similar to our Sun, with a massive Kuiper Belt analogue and possible multiplanet system that has been compared to our Solar system. We present Herschel Space Observatory images of the debris disc, finding the disc is resolved at 70 µm and 160 µm, and marginally resolved at 250 µm. The H…
Modelling the alumina abundance of oxygen-rich evolved stars in the Large Magellanic Cloud
Zijlstra, A. A.; McDonald, I.; Jones, O. C. +3 more
In order to determine the composition of the dust in the circumstellar envelopes of oxygen-rich asymptotic giant branch (AGB) stars, we have computed a grid of MODUST radiative-transfer models for a range of dust compositions, mass-loss rates, dust-shell inner radii and stellar parameters. We compare the resulting colours with the observed oxygen-…
Discovery of the Fomalhaut C debris disc
Duchêne, G.; Lestrade, J. -F.; Wyatt, M. C. +5 more
Fomalhaut is one of the most interesting and well-studied nearby stars, hosting at least one planet, a spectacular debris ring and two distant low-mass stellar companions (TW PsA and LP 876-10, a.k.a. Fomalhaut B and C). We observed both companions with Herschel, and while no disc was detected around the secondary, TW PsA, we have discovered the s…
A signature of chromospheric activity in brown dwarfs revealed by 2.5-5.0 µm AKARI spectra
Yamamura, I.; Sorahana, S.; Suzuki, T. K.
We propose that the 2.7-µm H2O, 3.3-µm CH4 and 4.6-µm CO absorption bands can be good tracers of chromospheric activity in brown dwarfs. In our previous study, we found that there are difficulties in explaining entire spectra between 1.0 and 5.0 µm with the unified cloudy model (UCM), a brown dwarf atm…
A radio characterization of Galactic compact bubbles
Paladini, R.; Umana, G.; Agliozzo, C. +6 more
We report the radio observations of a subsample of the 428 Galactic compact bubbles discovered at 24 µm with the MIPSGAL survey. Pervasive through the entire Galactic plane, these objects are thought to be different kinds of evolved stars. The very large majority of the bubbles (∼70 per cent) are however not yet classified. We conducted radi…
TYC 3159-6-1: a runaway blue supergiant
Miroshnichenko, A. S.; Gvaramadze, V. V.; Zharikov, S. V. +2 more
We report the results of optical spectroscopy of a candidate evolved massive star in the Cygnus-X region, TYC 3159-6-1, revealed via detection of its curious circumstellar nebula in archival data of the Spitzer Space Telescope. We classify TYC 3159-6-1 as an O9.5-O9.7 Ib star and derive its fundamental parameters by using the stellar atmosphere co…
What obscures low-X-ray-scattering active galactic nuclei
Hönig, S. F.; Gandhi, P.; Asmus, D. +4 more
X-ray surveys have revealed a new class of active galactic nuclei (AGN) with a very low observed fraction of scattered soft X-rays, fscat <0.5 per cent. Based on X-ray modelling, these `X-ray new-type', or low observed X-ray-scattering (hereafter, `low-scattering') sources have been interpreted as deeply buried AGN with a high coveri…
The first source counts at 18 µm from the AKARI NEP Survey
Im, M.; Lee, H. M.; Serjeant, S. +9 more
We present the first galaxy counts at 18 µm using the Japanese AKARI satellite's survey at the North Ecliptic Pole (NEP), produced from the images from the NEP-Deep and NEP-Wide surveys covering 0.6 and 5.8 deg2, respectively. We describe a procedure using a point source filtering algorithm to remove background structure and a min…