Published in ScienceOpen Astronomy & Astrophysics
Aims. Generally, the oblateness of a planet or moon is what causes rings to settle into its equatorial plane. However, the recent suggestion that a ring system might exist (or have existed) about Rhea, a moon whose shape includes a strong prolate component pointed toward Saturn, raises the question of whether rings around a triaxial primary can be ...
Published in ScienceOpen Astronomy & Astrophysics
Context. The unknown identity of the diffuse interstellar band (DIB) carriers poses one of the longest standing unresolved problems in astrophysics. While the presence, properties, and behaviour of hundreds of optical DIBs between 4000 Å and 9000 Å have been well established, information on DIBs in both the ultra-violet and near-infrared (NIR) rang...
Published in ScienceOpen Astronomy & Astrophysics
Context. The central star of the HR 8799 system is a γ Doradus-type pulsator. The system harbours four planetary-mass companions detected by direct imaging, and is a good solar system analogue. The masses of the companions are not accurately known because the estimation depends greatly on the age of the system, which is also not known with sufficie...
Published in ScienceOpen Astronomy & Astrophysics
We present J, H, CH 4 short (1.578 μ m), CH 4 long (1.652 μ m) and K s-band images of the dust ring around the 10 Myr old star HR 4796 A obtained using the Near Infrared Coronagraphic Imager (NICI) on the Gemini-South 8.1 m Telescope. Our images clearly show for the first time the position of the star relative to its circumstellar ring thanks to NI...
Published in ScienceOpen Astronomy & Astrophysics
In this work we study the kinematics of three small-scale (0.01 R⊙) blobs of chromospheric plasma falling back to the Sun after the huge eruptive event of June 7, 2011. From a study of 3D trajectories of blobs made with the Solar TErrestrial RElations Observatory (STEREO) data, we demonstrate the existence of a significant drag force acting on the ...
Published in ScienceOpen Astronomy & Astrophysics
Context. The internal structure of pre-main-sequence (PMS) stars is poorly constrained at present. This could change significantly through high-quality asteroseismological observations of a sample of such stars. Aims. We concentrate on an asteroseismological study of HD 261711, a rather hot δ Scuti-type pulsating member of the young open cluster NG...
Published in ScienceOpen Astronomy & Astrophysics
We discuss inversion methods for shape reconstruction with complementary data sources. The current main sources are photometry, adaptive optics or other images, occultation timings, and interferometry, and the procedure can readily be extended to include range-Doppler radar and thermal infrared data as well. We introduce the octantoid, a generally ...
Published in ScienceOpen Astronomy & Astrophysics
We report on the discovery of an infrared emission band in the Spitzer spectrum of the S-type AGB star NP Aurigae that is caused by TiO molecules in the circumstellar environment. We modeled the observed emission to derive the temperature of the TiO molecules (≈ 600 K), an upper limit on the column density (≈ 10 17.25 cm-2) and a lower limit on the...
Published in ScienceOpen Astronomy & Astrophysics
Context. The circumstellar environment of evolved stars is generally rich in molecular gas and dust. Typically, the entire environment is either oxygen-rich or carbon- rich, depending on the evolution of the central star. Aims. In this paper we discuss three evolved disc sources with evidence of atypical emission lines in their infrared spectra. Th...
Published in ScienceOpen Astronomy & Astrophysics
Context. The planetary system WASP-33 is an interesting target because of the discovery of a transiting planet, the misalignment of the stellar rotation axis and the planet orbit, the possible existence of an additional planet in the system, and the presence of δ Scuti pulsations in the hosting star. Its study promises in particular to help us unde...
