Search Publications
Determining the forsterite abundance of the dust around asymptotic giant branch stars
Waters, L. B. F. M.; Blommaert, J. A. D. L.; Min, M. +2 more
Aims: We present a diagnostic tool to determine the abundance of the crystalline silicate forsterite in AGB stars surrounded by a thick shell of silicate dust. Using six infrared spectra of high mass-loss oxygen rich AGB stars we obtain the forsterite abundance of their dust shells.
Methods: We use a monte carlo radiative transfer code t…
Physical properties of the ESA Rosetta target asteroid (21) Lutetia. I. The triaxial ellipsoid dimensions, rotational pole, and bulk density
Carry, B.; Weaver, H. A.; Merline, W. J. +6 more
Context. Asteroid (21) Lutetia was the target of the ESA Rosetta mission flyby in 2010 July.
Aims: We seek the best size estimates of the asteroid, the direction of its spin axis, and its bulk density, assuming its shape is well described by a smooth featureless triaxial ellipsoid. We also aim to evaluate the deviations from this assumption. …
Resolving the dusty circumstellar environment of the A[e] supergiant HD 62623 with the VLTI/MIDI
Lopez, B.; Meilland, A.; Millour, F. +4 more
Context. B[e] stars are hot stars surrounded by circumstellar gas and dust which is responsible for the presence of emission lines and IR-excess in their spectra. How dust can be formed in this highly illuminated and diluted environment remains an open issue.
Aims: HD 62623 is one of the very few A-type supergiants showing the B[e] phenomenon…
Properties of compact 250 µm emission and H II regions in M 33 (HERM33ES)
Boquien, M.; Braine, J.; Calzetti, D. +12 more
Aims: Within the framework of the HERM33ES key program, using the high resolution and sensitivity of the Herschel photometric data, we study the compact emission in the Local Group spiral galaxy M 33 to investigate the nature of the compact SPIRE emission sources. We extracted a catalogue of sources at 250 µm in order to investigate the…
An HST/WFPC2 survey of bright young clusters in M 31. IV. Age and mass estimates
Barmby, P.; Bellazzini, M.; Galleti, S. +11 more
Aims: We present the main results of an imaging survey of possible young massive clusters (YMC) in M 31 performed with the Wide Field and Planetary Camera 2 (WFPC2) on the Hubble Space Telescope (HST), with the aim of estimating their age and their mass. We obtained shallow (to B ∼ 25) photometry of individual stars in 19 clusters (of the 20 …
Trend of photospheric magnetic helicity flux in active regions generating halo coronal mass ejections
Guglielmino, S. L.; Romano, P.; Spadaro, D. +5 more
Context. Coronal mass ejections (CMEs) are very energetic events (~ 1032 erg) initiated in the solar atmosphere, resulting in the expulsion of magnetized plasma clouds that propagate into interplanetary space. It has been proposed that CMEs can play an important role in shedding magnetic helicity, avoiding its endless accumulation in th…
LoCuSS: A Herschel view of obscured star formation in Abell 1835
Finoguenov, A.; Smith, G. P.; Okabe, N. +7 more
We present Herschel/PACS, MMT/Hectospec and XMM-Newton observations of Abell 1835, one of the brightest X-ray clusters on the sky, and the host of a strong cool core. Even though Abell 1835 has a prototypically “relaxed” X-ray morphology and no signs of ongoing merger activity in strong- and weak-lensing mass maps, it has a complex velocity distri…
Herschel/HIFI deepens the circumstellar NH3 enigma
Waters, L. B. F. M.; Menten, K. M.; Olofsson, H. +23 more
Context. Circumstellar envelopes (CSEs) of a variety of evolved stars have been found to contain ammonia (NH3) in amounts that exceed predictions from conventional chemical models by many orders of magnitude.
Aims: The observations reported here were performed in order to better constrain the NH3 abundance in the CSEs of…
Deep Herschel view of obscured star formation in the Bullet cluster
Smail, I.; Kneib, J. -P.; Smith, G. P. +33 more
We use deep, five band (100-500 µm) data from the Herschel Lensing Survey (HLS) to fully constrain the obscured star formation rate, SFRFIR, of galaxies in the Bullet cluster (z = 0.296), and a smaller background system (z = 0.35) in the same field. Herschel detects 23 Bullet cluster members with a total SFRFIR = 144±14…
VERA observations of SiO maser emission from R Aquarii
Bujarrabal, V.; Hirota, T.; Sato, K. +9 more
Aims: We aim to study the spatial distribution of the v=1 and v=2J = 1-0 SiO maser emission from R Aqr, a well known stellar symbiotic system. In particular, we intend to determine the annual parallax and proper motion of the source by means of measurements of the absolute coordinates of the maser spots.
Methods: We performed VLBI observ…