Actions
  • shareshare
  • link
  • cite
  • add
add
auto_awesome_motion View all 6 versions
Publication . Article . 2007

Mass loss from dusty, low outflow-velocity AGB stars. II. The multiple wind of EP Aquarii

II. The multiple wind of EP Aquarii
Jan Martin Winters; T. Le Bertre; Jérôme Pety; R. Neri;
Open Access
English
Published: 01 Nov 2007
Publisher: HAL CCSD
Country: France
Abstract

Context: CO rotational lines are frequently used to trace the outflows from AGB stars. Some profiles are composite, with a narrow component super-imposed on a broader one. These profiles have been interpreted in different ways, calling for episodic mass loss, a bipolar flow, or a circumstellar disk. Aims: To investigate the structure of one of these outflows, we have obtained detailed 12CO(2-1) and 12CO(1-0) maps of EP Aqr, a prototypical source with composite CO profiles. Methods: Interferometric data were acquired with the IRAM interferometer and combined with on-the-fly maps obtained at the IRAM 30-m. The resulting maps in 12CO(2-1) and 12CO(1-0) cover a field of 100 arcsec × 100 arcsec with a spectral resolution of 0.1 km s-1 and with beams of 1.7 arcsec × 1.0 arcsec and 3.5 arcsec × 1.8 arcsec, respectively. Results: The source is clearly resolved with a size of about 15 arcsec (FWHM). We do not observe any obvious departure from circular symmetry, but there is evidence of a ringed structure in the CO(2-1) map with enhanced intensity at ~3.5 arcsec and 7.5 arcsec from the central star. The continuum level at 1.3 and 2.6 mm is consistent with the star's photospheric emission. We modeled the spatio-kinematic structure with Monte-Carlo radiative transfer simulations assuming spherical symmetry. We reached a reasonable fit to the map-integrated spectra, but not to the imaging data, possibly because the circumstellar shell of EP Aqr presents inhomogeneities on a scale that is not, or is only barely, resolved in our maps. EP Aqr may be a proto-typical oxygen-rich source for the class of theoretical models exhibiting mass loss variations on a ~100 yr timescale discovered by Winters et al. (2000), which show a layered structure in their extended circumstellar shells. Based on observations carried out with the IRAM Plateau de Bure Interferometer and the IRAM 30 m telescope on Pico Veleta. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). Data files (in FITS format) of the data presented in Figs. 6 and 7 are available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/475/559

Subjects by Vocabulary

Microsoft Academic Graph classification: Plateau de Bure Interferometer Astrophysics Telescope law.invention law Radiative transfer Physics Asymptotic giant branch Stellar mass Spectral line Stars Spectral resolution Astronomy

Subjects

hydrodynamics, stars: mass-loss, stars: AGB and post-AGB, stars: winds, outflows, radio lines: stars, circumstellar matter, [PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], Space and Planetary Science, Astronomy and Astrophysics, [PHYS.ASTR.CO] Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO], [SDU.ASTR.CO] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]

39 references, page 1 of 4

Beichman, C. A., Neugebauer, G., Habing, H. J., Clegg, P. E., & Chester, T. J. 1988, IRAS catalogues and atlases, Version 2, Explanatory supplement, NASA RP-1190 (NASA)

Boboltz, D. A., Diamond, P. J., & Kemball, A. J. 1997, ApJ, 487, L47

Cernicharo, J., Alcolea, J., Baudry, A., & González-Alfonso, E. 1997, A&A, 319, 607

Dumm, T., & Schild, H. 1998, New Astron., 3, 137

Fouqué, P., Le Bertre, T., Epchtein, N., Guglielmo, F., & Kerschbaum, F. 1992, A&AS, 93, 151

Glassgold, A. E., & Huggins, P. J. 1983, MNRAS, 203, 517

González Delgado, D., Olofsson, H., Kerschbaum, F., et al. 2003, A&A, 411, 123

Greenhill, L. J., Colomer, F., Moran, J. M., et al. 1995, ApJ, 449, 365

Herpin, F., Baudry, A., Alcolea, J., & Cernicharo, J. 1998, A&A, 334, 1037

Hogerheijde, M. R., & van der Tak, F. F. S. 2000, A&A, 362, 697

moresidebar