The wonderful complexity of the Mira AB system

Ramstedt, S.; Mohamed, S.; Vlemmings, Wouter; Maercker, M.; Montez, Rodolfo; Baudry, A.; Beck, E. De; Lindqvist, Michael; Olofsson, H.; Humphreys, E. M. L.; Jorissen, A.; Kerschbaum, F.; Mayer, Andreas; Wittkowski, M.; Cox, Nicholas; Lagadec, E.; Leal-Ferreira, M. L.; Paladini, C.; Pérez-Sánchez, A. F.; Sacuto, Stéphane

doi:10.1051/0004-6361/201425029

Cited by 88 publications

(107 citation statements)

References 23 publications

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“…The observations of o Cet were presented by Ramstedt et al (2014). The CO v = 1, J = 3 − 2 transition at 342.647 GHz (Gendriesch et al 2009) was de-L2 T. Khouri et al tected in the observed spectral windows 0.937 GHZ wide and centred at 342.883 GHz for R Scl and 1.875 GHz wide and centred at 343.30 GHz for the other four sources.…”

Section: Observationsmentioning

confidence: 96%

ALMA observations of the vibrationally excited rotational CO transition v = 1, J = 3 − 2 towards five AGB stars

Khouri

Vlemmings

Ramstedt

et al. 2016

Monthly Notices of the Royal Astronomical Society: Letters

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ALMA observations of the vibrationally-excited rotational CO transition v = 1, J = 3 − 2 towards five AGB stars ABSTRACTWe report the serendipitous detection with ALMA of the vibrationally-excited purerotational CO transition v = 1, J = 3 − 2 towards five asymptotic giant branch (AGB) stars, o Cet, R Aqr, R Scl, W Aql, and π 1 Gru. The observed lines are formed in the poorly-understood region located between the stellar surface and the region where the wind starts, the so-called warm molecular layer. We successfully reproduce the observed lines profiles using a simple model. We constrain the extents, densities, and kinematics of the region where the lines are produced. R Aqr and R Scl show inverse P-Cygni line profiles which indicate infall of material onto the stars. The line profiles of o Cet and R Scl show variability. The serendipitous detection towards these five sources shows that vibrationally-excited rotational lines can be observed towards a large number of nearby AGB stars using ALMA. This opens a new possibility for the study of the innermost regions of AGB circumstellar envelopes.

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Section: Observationsmentioning

confidence: 96%

ALMA observations of the vibrationally excited rotational CO transition v = 1, J = 3 − 2 towards five AGB stars

Khouri

Vlemmings

Ramstedt

et al. 2016

Monthly Notices of the Royal Astronomical Society: Letters

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“…High-resolution imaging of a few dusty AGB stars reveals bipolar or more complex, clumpy structures (e.g., Weigelt et al 1998;Monnier et al 2000;Hofmann et al 2001). Some AGB stars show spiral structures, which strongly suggests the influence of a companion (e.g., Mauron & Huggins 2006;Maercker et al 2012;Kim et al 2013;Ramstedt et al 2014;Mayer et al 2014;Decin et al 2015). These observations suggest that the seed of the morphological change already exists in the AGB phase.…”

Section: Introductionmentioning

confidence: 92%

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L₂Puppis

Ohnaka

Schertl

Hofmann

et al. 2015

A&A

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Aims. The red giant L 2 Pup started a dimming event in 1994, which is considered to be caused by the ejection of dust clouds. We present near-IR aperture-synthesis imaging of L 2 Pup achieved by combining data from VLT/NACO and the AMBER instrument of the Very Large Telescope Interferometer (VLTI). Our aim is to spatially resolve the innermost region of the circumstellar environment. Methods. We carried out speckle interferometric observations at 2.27 µm with VLT/NACO and long-baseline interferometric observations with VLTI/AMBER at 2.2-2.35 µm with baselines of 15-81 m. We also extracted an 8.7 µm image from the mid-IR VLTI instrument MIDI.Results. The diffraction-limited image obtained by bispectrum speckle interferometry with NACO with a spatial resolution of 57 mas shows an elongated component. The aperture-synthesis imaging combining the NACO speckle data and AMBER data with a spatial resolution of 5.6 × 7.3 mas further resolves not only this elongated component, but also the central star. The reconstructed image reveals that the elongated component is a nearly edge-on disk with a size of ∼180 × 50 mas lying in the E-W direction, and furthermore, that the southern hemisphere of the central star is severely obscured by the equatorial dust lane of the disk. The angular size of the disk is consistent with the distance that the dust clouds that were ejected at the onset of the dimming event should have traveled by the time of our observations, if we assume that the dust clouds moved radially. This implies that the formation of the disk may be responsible for the dimming event. The 8.7 µm image with a spatial resolution of 220 mas extracted from the MIDI data taken in 2004 (seven years before the AMBER and NACO observations) shows an approximately spherical envelope without a signature of the disk. This suggests that the mass loss before the dimming event may have been spherical.

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“…The HIFI observations of W Hya were modelled in detail by Khouri et al (2014a,b) using the same code as Decin et al (2010c). Mira has a very complex circumstellar environment due to binary interaction (Ramstedt et al 2014), and the remaining sources are OH/IR stars with high mass-loss rates. These sources are therefore not included in this study.…”

Section: Sourcesmentioning

confidence: 99%

A HIFI view on circumstellar H₂O in M-type AGB stars: radiative transfer, velocity profiles, and H₂O line cooling

Maercker

Danilovich

Olofsson

et al. 2016

A&A

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Aims. We aim to constrain the temperature and velocity structures, and H 2 O abundances in the winds of a sample of M-type asymptotic giant branch (AGB) stars. We further aim to determine the effect of H 2 O line cooling on the energy balance in the inner circumstellar envelope. Methods. We use two radiative-transfer codes to model molecular emission lines of CO and H 2 O towards four M-type AGB stars. We focus on spectrally resolved observations of CO and H 2 O from HIFI aboard the Herschel Space Observatory. The observations are complemented by ground-based CO observations, and spectrally unresolved CO and H 2 O observations with PACS aboard Herschel. The observed line profiles constrain the velocity structure throughout the circumstellar envelopes (CSEs), while the CO intensities constrain the temperature structure in the CSEs. The H 2 O observations constrain the o-H 2 O and p-H 2 O abundances relative to H 2 . Finally, the radiative-transfer modelling allows to solve the energy balance in the CSE, in principle including also H 2 O line cooling. Results. The fits to the line profiles only set moderate constraints on the velocity profile, indicating shallower acceleration profiles in the winds of M-type AGB stars than predicted by dynamical models, while the CO observations effectively constrain the temperature structure. Including H 2 O line cooling in the energy balance was only possible for the low-mass-loss-rate objects in the sample, and required an ad hoc adjustment of the dust velocity profile in order to counteract extreme cooling in the inner CSE. H 2 O line cooling was therefore excluded from the models. The constraints set on the temperature profile by the CO lines nevertheless allowed us to derive H 2 O abundances. The derived H 2 O abundances confirm previous estimates and are consistent with chemical models. However, the uncertainties in the derived abundances are relatively large, in particular for p-H 2 O, and consequently the derived o/p-H 2 O ratios are not well constrained.

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The wonderful complexity of the Mira AB system

Cited by 88 publications

References 23 publications

ALMA observations of the vibrationally excited rotational CO transition v = 1, J = 3 − 2 towards five AGB stars

ALMA observations of the vibrationally excited rotational CO transition v = 1, J = 3 − 2 towards five AGB stars

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L₂Puppis

A HIFI view on circumstellar H₂O in M-type AGB stars: radiative transfer, velocity profiles, and H₂O line cooling

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The wonderful complexity of the Mira AB system

Cited by 88 publications

References 23 publications

ALMA observations of the vibrationally excited rotational CO transition v = 1, J = 3 − 2 towards five AGB stars

ALMA observations of the vibrationally excited rotational CO transition v = 1, J = 3 − 2 towards five AGB stars

AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L2Puppis

A HIFI view on circumstellar H2O in M-type AGB stars: radiative transfer, velocity profiles, and H2O line cooling

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AMBER-NACO aperture-synthesis imaging of the half-obscured central star and the edge-on disk of the red giant L₂Puppis

A HIFI view on circumstellar H₂O in M-type AGB stars: radiative transfer, velocity profiles, and H₂O line cooling