Bibcode
Santander-García, M.; Bujarrabal, V.; Alcolea, J.; Castro-Carrizo, A.; Sánchez Contreras, C.; Quintana-Lacaci, G.; Corradi, R. L. M.; Neri, R.
Referencia bibliográfica
Astronomy and Astrophysics, Volume 597, id.A27, 16 pp.
Fecha de publicación:
1
2017
Revista
Número de citas
18
Número de citas referidas
17
Descripción
Context. The mechanism behind the shaping of bipolar planetary nebulae
is still poorly understood. It is becoming increasingly clear that the
main agents must operate at their innermost regions, where a significant
equatorial density enhancement should be present and related to the
collimation of light and jet launching from the central star
preferentially towards the polar directions. Most of the material in
this equatorial condensation must be lost during the asymptotic giant
branch as stellar wind and later released from the surface of dust
grains to the gas phase in molecular form. Accurately tracing the
molecule-rich regions of these objects can give valuable insight into
the ejection mechanisms themselves. Aims: We investigate the
physical conditions, structure and velocity field of the dense molecular
region of the planetary nebula NGC 6302 by means of ALMA band 7
interferometric maps. Methods: The high spatial resolution of the
12CO and 13CO J = 3-2 ALMA data allows for an
analysis of the geometry of the ejecta in unprecedented detail. We built
a spatio-kinematical model of the molecular region with the software
SHAPE and performed detailed non-LTE calculations of excitation and
radiative transfer with the shapemol plug-in. Results: We find
that the molecular region consists of a massive ring out of which a
system of fragments of lobe walls emerge and enclose the base of the
lobes visible in the optical. The general properties of this region are
in agreement with previous works, although the much greater spatial
resolution of the data allows for a very detailed description. We
confirm that the mass of the molecular region is 0.1 M⊙.
Additionally, we report a previously undetected component at the nebular
equator, an inner, younger ring inclined 60° with respect to the
main ring, showing a characteristic radius of 7.5 ×
1016 cm, a mass of 2.7 ×
10-3M⊙, and a counterpart in optical images of
the nebula. This inner ring has the same kinematical age as the
northwest optical lobes, implying it was ejected approximately at the
same time, hundreds of years after the ejection of the bulk of the
molecular ring-like region. We discuss a sequence of events leading to
the formation of the molecular and optical nebulae, and briefly
speculate on the origin of this intriguing inner ring.
The model file (in SHAPE format) is only available at the CDS via
anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/597/A27
Proyectos relacionados
Nebulosas Bipolares
Nuestro proyecto persigue tres objetivos principales: 1) Determinar las condiciones físico-químicas de las nebulosas planetarias con geometría bipolar y de las nebulosas alrededor de estrellas simbióticas. El fin es entender el origen de la bipolaridad y poner a prueba los modelos teóricos que intentan explicar la morfología y la cinemática nebular
Antonio
Mampaso Recio