A distance of 200 light years, L2 Puppis is one of the red giant closest to the Earth, about to begin the final phase of its existence. The new observations in the visible range using the instrument SHPERE positioned ZIMPOL fashion - using an extreme adaptive optics system, enabled to acquire images with a correction significantly higher than that obtained using a system conventional adaptive optics. So these pictures reveal, near bright sources, objects and structures with low luminosities, to a much higher level of detail. These are the first results from this mode, and the most detailed data acquired on such an object.
ZIMPOL is able to produce images with a resolution three times higher than those acquired by the Hubble Space Telescope consortium NASA / ESA The new observations show and dust that surrounds L2 Puppis into moultes details [2] and confirm the results previously obtained with NACO : dust is distributed along a preview disc edge-on from Earth. The polarization data acquired by ZIMPOL have also allowed the team to build a three-dimensional model of dust structures [3].
Astronomers have discovered that the dust disk began about 900 million kilometers from the star - either a slightly larger than the Sun distance between Jupiter - and it flared in the opposite direction, forming a kind symmetrical funnel around the star. The team also identified the existence of a second light source at about 300 million kilometers of L2 Puppis - which is twice the Earth-Sun distance. This companion star, located in very close proximity, is probably another red giant mass close, but younger age.
The fact that a star about to die is surrounded by a large amount of dust, the presence of a companion star also, are all necessary ingredients for the next likely creation of a bipolar planetary nebula. However, the emergence of a heavenly butterfly from a chrysalis that dusty requires a good dose of luck.
Pierre Kervella, lead author of the study, said the difficulty of the problem : "The origin of bipolar planetary nebula is one of the major puzzles of modern astrophysics, including the ejection process in the surrounding space , precious metal products within the stars - a material that enter into the composition of future generations of planetary systems. "
Besides the disk flared around L2 Puppis, the team discovered the existence of two terms of cones stretching from either side of the disc, in a perpendicular direction. Within these cones are two long animated material plumes of slow rotation. The study of the origin points of these plumes led to the formulation of the following assumptions : a plume seems to result from the interaction between the material of L2 Puppis one hand, radiation pressure and generated wind by the second companion star ; another plume appears to result from a collision between the stellar winds from the one and the other star, or come from an accretion disk around the companion star.
Although our knowledge should be further extended, two major theories, each based on the prior existence of a binary star system currently account for the formation of bipolar planetary nebulae [4]. The new observations suggest that all required processes are at work here, strengthening the likelihood that this pair of stars gives rise ultimately to a heavenly butterfly.
Pierre Kervella concluded : "Only a few years are needed for the companion star for one complete orbit around L2 Puppis, shaping the same disk of red giant. We will be able to monitor the characteristics of the dust disk in real time. - An extremely rare perspective and particularly exciting "
The second theory states that most of the ejected by the end of life star material is accreted by his close companion and is constituted as an accretion disk including two powerful jets to escape. The rest of the material is ejected by stellar winds from the star at the end of life, and forms a cloud of gas and dust usually feature a simple star system. Featuring a power much greater than that of stellar winds from the star at the end of life, newly created bipolar jets around the companion star create two cavities in the surrounding dust. Follows the emergence of a bipolar planetary nebula.
Source
- The dust disk and companion of the AGB star nearby L2 Puppis, P. Kervella et al., Astronomy & Astrophysics, June 10, 2015 of the journal
[1] Laboratoire Franco-Chilienne d’Astronomie (LFCA ; CNRS - France/Université du Chili - Chili) - LESIA (Observatoire de Paris/CNRS/UPMC/Université Paris-Diderot), - Institut de Radioastronomie Millimétrique (IRAM ; CNRS - France/Max Planck Gesellschaft - Allemagne/Instituto Geográfico Nacional - Esapagne) - Laboratoire Lagrange (Université de Nice-Sophia Antipolis/CNRS/Observatoire de la Côte d’Azur)
[2] SPHERE / ZIMPOL uses an extreme adaptive optics to create images with a diffraction limited, approaching so much more than the conventional adaptive optics to the theoretical limit of the telescope obtained in a sky devoid of atmosphere. The extreme adaptive optics also allows for much fainter objects to be observed in close proximity to a bright star. Such images can also be acquired in the visible range - at shorter wavelengths than the infrared, preferred field of classical adaptive optics. Consequently obtaining much sharper images than those obtained so far through the VLT. An even higher spatial resolution has been reached by the VLTI - however, the interferometer generates no direct images.
[3] The dust disk has remarkably diffused light from the star towards Earth. She has also polarized, which allowed the team to develop a three-dimensional map of the envelope from the data ZIMCO and NACO. The team has also established a model of disk-based modeling tool radiative transfer RADMC-3D that uses a defined set of dust-related parameters to simulate the propagation of photons in it.
[4] The first theory states that the dust produced by the stellar wind from the end of life star is confined within a ring orbiting the star. This confinement would result from the combined action of stellar winds and radiation pressure generated by the companion star. Any issue regarding the main star would be then channeled through this record, which would force it to escape, forming two opposing columns perpendicular to the disk.