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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 606249.0, MPI für Astronomie / Publikationen_mpia
The 2011 outburst of the recurrent nova T Pyxidis. Evidence for a face-on bipolar ejection
Authors:Chesneau, O.; Meilland, A.; Banerjee, D. P. K.; Le Bouquin, J. B.; McAlister, H.; Millour, F.; Ridgway, S. T.; Spang, A.; Ten Brummelaar, T.; Wittkowski, M.; Ashok, N. M.; Benisty, M.; Berger, J. P.; Boyajian, T.; Farrington, C.; Goldfinger, P. J.; Merand, A.; Nardetto, N.; Petrov, R.; Rivinius, T.; Schaefer, G.; Touhami, Y.; Zins, G.
Date of Publication (YYYY-MM-DD):2011
Journal Abbrev.:Astronomy and Astrophysics
Audience:Not Specified
Abstract / Description:<BR /> Aims: T Pyx is the first recurrent nova ever historically studied. It was seen in outburst six times between 1890 and 1966 and then not for 45 years. We report on near-IR interferometric observations of the recent outburst of 2011. <BR /> Methods: We obtained near-IR observations of <ASTROBJ>T Pyx</ASTROBJ> at dates ranging from t = 2.37 d to t = 48.2 d after the outburst, with the CLASSIC recombiner located at the CHARA array and with the PIONIER and AMBER recombiners located at the VLTI array. These data are supplemented with near-IR photometry and spectra obtained at Mount Abu, India. We compare expansion of the H and K band continua and the Brγ emission line, and infer information on the kinematics and morphology of the early ejecta. <BR /> Results: Slow expansion velocities were measured (≤300 km s-1) before t = 20 d. From t = 28 d on, the AMBER and PIONIER continuum visibilities (K and H band, respectively) are best simulated with a two-component model consisting of an unresolved source plus an extended source whose expansion velocity onto the sky plane is lower than ~700 km s-1. The expansion of the Brγ line-forming region, as inferred at t = 28 d and t = 35 d, is slightly larger, implying velocities in the range 500-800 km s-1, which is still strikingly lower than the velocities of 1300-1600 km s-1 inferred from the Doppler width of the line. Moreover, a remarkable pattern was observed in the Brγ differential phases. A semi-quantitative model using a bipolar flow with a contrast of 2 between the pole and equator velocities, an inclination of i = 15°, and a position angle PA = 110° provides a good match to the AMBER observables. At t = 48 d, a PIONIER dataset confirms the two-component nature of the H band emission, consisting of an unresolved stellar source and an extended region whose appearance is circular and symmetric within error bars. <BR /> Conclusions: These observations are most simply interpreted within the frame of a bipolar model, oriented nearly face-on. This finding has profound implications for interpreting past, current, and future observations of the expanding nebula.
Free Keywords:circumstellar matter; techniques: high angular resolution; novae; cataclysmic variables; stars: individual: T Pyx
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
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