VLTI monitoring of the dust formation event of the Nova V1280 Scorpii
Chesneau, O; Banerjee, DPK; Millour, F; et al.Nardetto, N; Sacuto, S; Spang, A; Wittkowski, M; Ashok, NM; Das, RK; Hummel, C; Kraus, S; Lagadec, E; Morel, S; Petr-Gotzens, M; Rantakyro, F; Schöller, M
Date: 1 August 2008
Journal
Astronomy and Astrophysics
Publisher
EDP Sciences for European Southern Observatory (ESO)
Publisher DOI
Abstract
Context. We present the first high spatial-resolution monitoring of the dust-forming nova V1280 Sco, performed with the Very Large
Telescope Interferometer (VLTI).
Aims. These observations promise to improve the distance determination of such events and constrain the mechanisms leading to very
efficient dust formation under the harsh ...
Context. We present the first high spatial-resolution monitoring of the dust-forming nova V1280 Sco, performed with the Very Large
Telescope Interferometer (VLTI).
Aims. These observations promise to improve the distance determination of such events and constrain the mechanisms leading to very
efficient dust formation under the harsh physical conditions encountered in novae ejecta.
Methods. Spectra and visibilities were regularly acquired between the onset of dust formation, 23 days after discovery (or 11 days
after maximum), and day 145, using the beam-combiner instruments AMBER (near-IR) and MIDI (mid-IR). These interferometric
observations were complemented by near-infrared data from the 1.2 m Mt. Abu Infrared Observatory, India. The observations are
initially interpreted in terms of simple uniform models; however more complex models, probably involving a second shell, are required
to explain data acquired following t = 110 d after outburst. This behavior is in accordance with the light curve of V1280 Sco, which
exhibits a secondary peak at about t = 106 d, followed by a new, steep decline, suggesting a new dust-forming event. Spherical dust
shell models generated with the DUSTY code are used to investigate the parameters of the main dust shell.
Results. Using uniform disk models, these observations allow us to determine an apparent linear expansion rate for the dust shell of
0.35 ± 0.03 mas day−1 and the approximate ejection time of the matter in which dust formed of tejec = 10.5 ± 7 d, i.e. close to the
maximum brightness. This information, combined with the expansion velocity of 500 ± 100 km s−1, implies a distance estimate of
1.6 ± 0.4 kpc. The sparse uv coverage does not enable deviations from spherical symmetry to be clearly discerned. The dust envelope
parameters were determined. The dust mass generated was typically 2–8 × 10−9 M day−1, with a probable peak in production at
about 20 days after the detection of dust and another peak shortly after t = 110 d, when the amount of dust in the shell was estimated
as 2.2 × 10−7 M. Considering that the dust-forming event lasted at least 200–250 d, the mass of the ejected material is likely to have
exceeded 10−4 M. The conditions for the formation of multiple shells of dust are also discussed.
Ke
Physics and Astronomy
Faculty of Environment, Science and Economy
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