Volume 398, Number 1, January IV 2003
|Page(s)||229 - 237|
|Section||Stellar structure and evolution|
|Published online||14 January 2003|
The IR-colour–mass-loss relation of carbon-rich, dust-driven superwinds and a synthetic (–, ) diagram
Astronomy Centre, CPES, University of Sussex, Falmer, Brighton BN1 9QJ, UK
2 Zentrum f. Astron. u. Astrophys., Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany
3 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
4 LERMA, FRE-K2460, Observatoire de Paris, 61 avenue de l'Observatoire, 75014 Paris, France
Corresponding author: K.-P. Schröder, firstname.lastname@example.org
Accepted: 4 November 2002
We derive relations between mass-loss rates and IR-colours (J–K, H–K, K–L, L–M and K–) for the carbon-rich, dust-driven stellar winds of extreme tip-AGB objects by applying a maximum-likelihood procedure to a representative set of 50 self-consistent, pulsating wind models. The J–K index shows the largest mass-loss related IR excess, which is consistent with observations. All synthetic IR-colours depend, in addition, on the luminosity of the individual model star. Consequently, the superwind mass-loss rates may be determined from observation by (J–K) , for J–K . As a case study for the interpretation of IR photometric data, we quantify the collective and individual tip-AGB mass-loss of the solar neighbourhood stellar population by means of a matching synthetic stellar sample, its IR properties and its present-day mass-loss distribution. The synthetic stars are generated on a grid of evolution tracks with a consistent mass-loss description (see Schröder et al. [CITE]; Wachter et al. [CITE]) and an IMF and SFR found in the local stellar population (Schröder & Sedlmayr [CITE]). The display of the tip-AGB stars in a (J–K, MBol) diagram could be compared directly with observations once appropriate data become available. On a basis of 1.4 million stars brighter than MV = 4.0, our synthetic present-day sample includes 5067 giant stars with B–V , and the collective mass-loss rate is 5.0 yr-1. There are 20 carbon-rich supergiants with an IR excess of J–K and a mass-loss rate well in excess of yr-1, including 10 dust-enshrouded, extreme tip-AGB stars with J–K , seen in their short-lived (≈30 000 yrs) superwind phase with yr-1. They produce about 50% of the collective mass-loss of the whole sample.
Key words: stars: carbon / stars: circumstellar matter / stars: evolution / stars: late-type / stars: mass-loss / infrared: stars
© ESO, 2003
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