Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
Schröder, K.-P., Wachter, A., Winters, J.M.
The IR-colour - mass-loss relation of
carbon-rich, dust-driven superwinds and a synthetic ( J-K, MBol
) diagram
Astronomy and Astrophysics, 398, 229 (2003)
Abstract.
We derive relations between mass-loss rates and IR-colours (J-K, H-K,
K-L,
L-M and K-[12]) 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 log( dot{M} ) =
-8.20 + 0.156 (J - K) - 0.463 MBol, for J-K > 4. 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. 1999, and Wachter et al. 2002) and
an IMF and SFR found in the local stellar population (Schröder &
Sedlmayr, 2001). 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 > 1.4, and the collective
mass-loss
rate is 5.0 times 10-4 Mo/yr. There are 20
carbon-rich supergiants with an IR excess of J-K > 4.0 and a
mass-loss
rate well in excess of 10-6 Mo/yr, including 10
dust-enshrouded, extreme tip-AGB stars with J-K > 6.0, seen in their
short-lived (approx. 30,000 yrs) superwind phase with dot{M} >
10-5 Mo/yr. They produce about 50% of the
collective
mass-loss of the whole sample.
You can get this publication ...