Abstract
 [*] The Tip of the Red Giant Branch and Distance of the Magellanic
Clouds: results from the DENIS survey
 Cioni M.R.L., van der Marel R.P., Loup C., Habing H.J.
 A&A, 359, 601614, 2000

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We present a precise determination of the apparent magnitude of the
tip of the red giant branch (TRGB) in the I (0.8 micron), J (1.25
micron), and K_S (2.15 micron) bands from the luminosity function of a
sample of data extracted from the DENIS catalogue towards the
Magellanic Clouds (Cioni et al. 2000). From the J and Ks magnitudes we
derive bolometric magnitudes m_bol. We present a new algorithm for the
determination of the TRGB magnitude, which we describe in detail and
test extensively using MonteCarlo simulations. We note that any
method that searches for a peak in the first derivative (used by most
authors) or the second derivative (used by us) of the observed
luminosity function does not yield an unbiased estimate for the actual
magnitude of the TRGB discontinuity. We stress the importance of
correcting for this bias, which is not generally done. We combine the
results of our algorithm with theoretical predictions to derive the
distance modulus of the Magellanic Clouds. We obtain mM = 18.55 (0.04
formal, 0.08 systematic) for the Large Magellanic Cloud (LMC), and mM
= 18.99 (0.03 formal, 0.08 systematic) for the Small Magellanic Cloud
(SMC). These are among the most accurate determinations of these
quantities currently available, which is a direct consequence of the
large size of our sample and the insensitivity of near infrared
observations to dust extinction.
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Last modified November 23, 2000.
Roeland van der Marel,
marel@stsci.edu.
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