Mass loss and evolution of asymptotic giant branch stars in the Magellanic Clouds van Loon, J.T.

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1 UvA-DARE (Digital Academic Repository) Mass loss and evolution of asymptotic giant branch stars in the Magellanic Clouds van Loon, J.T. Link to publication Citation for published version (APA): van Loon, J. T. (1999). Mass loss and evolution of asymptotic giant branch stars in the Magellanic Clouds General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. UvA-DARE is a service provided by the library of the University of Amsterdam ( Download date: 27 Dec 2018

2 Appendixx B IRR colour relations Wee have investigated the IR colour relations for the J, H, K and L-bands in the SAAO photometricc system, and the IRAS 12 and 25 //m bands. We define [12] = -2.51og(S 12 /28.3) are the flux andd [25] = -2.51og(S 25 /6.73), where S l2 and S 25 densities in Jy at 12 and 25 //m,, respectively (IRAS Explanatory Supplement 1988). The SAAO L-band has an effective wavelengthh of 3.45 /mi. Wee plot the (J - H), (K - L) and ([12] - [25]) colours versus the (H - K) colour (Fig. Bl). Thee dotted lines are linear fits to the data points: // {J-H) \ ( \ {K-L){K-L) = ([12]-[25])) j V // \ VV o ) x{h-k)x{h-k) Cohenn et al. (1981) showed that the {H - K) and {J-H) colours of optically visible carbon starss in the Milky Way are correlated, from which we derive on the SAAO system (Carter 1990): : (J-K)(J-K) = x{h-k) (B.2) Theyy explained the correlation as a result of line blanketing by molecular absorption bands. Fromm Costa & Frogel (1996) we derive a correlation between their (J-K) and {H-K) colours, transformedd to the SAAO system (Carter 1990), for optically visible carbon stars in the LMC: (B.1) (JJ - K) x (H - K) (B.3) Thee selected sample of Milky Way stars from Guglielmo et al. (1993) yield, after transformation too the SAAO system (Carter 1990), for the obscured carbon stars: andd for the obscured oxygen stars: (J-K)(J-K) = ( ) + ( ) x (H - K) (B.4) (j-k)(j-k) = ( ) + ( ) x (H - K) (B.5) Forr the obscured AGB stars in the LMC we derive: (j(j - K) = ( ) + ( ) x {H - K) (B.6) 153 3

3 154 4 AppendixAppend 0 0 (a) ) "ii I i i i r ^^ 2 D rr DD'..fff f J.tP' ü e e I D_: : J J W W (b) ) aa D '1 1 ann.-- a.- Pip p D a I I (c)) cv?? 2 c\2 2. n n.a.. BB B a. B.,, I I I I I H-K K Figuree B.l: (J - H) (a), {K - L) (b) and ([12] - [25]) (c) colours versus (H - K) colour for thee stars of our sample. The dotted lines are linear fits to the data.

4 IRIR colour relations Ö "" (a).^ tt tt I M I DD 16 6 H 4 ^^ H- - i -H i H i i i i- (b) ) D 12 2 D Bü ü?? 8u 8u DD. O O A A I. I 1 1 I L 4 4 LL (c) Ü---.D : g-d g-d D' ' J- 8 8 ii MI i nil n ii i in MI 10 0 (d) ) 8 8 D QO O "A A dp P 4 4 4ii 2 2 o o Ë Ë II ' 1 I _L L M bol l Figuree B.2: A' (a), (# - A') (b), N (c) and (A' - [12]) (d) as a function of absolute bolometric magnitudee for the LMC stars (squares, dotted in the case of lower limits to the N-band magnitudess and upper limits to the (A - N) colours, respectively), SMC stars (triangles) and VV Tucc (circle). The dotted lines are linear fits to the LMC data (see text).

5 156 6 AppendixAppendi Wee plot K and N-band magnitudes and {H-K) and (A"-[12]) colours versus the bolometric luminosityy (Fig. B2). The dotted lines are linear fits to the LMC data points (we also include thee stars with N-band lower limits, to diminish bias): K {{, ^ (H-K) (H-K) N N \(K-N)\(K-N) // \ (( ^ xx A/, bo!! (B.7) ) VV J / VV I Bolometricallyy fainter stars are relatively fainter in the K-band and relatively brighter in the N-band,, yielding larger (K - [12]) colours. Their (H - K) colours are also larger, indicating thatt fainter stars are optically thicker: at equal mass-loss rates, they have smaller inner radii off the CSEs, and consequently larger dust column densities than the more luminous stars. Thuss fainter stars have fainter K-band magnitudes due to increased circumstellar opacity, and brighterr N-band magnitudes due to increased circumstellar dust emission.