9 research outputs found
SN 1988Z: Spectro-photometric catalogue and energy estimates
We present a spectro-photometric catalogue of the evolution of supernova
1988Z which combines new and published observations in the radio, optical and
X-ray bands, with the aim of offering a comprehensive view of the evolution of
this object and deriving the total energy radiated since discovery. The major
contribution to the total radiated energy comes at optical to X-ray
frequencies, with a total emission of at least erg (for
Ho=50 km/s) in 8.5 years. A model-dependent extrapolation of this value
indicates that the total radiated energy may be as high as erg. The
high value of the radiated energy supports a scenario in which most of the
kinetic energy of the ejecta is thermalized and radiated in a short interaction
with a dense circumstellar medium of nearly constant density. In this sense,
1988Z is not a supernova but a young and compact supernova remnant.Comment: Accepted to be published in MNRAS (14 pages, 10 figures). Also
available at http://www.inaoep.mx/~itzia
Evolutionary tracks and isochrones for low- and intermediate-mass stars: from 0.15 to 7 M_sun, and from Z=0.0004 to 0.03
SIGLEAvailable from: http://www.mpa-garching.mpg.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
Envelope burning over-luminosity: a challenge to synthetic TP-AGB models
Until recently synthetic AGB models had not taken into account the break-down of the core mass-luminosity (M_c - L) relation due to the occurrence of envelope burning in the most massive (M >or#approx#3.5 M_sun) and luminous (M_b_o_l <or#approx#-6) stars. Marigo et al. (1998) made the first attempt to consistently include the related over-luminosity effect (i.e. above the M_c-L relation) in synthetic TP-AGB calculations. The method couples complete envelope integrations with analytical prescriptions, these latter being presently updated with the highly detailed relations by Wagenhuber and Groenewegen (1998). In this paper the reliability of the solution scheme is tested by comparison with the results of complete evolutionary calculations for a 7 M_sun AGB star undergoing envelope burning (e.g. Bloecker and Schoenberner 1991). Indeed, the method proves to be valid as it is able to reproduce with remarkable accuracy several evolutionary features of the 7 M_sun star (e.g. rate of brightening, luminosity evolution as a function of the core mass and envelope mass for different mass-loss prescriptions) as predicted by full AGB models. Basing on the new solution method, we present extensive synthetic TP-AGB calculations for stars with initial masses of 3.5, 4.0, 4.5, and 5.0 M_sun, and three choices of the initial metallicity, i.e. Z = 0.019, Z = 0.008, and Z = 0.004. Three values of the mixing-length parameter are used, i.e. #alpha# = 1.68, 2.0, 2.5. We investigate the dependence of envelope burning on such stellar parameters (M, Z, and #alpha#). The comparison between different cases gives hints on the interplay between envelope burning over-luminosity and mass loss, and related effects on TP-AGB lifetimes. (orig.)36 refs.Available from TIB Hannover: RR 4697(1091) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Large scale bias and the peak background split
SIGLEAvailable from: http://www.mpa-garching.mpg.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
Theoretical isochrones in several photometric systems I. Johnson-Cousins-Glass, HST/WFPC2, HST/NICMOS, Washington, and ESO Imaging Survey filter sets
SIGLEAvailable from: http://www.mpa-garching.mpg.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
Ellipsoidal collapse and an improved model for the number and spatial distribution of dark matter haloes
SIGLEAvailable from: http://www.mpa-garching.mpg.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
The satellite population of the Milky Way in a #LAMBDA#CDM universe
SIGLEAvailable from: http://www.mpa-garching.mpg.de / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman
The third dredge-up and the carbon star luminosity functions in the Magellanic Clouds
We investigate the formation of carbon stars as a function of the stellar mass and parent metallicity. Theoretical modelling is based on an improved scheme for treating the third dredge-up in synthetic calculations of thermally pulsing asymptotic giant branch (TP-AGB) stars. In this approach, the usual criterion based on a constant minimum core mass for the occurrence of dredge-up, M_c"m"i"n, is replaced by one on the minimum temperature at the base of the convective envelope, T_b"d"r"e"d, at the stage of the post-flash luminosity maximum. Envelope integrations allow then to determine M_c"m"i"n as a function of stellar mass, metallicity, and pulse strength (cf. Wood 1981), thus inferring if and when dredge-up first occurs. Moreover, the final possible shut down of the process is predicted. Extensive grids of TP-AGB models were computed by Marigo (1998) using this scheme. In this paper, we present and discuss the calibration of the two dredge-up parameters (i.e. efficiency #lambda# and T_b"d"r"e"d) aimed at reproducing the carbon star luminosity function (CSLF) in the LMC, using TP-AGB models with original metallicity Z = 0.008. In addition to this, the effects of different input quantities on the theoretical CSLF are analysed. It turns out that the faint tail is almost insensitive to the history of star formation rate (SFR) in the parent galaxy, contrarily to the bright wing which may be more affected by the details of the recent history. Actually, we find that the faint end of the CSLF is essentially determined by the temperature parameter T_b"d"r"e"d81 refs.Available from TIB Hannover: RR 4697(1116) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman
Globular cluster calibration of the peak brightness of the type Ia Supernova 1992A and the value of H_0
We have determined the absolute magnitude at maximum light of SN 1992A by using the turn-over magnitude of the Globular Cluster Luminosity Function of its parent galaxy, NGC 1380. A recalibration of the peak of the turn-over magnitude of the Milky Way clusters using the latest HIPPARCOS results has been made with an assessment of the complete random and systematic error budget. The following results emerge: a distance to NGC 1380 of 18.6#+-#1.4 Mpc, corresponding to (m-M)=31.35#+-#0.16, and an absolute magnitude of SN 1992A at maximum of M_B(max)=-18.79#+-#0.16. Taken at face value, SN 1992A seems to be more than half a magnitude fainter than the other SNeI-a for which accurate distances exist. We discuss the implications of this result and present possible explanations. We also discuss the Phillips's (1993) relationship between rate of decline and the absolute magnitude at maximum, on the basis of 9 SNeI-a, whose individual distances have been obtained with Cepheids and the Globular Cluster Luminosity Function. The new calibration of this relationship, applied to the most distant SNe of the Calan-Tololo survey, yields H_0=62#+-#6 km s"-"1 Mpc"-"1. (orig.)Available from TIB Hannover: RR 7310(98-14) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman