ar X iv : a st ro - p h / 01 07 55 4 v 1 2 8 Ju l 2 00 1 – 1 – WHY EVERY BIPOLAR PLANETARY NEBULA IS ‘ UNIQUE ’

ar X iv : a st ro - p h / 04 07 29 2 v 1 1 4 Ju l 2 00 4 Parameters of PNe : Old fashioned or Trendy ?

We derive the stellar and circumstellar parameters with two models: the classical constant density nebula model and a stellar wind model. Depending on the mass loss rate of the star the stellar wind model results in a range of valid values which can deviate from the classical model results. This is especially true for the elemental abundances which are for every valid stellar wind model larger ...

ar X iv : a st ro - p h / 01 12 30 4 v 1 1 3 D ec 2 00 1 1 The 1996 – 1997 Fading of V 651 Mon , the Binary Central Star

V651 Mon is the binary central star of the bipolar planetary nebula NGC 2346. The star showed the secondever deep fading in 1996–1997, which was presumably caused by obscuration by a dust cloud in the planetary nebula, as was proposed to explain the 1981–1985 event. The entire duration of the 1996–1997 event was ∼400 d, remarkably shorter than the 1981–1985 event, suggesting that the obscuring ...

ar X iv : a st ro - p h / 98 04 02 2 v 1 2 A pr 1 99 8 Birth and early evolution of a planetary nebula

ar X iv : a st ro - p h / 01 07 46 7 v 1 2 4 Ju l 2 00 1 The Spectacular BHR 71 Outflow

BHR 71 is a well isolated Bok globule located at ∼200 pc, which harbours a highly collimated bipolar outflow. The outflow is driven by a very young Class 0 protostar with a luminosity of ∼9 L⊙. It is one of a very small number that show enhanced abundances of a number of molecular species, notably SiO and CH3OH, due to shock processing of the ambient medium. In this paper the properties of the ...

ar X iv : a st ro - p h / 04 05 53 6 v 1 2 7 M ay 2 00 4 To appear in ApJ 9 / 04 A Minimum - Mass Extrasolar Nebula

By analogy with the minimum-mass solar nebula, we construct a surfacedensity profile using the orbits of the 26 precise-Doppler planets found in multiple-planet systems: Σ = 2200 g cm (a/1 AU), where a is the circumstellar radius and β = 2.0 ± 0.5. The minimum-mass solar nebula (β = 1.5) is consistent with this model, but the uniform-α accretion disk model (β ≈ 1) is not. In a nebula with β > 2...