ar X iv : a st ro - p h / 04 08 16 4 v 1 1 0 A ug 2 00 4 Substructure in the Circumstellar Disk around the Young Star AU Mic ( GJ 803 )

ar X iv : a st ro - p h / 04 08 56 1 v 1 3 0 A ug 2 00 4 The Nature of the Variable Galactic Center Source IRS

We report measurements of the light curve of the variable Galactic Center source IRS16SW. The light curve is not consistent with an eclipsing binary or any other obvious variable star. The source may be an example of a high mass variable predicted theoretically but not observed previously.

ar X iv : a st ro - p h / 04 08 13 5 v 1 9 A ug 2 00 4 A Determination of the Chemical Composition of α Centauri A from Strong Lines

ar X iv : a st ro - p h / 03 08 48 4 v 1 2 7 A ug 2 00 3 An Unusual Eclipse of a Pre - Main Sequence Star in IC 348

A solar-like pre-main sequence star (TJ 108 = H 187 = LRLL 35 = HMW 15) in the extremely young cluster IC 348 has been found, which apparently experienced an eclipse lasting ∼3.5 years, much longer than has ever been detected for any normal eclipsing binary. The light curve is flat-bottomed and rather symmetric, with a depth of 0.66 mag in Cousins I. During eclipse, the system reddened by ∼0.17...

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...

ar X iv : a st ro - p h / 04 05 53 6 v 2 7 J un 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...