64 research outputs found
Star and Planet Formation with ALMA: an Overview
Submillimeter observations with ALMA will be the essential next step in our
understanding of how stars and planets form. Key projects range from detailed
imaging of the collapse of pre-stellar cores and measuring the accretion rate
of matter onto deeply embedded protostars, to unravelling the chemistry and
dynamics of high-mass star-forming clusters and high-spatial resolution studies
of protoplanetary disks down to the 1 AU scale.Comment: Invited review, 8 pages, 5 figures; to appear in the proceedings of
"Science with ALMA: a New Era for Astrophysics". Astrophysics & Space
Science, in pres
Influence of indomethacin on lens regeneration in the newt notophthalmus viridescens
Following lentectomy newts were injected with indomethacin in a variety of carrier solutions at doses ranging from 1.2–120 mg/kg body weight every other day for 15–17 days. The results show that injection of this drug according to the regimen used has no significant effect on regeneration of the lens. The data suggest, but do not prove, that prostaglandins may not play a major role in the early phases of lens regeneration in the newt.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47503/1/427_2004_Article_BF00848434.pd
Origin of the hot gas in low-mass protostars, Herschel-PACS spectroscopy of HH 46
Aims. “Water In Star-forming regions with Herschel” (WISH) is a Herschel key programme aimed at understanding the physical and chemical
structure of young stellar objects (YSOs) with a focus on water and related species.
Methods. The low-mass protostar HH 46 was observed with the Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space
Observatory to measure emission in H2O, CO, OH, [O i], and [C ii] lines located between 63 and 186 μm. The excitation and spatial distribution
of emission can disentangle the different heating mechanisms of YSOs, with better spatial resolution and sensitivity than previously possible.
Results. Far-IR line emission is detected at the position of the protostar and along the outflow axis. The OH emission is concentrated at the
central position, CO emission is bright at the central position and along the outflow, and H2O emission is concentrated in the outflow. In addition,
[O i] emission is seen in low-velocity gas, assumed to be related to the envelope, and is also seen shifted up to 170 km s−1 in both the red- and
blue-shifted jets. Envelope models are constructed based on previous observational constraints. They indicate that passive heating of a spherical
envelope by the protostellar luminosity cannot explain the high-excitation molecular gas detected with PACS, including CO lines with upper levels
at >2500 K above the ground state. Instead, warm CO and H2O emission is probably produced in the walls of an outflow-carved cavity in the
envelope, which are heated by UV photons and non-dissociative C-type shocks. The bright OH and [Oi] emission is attributed to J-type shocks in
dense gas close to the protostar. In the scenario described here, the combined cooling by far-IR lines within the central spatial pixel is estimated to
be 2 × 10−2 L, with 60–80% attributed to J- and C-type shocks produced by interactions between the jet and the envelope
- …