Impressions

Publication for alumni and friends of Boston University Henry M. Goldman School of Dental Medicin

Impressions, Winter 2017

Magazine for alumni and friends of the Boston University Dental School

Impressions, Spring 2018

Magazine for alumni and friends of the Boston University Dental School

Impressions, Fall 2013

Magazine for alumni and friends of the Boston University Dental School

Impressions, Spring 2013

Magazine for alumni and friends of the Boston University Dental School

Impressions, Spring 2012

Magazine for alumni and friends of the Boston University Dental School

Impressions, Winter 2015

Magazine for alumni and friends of the Boston University Dental School

Impressions, Summer 2017

Magazine for alumni and friends of the Boston University Dental School

BUMC Annual Report

Annual report of the Boston University Medical Center

Spectroscopic confirmation of the planetary nebula nature of PM1-242, PM1-318 and PM1-333 and morphological analysis of the nebulae

We present intermediate resolution long-slit spectra and narrow-band Halpha, [NII] and [OIII] images of PM1-242, PM318 and PM1-333, three IRAS sources classified as possible planetary nebulae. The spectra show that the three objects are true planetary nebulae and allow us to study their physical properties; the images provide a detailed view of their morphology. PM1-242 is a medium-to-high-excitation (e.g., HeII4686/Hbeta ~0.4; [NII]6584/Halpha ~0.3) planetary nebula with an elliptical shape containing [NII] enhanced point-symmetric arcs. An electron temperature [Te([SIII])] of ~10250 K and an electron density [Ne([SII])] of ~2300 cm-3 are derived for PM1-242. Abundance calculations suggest a large helium abundance (He/H ~0.29) in PM1-242. PM1-318 is a high-excitation (HeII4686/Hbeta ~1) planetary nebula with a ring-like inner shell containing two enhanced opposite regions, surrounded by a fainter round attached shell brighter in the light of [OIII]. PM1-333 is an extended planetary nebula with a high-excitation (HeII4686/Hbeta up to ~0.9) patchy circular main body containing two low-excitation knotty arcs. A low Ne([SII]) of ~450 cm-3 and Te([OIII]) of ~15000 K are derived for this nebula. Abundance calculations suggest that PM1-333 is a type I planetary nebula. The lack of a sharp shell morphology, low electron density, and high-excitation strongly suggest that PM1-333 is an evolved planetary nebula. PM1-333 also shows two low-ionization polar structures whose morphology and emission properties are reminiscent of collimated outflows. We compare PM1-333 with other evolved planetary nebulae with collimated outflows and find that outflows among evolved planetary nebulae exhibit a large variety of properties, in accordance with these observed in younger planetary nebula.Comment: Accepted in The Astronomical Journal, 23 pages, 6 figure