Related papers: Is the nitrogen-rich source PN K4-47 a true planet…
The rate of stellar evolution can rarely be measured in real time. The fastest evolution (excluding event-driven evolution), where stars may evolve measurably over decades, is during the post-AGB phase. In this paper we provide direct…
We have found a photoevaporated disk in the Orion Nebula that includes a wide binary. HST/ACS observations of the proplyd 124-132 show two point-like sources separated by 0".15, or about 60 AU at the distance of Orion. The two sources have…
We present high resolution radio continuum maps of the Galactic nebula Simeis 57 (= HS 191 = G 80.3+4.7) made with the WSRT and the DRAObservatory at frequencies of 609, 1412 and 1420 MHz. At optical and at radio wavelengths, the nebula has…
V510 Pup (IRAS 08005-2356) is a binary post-AGB system with a fast molecular outflow that has been noted for its puzzling mixture of carbon- and oxygen-rich features in the optical and infrared. To explore this chemical dichotomy and relate…
There is a class of binary post-asymptotic giant branch (post-AGB) stars that exhibit remarkable near-infrared (NIR) excess. These stars are surrounded by disks with Keplerian or quasi-Keplerian dynamics and outflows composed of gas…
We present early results from our program of ALMA Band 6 (1.3mm) molecular line mapping of a sample of nearby, well-studied examples of high-excitation, bipolar/pinched-waist and molecule-rich planetary nebulae (Hubble 5 and NGC 2440, 2818,…
We report the serendipitous detection by the XMM-Newton X-ray Observatory of an X-ray source at the position of the Type I (He- and N-rich) bipolar planetary nebula Hb 5. The Hb 5 X-ray source appears marginally resolved. While the small…
CO emission has been imaged at 2" resolution in the central 10 kpc of the barred spiral galaxy NGC 3367. This galaxy has bipolar synchrotron lobes out to a radii of 6 kpc, straddling the compact nucleus. The peak molecular emission is in a…
We analyse continuum and molecular emission, observed with ALMA, from the dust-enshrouded intermediate-mass AGB star OH 30.1 -0.7. We find a secondary peak in the continuum maps, "feature B", separated by 4.6" from the AGB star, which…
The BN/KL region in the Orion molecular cloud is an archetype in the study of the formation of stars much more massive than the Sun. This region contains luminous young stars and protostars, but it is difficult to study because of overlying…
This paper presents a homogeneous study of abundances in a sample of 79 northern galactic planetary nebulae whose morphological classes have been uniformly determined. Ionic abundances and plasma diagnostics were derived from selected…
We present observations of continuum (lambda = 0.7, 1.3, 3.6 and 18 cm) and OH maser (lambda = 18 cm) emission toward the young planetary nebula IRAS 17347-3139, which is one of the three planetary nebulae that are known to harbor water…
We present narrow-band images and long-slit echelle spectra of the planetary nebula (PN) NGC 6778. The data show this PN as bipolar, with a very prominent low-excitation equatorial toroid, high-excitation lobes and two pairs of collimated…
Our Cycle 0 ALMA observations confirmed that the Boomerang Nebula is the coldest known object in the Universe, with a massive high-speed outflow that has cooled significantly below the cosmic background temperature. Our new CO 1-0 data…
Spitzer MIPS 24 um images were obtained for 36 Galactic planetary nebulae (PNe) whose central stars are hot white dwarfs (WDs) or pre-WDs with effective temperatures of ~100,000 K or higher. Diffuse 24 um emission is detected in 28 of these…
Studying the earliest stages in the birth of stars is crucial for understanding how they form. Brown dwarfs with masses between that of stars and planets are not massive enough to maintain stable hydrogen-burning fusion reactions during…
A considerable fraction of the central stars of planetary nebulae (CSPNe) are hydrogen-deficient. As a rule, these CSPNe exhibit a chemical composition of helium, carbon, and oxygen with the majority showing Wolf-Rayet-like emission line…
We present Spitzer Space Telescope observations of V1647 Ori, the outbursting source lighting McNeil's nebula, taken near the optical peak of the outburst in early March 2004. The source is easily detected in all Spitzer imaging bands from…
Abell 70 (PN G038.1-25.4, hereafter A 70) is a planetary nebula (PN) known for its diamond ring appearance due a superposition with a background galaxy. The previously unstudied central star is found to be a binary consisting of a G8IV-V…
We present the mid-infrared spectrum of the planetary nebula IC 2448. In order to determine the chemical composition of the nebula, we use the infrared line fluxes from the Spitzer spectrum along with optical line fluxes from the literature…