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Full-Text Articles in Astrophysics and Astronomy
Direct Distance Measurement To The Dusty White Dwarf Gd 362, Mukremin Kilic, John R. Thorstensen, D. Koester
Direct Distance Measurement To The Dusty White Dwarf Gd 362, Mukremin Kilic, John R. Thorstensen, D. Koester
Dartmouth Scholarship
We present trigonometric parallax observations of GD 362 obtained over seven epochs using the MDM 2.4m Hiltner Telescope. The existence of a dust disk around this possibly massive white dwarf makes it an interesting target for parallax observations. The measured parallax for GD 362 places it at a distance of 50.6 pc, which implies that its radius and mass are ~ 0.0106 Rsun and 0.71 Msun, respectively. GD 362 is not as massive as initially thought (1.2Msun). Our results are entirely consistent with the distance and mass estimates (52.2 pc and 0.73 Msun) by Zuckerman et al., who demonstrated that …
Parallax And Distance Estimates For Twelve Cataclysmic Variable Stars, John R. Thorstensen, Sébastien Lépine, Michael Shara
Parallax And Distance Estimates For Twelve Cataclysmic Variable Stars, John R. Thorstensen, Sébastien Lépine, Michael Shara
Dartmouth Scholarship
We report parallax and distance estimates for 12 more cataclysmic binaries and related objects observed with the 2.4 m Hiltner telescope at MDM Observatory. The final parallax accuracy is typically ~1 mas. Notable results include distances for V396 Hya (CE 315), a helium double degenerate with a relatively long orbital period, and for MQ Dra (SDSSJ155331+551615), a magnetic system with a very low accretion rate. We find that the Z Cam star KT Persei is physically paired with a K main-sequence star lying 15 arcsec away. Several of the targets have distance estimates in the literature that are based on …
The Evolution Of Late‐Time Optical Emission From Sn 1986j, Dan Milisavljevic, Robert A. Fesen, Bruno Leibundgut, Robert P. Kirshner
The Evolution Of Late‐Time Optical Emission From Sn 1986j, Dan Milisavljevic, Robert A. Fesen, Bruno Leibundgut, Robert P. Kirshner
Dartmouth Scholarship
We present late-time optical images and spectra of the Type IIn supernova SN 1986J. HST ACS/WFC images obtained in 2003 February show it to be still relatively bright, with mF606W = 21.4 and mF814W = 20.0 mag. Compared to 1994 December HST WFPC2 images, SN 1986J shows a decline of only <1 mag in brightness over 8 years. Ground-based spectra taken in 1989, 1991, and 2007 show a 50% decline in Hα emission between 1989 and 1991, and an order of magnitude drop between 1991 and 2007, along with the disappearance of He I line emissions during the period 1991-2007. The object's [O I] λλ6300, 6364, [O II] λλ7319, 7330 and [O III] λλ4959, 5007 emission lines show two prominent peaks near –1000 and –3500 km s−1, with the more blueshifted component declining significantly in strength between 1991 and 2007. The observed spectral evolution suggests two different origins for SN 1986J's late-time optical emission: dense, shock-heated circumstellar material, which gave rise to the initially bright Hα, He I, and [N II] λ5755 …
A Multiwavelength Analysis Of The Halo Planetary Nebula Dddm‐1, R. B. C. Henry, K. B. Kwitter, R. J. Dufour, J. N. Skinner
A Multiwavelength Analysis Of The Halo Planetary Nebula Dddm‐1, R. B. C. Henry, K. B. Kwitter, R. J. Dufour, J. N. Skinner
Dartmouth Scholarship
We present new HST optical imagery as well as new UV and IR spectroscopic data obtained with the Hubble Space Telescope and Spitzer Space Telescope, respectively, of the halo planetary nebula DdDm-1. For the first time we present a resolved image of this object, which indicates that the morphology of DdDm-1 can be described as two orthogonal elliptical components in the central part surrounded by an extended halo. The extent of the emission is somewhat larger than was previously reported in the literature. We combine the spectral data with our own previously published optical measurements to derive nebular abundances …
A New, Bright, Short-Period, Emission Line Binary In Ophiuchus, M. A. Stark, Richard A. Wade, John R. Thorstensen, Christopher S. Peters
A New, Bright, Short-Period, Emission Line Binary In Ophiuchus, M. A. Stark, Richard A. Wade, John R. Thorstensen, Christopher S. Peters
Dartmouth Scholarship
The 11th magnitude star LS IV-08°3 has been classified previously as an OB star in the Luminous Stars survey, or alternatively as a hot subdwarf. It is actually a binary star. We present spectroscopy, spectroscopic orbital elements, and time-series photometry from observations made at the Kitt Peak National Observatory 2.1 m, Steward Observatory 2.3 m, MDM Observatory 1.3 m and 2.4 m, Hobby-Eberly 9.2 m, and Michigan State University 0.6 m telescopes. The star exhibits emission of varying strength in the cores of H and He I absorption lines. Emission is also present at 4686 Å (He II) and near …