The Solar Neighborhood. XIX. Discovery and Characterization of 33 New Nearby White Dwarf Systems

Abstract

We present spectra for 33 previously unclassified white dwarf systems brighter than V ¼ 17, primarily in the southern hemisphere. Of these new systems, 26 are DA, 4 are DC, 2 are DZ, and 1 is DQ. We suspect that three of these systems are unresolved double degenerates. We obtained VRI photometry for these 33 objects, as well as for 23 known white dwarf systems without trigonometric parallaxes, also primarily in the southern hemisphere. For the 56 objects, we converted the photometry values to fluxes and fit them to a spectral energy distribution using the spectroscopy to determine which model to use (i.e., pure hydrogen, pure helium, or metal-rich helium), resulting in estimates of T eA and distance. Eight of the new and 12 of the known systems are estimated to be within the NStars and Catalogue of Nearby Stars horizons of 25 pc, constituting a potential 18% increase in the nearby white dwarf sample. Trigonometric parallax determinations are under way via CTIOPI for these 20 systems. One of the DCs is cool, so it displays absorption in the near-infrared. Using the distance determined via trigonometric parallax, we are able to constrain the model-dependent physical parameters and find that this object is most likely a mixed H /He atmosphere white dwarf similar to other cool white dwarfs identified in recent years with significant absorption in the infrared due to collision-induced absorptions by molecular hydrogen.

New Neighbors: Parallaxes of 18 Nearby Stars Selected From the LSPM-North Catalog

“…The star is identified to be within the 20pc horizon by Holberg et al (2008), from the photometric distance of 15.6±2.5pc estimated by Subasavage et al (2007). Our parallax indeed places the WD at 14.22±0.24pc.…”

A Spectroscopic Survey and Analysis of Bright, Hydrogen-Rich White Dwarfs

“…In addition, we report for the first time that 0543+436 and 1054−226 are also members of the DAZ class. In particular, 1054−226 was initially discovered by Subasavage et al (2007) but their discovery spectrum lacked the necessary S/N to detect the H and K lines of calcium. In addition, there are eight white dwarfs whose spectra are completely devoid of absorption lines in the observed wavelength range.…”

Signs of a faint disc population at polluted white dwarfs

“…The WISE 4.6µm photometry (light grey) have been slightly offset from the central wavelength in the plot for clarity. Subasavage et al (2007Subasavage et al ( , 2008, and in the near-infrared from Table 4 or the Two Micron All Sky Survey (2MASS; Skrutskie et al 2006). We also plot in Fig.…”