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Creators/Authors contains: "Gianninas, A."

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  1. Abstract

    We present the discovery of 17 double white dwarf (WD) binaries from our ongoing search for extremely low mass (ELM) < 0.3MWDs, objects that form from binary evolution. Gaia parallax provides a new means of target selection that we use to evaluate our original ELM Survey selection criteria. Cross-matching the Gaia and Sloan Digital Sky Survey (SDSS) catalogs, we identify an additional 36 ELM WD candidates with 17 <g< 19 mag and within the 3σuncertainties of our original color selection. The resulting discoveries imply the ELM Survey sample was 90% complete in the color range −0.4 < (gr)0< −0.1 mag (approximately 9000 K <Teff< 22,000 K). Our observations complete the sample in the SDSS footprint. Two newly discovered binaries, J123950.370−204142.28 and J232208.733+210352.81, have orbital periods of 22.5 and 32 minutes, respectively, and are future Laser Interferometer Space Antenna gravitational-wave sources.

  2. Abstract

    We present minute cadence photometry of 31 732 point sources observed in one 3 $\rm deg^{2}$ DECam pointing centred at RA = 09:03:02 and Dec. = −04:35:00 over eight consecutive half-nights. We use these data to search for eclipse-like events consistent with a planetary transit of a white dwarf and other sources of stellar variability within the field. We do not find any significant evidence for minute-long transits around our targets, hence we rule out planetary transits around ∼370 white dwarfs that should be present in this field. Additionally, we identify 49 variables, including 40 new systems. These include 23 detached or contact stellar binaries, one eclipsing white dwarf + M dwarf binary, 16 δ Scuti, three RR Lyrae, and two ZZ Ceti pulsators. Results from the remaining two fields in our survey will allow us to place more stringent constraints on the frequency of planets orbiting white dwarfs in the habitable zone.