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Register a new userIdentification of SIPS~J2045$-$6332 as a partially resolved binary
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Authors
Niall R Deacon
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We show that SIPS J2045-6332, a late M/early L object previously identified as a candidate spectral mix binary, shows an elongated image shape. Using shape measurement techniques originally developed for cosmological weak lensing surveys on VISTA VHS images we show that this likely blended binary has an implied position angle of ~290 degrees East of North with a secondary companion that is likely to be a late L dwarf. This object would be a good follow-up target for high resolution imaging studies
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Using shape measurement techniques developed for weak lensing surveys we have identified three new ultracool binaries in the Pan-STARRS1 survey. Binary companions which are not completely resolved can still alter the shapes of stellar images. These shape distortions can be measured if PSF anisotropy caused by the telescope is properly accounted for. We show using both a sample of known binary stars and simulated binaries that we can reliably recover binaries wider than around 0.3 and with flux ratios greater than around 0.1. We then applied our method to a sample of ultracool dwarfs within 30pc with 293 objects having sufficient Pan-STARRS1 data for our method. In total we recovered all but one of the 11 binaries wider than 0.3 in this sample. Our one failure was a true binary detected with a significant but erroneously high ellipticity which led it to be rejected in our analysis. We identify three new binaries, one a simultaneous discovery, with primary spectral types M6.5, L1 and T0.5. These latter two were confirmed with Keck/NIRC2 follow-up imaging. This technique will be useful for identifying large numbers of stellar and substellar binaries in the upcoming LSST and DES sky surveys.
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We report the identification of the bright (V${sim}13.3$ mag) star FY Sct as a long period detached eclipsing binary using a combined ASAS-SN and ASAS light curve spanning 2000-2018. The orbital period is P${sim}2.57$ years and the primary eclipse lasts ${sim}73$ days. The eclipse profile is suggestive of a disk eclipsing binary rather than a stellar component. We also detect ${sim}0.4$ mag pulsations with a period of P${sim78}$ d. The next eclipse begins on September, 28, 2018. Further photometric and spectroscopic observations are encouraged, particularly when the system is in eclipse.
We present the results of a timing analysis undertaken with the goal of obtaining an improved mass measurement of the recycled pulsar J2045+3633. Using regular high-cadence observations with the Effelsberg, Nanc{c}ay, and Lovell radio telescopes, together with targeted campaigns with the Arecibo Telescope and Effelsberg, we have assembled a 6-yr timing data set for this pulsar. We measure highly significant values for the proper motion and the related rate of change of orbital semi-major axis ($dot{x}$), and have obtained high precision values of the rate of advance of periastron time ($dot{omega}$), and two of the Shapiro delay parameters ($h_{3}$ and $varsigma$). This has allowed us to improve the measurements of the pulsar and companion masses by an order of magnitude, yielding (with $1sigma$ uncertainties) $1.251^{+0.021}_{-0.021},text{M}_{odot}$ for PSR J2045+3633, and $0.873^{+0.016}_{-0.014},text{M}_{odot}$ for its white dwarf companion, and has allowed us to place improved constraints on the geometrical orientation of the binary system. Using our measurements of the binary component masses and the orbital size, we consider possible evolutionary scenarios for the system.
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