Orbital Parameter Determination for Wide Stellar Binary Systems in the Age of Gaia

The orbits of binary stars and planets, particularly eccentricities and inclinations, encode the angular momentum within these systems. Within stellar multiple systems, the magnitude and (mis)alignment of angular momentum vectors among stars, disks, and planets probes the complex dynamical processes guiding their formation and evolution. The accuracy of the \textit{Gaia} catalog can be exploited to enable comparison of binary orbits with known planet or disk inclinations without costly long-term astrometric campaigns. We show that \textit{Gaia} astrometry can place meaningful limits on orbital elements in cases with reliable astrometry, and discuss metrics for assessing the reliability of \textit{Gaia} DR2 solutions for orbit fitting. We demonstrate our method by determining orbital elements for three systems (DS Tuc AB, GK/GI Tau, and Kepler-25/KOI-1803) using \textit{Gaia} astrometry alone. We show that DS Tuc AB's orbit is nearly aligned with the orbit of DS Tuc Ab, GK/GI Tau's orbit might be misaligned with their respective protoplanetary disks, and the Kepler-25/KOI-1803 orbit is not aligned with either component's transiting planetary system. We also demonstrate cases where \textit{Gaia} astrometry alone fails to provide useful constraints on orbital elements. To enable broader application of this technique, we introduce the python tool \texttt{lofti\_gaiaDR2} to allow users to easily determine orbital element posteriors.Comment: 18 pages, 10 figures, accepted for publication in Ap

The Impact of Stellar Multiplicity on Planetary Systems, I.:The Ruinous Influence of Close Binary Companions

The dynamical influence of binary companions is expected to profoundly influence planetary systems. However, the difficulty of identifying planets in binary systems has left the magnitude of this effect uncertain; despite numerous theoretical hurdles to their formation and survival, at least some binary systems clearly host planets. We present high-resolution imaging of 382 Kepler Objects of Interest (KOIs) obtained using adaptive-optics imaging and nonredundant aperture-mask interferometry on the Keck II telescope. Among the full sample of 506 candidate binary companions to KOIs, we super-resolve some binary systems to projected separations of 0.4; we instead only found 23 companions (a 4.6σ deficit), many of which must be wider pairs that are only close in projection. When the binary population is parametrized with a semimajor axis cutoff a cut and a suppression factor inside that cutoff S bin, we find with correlated uncertainties that inside ${a}_{\mathrm{cut}}={47}_{-23}^{+59}$ au, the planet occurrence rate in binary systems is only ${S}_{\mathrm{bin}}={0.34}_{-0.15}^{+0.14}$ times that of wider binaries or single stars. Our results demonstrate that a fifth of all solar-type stars in the Milky Way are disallowed from hosting planetary systems due to the influence of a binary companion

Boyajian's Star B::The co-moving stellar companion to KIC 8462852 A

The light curve of KIC 8462852, a.k.a Boyajian's Star, undergoes deep dips the origin of which remains unclear. A faint star $\approx$2\arcsec to the east was discovered in Keck/NIRC2 imaging in Boyajian et al. (2016), but its status as a binary, and possible contribution to the observed variability, was unclear. Here, we use three epochs of Keck/NIRC2 imaging, spanning five years, in JHK near-infrared bands to obtain 1-mas precision astrometry. We show that the two objects exhibit common proper motion, measure a relative velocity of $\mu=0.14\pm0.44$ mas yr$^{-1}$ ($\mu=0.30\pm0.93$ km s$^{-1}$) and conclude that they are a binary pair at $880\pm10$ AU projected separation. There is marginal detection of possible orbital motion, but our astrometry is insufficient to characterize the orbit. We show that two other point sources are not associated with KIC 8462852. We recommend that attempts to model KIC 8462852 A's light curve should revisit the possibility that the bound stellar companion may play a role in causing the irregular brightness variations, for example through disruption of the orbits of bodies around the primary due to long-term orbital evolution of the binary orbit.Comment: 11 pages, 7 figures, 2 tables Accepted for publication in Ap

Ectopic Expression of Zmiz1 Induces Cutaneous Squamous Cell Malignancies in a Mouse Model of Cancer

Cutaneous squamous cell carcinoma (SCC) is the second most common form of cancer in the human population, yet the underlying genetic mechanisms contributing to the disease are not well understood. We recently identified Zmiz1 as a candidate oncogene in nonmelanoma skin cancer through a transposon mutagenesis screen. Here we show that transposon-induced mutations in Zmiz1 drive expression of a truncated transcript that is similar to an alternative endogenous ZMIZ1 transcript found to be overexpressed in human SCCs relative to normal skin. We also describe an original mouse model of invasive keratoacanthoma driven by skin-specific expression of the truncated Zmiz1 transcript. Unlike most mouse models, Zmiz1-induced skin tumors develop rapidly and in the absence of promoting agents such as phorbol esters. In addition, we found that the alternative Zmiz1 isoform has greater protein stability than its full-length counterpart. Finally, we provide evidence that ZMIZ1 is overexpressed in a significant percentage of human breast, ovarian, and colon cancers in addition to human SCCs, suggesting that ZMIZ1 may play a broader role in epithelial cancers

Three Wide Planetary-mass Companions to FW Tau, ROXs 12, and ROXs 42B

We report the discovery of three planetary-mass companions (M = 6-20 M_(Jup)) in wide orbits (ρ ~ 150-300 AU) around the young stars FW Tau (Taurus-Auriga), ROXs 12 (Ophiuchus), and ROXs 42B (Ophiuchus). All three wide planetary-mass companions (PMCs) were reported as candidate companions in previous binary survey programs, but then were neglected for >10 yr. We therefore obtained followup observations that demonstrate that each candidate is comoving with its host star. Based on the absolute M_K' magnitudes, we infer masses (from hot-start evolutionary models) and projected separations of 10 ± 4 M_(Jup) and 330 ± 30 AU for FW Tau b, 16 ± 4 M_(Jup) and 210 ± 20 AU for ROXs 12, and 10 ± 4 M_(Jup) and 140 ± 10 AU for ROXs 42B b. We also present similar observations for 10 other candidates that show that they are unassociated field stars, as well as multicolor JHK'L' near-infrared photometry for our new PMCs and for five previously identified substellar or planetary-mass companions. The near-infrared photometry for our sample of eight known and new companions generally parallels the properties of free-floating, low-mass brown dwarfs in these star-forming regions. However, five of the seven objects with M < 30 M_(Jup) are redder in K' – L' than the distribution of young free-floating counterparts of similar J – K' color. We speculate that this distinction could indicate a structural difference in circumplanetary disks, perhaps tied to higher disk mass since at least two of the objects in our sample are known to be accreting more vigorously than typical free-floating counterparts

Zmiz1 is overexpressed in epithelial ovarian cancer and associated with p53 gene mutations

Zmiz1 staining is elevated in patients with epithelial ovarian cancer. Tumors that are Zmiz1 positive are associated with mutations of the p53 gene. Zmiz1 overexpression may be associated with decreased survival in patients with epithelial ovarian cancer. Additional studies are needed to more clearly determine the role of Zmiz1 in patients with epithelial ovarian cancer