English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Theoretical models of stars constitute a fundamental bedrock upon which muchof astrophysics is built, but large swaths of model parameter space remainuncalibrated by observations. The best calibrators are eclipsing binaries inclusters, allowing measurement of masses, radii, luminosities, andtemperatures, for stars of known metallicity and age. We present the discoveryand detailed characterization of PTFEB132.707+19.810, a P=6.0 day eclipsingbinary in the Praesepe cluster ($\tau$~600--800 Myr; [Fe/H]=0.14$\pm$0.04). Thesystem contains two late-type stars (SpT$_P$=M3.5$\pm$0.2;SpT$_S$=M4.3$\pm$0.7) with precise masses ($M_p=0.3953\pm0.0020$~$M_{\odot}$;$M_s=0.2098\pm0.0014$~$M_{\odot}$) and radii ($R_p=0.363\pm0.008$~$R_{\odot}$;$R_s=0.272\pm0.012$~$R_{\odot}$). Neither star meets the predictions of stellarevolutionary models. The primary has the expected radius, but is cooler andless luminous, while the secondary has the expected luminosity, but is coolerand substantially larger (by 20%). The system is not tidally locked orcircularized. Exploiting a fortuitous 4:5 commensurability between $P_{orb}$and $P_{rot,prim}$, we demonstrate that fitting errors from the unknown spotconfiguration only change the inferred radii by <1--2%. We also analyze subsetsof data to test the robustness of radius measurements; the radius sum is morerobust to systematic errors and preferable for model comparisons. We also testplausible changes in limb darkening, and find corresponding uncertainties of~1%. Finally, we validate our pipeline using extant data for GU Boo, findingthat our independent results match previous radii to within the mutualuncertainties (2--3%). We therefore suggest that the substantial discrepanciesare astrophysical; since they are larger than for old field stars, they may betied to the intermediate age of PTFEB132.707+19.810.

The Factory and the Beehive III: PTFEB132.707+19.810, a Low-Mass Eclipsing Binary in Praesepe Observed by PTF and K2