Astronomy Tea Talk

Speaker 1: Oryna Ivashtenko (PhD candidate at the Weizmann Institute of Science)

Title: Towards re-estimating the population of small long-period planets from Kepler data

Abstract: The Kepler spacecraft provided unprecedented photometric precision, enabling the detection of Earth-like planets. However, the final Kepler catalog lacks sufficient reliability for small, long-period planets, complicating estimates of occurrence rates in this regime. A major source of this problem is the difficulty in distinguishing genuine but faint planetary signals from systematic false alarms—spurious detections caused by correlated, non-Gaussian noise.
We developed an independent search and vetting pipeline that addresses this noise structure with tailored statistical methods, yielding a clean background distribution free of the false-alarm tail. The pipeline was applied to the entire Kepler dataset, resulting in a list of planetary candidates. For each candidate, we estimated its probability of being a real astrophysical periodic signal, using empirical per-target background estimation and an injection-recovery campaign. To estimate the posterior distribution of the planetary radii, we developed a dimensionality-reduction method to accelerate posterior computation while propagating uncertainties associated with unknown orbital parameters, uncertain stellar parameters, and limb-darkening coefficients. Together, these results provide a basis for estimating the occurrence rates of small, long-period planets, which I am currently working on.
In this talk, I will explain the methodology behind the search, present its results, and explain how these results will be used to estimate occurrence rates.

Speaker 2: Anthony Englert (Postdoc at Brown University & UC Davis)

Title: Preparing for the Next Generation of Science with Galaxy Clusters: Lessons Learned from DECam and Visions for LSST

Abstract: Over the past several years, the Local Volume Complete Cluster Survey (LoVoCCS) has been leading a volume-complete survey of over 100 local (0.03 < z < 0.12), X-ray luminous (L500 > 1044 erg s-1) galaxy clusters. LoVoCCS provides a low-redshift anchor for the properties of galaxy clusters which future simulations and higher redshift surveys can utilize and has been reduced using the LSST Science Pipelines architecture, providing a platform for future cluster science with LSST. In this talk, I will discuss the "third generation" pipeline for reducing LoVoCCS data and use it to carry out a weak lensing analysis of the Hercules Supercluster. Then, I will review the lessons learned from reducing LoVoCCS observations and discuss what the next generation of volume-complete cluster surveys will look like.