A Hot Saturn near (but Unassociated with) the Open Cluster NGC 1817

We report on the discovery of a hot Saturn-sized planet (9.916 ±0.985 R ⊕) around a late F-star, K2-308, observed in Campaign 13 of the K2 mission. We began studying this planet candidate because prior to the release of Gaia DR2, the host star was thought to have been a member (membership probability) of the open cluster NGC 1817 based on its kinematics and photometric distance. We identify the host star (among three stars within the K2 photometric aperture) using seeing-limited photometry and rule out false-positive scenarios using adaptive optics imaging and radial velocity observations. We statistically validate K2-308b by calculating a false-positive probability rate of . However, we also show using new kinematic measurements provided by Gaia DR2 and our measured radial velocity of the system that K2-308 is unassociated with the cluster NGC 1817. Therefore, the long running search for a giant transiting planet in an open cluster remains fruitless. Finally, we note that our use of seeing-limited photometry is a good demonstration of similar techniques that are already being used to follow up Transiting Exoplanet Survey Satellite (TESS) planet candidates, especially in crowded regions

Zodiacal Exoplanets in Time (ZEIT). VII. A Temperate Candidate Super-Earth in the Hyades Cluster

Transiting exoplanets in young open clusters present opportunities to study how exoplanets evolve over their lifetimes. Recently, significant progress detecting transiting planets in young open clusters has been made with the K2 mission, but so far all of these transiting cluster planets orbit close to their host stars, so planet evolution can only be studied in a high-irradiation regime. Here, we report the discovery of a long-period planet candidate, called HD 283869 b, orbiting a member of the Hyades cluster. Using data from the K2 mission, we detected a single transit of a super-Earth-sized (1.96 0.12 R ⊕) planet candidate orbiting the K-dwarf HD 283869 with a period longer than 72 days. As we only detected a single-transit event, we cannot validate HD 283869 b with high confidence, but our analysis of the K2 images, archival data, and follow-up observations suggests that the source of the event is indeed a transiting planet. We estimated the candidate's orbital parameters and find that if real, it has a period P ≈ 100 days and receives approximately Earth-like incident flux, giving the candidate a 71% chance of falling within the circumstellar habitable zone. If confirmed, HD 283869 b would have the longest orbital period, lowest incident flux, and brightest host star of any known transiting planet in an open cluster, making it uniquely important to future studies of how stellar irradiation affects planetary evolution

The Caravan Rolls On

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68409/2/10.1177_107554707900100103.pd

The TESS-keck survey. III. A stellar obliquity measurement of TOI-1726 c

We report the measurement of a spectroscopic transit of TOI-1726c, one of two planets transiting a G-type star with V = 6.9 in the Ursa Major Moving Group (∼400 Myr). With a precise age constraint from cluster membership, TOI-1726 provides a great opportunity to test various obliquity excitation scenarios that operate on different timescales. By modeling the Rossiter-McLaughlin (RM) effect, we derived a sky-projected obliquity of -1-+3235∘. This result rules out a polar/retrograde orbit and is consistent with an aligned orbit for planet c. Considering the previously reported, similarly prograde RM measurement of planet b and the transiting nature of both planets, TOI-1726 tentatively conforms to the overall picture that compact multitransiting planetary systems tend to have coplanar, likely aligned orbits. TOI-1726 is also a great atmospheric target for understanding differential atmospheric loss of sub-Neptune planets (planet b 2.2 R☉ and c 2.7 R☉ both likely underwent photoevaporation). The coplanar geometry points to a dynamically cold history of the system that simplifies any future modeling of atmospheric escape

A pair of sub-Neptunes transiting the bright K-dwarf TOI-1064 characterized with CHEOPS

Stars and planetary system

Column Chromatography

Column chromatography is used extensively in nucleic acid chemistry to purify or characterize products from chemical reactions. This appendix focuses on separations using silica gel or alumina. The procedures described include loading the column, assembling the apparatus, separating compounds and collecting fractions, and optimizing chromatography conditions.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/152525/1/cpnca03e.pd