arXiv subjects

Yadira Gaibor

Publications and source records attributed to Yadira Gaibor.

4 recordsLinked to original sources

arXiv2026

Giant Planets and Eccentric Orbits Are Common Around Galactic Thick Disc Stars

Planet formation in the Galactic thick disc is expected to be inefficient---low solid reservoirs, short disc lifetimes, and harsh irradiation environments should conspire to inhibit the assembly of planetary bodies---yet, planets are there, and they are stranger than we expected. Here, we present a homogeneous characterisation of 32 exoplanetary systems orbiting chemically and kinematically confirmed thick disc stars, combining new detections with a systematic reassessment of archival systems, increasing the total number of exoplanets orbiting thick disc stars to 66. When planets form in the thick disc, a notable fraction are giants and move on more eccentric orbits than their thin disc counterparts---two results that challenge standard disc-evolution models. However, this should be interpreted with caution given detection biases and sample size. We also report TOI-1927 b and TOI-2643 b, the first puffy, low-density giant planets known to orbit thick disc stars, unexpected in old, metal-poor environments where planets should cool and contract efficiently. Together, these findings reveal an early Milky Way far more hospitable to planetary diversity than its harsh conditions would initially suggest.

astro-ph.EP↗

arXiv2026

The T16 Planet Hunt: 10,000 New Planet Candidates from TESS Cycle 1 and the Confirmation of a Hot Jupiter Around TIC 183374187

The T16 project has produced a uniformly detrended and systematics-corrected set of 83,717,159 TESS Cycle 1 full-frame image light curves for stars observed by TESS in its primary mission down to T=16 mag, enabling sensitive transit searches beyond the official TESS pipelines. While most existing TESS planet searches focus on relatively bright targets, planet occurrence rates suggest that a substantial number of planets should exist around fainter stars. We therefore use the T16 light curves to conduct a semi-automated search for transiting exoplanets across the full Cycle 1 FFI sample, resulting in 11,554 planet candidates orbiting stars down to 16th magnitude in the TESS band with orbital periods between 0.5 and 27 days. Of these, 10,091 are new planet candidates, and 411 are single-transit events, for which we do not attempt to determine orbital parameters. The remaining 1,052 candidates are previously known TESS candidates. We validate our pipeline through Magellan/PFS radial-velocity follow-up measurements on one of our candidate hosts, TIC 183374187, a metal poor thick-disk star, confirming the signal as newly identified hot Jupiter. This detection demonstrates our pipeline's ability to identify real, previously undiscovered, transiting planets. Overall, this work shows that large-scale, machine learning-assisted transit searches of TESS full-frame images can significantly expand the census of transiting planet candidates, particularly around faint stars, providing a rich target set for future validation and follow-up efforts. Our findings more than double the number of known TESS exoplanet candidates.

astro-ph.EP↗

arXiv2025

An Eccentric Sub-Neptune Moving Into the Evaporation Desert

Though missions such as Kepler, K2, and TESS have discovered $>$2,000 sub-Neptune and Neptunian planets, there is a dearth of such planets at close-in (P$\lesssim$3 days) orbits. This feature, called the Neptune desert or the evaporation desert, is believed to be primarily shaped by planetary migration and photoevaporation. However, this region is not completely devoid of planets--a small number of very hot Neptunes reside within the desert. These planets provide an opportunity to directly probe the effects of migration and photoevaporation. We present confirmation of TOI-5800 b, an eccentric sub-Neptune on a $\approx$2.6 day period that is likely actively undergoing tidal migration. We use radial velocity measurements from the Carnegie Planet Finder Spectrograph (PFS) to constrain TOI-5800 b's mass and eccentricity. We find that it has an unusually high eccentricity (0.39$\pm$0.07) for its short orbit. TOI-5800 is therefore currently experiencing high levels of tidal heating as it moves into the desert. Ranked as a top candidate for transmission and emission spectroscopy within its temperature and radius regime, TOI-5800 b is a prime target for atmospheric characterization with JWST. TOI-5800 b presents a unique opportunity to study the atmosphere of a planet undergoing tidal heating and to probe the composition of sub-Neptune planets.

astro-ph.EP↗

arXiv2020

An Improved Spin-Down Rate for the Proposed White-Dwarf Pulsar AR Scorpii

We analyze rapid-cadence, multiwavelength photometry of AR Scorpii from three observatories, covering five observing seasons. We measure the arrival times of the system's beat pulses and use them to compute an updated ephemeris. The white dwarf spin-down rate is estimated with an uncertainty of only 4%. These results confirm, beyond any doubt, that the white dwarf's spin period is increasing at the rate consistent with by that of Stiller et al. (2018). We study the evolution of the beat pulse's color index across the orbit. The color of the primary pulse maxima varies significantly across the orbit, with the peaks being bluer after superior conjunction than in the first half of the orbit. Specifically, at orbital phase 0.5, the color index of the primary pulse shows a very sharp discontinuity towards bluer indices. This supports the Potter & Buckley (2018b) synchrotron emission model where the two emitting poles differ significantly in color. However, no corresponding jump in the color of the secondary pulses is seen. Furthermore, our analysis reveals that the arrival times of the pulses can differ by as much as 6s in simultaneous $u$ and $r$ photometry, depending on the binary orbital phase. If left uncorrected, this wavelength-dependent timing offset could lead to erroneous measurements of the spin-period derivative, particularly with heterogeneous datasets.

astro-ph.SR↗