Past studies have identified a spatially extended excess of \(\sim\)1-3 GeV gamma rays from the region surrounding the Galactic Center, consistent with the emission expected from annihilating dark ...matter. We revisit and scrutinize this signal with the intention of further constraining its characteristics and origin. By applying cuts to the \textit{Fermi} event parameter CTBCORE, we suppress the tails of the point spread function and generate high resolution gamma-ray maps, enabling us to more easily separate the various gamma-ray components. Within these maps, we find the GeV excess to be robust and highly statistically significant, with a spectrum, angular distribution, and overall normalization that is in good agreement with that predicted by simple annihilating dark matter models. For example, the signal is very well fit by a 36-51 GeV dark matter particle annihilating to \(b\bar{b}\) with an annihilation cross section of \(\sigma v = (1-3)\times 10^{-26}\) cm\(^3\)/s (normalized to a local dark matter density of 0.4 GeV/cm\(^3\)). Furthermore, we confirm that the angular distribution of the excess is approximately spherically symmetric and centered around the dynamical center of the Milky Way (within $\sim$$0.05^{\circ}\( of Sgr A\)^*\(), showing no sign of elongation along the Galactic Plane. The signal is observed to extend to at least \)\simeq10^{\circ}$ from the Galactic Center, disfavoring the possibility that this emission originates from millisecond pulsars.
We report the Transiting Exoplanet Survey Satellite (\(TESS\)) detection of a multi-planet system orbiting the \(V=10.9\) K0 dwarf TOI 125. We find evidence for up to five planets, with varying ...confidence. Three high signal-to-noise transit signals correspond to sub-Neptune-sized planets (\(2.76\), \(2.79\), and \(2.94\ R_{\oplus}\)), and we statistically validate the planetary nature of the two inner planets (\(P_b = 4.65\) days, \(P_c = 9.15\) days). With only two transits observed, we report the outer object (\(P_{.03} = 19.98\) days) as a high signal-to-noise ratio planet candidate. We also detect a candidate transiting super-Earth (\(1.4\ R_{\oplus}\)) with an orbital period of only \(12.7\) hours and a candidate Neptune-sized planet (\(4.2\ R_{\oplus}\)) with a period of \(13.28\) days, both at low signal-to-noise. This system is amenable to mass determination via radial velocities and transit timing variations, and provides an opportunity to study planets of similar size while controlling for age and environment. The ratio of orbital periods between TOI 125 b and c (\(P_c/P_b = 1.97\)) is slightly smaller than an exact 2:1 commensurability and is atypical of multiple planet systems from \(Kepler\), which show a preference for period ratios just \(wide\) of first-order period ratios. A dynamical analysis refines the allowed parameter space through stability arguments and suggests that, despite the nearly commensurate periods, the system is unlikely to be in resonance.
We report the discovery of a transiting, temperate, Neptune-sized exoplanet orbiting the nearby (d = 27.5 pc), M3V star TOI-1231 (NLTT 24399, L 248-27, 2MASS J10265947-5228099). The planet was ...detected using photometric data from the Transiting Exoplanet Survey Satellite and followed up with observations from the Las Cumbres Observatory and the Antarctica Search for Transiting ExoPlanets program. Combining the photometric data sets, we find that the newly discovered planet has a radius of 3.65(+0.16,-0.15)Rꚛ and an orbital period of 24.246 days. Radial velocity measurements obtained with the Planet Finder Spectrograph on the Magellan Clay telescope confirm the existence of the planet and lead to a mass measurement of 15.5 ± 3.3 Mꚛ. With an equilibrium temperature of just 330 K, TOI-1231 b is one of the coolest small planets accessible for atmospheric studies thus far, and its host star's bright near-infrared brightness (J = 8.88, Ks = 8.07) makes it an exciting target for the Hubble Space Telescope and the James Webb Space Telescope. Future atmospheric observations would enable the first comparative planetology efforts in the 250–350 K temperature regime via comparisons with K2-18 b. Furthermore, TOI-1231's high systemic radial velocity (70.5 km/s) may allow for the detection of low-velocity hydrogen atoms escaping the planet by Doppler, shifting the H i Lyα stellar emission away from the geocoronal and interstellar medium absorption features.
We report the discovery of GJ 1252 b, a planet with a radius of 1.193 \(\pm\) 0.074 \(R_{\oplus}\) and an orbital period of 0.52 days around an M3-type star (0.381 \(\pm\) 0.019 \(M_{\odot}\), 0.391 ...\(\pm\) 0.020 \(R_{\odot}\)) located 20.385 \(\pm\) 0.019 pc away. We use TESS data, ground-based photometry and spectroscopy, Gaia astrometry, and high angular resolution imaging to show that the transit signal seen in the TESS data must originate from a transiting planet. We do so by ruling out all false positive scenarios that attempt to explain the transit signal as originating from an eclipsing stellar binary. Precise Doppler monitoring also leads to a tentative mass measurement of 2.09 \(\pm\) 0.56 \(M_{\oplus}\). The host star proximity, brightness (\(V\) = 12.19 mag, \(K\) = 7.92 mag), low stellar activity, and the system's short orbital period make this planet an attractive target for detailed characterization, including precise mass measurement, looking for other objects in the system, and planet atmosphere characterization.
