Browsing by Author "Santana, F."
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- ItemCoupling people and nature: social-ecological filters of beetle functional diversity in local campesino and migrant homegardens of the southern Andes(2021) Ibarra Eliessetch, Jose Tomas; Caviedes, J.; Altamirano, T.A.; Urra, R.; Barreau, A.; Santana, F.
- ItemFour Jovian planets around low-luminosity giant stars observed by the EXPRESS and PPPS(2021) Jones, M. I.; Wittenmyer, R.; Aguilera-Gomez, C.; Soto, M. G.; Torres, P.; Trifonov, T.; Jenkins, J. S.; Zapata, A.; Sarkis, P.; Zakhozhay, O.; Brahm, R.; Ramirez, R.; Santana, F.; Vines, J. I.; Diaz, M. R.; Vuckovic, M.; Pantoja, B.We report the discovery of planetary companions orbiting four low-luminosity giant stars with M-star between 1.04 and 1.39 M-circle dot. All four host stars have been independently observed by the EXoPlanets aRound Evolved StarS (EXPRESS) program and the Pan-Pacific Planet Search (PPPS). The companion signals were revealed by multi-epoch precision radial velocities obtained in nearly a decade. The planetary companions exhibit orbital periods between similar to 1.2 and 7.1 yr, minimum masses of m(p)sin i similar to 1.8-3.7 M-J, and eccentricities between 0.08 and 0.42. With these four new systems, we have detected planetary companions to 11 out of the 37 giant stars that are common targets in the EXPRESS and PPPS. After excluding four compact binaries from the common sample, we obtained a fraction of giant planets (m(p) greater than or similar to 1- 2 M-J) orbiting within 5 AU from their parent star of f = 33.3(-7.1)(+9.0)%. This fraction is slightly higher than but consistent at the 1 sigma level with previous results obtained by different radial velocity surveys. Finally, this value is substantially higher than the fraction predicted by planet formation models of gas giants around stars more massive than the Sun.
- ItemH-band discovery of additional second-generation stars in the Galactic bulge globular cluster NGC 6522 as observed by APOGEE and Gaia(2019) Fernandez-Trincado, J. G.; Zamora, O.; Souto, Diogo; Cohen, R. E.; Agli, F. Dell; Garcia-Hernandez, D. A.; Masseron, T.; Schiavon, R. P.; Meszaros, Sz; Cunha, K.; Hasselquist, S.; Shetrone, M.; Schiappacasse Ulloa, J.; Tang, B.; Geisler, D.; Schleicher, D. R. G.; Villanova, S.; Mennickent, R. E.; Minniti, D.; Alonso-Garcia, J.; Manchado, A.; Beers, T. C.; Sobeck, J.; Zasowski, G.; Schultheis, M.; Majewski, S. R.; Rojas-Arriagada, A.; Almeida, A.; Santana, F.; Oelkers, R. J.; Longa-Pena, P.; Carrera, R.; Burgasser, A. J.; Lane, R. R.; Roman-Lopes, A.; Ivans, I. I.; Hearty, F. R.We present an elemental abundance analysis of high-resolution spectra for five giant stars spatially located within the innermost regions of the bulge globular cluster NGC 6522 and derive Fe, Mg, Al, C, N, O, Si, and Ce abundances based on H-band spectra taken with the multi-object APOGEE-north spectrograph from the SDSS-IV Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. Of the five cluster candidates, two previously unremarked stars are confirmed to have second-generation (SG) abundance patterns, with the basic pattern of depletion in C and Mg simultaneous with enrichment in N and Al as seen in other SG globular cluster populations at similar metallicity. In agreement with the most recent optical studies, the NGC 6522 stars analyzed exhibit (when available) only mild overabundances of the s-process element Ce, contradicting the idea that NGC 6522 stars are formed from gas enriched by spinstars and indicating that other stellar sources such as massive AGB stars could be the primary polluters of intra-cluster medium. The peculiar abundance signatures of SG stars have been observed in our data, confirming the presence of multiple generations of stars in NGC 6522.
- ItemSocial-ecological filters drive the functional diversity of beetles in homegardens of campesinos and migrants in the southern Andes(2021) Ibarra Eliessetch, Jose Tomas; Caviedes, J.; Altamirano, T.A.; Urra, R.; Barreau, A.; Santana, F.