Publication: Pre-main sequence evolution of low-mass stars in Eddington-inspired Born-Infeld gravity
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We study three aspects of the early-evolutionary phases in low-mass stars within Eddington-inspired Born-Infeld (EiBI) gravity, a viable extension of General Relativity. These aspects are concerned with the Hayashi tracks (i.e. the effective temperature-luminosity relation); the minimum mass required to belong to the main sequence; and the maximum mass allowed for a fully convective star within the main sequence. Using analytical models accounting for the most relevant physics of these processes, we find in all cases a dependence of these quantities not only on the theory's parameter, but also on the star's central density, a feature previously found in Palatini f(R) gravity. Using this, we investigate the evolution of these quantities with the (sign of the) EiBI parameter, finding a shift in the Hayashi tracks in opposite directions in the positive/negative branches of it, and an increase (decrease) for positive (negative) parameter in the two masses above. We use these results to elaborate on the chances to seek for traces of new physics in low-mass stars within this theory, and the limitations and difficulties faced by this approach.
© The Author(s) 2022 MG is funded by the predoctoral contract 2018-T1/TIC-10431 and acknowledges further support by the European Regional Development Fund under the Dora Plus scholarship grants. DRG is funded by the Atraccion de Talento Investigador programme of the Comunidad de Madrid (Spain) No. 2018-T1/TIC-10431, and acknowledges further support from the Ministerio de Ciencia, Innovacion y Universidades (Spain) project No. PID2019-108485GB-I00/AEI/10.13039/501100011033, and the FCT projects No. PTDC/FIS-PAR/31938/2017 and PTDC/FIS-OUT/29048/2017. AW is supported by the EU through the European Regional Development Fund CoE program TK133 "The Dark Side of the Universe". This work is also supported by the Spanish projects Nos. FIS2017-84440-C2-1-P and PID2020-117301GA-I00, the project PROMETEO/2020/079 (Generalitat Valenciana), and the Edital 006/2018 PRONEX (FAPESQPB/CNPQ, Brazil, Grant 0015/2019). MG thanks the Laboratory of Theoretical Physics at the University of Tartu, and AW the Department of Theoretical Physics at the Complutense University of Madrid, for their kind hospitality while doing this work.