HiPERCAM and TESS observations of the rapidly rotating M7V star LP 89--187
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arXiv
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| Auteurs principaux: | , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866917072695459840 |
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| author | Ramsay, Gavin Doyle, J. G. Littlefair, Stuart Dhillon, Vik Garcia, David Alvarez |
| author_facet | Ramsay, Gavin Doyle, J. G. Littlefair, Stuart Dhillon, Vik Garcia, David Alvarez |
| contents | The discovery of a significant number of rapidly rotating low mass stars showing no or few flares in TESS observations was a surprise as rapid rotation has previously been taken as implying high stellar activity. Here we present TESS and HiPERCAM $u_{s}g_{s}r_{s}i_{s}z_{s}$ observations of one of these stars LP 89--187 which has a rotation period of 0.117 d. TESS data covering three sectors (64.6 d) only show three flares which have energies a few $\times10^{33}$ erg, whilst HiPERCAM observations, which cover 0.78 of the rotation period, show no evidence for flares more energetic than $\sim10^{31}$ erg. Intriguingly, other surveys show LP 89--187 has shown weak H$α$ in emission. We compare the flare energy distribution of LP 89--187 with low mass stars in the $β$ Pic moving group, which have an age of $\sim$24 Myr. We find LP 89--187 has a lower flare rate than the $β$ Pic stars. In addition, we find that TRAPPIST-1 analogue stars, which are likely significantly older than the $β$ Pic stars, show fewer flares with energies $>10^{33}$ erg in TESS data. We examine the relationship between amplitude and period for a sample of low mass stars and find that more rapid rotators have a higher amplitude. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_15941 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | HiPERCAM and TESS observations of the rapidly rotating M7V star LP 89--187 Ramsay, Gavin Doyle, J. G. Littlefair, Stuart Dhillon, Vik Garcia, David Alvarez Solar and Stellar Astrophysics The discovery of a significant number of rapidly rotating low mass stars showing no or few flares in TESS observations was a surprise as rapid rotation has previously been taken as implying high stellar activity. Here we present TESS and HiPERCAM $u_{s}g_{s}r_{s}i_{s}z_{s}$ observations of one of these stars LP 89--187 which has a rotation period of 0.117 d. TESS data covering three sectors (64.6 d) only show three flares which have energies a few $\times10^{33}$ erg, whilst HiPERCAM observations, which cover 0.78 of the rotation period, show no evidence for flares more energetic than $\sim10^{31}$ erg. Intriguingly, other surveys show LP 89--187 has shown weak H$α$ in emission. We compare the flare energy distribution of LP 89--187 with low mass stars in the $β$ Pic moving group, which have an age of $\sim$24 Myr. We find LP 89--187 has a lower flare rate than the $β$ Pic stars. In addition, we find that TRAPPIST-1 analogue stars, which are likely significantly older than the $β$ Pic stars, show fewer flares with energies $>10^{33}$ erg in TESS data. We examine the relationship between amplitude and period for a sample of low mass stars and find that more rapid rotators have a higher amplitude. |
| title | HiPERCAM and TESS observations of the rapidly rotating M7V star LP 89--187 |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2509.15941 |