RT Journal Article T1 Simultaneous photometric and CARMENES spectroscopic monitoring of fast-rotating M dwarf GJ 3270: discovery of a post-flare corotating feature A1 Caballero, J. A. A1 Cortés Contreras, Miriam A1 Montes Gutiérrez, David AB Context. Active M dwarfs frequently exhibit large flares, which can pose an existential threat to the habitability of any planet in orbit in addition to making said planets more difficult to detect. M dwarfs do not lose angular momentum as easily as earlier-type stars, which maintain the high levels of stellar activity for far longer. Studying young, fast-rotating M dwarfs is key to understanding their near stellar environment and the evolution of activity.Aims. We study stellar activity on the fast-rotating M dwarf GJ 3270.Methods. We analyzed dedicated high cadence, simultaneous, photometric and high-resolution spectroscopic observations obtained with CARMENES of GJ 3270 over 7.7 h, covering a total of eight flares of which two are strong enough to facilitate a detailed analysis. We consult the TESS data, obtained in the month prior to our own observations, to study rotational modulation and to compare the TESS flares to those observed in our campaign.Results. The TESS data exhibit rotational modulation with a period of 0.37 d. The strongest flare covered by our observing campaign released a total energy of about 3.6 × 10^(32) erg, putting it close to the superflare regime. This flare is visible in the B,V, r, i, and z photometric bands, which allows us to determine a peak temperature of about 10 000 K. The flare also leaves clear marks in the spectral time series. In particular, we observe an evolving, mainly blue asymmetry in chromospheric lines, which we attribute to a post-flare, corotating feature. To our knowledge this is the first time such a feature has been seen on a star other than our Sun. Conclusions. Our photometric and spectroscopic time series covers the eruption of a strong flare followed up by a corotating feature analogous to a post-flare arcadal loop on the Sun with a possible failed ejection of material. PB EDP Sciencies SN 0004-6361 YR 2021 FD 2021-07-27 LK https://hdl.handle.net/20.500.14352/4450 UL https://hdl.handle.net/20.500.14352/4450 LA eng NO © E.N. Johnson et al. 2021. This project was funded principally by the Deutsche Forschungsgemeinschaft through the Major Research Instrumentation Programme and Research Unit FOR2544 “Blue Planets around Red Stars”. CARMENES is an instrument at the Centro Astronómico Hispano-Alemán (CAHA) at Calar Alto (Almería, Spain), operated jointly by the Junta de Andalucía and the Instituto de Astrofísica de Andalucía (CSIC). The authors wish to express their sincere thanks to all members of the Calar Alto staff for their expert support of the instrument and telescope operation. CARMENES was funded by the Max-Planck-Gesellschaft (MPG), the Consejo Superior de Investigaciones Científicas (CSIC), the Ministerio de Economía y Competitividad (MINECO) and the European Regional Development Fund (ERDF) through projects FICTS-2011-02, ICTS-2017-07-CAHA-4, and CAHA16-CE-3978, and the members of the CARMENES Consortium (Max-Planck-Institut für Astronomie, Instituto de Astrofísica de Andalucía, Landessternwarte Königstuhl, Institut de Ciències de l’Espai, Institut für Astrophysik Göttingen, Universidad Complutense de Madrid, Thüringer Landessternwarte Tautenburg, Instituto de Astrofísica de Canarias, Hamburger Sternwarte, Centro de Astrobiología and Centro Astronómico Hispano-Alemán), with additional contributions by the MINECO, the Klaus Tschira Stiftung, the states of Baden-Württemberg and Niedersachsen and by the Junta de Andalucía. We acknowledge financial support from the Agencia Estatal de Investigación of the Ministerio de Ciencia, Innovación y Universidades and the ERDF through projects PID2019- 109522GB-C5[1:4]/AEI/10.13039/501100011033 and PGC2018-098153-B-C33 and the Centre of Excellence “Severo Ochoa” and “María de Maeztu” awards to the Instituto de Astrofísica de Canarias (SEV-2015-0548), Instituto de Astrofísica de Andalucía (SEV-2017-0709), and Centro de Astrobiología (MDM-2017-0737), the Generalitat de Catalunya/CERCA programme, JSPS KAKENHI via grants JP18H01265 and JP18H05439, and JST PRESTO via grant JPMJPR1775. This work was based on data from the CARMENES data archive at CAB (CSIC-INTA). Data were partly collected with the 150 cm and 90 cm telescopes at the Observatorio de Sierra Nevada (SNO) operated by the Instituto de Astrofífica de Andalucía (IAA-CSIC). This article is based on observations made with the MuSCAT2 instrument, developed by ABC, at Telescopio Carlos Sánchez operated on the island of Tenerife by the IAC in the Spanish Observatorio del Teide. NO Ministerio de Economía y Competitividad (MINECO)/FEDER NO Ministerio de Ciencia e Innovación (MICINN)/FEDER NO Centro de Excelencia Severo Ochoa NO Unidad de Excelencia María de Maeztu NO Ministerio de Economía y Competitividad (MINECO) NO Deutsche Forschungsgemeinschaft through the Major Research Instrumentation Programme "Blue Planets around Red Stars" NO Max Planck Society NO Consejo Superior de Investigaciones Cientificas (CSIC) NO Comisión Europea NO Astrofisica de Andalucia NO Landessternwarte Konigstuhl NO Institut de Ciencies de l'Espai NO Institut fur Astrophysik Gottingen NO Universidad Complutense de Madrid NO Thuringer Landessternwarte NO Klaus Tschira Stiftung NO states of Baden-Wurttemberg NO Junta de Andalucia NO Instituto de Astrofisica de Canarias NO Instituto de Astrofisica de Andalucia NO Centro de Astrobiologia NO Generalitat de Catalunya/CERCA programme NO Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT) NO Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research (KAKENHI) NO Japan Science & Technology Agency (JST) DS Docta Complutense RD 7 abr 2025