Stellar activity plays a fundamental role in determining the radiation environment and habitability of orbiting planets. Variations in stellar output, ranging from transient flares to long-term magnetic cycles, directly influence atmospheric chemistry, circulation, and potential biosignatures. Among cool stars, M dwarfs are especially active, showing strong magnetic fields and intense chromospheric emission in lines such as Ca II H&K (393 nm), Na I D1&D2 (580 nm), and the Balmer series (Hα, Hβ, H\u03f5). Proxima Centauri (M5.5Ve) is a key benchmark for understanding magnetic activity in active M dwarfs and its impact on the habitability of terrestrial exoplanets. While its reported ~7-year activity cycle is quite well-documented, the physical changes in its atmosphere remain poorly constrained.
\nIn this work, we present the semi-empirical modeling of Proxima Centauri’s atmosphere at the minimum and maximum of its activity cycle to investigate the evolution of its chromospheric thermal structure. Our analysis is based on flux-calibrated visible spectra from the HKα Project at CASLEO Observatory. We find that the integrated flux of Ca II K and Hβ show variations of 114% and 58% respectively between the cycle extremes. Using the SSRPM (Solar Stellar Radiative Physical Modelling) library of codes, we construct self-consistent non-LTE atmospheric models for both stages by fitting these diagnostic lines. The ultimate goal of this research is to reconstruct the full spectral irradiance at the orbit of Proxima b to provide physically-grounded stellar forcing for future planetary climate and photochemical models.
\n", "languages": [ { "id": "eng", "title": { "en": "English" } } ], "publication_date": "2026-06-13", "publisher": "Zenodo", "related_identifiers": [ { "identifier": "2024BAAA...65...87B", "relation_type": { "id": "cites", "title": { "de": "Zitiert", "en": "Cites" } }, "resource_type": { "id": "publication", "title": { "de": "Publikation", "en": "Publication" } }, "scheme": "ads" }, { "identifier": "2016ApJ...830..154F", "relation_type": { "id": "cites", "title": { "de": "Zitiert", "en": "Cites" } }, "resource_type": { "id": "publication", "title": { "de": "Publikation", "en": "Publication" } }, "scheme": "ads" }, { "identifier": "2025A&A...696A.230I", "relation_type": { "id": "cites", "title": { "de": "Zitiert", "en": "Cites" } }, "resource_type": { "id": "publication", "title": { "de": "Publikation", "en": "Publication" } }, "scheme": "ads" }, { "identifier": "10.1093/mnras/stad1391", "relation_type": { "id": "cites", "title": { "de": "Zitiert", "en": "Cites" } }, "resource_type": { "id": "publication", "title": { "de": "Publikation", "en": "Publication" } }, "scheme": "doi" }, { "identifier": "10.1051/0004-6361/202553728", "relation_type": { "id": "cites", "title": { "de": "Zitiert", "en": "Cites" } }, "resource_type": { "id": "publication", "title": { "de": "Publikation", "en": "Publication" } }, "scheme": "doi" }, { "identifier": "10.3847/1538-4357/abd62f", "relation_type": { "id": "cites", "title": { "de": "Zitiert", "en": "Cites" } }, "resource_type": { "id": "publication", "title": { "de": "Publikation", "en": "Publication" } }, "scheme": "doi" }, { "identifier": "10.3847/1538-4357/adb0c6", "relation_type": { "id": "cites", "title": { "de": "Zitiert", "en": "Cites" } }, "resource_type": { "id": "publication", "title": { "de": "Publikation", "en": "Publication" } }, "scheme": "doi" }, { "identifier": "10.3847/1538-4357/adb0c6", "relation_type": { "id": "cites", "title": { "de": "Zitiert", "en": "Cites" } }, "resource_type": { "id": "publication", "title": { "de": "Publikation", "en": "Publication" } }, "scheme": "doi" }, { "identifier": "10.1093/mnras/stw2570", "relation_type": { "id": "cites", "title": { "de": "Zitiert", "en": "Cites" } }, "resource_type": { "id": "publication", "title": { "de": "Publikation", "en": "Publication" } }, "scheme": "doi" } ], "resource_type": { "id": "poster", "title": { "de": "Poster", "en": "Poster" } }, "rights": [ { "description": { "en": "The Creative Commons Attribution license allows re-distribution and re-use of a licensed work on the condition that the creator is appropriately credited." }, "icon": "cc-by-icon", "id": "cc-by-4.0", "props": { "scheme": "spdx", "url": "https://creativecommons.org/licenses/by/4.0/legalcode" }, "title": { "en": "Creative Commons Attribution 4.0 International" } } ], "subjects": [ { "subject": "Stellar Activity" }, { "subject": "Porxima Centauri" }, { "subject": "Stellar atmospheric models" }, { "subject": "Proxima b" } ], "title": "Chromospheric Semi-empirical Model of Proxima Centauri at Activity Cycle Extremes: Reconstructing the Radiative Environment of Proxima b" }, "parent": { "access": { "owned_by": { "user": "1686453" }, "settings": { "accept_conditions_text": null, "allow_guest_requests": false, "allow_user_requests": false, "secret_link_expiration": 0 } }, "communities": { "default": "9ba7fd7e-a60f-4b7a-b3da-a178c21c5fda", "entries": [ { "access": { "member_policy": "open", "members_visibility": "public", "record_submission_policy": "open", "review_policy": "closed", "visibility": "public" }, "children": { "allow": false }, "created": "2026-04-06T12:19:20.716447+00:00", "custom_fields": { "subjects": [ { "id": "euroscivoc:769" }, { "id": "euroscivoc:763" }, { "id": "euroscivoc:1807" }, { "id": "euroscivoc:757" } ] }, "deletion_status": { "is_deleted": false, "status": "P" }, "id": "9ba7fd7e-a60f-4b7a-b3da-a178c21c5fda", "links": {}, "metadata": { "curation_policy": "
All proceeding submissions will be reviewed by the curator(s) to ensure they are from registered conference attendees (in person or virtual) and adhere to the conference code of conduct.
", "description": "Presentations made at the 23rd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (\"Cool Stars 23\"), held in Tokyo, Japan, from June 15 to 19, 2026.", "title": "The 23rd Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (Tokyo, June 15-19, 2026)", "type": { "id": "event" }, "website": "https://coolstars23.github.io" }, "revision_id": 9, "slug": "coolstars23", "updated": "2026-04-07T08:31:24.965586+00:00" } ], "ids": [ "9ba7fd7e-a60f-4b7a-b3da-a178c21c5fda" ] }, "id": "20673072", "pids": { "doi": { "client": "datacite", "identifier": "10.5281/zenodo.20673072", "provider": "datacite" } } }, "pids": { "doi": { "client": "datacite", "identifier": "10.5281/zenodo.20673073", "provider": "datacite" }, "oai": { "identifier": "oai:zenodo.org:20673073", "provider": "oai" } }, "revision_id": 4, "stats": { "all_versions": { "data_volume": 141091794.0, "downloads": 54, "unique_downloads": 39, "unique_views": 46, "views": 52 }, "this_version": { "data_volume": 141091794.0, "downloads": 54, "unique_downloads": 39, "unique_views": 46, "views": 52 } }, "status": "published", "swh": {}, "updated": "2026-06-13T03:13:27.624980+00:00", "versions": { "index": 1, "is_latest": true } }