{ "abstract": "Context. γ Cas stars are Oe or Be stars that exhibit bright and hard X-ray emission. HD 45314 belonged to this category, but lost its γ Cas characteristics as its circumstellar disc started to fade away. Aims. The successive steps of the disc dissipation and its subsequent ongoing rebuilding provide insight into the physical processes at work. Methods. The star was monitored in optical spectroscopy, optical photometry, and X-ray spectroscopy to follow its variability on timescales of hours to years. Emission line properties were measured on the spectra and compared with optical brightness and colours. Time series of magnitudes, colours, line equivalent widths, and violet over red peak intensity ratios were analysed with Fourier methods to uncover possible periodicities. Results. For five years, HD 45314 exhibited magnitude and line strength oscillations on a timescale of 230 d. It then declined towards a nearly disc-free stage and is now slowly rebuilding its disc. During these phases, the violet over red peak intensity ratio exhibited a modulation on a timescale of about 1190 d. Over the whole campaign, prominent short-term photometric variations, notably at a frequency of 3.369 d−1, were probably due to β Cep-type pulsations. The amplitude of these pulsations was stronger during phases of overall brightness changes. In parallel, the X-ray spectrum switched to a low state at the onset of the oscillation phase and has remained in this low state since then. However, some residual hard emission is observed. Conclusions. HD 45314’s long-term optical variations bear resemblance to the predictions of smooth particle hydrodynamics calculations, although a close look does reveal some inconsistencies. Unlike some other γ Cas stars, where the X-ray emission remained nearly constant despite major changes of the circumstellar disc, HD 45314’s X-ray properties changed dramatically as the disc began to dissipate. These differences might arise from a wider orbital separation between the Oe star and its putative white dwarf companion or from the ablation of the disc by the radiation field of the Oe star.", "abstract_shown": true, "affiliations": [ "Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège", "BRIXIIS Observatory", "BAV Bundesdeutsche Arbeitsgemeinschaft Veränderliche Sterne", "Piera Remote Observatory", "Observer of the Be Star Spectra (BeSS) database", "NSF OIR Lab", "Université de Strasbourg, CNRS, Observatoire Astronomique de Strasbourg", "Tennessee State University (retired)", "Hamburger Sternwarte", "2SPOT", "Bd. Carnot", "Observer of the American Association of Variable Stars Observers (AAVSO)", "Verny Observatory (FR57)", "Swedish Association of Amateur Astronomers", "Three Hills Observatory", "Route du Paradis", "Observatoire Belle Etoile" ], "article_type": null, "arxiv": null, "author_total": 28, "authors": [ { "affs": [ 0 ], "name": "Rauw G.", "orcid": "0000-0003-4715-9871" }, { "affs": [ 0 ], "name": "Nazé Y.", "orcid": "0000-0003-4071-9346" }, { "affs": [ 1 ], "name": "Bryssinck E.", "orcid": "0000-0003-4523-0005" }, { "affs": [ 2 ], "name": "Vollmann W." }, { "affs": [ 3 ], "name": "Guarro Fló J." }, { "affs": [ 4 ], "name": "Dupont X." }, { "affs": [ 5 ], "name": "Smith M. A.", "orcid": "0000-0003-4240-4794" }, { "affs": [ 6 ], "name": "Motch C.", "orcid": "0000-0002-4298-5624" }, { "affs": [ 7 ], "name": "Henry G. W.", "orcid": "0000-0003-4155-8513" }, { "affs": [ 8 ], "name": "Robrade J.", "orcid": "0000-0002-4939-8940" }, { "affs": [ 4 ], "name": "de Bruin A." }, { "affs": [ 9 ], "name": "Charbonnel S.", "orcid": "0009-0006-0817-4699" }, { "affs": [ 10 ], "name": "Favaro A." }, { "affs": [ 4 ], "name": "Fricker P.", "orcid": "0009-0008-9233-0336" }, { "affs": [ 9 ], "name": "Garde O.", "orcid": "0000-0002-7850-8360" }, { "affs": [ 4 ], "name": "Gayrard O." }, { "affs": [ 11 ], "name": "Güssregen S." }, { "affs": [ 12 ], "name": "Houpert F." }, { "affs": [ 13 ], "name": "Larsson M.", "orcid": "0000-0002-7462-9106" }, { "affs": [ 14 ], "name": "Leadbeater R." }, { "affs": [ 15 ], "name": "Lecocq V." }, { "affs": [ 9 ], "name": "Le Dû P.", "orcid": "0000-0003-2385-0967" }, { "name": "Lester T." }, { "affs": [ 9 ], "name": "Mulato L.", "orcid": "0000-0002-6822-9368" }, { "affs": [ 9 ], "name": "Petit T." }, { "affs": [ 11 ], "name": "Pomillo R." }, { "affs": [ 16 ], "name": "Thizy O." }, { "affs": [ 4 ], "name": "Weil F." } ], "bibtex": "https://research.draconitic.com/paper/fm5y9txjx57es.bib", "cited_by": 0, "doi": "10.1051/0004-6361/202660772", "fulltext_url": "https://www.aanda.org/articles/aa/full_html/2026/10/aa60772-26/aa60772-26.html", "id": "fm5y9txjx57es", "issns": [ "0004-6361", "1432-0746" ], "landing_url": "https://doi.org/10.1051/0004-6361/202660772", "language": "en", "licence": "CC-BY-4.0", "licence_label": "CC BY 4.0", "licence_source": "article", "licence_url": "https://creativecommons.org/licenses/by/4.0/", "metadata_licence": null, "native_subjects": [ [ "hal", "0.sdu" ], [ "hal", "1.sdu.astr" ], [ "hal", "2.sdu.astr.sr" ], [ "lcc", "QB1-991" ], [ "openalex", "3103|Stellar, planetary, and galactic studies" ] ], "openalex": "W7212120217", "pdf_url": "https://hal.science/hal-05857177/document", "pmcid": null, "pmid": null, "published": "2026-10-24", "publisher": "EDP Sciences", "ris": "https://research.draconitic.com/paper/fm5y9txjx57es.ris", "sources": [ { "first_seen": "2026-10-30T13:44:42Z", "native_id": "152c2392c3fa45f3ac1edeedaaad6d27", "source": "doaj", "url": "https://doi.org/10.1051/0004-6361/202660772" }, { "first_seen": "2026-11-09T12:20:29Z", "native_id": "hal-05857177", "source": "hal", "url": "https://hal.science/hal-05857177v1" } ], "subjects": [ { "field": "astronomy", "origin": "hal:2.sdu.astr.sr", "subfield": "stellar" }, { "field": "earth", "origin": "hal:0.sdu", "subfield": "general" } ], "title": "The changing optical and X-ray emission of the dormant γ Cas star HD 45314", "title_text": "The changing optical and X-ray emission of the dormant γ Cas star HD 45314", "type": "peer-reviewed", "updated_at": "2026-11-09T12:20:29Z", "url": "https://research.draconitic.com/paper/fm5y9txjx57es", "venue": "Astronomy & Astrophysics", "versions": [] }