Spectral ornaments: the chemical fabric of NGC 2264’s Christmas Tree
Monthly Notices of the Royal Astronomical Society, cilt.551, sa.4, 2026 (SCI-Expanded, Scopus)
- Yayın Türü: Makale / Tam Makale
- Cilt numarası: 551 Sayı: 4
- Basım Tarihi: 2026
- Doi Numarası: 10.1093/mnras/stag1572
- Dergi Adı: Monthly Notices of the Royal Astronomical Society
- Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, Applied Science & Technology Source, Compendex, INSPEC, zbMATH, Directory of Open Access Journals, Academic Search Ultimate (EBSCO), Technology Collection (ProQuest)
- Anahtar Kelimeler: asteroseismology, ISM: individual objects: Christmas Tree Cluster (NGC 2264), stars: abundances, stars: early-type, stars: fundamental parameters, techniques: spectroscopic
- Ankara Üniversitesi Adresli: Evet
Özet
This study presents a detailed spectroscopic and photometric analysis of the early B-type stars HD 47777, HD 47887, and HD 261810 in the Christmas Tree Cluster. Using fully self-consistent non-local thermodynamic equilibrium tlusty208/synspec54 modelling of high-resolution ESPaDOnS spectra, combined with spectral energy distributions (SEDs) and Transiting Exoplanet Survey Satellite (TESS) photometry, we derive significantly improved stellar parameters. Unlike previous He-weak classifications, HD 47777 shows a solar helium abundance, whereas HD 47887 and HD 261810 exhibit mild helium enrichment ((Formula presented) and 0.16 dex). We also report a considerably revised effective temperature of 27 000 K for HD 47887 based on Si iv (Formula presented) 4116 and O ii (Formula presented) 4189 lines. TESS data reveal rotational modulation for HD 47777 ((Formula presented) d) and HD 47887 ((Formula presented) d). For HD 261810, alongside confirming its slowly pulsating B nature, we detect an extraordinary 17-peak high-frequency harmonic ladder ((Formula presented) ). Supported by SED-derived infrared excess and an asymmetric dual-dip phase-folded light curve, we suggest that this modulation may be driven by magnetospheric accretion, where gas from a truncated inner disc ((Formula presented) ) is channelled into two discrete magnetic funnels. Overall, these findings highlight the complex interplay of rotation, localized magnetic fields, and active accretion environments shaping the early B-type population within the Christmas Tree Cluster.