| Title: |
Measurement of the Photosphere Oblateness of γ Cassiopeiae via Stellar Intensity Interferometry with the VERITAS Observatory |
| Authors: |
A. Archer; J. P. Aufdenberg; P. Bangale; J. T. Bartkoske; W. Benbow; J. H. Buckley; Y. Chen; N. B. Y. Chin; J. L. Christiansen; A. J. Chromey; A. Duerr; M. Escobar Godoy; S. Feldman; Q. Feng; S. Filbert; L. Fortson; A. Furniss; W. Hanlon; O. Hervet; C. E. Hinrichs; J. Holder; Z. Hughes; T. B. Humensky; W. Jin; M. N. Johnson; M. Kertzman; M. Kherlakian; D. Kieda; N. Korzoun; T. LeBohec; M. A. Lisa; M. Lundy; G. Maier; N. Matthews; P. Moriarty; R. Mukherjee; W. Ning; R. A. Ong; A. Pandey; M. Pohl; E. Pueschel; J. Quinn; P. L. Rabinowitz; K. Ragan; P. T. Reynolds; D. Ribeiro; E. Roache; J. G. Rose; I. Sadeh; L. Saha; M. Santander; J. Scott; G. H. Sembroski; R. Shang; D. Tak; J. V. Tucci; J. Valverde; V. V. Vassiliev; D. A. Williams; S. L. Wong; (The VERITAS Collaboration) |
| Source: |
The Astrophysical Journal, Vol 995, Iss 2, p 191 (2025) |
| Publisher Information: |
IOP Publishing |
| Publication Year: |
2025 |
| Collection: |
Directory of Open Access Journals: DOAJ Articles |
| Subject Terms: |
Astronomy data modeling; High angular resolution; Long baseline interferometry; Nonclassical interferometry; Stellar radii; Stellar rotation; Astrophysics; QB460-466 |
| Description: |
We use the stellar intensity interferometry system implemented with the Very Energetic Radiation Imaging Telescope Array System at Fred Lawrence Whipple Observatory as a light collector to obtain measurements of the rapid rotator star γ Cassiopeiae, at a wavelength of 416 nm. Using data from baselines sampling different position angles, we extract the size, oblateness, and projected orientation of the photosphere. Fitting the data with a uniform ellipse model yields a minor-axis angular diameter of 0.43 ± 0.02 mas, a major-to-minor-radius ratio of 1.28 ± 0.04, and a position angle of 116° ± 5° for the axis of rotation. A rapidly rotating stellar atmosphere model that includes limb and gravity darkening describes the data well with a fitted angular diameter of $0.60{4}_{-0.034}^{+0.041}$ mas corresponding to an equatorial radius of ${10.9}_{-0.6}^{+0.8}\,{R}_{\odot }$ , a rotational velocity with a 1 σ lower limit at 97.7% of breakup velocity, and a position angle of $114\mathop{.}\limits^{{\rm{^\circ }}}{7}_{-5.7}^{+6.4}$ . These parameters are consistent with H α line spectroscopy and infrared-wavelength Michelson interferometric measurements of the star’s decretion disk. This is the first measurement of an oblate photosphere using intensity interferometry. |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| Relation: |
https://doi.org/10.3847/1538-4357/ae0744; https://doaj.org/toc/1538-4357; https://doaj.org/article/d1b60a4faa1b4be78d1515d760732856 |
| DOI: |
10.3847/1538-4357/ae0744 |
| Availability: |
https://doi.org/10.3847/1538-4357/ae0744; https://doaj.org/article/d1b60a4faa1b4be78d1515d760732856 |
| Accession Number: |
edsbas.DA58DC1C |
| Database: |
BASE |