Rotation and H$α$ emission in a young SMC cluster: a spectroscopic view of NGC 330
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| Format: | Preprint |
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2024
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| _version_ | 1866910488802099200 |
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| author | Cristofari, Paul I. Dupree, Andrea K. Milone, Antonino P. Walker, Matthew G. Mateo, Mario Dotter, Aaron Bailey III, John I. |
| author_facet | Cristofari, Paul I. Dupree, Andrea K. Milone, Antonino P. Walker, Matthew G. Mateo, Mario Dotter, Aaron Bailey III, John I. |
| contents | We present an analysis of high-resolution optical spectra recorded for 30 stars of the split extended main-sequence turnoff (eMSTO) of the young ($\sim$ 40 Myr) Small Magellanic Cloud (SMC) globular cluster NGC 330. Spectra were obtained with the M2FS and MIKE spectrographs located on the Magellan-Clay 6.5m telescope. These spectra revealed the presence of Be stars, occupying primarily the cool side of the split main sequence (MS). Rotational velocity ($v\sin{i}$) measurements for most of the targets are consistent with the presence of two populations of stars in the cluster: one made up of rapidly rotating Be stars ($<v\sin{i}> \approx 200$ $\rm km\,s^{-1}$), and {the other} consisting of warmer stars with slower rotation ($<\!v\sin{i}\!>\approx50$ $\rm km\,s^{-1}$). Core emission in the H$δ$ photospheric lines was observed for most of the H$α$ emitters. The shell parameter computed for the targets in our sample indicate that most of the observed stars should have inclinations below 75$^{\circ}$. These results confirm the detection of Be stars obtained through photometry, but also reveal the presence of narrow H$α$ and H$δ$ features for some targets that cannot be detected with low-resolution spectroscopy or photometry. Asymmetry variability of H$α$ line profiles on the timescales of a few years is also observed, and could provide information on the geometry of the decretion disks. Observations revealed the presence of nebular H$α$ emission, strong enough in faint targets to compromise the extraction of spectra and to impact narrow band photometry used to assess the presence of H$α$ emission. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2406_10413 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Rotation and H$α$ emission in a young SMC cluster: a spectroscopic view of NGC 330 Cristofari, Paul I. Dupree, Andrea K. Milone, Antonino P. Walker, Matthew G. Mateo, Mario Dotter, Aaron Bailey III, John I. Solar and Stellar Astrophysics Astrophysics of Galaxies We present an analysis of high-resolution optical spectra recorded for 30 stars of the split extended main-sequence turnoff (eMSTO) of the young ($\sim$ 40 Myr) Small Magellanic Cloud (SMC) globular cluster NGC 330. Spectra were obtained with the M2FS and MIKE spectrographs located on the Magellan-Clay 6.5m telescope. These spectra revealed the presence of Be stars, occupying primarily the cool side of the split main sequence (MS). Rotational velocity ($v\sin{i}$) measurements for most of the targets are consistent with the presence of two populations of stars in the cluster: one made up of rapidly rotating Be stars ($<v\sin{i}> \approx 200$ $\rm km\,s^{-1}$), and {the other} consisting of warmer stars with slower rotation ($<\!v\sin{i}\!>\approx50$ $\rm km\,s^{-1}$). Core emission in the H$δ$ photospheric lines was observed for most of the H$α$ emitters. The shell parameter computed for the targets in our sample indicate that most of the observed stars should have inclinations below 75$^{\circ}$. These results confirm the detection of Be stars obtained through photometry, but also reveal the presence of narrow H$α$ and H$δ$ features for some targets that cannot be detected with low-resolution spectroscopy or photometry. Asymmetry variability of H$α$ line profiles on the timescales of a few years is also observed, and could provide information on the geometry of the decretion disks. Observations revealed the presence of nebular H$α$ emission, strong enough in faint targets to compromise the extraction of spectra and to impact narrow band photometry used to assess the presence of H$α$ emission. |
| title | Rotation and H$α$ emission in a young SMC cluster: a spectroscopic view of NGC 330 |
| topic | Solar and Stellar Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2406.10413 |