The Factory and the Beehive. V. Chromospheric and Coronal Activity and Its Dependence on Rotation in Praesepe and the Hyades
Fuente:
arXiv
Guardado en:
| Autores principales: | , , , , , , , , |
|---|---|
| Formato: | Preprint |
| Publicado: |
2023
|
| Materias: | |
| Acceso en línea: | |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| _version_ | 1866929231425961984 |
|---|---|
| author | Núñez, Alejandro Agüeros, M. A. Curtis, J. L. Covey, K. R. Douglas, S. T. Chu, S. R. DeLaurentiis, S. Wang, M. Drake, J. J. |
| author_facet | Núñez, Alejandro Agüeros, M. A. Curtis, J. L. Covey, K. R. Douglas, S. T. Chu, S. R. DeLaurentiis, S. Wang, M. Drake, J. J. |
| contents | Low-mass (< 1.2 Solar mass) main-sequence stars lose angular momentum over time, leading to a decrease in their magnetic activity. The details of this rotation-activity relation remain poorly understood. Using observations of members of the $\approx$700 Myr-old Praesepe and Hyades open clusters, we aim to characterize the rotation-activity relation for different tracers of activity at this age. To complement published data, we obtained new optical spectra for 250 Praesepe stars, new X-ray detections for ten, and new rotation periods for 28. These numbers for Hyads are 131, 23, and 137, respectively. The latter increases the number of Hyads with periods by 50%. We used these data to measure the fractional H$α$ and X-ray luminosities, $\mathit{L}_{Hα}/\mathit{L}_{bol}$ and $\mathit{L}_X/\mathit{L}_{bol}$, and to calculate Rossby numbers $\mathit{R}_o$. We found that at $\approx$700 Myr almost all M dwarfs exhibit H$α$ emission, with binaries having the same overall color-H$α$ equivalent width distribution as single stars. In the $\mathit{R}_o-\mathit{L}_{Hα}/\mathit{L}_{bol}$ plane, unsaturated single stars follow a power-law with index $β= -5.9 \pm 0.8$ for $\mathit{R}_o > 0.3$. In the $\mathit{R}_o-\mathit{L}_X/\mathit{L}_{bol}$ plane, we see evidence for supersaturation for single stars with $\mathit{R}_o \lesssim 0.01$, following a power-law with index $β_{sup} = 0.5^{+0.2}_{-0.1}$, supporting the hypothesis that stellar coronae are being centrifugally stripped. We found that the critical $\mathit{R}_o$ value at which activity saturates is smaller for $\mathit{L}_X/\mathit{L}_{bol}$ than for $\mathit{L}_{Hα}/\mathit{L}_{bol}$. Finally, we observed an almost 1:1 relation between $\mathit{L}_{Hα}/\mathit{L}_{bol}$ and $\mathit{L}_X/\mathit{L}_{bol}$, suggesting that both the corona and the chromosphere experience similar magnetic heating. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2311_18690 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | The Factory and the Beehive. V. Chromospheric and Coronal Activity and Its Dependence on Rotation in Praesepe and the Hyades Núñez, Alejandro Agüeros, M. A. Curtis, J. L. Covey, K. R. Douglas, S. T. Chu, S. R. DeLaurentiis, S. Wang, M. Drake, J. J. Solar and Stellar Astrophysics Low-mass (< 1.2 Solar mass) main-sequence stars lose angular momentum over time, leading to a decrease in their magnetic activity. The details of this rotation-activity relation remain poorly understood. Using observations of members of the $\approx$700 Myr-old Praesepe and Hyades open clusters, we aim to characterize the rotation-activity relation for different tracers of activity at this age. To complement published data, we obtained new optical spectra for 250 Praesepe stars, new X-ray detections for ten, and new rotation periods for 28. These numbers for Hyads are 131, 23, and 137, respectively. The latter increases the number of Hyads with periods by 50%. We used these data to measure the fractional H$α$ and X-ray luminosities, $\mathit{L}_{Hα}/\mathit{L}_{bol}$ and $\mathit{L}_X/\mathit{L}_{bol}$, and to calculate Rossby numbers $\mathit{R}_o$. We found that at $\approx$700 Myr almost all M dwarfs exhibit H$α$ emission, with binaries having the same overall color-H$α$ equivalent width distribution as single stars. In the $\mathit{R}_o-\mathit{L}_{Hα}/\mathit{L}_{bol}$ plane, unsaturated single stars follow a power-law with index $β= -5.9 \pm 0.8$ for $\mathit{R}_o > 0.3$. In the $\mathit{R}_o-\mathit{L}_X/\mathit{L}_{bol}$ plane, we see evidence for supersaturation for single stars with $\mathit{R}_o \lesssim 0.01$, following a power-law with index $β_{sup} = 0.5^{+0.2}_{-0.1}$, supporting the hypothesis that stellar coronae are being centrifugally stripped. We found that the critical $\mathit{R}_o$ value at which activity saturates is smaller for $\mathit{L}_X/\mathit{L}_{bol}$ than for $\mathit{L}_{Hα}/\mathit{L}_{bol}$. Finally, we observed an almost 1:1 relation between $\mathit{L}_{Hα}/\mathit{L}_{bol}$ and $\mathit{L}_X/\mathit{L}_{bol}$, suggesting that both the corona and the chromosphere experience similar magnetic heating. |
| title | The Factory and the Beehive. V. Chromospheric and Coronal Activity and Its Dependence on Rotation in Praesepe and the Hyades |
| topic | Solar and Stellar Astrophysics |
| url | https://arxiv.org/abs/2311.18690 |