Effects of planetary day-night temperature gradients on He 1083 nm transit spectra
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_ | 1866911755170480128 |
|---|---|
| author | Nail, Fabienne Oklopčić, Antonija MacLeod, Morgan |
| author_facet | Nail, Fabienne Oklopčić, Antonija MacLeod, Morgan |
| contents | A notable fraction of helium observations probing the evaporating atmospheres of short-period gas giants at 1083~nm exhibit a blueshift during transit, which might be indicative of a day-to-night side flow. In this study, we explore the gas dynamic effects of day-to-night temperature contrasts on the escaping atmosphere of a tidally locked planet. Using a combination of 3D hydrodynamic simulations and radiative transfer post-processing, we modeled the transmission spectra of the metastable helium triplet. Our key findings are as follows: (1) Increasing the day-night anisotropy leads to a narrowing of the helium line and an increase in the blueshift of the line centroid of a few km~s$^{-1}$. (2) The velocity shift of the line depends on the line-forming altitude, with higher planetary mass-loss rates causing the line to form at higher altitudes, resulting in a more pronounced velocity shift. (3) A critical point of day-night anisotropy comes about when the blueshift saturates, due to turbulent flows generated by outflow material falling back onto the planet's night side. (4) A strong stellar wind and the presence of turbulent flows may induce time variations in the velocity shift. Assuming that the day-night temperature gradient is the main cause of the observed blueshifts in the He-1083~nm triplet, the correlation between the velocity shift and day-night anisotropy provides an opportunity to constrain the temperature gradient of the line-forming region. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2312_04682 |
| institution | arXiv |
| publishDate | 2023 |
| record_format | arxiv |
| spellingShingle | Effects of planetary day-night temperature gradients on He 1083 nm transit spectra Nail, Fabienne Oklopčić, Antonija MacLeod, Morgan Earth and Planetary Astrophysics A notable fraction of helium observations probing the evaporating atmospheres of short-period gas giants at 1083~nm exhibit a blueshift during transit, which might be indicative of a day-to-night side flow. In this study, we explore the gas dynamic effects of day-to-night temperature contrasts on the escaping atmosphere of a tidally locked planet. Using a combination of 3D hydrodynamic simulations and radiative transfer post-processing, we modeled the transmission spectra of the metastable helium triplet. Our key findings are as follows: (1) Increasing the day-night anisotropy leads to a narrowing of the helium line and an increase in the blueshift of the line centroid of a few km~s$^{-1}$. (2) The velocity shift of the line depends on the line-forming altitude, with higher planetary mass-loss rates causing the line to form at higher altitudes, resulting in a more pronounced velocity shift. (3) A critical point of day-night anisotropy comes about when the blueshift saturates, due to turbulent flows generated by outflow material falling back onto the planet's night side. (4) A strong stellar wind and the presence of turbulent flows may induce time variations in the velocity shift. Assuming that the day-night temperature gradient is the main cause of the observed blueshifts in the He-1083~nm triplet, the correlation between the velocity shift and day-night anisotropy provides an opportunity to constrain the temperature gradient of the line-forming region. |
| title | Effects of planetary day-night temperature gradients on He 1083 nm transit spectra |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2312.04682 |