Continuous helium absorption from the leading and trailing tails of WASP-107b
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866915306005331968 |
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| author | Krishnamurthy, Vigneshwaran Carteret, Yann Piaulet-Ghorayeb, Caroline Splinter, Jared Doshi, Dhvani Radica, Michael Coulombe, Louis-Philippe Allart, Romain Bourrier, Vincent Cowan, Nicolas B. Lafrenière, David Albert, Loïc Dang, Lisa Jayawardhana, Ray Johnstone, Doug Kaltenegger, Lisa Langeveld, Adam B. Pelletier, Stefan Rowe, Jason F. Roy, Pierre-Alexis Taylor, Jake Turner, Jake D. |
| author_facet | Krishnamurthy, Vigneshwaran Carteret, Yann Piaulet-Ghorayeb, Caroline Splinter, Jared Doshi, Dhvani Radica, Michael Coulombe, Louis-Philippe Allart, Romain Bourrier, Vincent Cowan, Nicolas B. Lafrenière, David Albert, Loïc Dang, Lisa Jayawardhana, Ray Johnstone, Doug Kaltenegger, Lisa Langeveld, Adam B. Pelletier, Stefan Rowe, Jason F. Roy, Pierre-Alexis Taylor, Jake Turner, Jake D. |
| contents | The detection of helium escaping the atmosphere of exoplanets has revolutionized our understanding of atmospheric escape and exoplanetary evolution. Using high-precision spectroscopic observations from the James Webb Space Telescope (JWST) NIRISS-SOSS mode, we report the detection of significant helium absorption during the pre-transit phase of WASP-107b (17$σ$), as well as in the transit and post-transit phases. This unique continuous helium absorption begins approximately 1.5 hours before the planet's ingress and reveals the presence of an extended thermosphere. The observations show a maximum transit depth of 2.395$\% \pm$ 0.01$\%$ near the helium triplet (36$σ$; at NIRISS-SOSS resolution $\sim$ 700). Our ellipsoidal model of the planetary thermosphere matches well the measured light curve suggesting an outflow extending to tens of planetary radii. Furthermore, we confidently detect water absorption (log10 H2O=-2.5 $\pm$ 0.6), superimposed with a short-wavelength slope which we attribute to a prominent signature from unocculted stellar spots (5.2$σ$), rather than a small-particle haze slope. We place an upper limit on the abundance of K (log10 K$<$-4.86, or K/H$<$ 75$\times$ stellar) at 2$σ$, which is consistent with the O/H super-solar metallicity estimate. This study underscores the transformative potential of JWST for tracing atmospheric and mass-loss processes, while offering a benchmark for future studies targeting helium escape and its implications for planetary evolution. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2505_20588 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Continuous helium absorption from the leading and trailing tails of WASP-107b Krishnamurthy, Vigneshwaran Carteret, Yann Piaulet-Ghorayeb, Caroline Splinter, Jared Doshi, Dhvani Radica, Michael Coulombe, Louis-Philippe Allart, Romain Bourrier, Vincent Cowan, Nicolas B. Lafrenière, David Albert, Loïc Dang, Lisa Jayawardhana, Ray Johnstone, Doug Kaltenegger, Lisa Langeveld, Adam B. Pelletier, Stefan Rowe, Jason F. Roy, Pierre-Alexis Taylor, Jake Turner, Jake D. Earth and Planetary Astrophysics The detection of helium escaping the atmosphere of exoplanets has revolutionized our understanding of atmospheric escape and exoplanetary evolution. Using high-precision spectroscopic observations from the James Webb Space Telescope (JWST) NIRISS-SOSS mode, we report the detection of significant helium absorption during the pre-transit phase of WASP-107b (17$σ$), as well as in the transit and post-transit phases. This unique continuous helium absorption begins approximately 1.5 hours before the planet's ingress and reveals the presence of an extended thermosphere. The observations show a maximum transit depth of 2.395$\% \pm$ 0.01$\%$ near the helium triplet (36$σ$; at NIRISS-SOSS resolution $\sim$ 700). Our ellipsoidal model of the planetary thermosphere matches well the measured light curve suggesting an outflow extending to tens of planetary radii. Furthermore, we confidently detect water absorption (log10 H2O=-2.5 $\pm$ 0.6), superimposed with a short-wavelength slope which we attribute to a prominent signature from unocculted stellar spots (5.2$σ$), rather than a small-particle haze slope. We place an upper limit on the abundance of K (log10 K$<$-4.86, or K/H$<$ 75$\times$ stellar) at 2$σ$, which is consistent with the O/H super-solar metallicity estimate. This study underscores the transformative potential of JWST for tracing atmospheric and mass-loss processes, while offering a benchmark for future studies targeting helium escape and its implications for planetary evolution. |
| title | Continuous helium absorption from the leading and trailing tails of WASP-107b |
| topic | Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2505.20588 |