HST SHEL: Revealing Haze and Confirming Elevated Metallicity in the Warm Neptune HAT-P-26b
We present a new and extended transmission spectrum of the warm Neptune HAT-P-26b spanning wavelengths between 0.29 and 5.0 μ m. This spectrum is derived from new HST STIS G430L observations from the PanCET program, a reanalysis of the previously published HST STIS G750L data, along with the previou...
Saved in:
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
IOP Publishing
2025-01-01
|
| Series: | The Astronomical Journal |
| Subjects: | |
| Online Access: | https://doi.org/10.3847/1538-3881/adc1c1 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1850145581897351168 |
|---|---|
| author | Lakeisha M. Ramos Rosado David K. Sing Natalie H. Allen Hannah R. Wakeford Mercedes López-Morales Nikolay K. Nikolov Kevin B. Stevenson Munazza K. Alam Thomas M. Evans-Soma |
| author_facet | Lakeisha M. Ramos Rosado David K. Sing Natalie H. Allen Hannah R. Wakeford Mercedes López-Morales Nikolay K. Nikolov Kevin B. Stevenson Munazza K. Alam Thomas M. Evans-Soma |
| author_sort | Lakeisha M. Ramos Rosado |
| collection | DOAJ |
| description | We present a new and extended transmission spectrum of the warm Neptune HAT-P-26b spanning wavelengths between 0.29 and 5.0 μ m. This spectrum is derived from new HST STIS G430L observations from the PanCET program, a reanalysis of the previously published HST STIS G750L data, along with the previously published HST WFC3 IR G102 and G141 data, and the two Spitzer IRAC photometric points at 3.6 and 4.5 μ m. We present this analysis as part of the Sculpting Hubble’s Exoplanet Legacy program, where the goals are to analyze all HST archival observations of transiting exoplanets using a uniform and homogeneous reduction technique. With the new wavelength coverage, we identify a scattering slope that is weaker than Rayleigh scattering and is best-matched by models incorporating a haze-only scenario. Our retrieval analysis reveals an atmospheric metallicity of 15 ${}_{-8}^{+22}$ × solar which suggests that HAT-P-26b may have formed further out in the protoplanetary disk, in a region rich in hydrogen and helium but with fewer heavy elements, and later migrated inward. This supersolar metallicity places HAT-P-26b below the mass–metallicity trend of the solar system. Looking ahead, recent observations from JWST NIRISS/SOSS and NIRSpec/G495H will provide critical, high-precision data that extend the spectral coverage into the infrared to further constrain the atmospheric composition and structure of HAT-P-26b. These observations have the potential to confirm or refine the metallicity and haze scenario presented here, offering unprecedented insights into the atmospheric properties of warm Neptunes and the processes governing their formation and migration histories. |
| format | Article |
| id | doaj-art-58c2df5d6d5c475795d88c17d43e8a1c |
| institution | OA Journals |
| issn | 1538-3881 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astronomical Journal |
| spelling | doaj-art-58c2df5d6d5c475795d88c17d43e8a1c2025-08-20T02:28:04ZengIOP PublishingThe Astronomical Journal1538-38812025-01-01169525910.3847/1538-3881/adc1c1HST SHEL: Revealing Haze and Confirming Elevated Metallicity in the Warm Neptune HAT-P-26bLakeisha M. Ramos Rosado0https://orcid.org/0000-0002-1056-3144David K. Sing1https://orcid.org/0000-0001-6050-7645Natalie H. Allen2https://orcid.org/0000-0002-0832-710XHannah R. Wakeford3https://orcid.org/0000-0003-4328-3867Mercedes López-Morales4https://orcid.org/0000-0003-3204-8183Nikolay K. Nikolov5https://orcid.org/0000-0002-6500-3574Kevin B. Stevenson6https://orcid.org/0000-0002-7352-7941Munazza K. Alam7https://orcid.org/0000-0003-4157-832XThomas M. Evans-Soma8https://orcid.org/0000-0001-5442-1300William H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA ; lramosr1@jhu.eduWilliam H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA ; lramosr1@jhu.edu; Department of Earth and Planetary Sciences, Johns Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USAWilliam H. Miller III Department of Physics and Astronomy, Johns Hopkins University , 3400 N. Charles Street, Baltimore, MD 21218, USA ; lramosr1@jhu.eduSchool of Physics, University of Bristol , HH Wills Physics Laboratory, Tyndall Avenue, Bristol BS8 1TL, UKSpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USAJohns Hopkins APL , 11100 Johns Hopkins Road, Laurel, MD 20723, USASpace Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USASchool of Information and Physical Sciences, University of Newcastle , Callaghan, NSW, Australia; Max Planck Institute for Astronomy , Königstuhl 17, D-69117 Heidelberg, GermanyWe present a new and extended transmission spectrum of the warm Neptune HAT-P-26b spanning wavelengths between 0.29 and 5.0 μ m. This spectrum is derived from new HST STIS G430L observations from the PanCET program, a reanalysis of the previously published HST STIS G750L data, along with the previously published HST WFC3 IR G102 and G141 data, and the two Spitzer IRAC photometric points at 3.6 and 4.5 μ m. We present this analysis as part of the Sculpting Hubble’s Exoplanet Legacy program, where the goals are to analyze all HST archival observations of transiting exoplanets using a uniform and homogeneous reduction technique. With the new wavelength coverage, we identify a scattering slope that is weaker than Rayleigh scattering and is best-matched by models incorporating a haze-only scenario. Our retrieval analysis reveals an atmospheric metallicity of 15 ${}_{-8}^{+22}$ × solar which suggests that HAT-P-26b may have formed further out in the protoplanetary disk, in a region rich in hydrogen and helium but with fewer heavy elements, and later migrated inward. This supersolar metallicity places HAT-P-26b below the mass–metallicity trend of the solar system. Looking ahead, recent observations from JWST NIRISS/SOSS and NIRSpec/G495H will provide critical, high-precision data that extend the spectral coverage into the infrared to further constrain the atmospheric composition and structure of HAT-P-26b. These observations have the potential to confirm or refine the metallicity and haze scenario presented here, offering unprecedented insights into the atmospheric properties of warm Neptunes and the processes governing their formation and migration histories.https://doi.org/10.3847/1538-3881/adc1c1ExoplanetsExoplanet atmospheresTransitsTransmission spectroscopy |
| spellingShingle | Lakeisha M. Ramos Rosado David K. Sing Natalie H. Allen Hannah R. Wakeford Mercedes López-Morales Nikolay K. Nikolov Kevin B. Stevenson Munazza K. Alam Thomas M. Evans-Soma HST SHEL: Revealing Haze and Confirming Elevated Metallicity in the Warm Neptune HAT-P-26b The Astronomical Journal Exoplanets Exoplanet atmospheres Transits Transmission spectroscopy |
| title | HST SHEL: Revealing Haze and Confirming Elevated Metallicity in the Warm Neptune HAT-P-26b |
| title_full | HST SHEL: Revealing Haze and Confirming Elevated Metallicity in the Warm Neptune HAT-P-26b |
| title_fullStr | HST SHEL: Revealing Haze and Confirming Elevated Metallicity in the Warm Neptune HAT-P-26b |
| title_full_unstemmed | HST SHEL: Revealing Haze and Confirming Elevated Metallicity in the Warm Neptune HAT-P-26b |
| title_short | HST SHEL: Revealing Haze and Confirming Elevated Metallicity in the Warm Neptune HAT-P-26b |
| title_sort | hst shel revealing haze and confirming elevated metallicity in the warm neptune hat p 26b |
| topic | Exoplanets Exoplanet atmospheres Transits Transmission spectroscopy |
| url | https://doi.org/10.3847/1538-3881/adc1c1 |
| work_keys_str_mv | AT lakeishamramosrosado hstshelrevealinghazeandconfirmingelevatedmetallicityinthewarmneptunehatp26b AT davidksing hstshelrevealinghazeandconfirmingelevatedmetallicityinthewarmneptunehatp26b AT nataliehallen hstshelrevealinghazeandconfirmingelevatedmetallicityinthewarmneptunehatp26b AT hannahrwakeford hstshelrevealinghazeandconfirmingelevatedmetallicityinthewarmneptunehatp26b AT mercedeslopezmorales hstshelrevealinghazeandconfirmingelevatedmetallicityinthewarmneptunehatp26b AT nikolayknikolov hstshelrevealinghazeandconfirmingelevatedmetallicityinthewarmneptunehatp26b AT kevinbstevenson hstshelrevealinghazeandconfirmingelevatedmetallicityinthewarmneptunehatp26b AT munazzakalam hstshelrevealinghazeandconfirmingelevatedmetallicityinthewarmneptunehatp26b AT thomasmevanssoma hstshelrevealinghazeandconfirmingelevatedmetallicityinthewarmneptunehatp26b |