The MUSCLES Extension for Atmospheric Transmission Spectroscopy: UV and X-Ray Host-star Observations for JWST ERS &amp; GTO Targets

Behr, Patrick; France, Kevin; Brown, Alexander; Duvvuri, Girish M.; Bean, Jacob L.; Berta-Thompson, Zachory K.; Froning, Cynthia S.; Miguel, Yamila; Pineda, J. Sebastian; Wilson, D. J.; Youngblood, Allison

doi:10.3847/1538-3881/acdb70

Cited by 9 publications

(5 citation statements)

References 137 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Using the ATES model grid from Caldiroli et al (2022), we calculated a predicted massloss rate of  = Ḿ 7.3 10 10 g s −1 . This is in good agreement with Edwards et al (2023), who also used the MUSCLES spectrum from Behr et al (2023) and predicted a mass-loss rate of  » M 10 11 g s −1 with a detailed outflow model based on Allan & Vidotto (2019). These mass-loss rates are ruled out by our observations at the 95% level.…”

Section: Discussionsupporting

confidence: 89%

“…Using an isothermal Parker wind model, we found the planetary mass-loss rate to be <10 10.03 g s −1 and <10 11.11 g s −1 at the 95th and 99.7th percentiles, respectively. Our model accounted for the relatively low XUV luminosity of LTT 9779, which certainly contributes to the non-detection (Behr et al 2023;Fernández Fernández et al 2024). Even so, our inferred mass-loss rate is at least a factor of a few smaller than predicted by photoevaporation models that assume a pure H/He composition for the planetary envelope (Kubyshkina et al 2018;Caldiroli et al 2022;Edwards et al 2023;Fernández Fernández et al 2024).…”

Section: Discussionmentioning

confidence: 74%

“…Our retrieval relies on an estimate for the high-energy spectral energy distribution (SED) of LTT 9779, which is a slowly rotating ( =  v i sin 1.06 0.37 km s −1 ) and relatively inactive ( ¢ = - R log 5.10 0.04 HK ) star (Jenkins et al 2020). We used the MUSCLES Extension SED for TOI-193/LTT 9779 from Behr et al (2023). The SED includes a scaled spectrum of the quiet Sun for the X-ray (5-100 Å) and farultraviolet (FUV; 1170-2180 Å), as the star was not detected in a 22.9 ks Chandra/ACIS-S observation.…”

Section: Modelingmentioning

confidence: 99%

See 2 more Smart Citations

A High-resolution Non-detection of Escaping Helium in the Ultrahot Neptune LTT 9779b: Evidence for Weakened Evaporation

Vissapragada,

McCreery,

Dos Santos

et al. 2024

ApJL

Self Cite

View full text Add to dashboard Cite

The recent discovery of “ultrahot” (P < 1 day) Neptunes has come as a surprise: some of these planets have managed to retain gaseous envelopes despite being close enough to their host stars to trigger strong photoevaporation and/or Roche lobe overflow. Here, we investigate atmospheric escape in LTT 9779b, an ultrahot Neptune with a volatile-rich envelope. We observed two transits of this planet using the newly commissioned WINERED spectrograph (R ∼ 68,000) on the 6.5 m Clay/Magellan II Telescope, aiming to detect an extended upper atmosphere in the He 10830 Å triplet. We found no detectable planetary absorption: in a 0.75 Å passband centered on the triplet, we set a 2σ upper limit of 0.12% (δ R p /H < 14) and a 3σ upper limit of 0.20% (δ R p /H < 22). Using a H/He isothermal Parker wind model, we found corresponding 95% and 99.7% upper limits on the planetary mass-loss rate of M ̇ < 10 10.03 g s−1 and M ̇ < 10 11.11 g s−1, respectively, smaller than predicted by outflow models even considering the weak stellar X-ray and ultraviolet emission. The low evaporation rate is plausibly explained by a metal-rich envelope, which would decrease the atmospheric scale height and increase the cooling rate of the outflow. This hypothesis is imminently testable: if metals commonly weaken planetary outflows, then we expect that JWST will find high atmospheric metallicities for small planets that have evaded detection in He 10830 Å.

show abstract

Section: Discussionsupporting

confidence: 89%

Section: Discussionmentioning

confidence: 74%

Section: Modelingmentioning

confidence: 99%

See 1 more Smart Citation

A High-resolution Non-detection of Escaping Helium in the Ultrahot Neptune LTT 9779b: Evidence for Weakened Evaporation

Vissapragada,

McCreery,

Dos Santos

et al. 2024

ApJL

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is unclear what differentiates the planet-hosting systems with higher flare rates from the control sample. France et al (2018) and Behr et al (2023) found that planet-hosting stars are less active than an equivalent control sample of field-age stars in the UV. In Figure 9 the color of the points corresponds to the effective temperature of the star.…”

Section: Flare Rates Of Young Planet Host Stars Versus Comparison Samplementioning

confidence: 99%

Evolution of Flare Activity in GKM Stars Younger Than 300 Myr over Five Years of TESS Observations

Feinstein,

Seligman,

France

et al. 2024

Self Cite

View full text Add to dashboard Cite

Stellar flares are short-duration (< hours) bursts of radiation associated with surface magnetic reconnection events. Stellar magnetic activity generally decreases as a function of both the age and Rossby number, R 0, a measure of the relative importance of the convective and rotational dynamos. Young stars (<300 Myr) have typically been overlooked in population-level flare studies due to challenges with flare-detection methods. Here, we select a sample of stars that are members of 26 nearby moving groups, clusters, or associations with ages <300 Myr that have been observed by the Transiting Exoplanet Survey Satellite at 2 minute cadence. We identified 26,355 flares originating from 3160 stars and robustly measured the rotation periods of 1847 stars. We measure and find the flare frequency distribution slope, α, saturates for all spectral types at α ∼ −0.5 and is constant over 300 Myr. Additionally, we find that flare rates for stars t age = 50–250 Myr are saturated below R 0 < 0.14, which is consistent with other indicators of magnetic activity. We find evidence of annual flare rate variability in eleven stars, potentially correlated with long-term stellar activity cycles. Additionally, we crossmatch our entire sample with the Galaxy Evolution Explorer and find no correlation between flare rate and far- and near-ultraviolet flux. Finally, we find the flare rates of planet-hosting stars are relatively lower than comparable, larger samples of stars, which may have ramifications for the atmospheric evolution of short-period exoplanets.

show abstract

“…exoplanet mass-loss rates derived with proxy stellar spectra from another star are similarly uncertain (Behr et al 2023). Compounding the issue, the X-ray output from a given star is often time variable (Wagner 1988;Woods & Rottman 2005;Chadney et al 2015) and should alter exoplanetary atmospheric conditions accordingly (Wang & Dai 2021).…”

Section: Introductionmentioning

confidence: 99%

Exoplanet Aeronomy: A Case Study of WASP-69 b’s Variable Thermosphere

Levine,

Vissapragada,

Feinstein

et al. 2024

View full text Add to dashboard Cite

Aeronomy, the study of Earth’s upper atmosphere and its interaction with the local space environment, has long traced changes in the thermospheres of Earth and other solar system planets to solar variability in the X-ray and extreme-ultraviolet (collectively, XUV) bands. Extending comparative aeronomy to the short-period extrasolar planets may illuminate whether stellar XUV irradiation powers atmospheric outflows that change planetary radii on astronomical timescales. In recent years, near-IR transit spectroscopy of metastable Hei has been a prolific tracer of high-altitude planetary gas. We present a case study of exoplanet aeronomy using metastable Hei transit observations from Palomar Observatory's Wide Field InfraRed Camera and follow-up high-energy data from the Neil Gehrels Swift Observatory that were taken within 1 month of the WASP-69 system, a K-type main-sequence star with a well-studied hot Jupiter companion. Supplemented by archival data, we find that WASP-69's X-ray flux in 2023 was less than 50% of what was recorded in 2016 and that the metastable Hei absorption from WASP-69 b was lower in 2023 versus past epochs from 2017 to 2019. Via atmospheric modeling, we show that this time-variable metastable Hei signal is in the expected direction given the observed change in stellar XUV, possibly stemming from WASP-69's magnetic activity cycle. Our results underscore the ability of multiepoch, multiwavelength observations to paint a cohesive picture of the interaction between an exoplanet’s atmosphere and its host star.

show abstract

The MUSCLES Extension for Atmospheric Transmission Spectroscopy: UV and X-Ray Host-star Observations for JWST ERS & GTO Targets

Cited by 9 publications

References 137 publications

A High-resolution Non-detection of Escaping Helium in the Ultrahot Neptune LTT 9779b: Evidence for Weakened Evaporation

A High-resolution Non-detection of Escaping Helium in the Ultrahot Neptune LTT 9779b: Evidence for Weakened Evaporation

Evolution of Flare Activity in GKM Stars Younger Than 300 Myr over Five Years of TESS Observations

Exoplanet Aeronomy: A Case Study of WASP-69 b’s Variable Thermosphere

Contact Info

Product

Resources

About