English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We characterized the transiting planetary system orbiting the G2V star K2-38using the new-generation echelle spectrograph ESPRESSO. We carried out aphotometric analysis of the available K2 photometric light curve of this starto measure the radius of its two known planets. Using 43 ESPRESSOhigh-precision radial velocity measurements taken over the course of 8 monthsalong with the 14 previously published HIRES RV measurements, we modeled theorbits of the two planets through a MCMC analysis, significantly improvingtheir mass measurements. Using ESPRESSO spectra, we derived the stellarparameters, $T_{\rm eff}$=5731$\pm$66, $\log g$=4.38$\pm$0.11~dex, and$[Fe/H]$=0.26$\pm$0.05~dex, and thus the mass and radius of K2-38,$M_{\star}$=1.03 $^{+0.04}_{-0.02}$~M$_{\oplus}$ and $R_{\star}$=1.06$^{+0.09}_{-0.06}$~R$_{\oplus}$. We determine new values for the planetaryproperties of both planets. We characterize K2-38b as a super-Earth with$R_{\rm P}$=1.54$\pm$0.14~R$_{\rm \oplus}$ and $M_{\rmp}$=7.3$^{+1.1}_{-1.0}$~M$_{\oplus}$, and K2-38c as a sub-Neptune with $R_{\rmP}$=2.29$\pm$0.26~R$_{\rm \oplus}$ and $M_{\rmp}$=8.3$^{+1.3}_{-1.3}$~M$_{\oplus}$. We derived a mean density of $\rho_{\rmp}$=11.0$^{+4.1}_{-2.8}$~g cm$^{-3}$ for K2-38b and $\rho_{\rmp}$=3.8$^{+1.8}_{-1.1}$~g~cm$^{-3}$ for K2-38c, confirming K2-38b as one of thedensest planets known to date. The best description for the composition ofK2-38b comes from an iron-rich Mercury-like model, while K2-38c is betterdescribed by a rocky model with a H2 envelope. The maximum collision strippingboundary shows how giant impacts could be the cause for the high density ofK2-38b. The irradiation received by each planet places them on opposite sidesof the radius valley. We find evidence of a long-period signal in the radialvelocity time-series whose origin could be linked to a 0.25-3~M$_{\rm J}$planet or stellar activity.

Characterization of the K2-38 planetary system. Unraveling one of the densest planets known to date