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

LTT 1445 is a hierarchical triple M-dwarf star system located at a distanceof 6.86 parsecs. The primary star LTT 1445A (0.257 M_Sun) is known to host thetransiting planet LTT 1445Ab with an orbital period of 5.4 days, making it thesecond closest known transiting exoplanet system, and the closest one for whichthe host is an M dwarf. Using TESS data, we present the discovery of a secondplanet in the LTT 1445 system, with an orbital period of 3.1 days. We combineradial velocity measurements obtained from the five spectrographs ESPRESSO,HARPS, HIRES, MAROON-X, and PFS to establish that the new world also orbits LTT1445A. We determine the mass and radius of LTT 1445Ab to be 2.87+/-0.25 M_Earthand 1.304^{+0.067}_{-0.060} R_Earth, consistent with an Earth-like composition.For the newly discovered LTT 1445Ac, we measure a mass of 1.54^{+0.20}_{-0.19}M_Earth and a minimum radius of 1.15 R_Earth, but we cannot determine theradius directly as the signal-to-noise of our light curve permits both grazingand non-grazing configurations. Using MEarth photometry and ground-basedspectroscopy, we establish that star C (0.161 M_Sun) is likely the source ofthe 1.4-day rotation period, and star B (0.215 M_Sun) has a likely rotationperiod of 6.7 days. We estimate a probable rotation period of 85 days for LTT1445A. Thus, this triple M-dwarf system appears to be in a special evolutionarystage where the most massive M dwarf has spun down, the intermediate mass Mdwarf is in the process of spinning down, while the least massive stellarcomponent has not yet begun to spin down.

A Second Planet Transiting LTT 1445A and a Determination of the Masses of Both Worlds