A key legacy of the recently launched TESS mission will be to provide the astronomical community with many of the best transiting exoplanet targets for atmospheric characterization. However, time is of the essence to take full advantage of this opportunity. JWST, although delayed, will still complete its nominal five year mission on a timeline that motivates rapid identification, confirmation, and mass measurement of the top atmospheric characterization targets from TESS. Beyond JWST, future dedicated missions for atmospheric studies such as ARIEL require the discovery and confirmation of several hundred additional sub-Jovian size planets (R p < 10 R ⊕ ) orbiting bright stars, beyond those known today, to ensure a successful statistical census of exoplanet atmospheres. Ground-based ELTs will also contribute to surveying the atmospheres of the transiting planets discovered by TESS. Here we present a set of two straightforward analytic metrics, quantifying the expected signal-to-noise in transmission and thermal emission spectroscopy for a given planet, that will allow the top atmospheric characterization targets to be readily identified among the TESS planet candidates. Targets that meet our proposed threshold values for these metrics would be encouraged for rapid follow-up and confirmation via radial velocity mass measurements. Based on the catalog of simulated TESS detections by Sullivan et al. (2015), we determine appropriate cutoff values of the metrics, such that the TESS mission will ultimately yield a sample of ∼ 300 high-quality atmospheric characterization targets across a range of planet size bins, extending down to Earth-size, potentially habitable worlds.

Evidence suggesting an observable magnetic interaction between a star and its hot Jupiter (P orb < 7 days, a < 0.1 AU, M p sini > 0.2 M J ) appears as a cyclic variation of stellar activity synchronized to the planet's orbit. In this study, we monitored the chromospheric activity of 7 stars with hot Jupiters using new high-resolutionéchelle spectra collected with ESPaDOnS over a few nights in 1 Based on observations collected at the Canada-France-Hawaii Telescope operated by the National Research Council of Canada, the Centre National de la Recherche Scientifique of France, and the University of Hawaii.-2 -2005 and 2006 from the CFHT. We searched for variability in several stellar activity indicators (Ca II H λ3968, K λ3933, the Ca II infrared triplet (IRT) λ8662 line, Hα λ6563 and He I λ5876). HD 179949 has been observed almost every year since 2001. Synchronicity of the Ca II H & K emission with the orbit is clearly seen in four out of six epochs, while rotational modulation with P rot =7 days is apparent in the other two seasons. We observe a similar phenomenon on υ And, which displays rotational modulation (P rot =12 days) in September 2005, in 2002 and 2003 variations appear to correlate with the planet's orbital period. This on/off nature of star-planet interaction (SPI) in the two systems is likely a function of the changing stellar magnetic field structure throughout its activity cycle. Variability in the transiting system HD 189733 is likely associated with an active region rotating with the star, however, the flaring in excess of the rotational modulation may be associated with its hot Jupiter. As for HD 179949, the peak variability as measured by the mean absolute deviation (MAD) for both HD 189733 and τ Boo leads the sub-planetary longitude by ∼ 70 • . The tentative correlation between this activity and the ratio of M p sini to the planet's rotation period, a quantity proportional to the hot Jupiter's magnetic moment, first presented in Shkolnik et al. 2005 remains viable. This work furthers the characterization of SPI, improving its potential as a probe of extrasolar planetary magnetic fields.

We report the selection and spectroscopic confirmation of 129 new late-type (SpT=K3-M6) members of the Tucana-Horologium moving group, a nearby (d ∼ 40 pc), young (τ ∼ 40 Myr) population of comoving stars. We also report observations for 13 of the 17 known Tuc-Hor members in this spectral type range, and that 62 additional candidates are likely to be unassociated field stars; the confirmation frequency for new candidates is therefore 129/191 = 67%. We have used radial velocities, Hα emission, and Li 6708 absorption to distinguish between contaminants and bona fide members. Our expanded census of Tuc-Hor increases the known population by a factor of ∼3 in total and by a factor of ∼8 for members with SpT≥K3, but even so, the K-M dwarf population of Tuc-Hor is still markedly incomplete. Our expanded census allows for a much more detailed study of Tuc-Hor than was previously feasible. The spatial distribution of members appears to trace a two-dimensional sheet, with a broad distribution in X and Y , but a very narrow distribution (±5 pc) in Z. The corresponding velocity distribution is very small, with a scatter of ±1.1 km/s about the mean U V W velocity for stars spanning the entire 50 pc extent of Tuc-Hor. We also show that the isochronal age (τ ∼ 20-30 Myr) and the lithium depletion boundary age (τ ∼ 40 Myr) disagree, following the trend in other pre-main sequence populations for isochrones to yield systematically younger ages. The Hα emission line strength follows a trend of increasing equivalent width with later spectral type, as is seen for young clusters. We find that moving group members have been depleted of measurable lithium for spectral types of K7.0-M4.5. None of our targets have significant infrared excesses in the WISE W3 band, yielding an upper limit on warm debris disks of F < 0.7%. Finally, our purely kinematic and color-magnitude selection procedure allows us to test the efficiency and completeness for activity-based selection of young stars. We find that 60% of K-M dwarfs in Tuc-Hor do not have ROSAT counterparts and would have been omitted in X-ray selected samples. In contrast, GALEX UV-selected samples using a previously suggested criterion for youth achieve completeness of 77% and purity of 78%, and we suggest new SpT-dependent selection criteria that will yield >95% completeness for τ ∼ 40 Myr populations with GALEX data available.

We monitored the chromospheric activity in the Ca ii H and K lines of 13 solar-type stars (including the Sun): 8 of them over 3 years at the Canada-France-Hawaii Telescope (CFHT) and 5 in a single run at the Very Large Telescope (VLT). A total of 10 of the 13 targets have close planetary companions. All of the stars observed at the CFHT show long-term (months to years) changes in H and K intensity levels. Four stars display short-term (days) cyclical activity. For two, HD 73256 and 1 Cet, the activity is likely associated with an active region rotating with the star; however, the flaring in excess of the rotational modulation may be associated with a hot Jupiter. A planetary companion remains a possibility for 1 Cet. For the other two, HD 179949 and And, the cyclic variation is synchronized to the hot Jupiter's orbit. For both stars this synchronicity with the orbit is clearly seen in two out of three epochs. The effect is only marginal in the third epoch at which the seasonal level of chromospheric activity had changed for both stars. Short-term chromospheric activity appears weakly dependent on the mean K line reversal intensities for the sample of 13 stars. In addition, a suggestive correlation exists between this activity and the M p sin i of the star's hot Jupiter. Because of their small separation ( 0.1 AU ), many of the hot Jupiters lie within the Alfvén radius of their host stars, which allows a direct magnetic interaction with the stellar surface. We discuss the conditions under which a planet's magnetic field might induce activity on the stellar surface and why no such effect was seen for the prime candidate, Boo. This work opens up the possibility of characterizing planet-star interactions, with implications for extrasolar planet magnetic fields and the energy contribution to stellar atmospheres.

We have detected the synchronous enhancement of Ca ii H and K emission with the short-period planetary orbit in HD 179949. High-resolution spectra taken on three observing runs extending over more than a year show the enhancement coincides with $ 0 (the sub-planetary point) of the 3.093 day orbit, with the effect persisting for more than 100 orbits. The synchronous enhancement is consistent with planet-induced chromospheric heating by magnetic rather than tidal interaction, but awaits confirmation by further observations. Independent observations are needed to determine whether the stellar rotation is synchronous with the planet's orbit. Of the five 51 Peg-type systems monitored, HD 179949 shows the greatest chromospheric H and K activity. Three others show significant nightly variations, but the lack of any phase coherence prevents us saying whether the activity is induced by the planet. Our two standards, Ceti and the Sun, show no such nightly variations. Revised periods and updated ephemerides for the planetary orbits are also included.