We present a census of molecular outflows across four active regions of star formation in the Perseus molecular cloud (NGC 1333, IC348/HH211, L1448 and L1455), totalling an area of over 1000 arcmin 2 . This is one of the largest surveys of outflow evolution in a single molecular cloud published to date. We analyse large-scale, sensitive CO J = 3 → 2 data sets from the James Clerk Maxwell Telescope, including new data towards NGC 1333. Where possible we make use of our complementary 13 CO and C 18 O data to correct for the 12 CO optical depth and measure ambient cloud properties. Of the 65 submillimetre cores in our fields, we detect outflows towards 45. 24 of these are marginal detections where the outflow's shape is unclear or could be confused with the other outflows. We compare various parameters between the outflows from Class 0 and I protostars, including their mass, momentum, energy and momentum flux. Class 0 outflows are longer, faster, more massive and have more energy than Class I outflows. The dynamical time-scales we derive from these outflows are uncorrelated to the age of the outflow driving source, computed from the protostar's bolometric temperature. We confirm the results of Bontemps et al. that outflows decrease in force as they age. There is a decrease in momentum flux from the Class 0 to I stage: F CO = (0.8 ± 0.3) × 10 −4 compared to (1.1 ± 0.3) × 10 −5 M km s −1 yr −1 , suggesting a decline in the mass accretion rate assuming the same entrainment fraction for both classes of outflow. If F rad = L bol /c is the flux expected in radiation from the central source, then F CO (Class I) ∼ 100F rad and F CO (Class 0) ∼ 1000F rad . Furthermore, we confirm there are additional sources of mass loss from protostars. If a core's mass is only lost from outflows at the current rate, cores would endure a few million years, much longer than current estimates for the duration of the protostellar stage. Finally, we note that the total energy contained in outflows in NGC 1333, L1448 and L1455 is greater than the estimated turbulent energy in the respective regions, which may have implications for the regions' evolution.

Based in part on observations made with ESO telescopes at Paranal Observatory, under ESO program 083.C-0459(A). ABSTRACTWe have obtained millimeter wavelength photometry, high-resolution optical spectroscopy and adaptive optics near-infrared imaging for a sample of 26Spitzer -selected transition circumstellar disks. All of our targets are located in the Ophiuchus molecular cloud (d ∼125 pc) and have Spectral Energy Distributions (SEDs) suggesting the presence of inner opacity holes. We use these ground-based data to estimate the disk mass, multiplicity, and accretion rate for each object in our sample in order to investigate the mechanisms potentially responsible for their inner holes. We find that transition disks are a heterogeneous group of objects, with disk masses ranging from < 0.6 to 40 M JU P and accretion rates ranging from <10 −11 to 10 −7 M yr −1 , but most tend to have much lower masses and accretion rates than "full disks" (i.e., disks without opacity holes).Eight of our targets have stellar companions: 6 of them are binaries and the other 2 are triple systems. In four cases, the stellar companions are close enough to suspect they are responsible for the inferred inner holes. We find that 9 of our 26 targets have low disk mass (< 2.5 M JU P ) and negligible accretion (< 10 −11 M yr −1 ), and are thus consistent with photoevaporating (or photoevaporated) disks. Four of these 9 non-accreting objects have fractional disk luminosities < 10 −3 and could already be in a debris disk stage. Seventeen of our transition disks are accreting. Thirteen of these accreting objects are consistent with grain growth. The remaining 4 accreting objects have SEDs suggesting the presence of sharp inner holes, and thus are excellent candidates for harboring giant planets.

We calculate an empirical, non-parametric estimate of the shape of the period-marginalized radius distribution of planets with periods less than 150 days using the small yet well-characterized sample of cool (T eff < 4000K) dwarf stars in the Kepler catalog. In particular, we present and validate a new procedure, based on weighted kernel density estimation, to reconstruct the shape of the planet radius function down to radii smaller than the completeness limit of the survey at the longest periods. Under the assumption that the period distribution of planets does not change dramatically with planet radius, we show that the occurrence of planets around these stars continues to increase to below 1 R ⊕ , and that there is no strong evidence for a turnover in the planet radius function. In fact, we demonstrate using many iterations of simulated data that a spurious turnover may be inferred from data even when the true distribution continues to rise toward smaller radii. Finally, the sharp rise in the radius distribution below ∼3 R ⊕ implies that a large number of planets await discovery around cool dwarfs as the sensitivities of ground-based transit surveys increase.

The chemical composition of stars hosting small exoplanets (with radii less than four Earth radii) appears to be more diverse than that of gas-giant hosts, which tend to be metal-rich. This implies that small, including Earth-size, planets may have readily many -3formed at earlier epochs in the Universe's history when metals were more scarce. We report Kepler spacecraft observations of Kepler-444, a metal-poor Sun-like star from the old population of the Galactic thick disk and the host to a compact system of five transiting planets with sizes between those of Mercury and Venus. We validate this system as a true five-planet system orbiting the target star and provide a detailed characterization of its planetary and orbital parameters based on an analysis of the transit photometry. Kepler-444 is the densest star with detected solar-like oscillations. We use asteroseismology to directly measure a precise age of 11.2 ± 1.0 Gyr for the host star, indicating that Kepler-444 formed when the Universe was less than 20 % of its current age and making it the oldest known system of terrestrial-size planets. We thus show that Earth-size planets have formed throughout most of the Universe's 13.8billion-year history, leaving open the possibility for the existence of ancient life in the Galaxy. The age of Kepler-444 not only suggests that thick-disk stars were among the hosts to the first Galactic planets, but may also help to pinpoint the beginning of the era of planet formation.

We confirm and characterize the exoplanetary systems Kepler-445 and Kepler-446: two mid-M dwarf stars, each with multiple, small, short-period transiting planets. Kepler-445 is a metal-rich ([Fe/H]=+0.25 ± 0.10) M4 dwarf with three transiting planets, and Kepler-446 is a metal-poor ([Fe/H]=-0.30 ± 0.10) M4 dwarf also with three transiting planets. Kepler-445c is similar to GJ 1214b: both in planetary radius and the properties of the host star. The Kepler-446 system is similar to the Kepler-42 system: both are metal-poor with large galactic space velocities and three shortperiod, likely-rocky transiting planets that were initially assigned erroneously large planet-to-star radius ratios. We independently determined stellar parameters from spectroscopy and searched for and fitted the transit light curves for the planets, imposing a strict prior on stellar density in order to remove correlations between the fitted impact parameter and planet-to-star radius ratio for shortduration transits. Combining Kepler-445, Kepler-446 and Kepler-42, and isolating all mid-M dwarf stars observed by Kepler with the precision necessary to detect similar systems, we calculate that 21 +7−5 % of mid-M dwarf stars host compact multiples (multiple planets with periods of less than 10 days) for a wide range of metallicities. We suggest that the inferred planet masses for these systems support highly efficient accretion of protoplanetary disk metals by mid-M dwarf protoplanets.The same calculation for the Sun results in only 5% of disk metals contributing to rocky planets (Earth, Venus, Mars and Mercury), with significantly more contributing to the cores of the solar system's gas giant planets.The preference for metals to contribute to rocky planets rather than gas-giant cores would be strong evidence for the planet-formation scenario suggested by Laughlin et al. (2004), in which gas-giant-core embryos form in the protoplanetary disks around M dwarf stars; however, the gas in the disk dissipates before those embryos grow large enough to accrete and are cut-off as terrestrial planets. The scenario is already supported by the relative scarcity of gas-giant exoplanets found to orbit M dwarf stars. Using radial velocity observations, Johnson et al. (2010) found a statistical decrease in giant planet planet occurrence with decreasing host star mass, including M dwarfs in the radial velocity sample. However, Gaidos & Mann (2014) do not find strong support for a statistical deficiency of gas giant planets orbiting M dwarfs, though they cannot statistically rule out a deficiency. Regardless, the presence of failed embryos in some consistent proportion to the amount of available metals in the protoplanetary disk would provide support for the cut-off accretion scenario.