Pre-main sequence disk accretion is pivotal in determining the final stellar properties and the early conditions for close-in planets. We aim to establish the impact of internal (stellar mass) and external (radiation field) parameters on disk evolution in the Lagoon Nebula massive star-forming region. We employ simultaneous $u,g,r,i,H\alpha$ time series photometry, archival infrared data, and high-precision $K2$ light curves, to derive stellar, disk, and accretion properties for 1012 Lagoon Nebula members. Of all young stars in the Lagoon Nebula, we estimate $34\%-37\%$ have inner disks traceable down to $\sim 12$ $\mu$m, while $38\%-41\%$ are actively accreting. We detect disks $\sim$1.5 times more frequently around G/K/M stars than higher-mass stars, which appear to deplete their inner disks on shorter timescales. We find tentative evidence for faster disk evolution in the central regions of the Lagoon Nebula, where the bulk of the O/B population is located. Conversely, disks appear to last longer at its outskirts, where the measured fraction of disk-bearing stars tends to exceed those of accreting and disk-free stars. The derived mass accretion rates show a non-uniform dependence on stellar mass between $\sim 0.2-5$ $M_\odot$. In addition, the typical accretion rates appear to differ across the Lagoon Nebula extension, with values two times lower in the core region than at its periphery. Finally, we detect tentative density gradients in the accretion shocks, with lags in the appearance of brightness features as a function of wavelength that can amount to $\sim7\%-30\%$ of the rotation period.

ABSTRACTWe present K2-2016-BLG-0005Lb, a densely sampled, planetary binary caustic-crossing microlensing event found from a blind search of data gathered from Campaign 9 of the Kepler K2 mission (K2C9). K2-2016-BLG-0005Lb is the first bound microlensing exoplanet discovered from space-based data. The event has caustic entry and exit points that are resolved in the K2C9 data, enabling the lens-source relative proper motion to be measured. We have fitted a binary microlens model to the Kepler data and to simultaneous observations from multiple ground-based surveys. Whilst the ground-based data only sparsely sample the binary caustic, they provide a clear detection of parallax that allows us to break completely the microlensing mass-position-velocity degeneracy and measure the planet’s mass directly. We find a host mass of 0.58 ± 0.04 M⊙ and a planetary mass of 1.1 ± 0.1 MJ. The system lies at a distance of 5.2 ± 0.2 kpc from Earth towards the Galactic bulge, more than twice the distance of the previous most distant planet found by Kepler. The sky-projected separation of the planet from its host is found to be 4.2 ± 0.3 au which, for circular orbits, deprojects to a host separation $a = 4.4^{+1.9}_{-0.4}$ au and orbital period $P = 13^{+9}_{-2}$ yr. This makes K2-2016-BLG-0005Lb a close Jupiter analogue orbiting a low-mass host star. According to current planet formation models, this system is very close to the host mass threshold below which Jupiters are not expected to form. Upcoming space-based exoplanet microlensing surveys by NASA’s Nancy Grace Roman Space Telescope and, possibly, ESA’s Euclid mission, will provide demanding tests of current planet formation models.

The Astropy Project supports and fosters the development of open-source and openly developed Python packages that provide commonly needed functionality to the astronomical community. A key element of the Astropy Project is the core package astropy, which serves as the foundation for more specialized projects and packages. In this article, we summarize key features in the core package as of the recent major release, version 5.0, and provide major updates on the Project. We then discuss supporting a broader ecosystem of interoperable packages, including connections with several astronomical observatories and missions. We also revisit the future outlook of the Astropy Project and the current status of Learn Astropy. We conclude by raising and discussing the current and future challenges facing the Project.

NASA's Kepler mission observed background regions across its field of view for more than 3 consecutive yr using custom designed superapertures (EXBA masks). Since these apertures were designed to capture a region of the sky rather than single targets, the Kepler Science Data Processing Pipeline produced target pixel files but did not produce light curves for the sources within these background regions. In this work, we produce light curves for 9327 sources observed in the EXBA masks. These light curves are generated using aperture photometry estimated from the instrument's pixel response function (PRF) profile computed from Kepler's full-frame images. The PRF models enable the creation of apertures that follow the characteristic shapes of the point-spread function in the image and the computation of flux completeness and contamination metrics. The light curves are available at MAST as a high-level science product (kbonus-apexba). Alongside this data set, we present kepler-apertures, a Python library to compute PRF models and use them to perform aperture photometry on Kepler-like data. Using light curves from the EXBA masks, we found an exoplanet candidate around Gaia EDR3 2077240046296834304 consistent with a large planet companion with a 0.81 R (J) radius. Additionally, we report a catalog of 69 eclipsing binaries. We encourage the community to exploit this new data set to perform in-depth time domain analysis, such as eclipsing binaries demographics and other types of studies.

We present the 30 minutes cadence Kepler/K2 light curve of the Type Ia supernova (SN Ia) SN 2018agk, covering approximately one week before explosion, the full rise phase, and the decline until 40 days after peak. We additionally present ground-based observations in multiple bands within the same time range, including the 1 day cadence DECam observations within the first ∼5 days after the first light. The Kepler early light curve is fully consistent with a single power-law rise, without evidence of any bump feature. We compare SN 2018agk with a sample of other SNe Ia without early excess flux from the literature. We find that SNe Ia without excess flux have slowly evolving early colors in a narrow range ( g − i ≈ −0.20 ± 0.20 mag) within the first ∼10 days. On the other hand, among SNe Ia detected with excess, SN 2017cbv and SN 2018oh tend to be bluer, while iPTF16abc’s evolution is similar to normal SNe Ia without excess in g − i . We further compare the Kepler light curve of SN 2018agk with companion-interaction models, and rule out the existence of a typical nondegenerate companion undergoing Roche lobe overflow at viewing angles smaller than 45°.

NASA’s Kepler, K2, and TESS missions employ simple aperture photometry to derive time-series photometry, where an aperture is estimated for each star, and pixels containing each star are summed to create a single light curve. This method is simple, but in crowded fields, the derived time series can be highly contaminated. The alternate method of fitting a point-spread function (PSF) to the data is able to account for crowding but is computationally expensive. In this paper, we present a new approach to extracting photometry from these time-series missions that fits the PSF directly but makes simplifying assumptions in order to greatly reduce the computation expense. Our method fixes the scene of the field in each image, estimates the PSF shape of the instrument with a linear model, and allows only source flux and position to vary. We demonstrate that our method is able to separate the photometry from blended targets in the Kepler data set that are separated by less than a pixel. Our method is fast to compute and fully accounts for uncertainties from degeneracies due to crowded fields. We name the method described in this work linearized field deblending photometry. We demonstrate our method on the false-positive Kepler target KOI-608. We are able to separate the photometry of the two sources in the data and demonstrate that the contaminating transiting signal is consistent with a small, substellar companion with a radius of 2.67 R Jup (0.27 R ☉). Our method is equally applicable to extracting photometry from NASA’s TESS mission.

K2 greatly extended Kepler’s ability to find new planets, but it was typically limited to identifying transiting planets with orbital periods below 40 days. While analyzing K2 data through the Exoplanet Explorers project, citizen scientists helped discover one super-Earth and four sub-Neptune sized planets in the relatively bright (V = 12.21, K = 10.3) K2-138 system, all which orbit near 3:2 mean-motion resonances. The K2 light curve showed two additional transit events consistent with a sixth planet. Using Spitzer photometry, we validate the sixth planet’s orbital period of 41.966 ± 0.006 days and measure a radius of , solidifying K2-138 as the K2 system with the most currently known planets. There is a sizeable gap between the outer two planets, since the fifth planet in the system, K2-138 f, orbits at 12.76 days. We explore the possibility of additional nontransiting planets in the gap between f and g. Due to the relative brightness of the K2-138 host star, and the near resonance of the inner planets, K2-138 could be a key benchmark system for both radial velocity and transit-timing variation mass measurements, and indeed radial velocity masses for the inner four planets have already been obtained. With its five sub-Neptunes and one super-Earth, the K2-138 system provides a unique test bed for comparative atmospheric studies of warm to temperate planets of similar size, dynamical studies of near-resonant planets, and models of planet formation and migration.

ABSTRACT SN 2017jgh is a type IIb supernova discovered by Pan-STARRS during the C16/C17 campaigns of the Kepler/K2 mission. Here, we present the Kepler/K2 and ground based observations of SN 2017jgh, which captured the shock cooling of the progenitor shock breakout with an unprecedented cadence. This event presents a unique opportunity to investigate the progenitors of stripped envelope supernovae. By fitting analytical models to the SN 2017jgh light curve, we find that the progenitor of SN 2017jgh was likely a yellow supergiant with an envelope radius of $\sim 50{\!-\!}290\, {\rm R}_{\odot }$, and an envelope mass of $\sim 0{\!-\!}1.7\, {\rm M}_{\odot }$. SN 2017jgh likely had a shock velocity of ∼7500−10 300 km s−1. Additionally, we use the light curve of SN 2017jgh to investigate how early observations of the rise contribute to constraints on progenitor models. Fitting just the ground based observations, we find an envelope radius of $\sim 50{\!-\!}330\, {\rm R}_{\odot }$, an envelope mass of $\sim 0.3{\!-\!}1.7\, {\rm M}_{\odot }$ and a shock velocity of ∼9000−15 000 km s−1. Without the rise, the explosion time cannot be well constrained that leads to a systematic offset in the velocity parameter and larger uncertainties in the mass and radius. Therefore, it is likely that progenitor property estimates through these models may have larger systematic uncertainties than previously calculated.

The Kepler mission has provided a wealth of data, revealing new insights in time-domain astronomy. However, Kepler’s single bandpass has limited studies to a single wavelength. In this work we build a data-driven, pixel-level model for the pixel response function (PRF) of Kepler targets, modeling the image data from the spacecraft. Our model is sufficiently flexible to capture known detector effects, such as nonlinearity, intrapixel sensitivity variations, and focus change. In theory, the shape of the Kepler PRF should also be weakly wavelength-dependent, due to optical chromatic aberration and a wavelength-dependent detector response functions. We are able to identify these predicted changes in shape of the PRF using the residuals between Kepler data and our model. In this work, we show that these PRF changes correspond to wavelength variability in Kepler targets using a small sample of eclipsing binaries. Using our model, we demonstrate that pixel-level light curves of eclipsing binaries show variable eclipse depths, ellipsoidal modulation, and limb darkening. These changes at the pixel level are consistent with multiwavelength photometry. Our work suggests that each pixel in the Kepler data of a single target has a different effective wavelength, ranging from ≈550 to 750 nm. In this proof of concept, we demonstrate our model, and discuss possible uses for the wavelength-dependent PRF of Kepler. These uses include characterizing variable systems, and vetting exoplanet discoveries at the pixel level. The chromatic PRF of Kepler is due to weak wavelength dependence in the optical systems and detector of the telescope, and similar chromatic PRFs are expected in other similar telescopes, notably the NASA TESS telescope.

The INT Galactic Plane Survey (IGAPS) is the merger of the optical photometric surveys, IPHAS and UVEX, based on data from the Isaac Newton Telescope (INT) obtained between 2003 and 2018. These capture the entire northern Galactic plane within the Galactic coordinate range, -5

We present the occurrence rates for rocky planets in the habitable zones (HZs) of main-sequence dwarf stars based on the Kepler DR25 planet candidate catalog and Gaia-based stellar properties. We provide the first analysis in terms of star-dependent instellation flux, which allows us to track HZ planets. We define eta(circle plus) as the HZ occurrence of planets with radii between 0.5 and 1.5 R-circle plus orbiting stars with effective temperatures between 4800 and 6300 K. We find that eta(circle plus) for the conservative HZ is between 0.37(-0.21)(+0.48) (errors reflect 68% credible intervals) and 0.60(-0.36)(+0.90) planets per star, while the optimistic HZ occurrence is between 0.58(-0.33)(+0.73) and 0.88(-0.51)(+1.28) planets per star. These bounds reflect two extreme assumptions about the extrapolation of completeness beyond orbital periods where DR25 completeness data are available. The large uncertainties are due to the small number of detected small HZ planets. We find similar occurrence rates between using Poisson likelihood Bayesian analysis and using Approximate Bayesian Computation. Our results are corrected for catalog completeness and reliability. Both completeness and the planet occurrence rate are dependent on stellar effective temperature. We also present occurrence rates for various stellar populations and planet size ranges. We estimate with 95% confidence that, on average, the nearest HZ planet around G and K dwarfs is similar to 6 pc away and there are similar to 4 HZ rocky planets around G and K dwarfs within 10 pc of the Sun.

Space observatories have provided unprecedented depictions of the many variability behaviors typical of low-mass, young stars. However, those studies have so far largely omitted more massive objects ($\sim$2 $M_\odot$ to 4-5 $M_\odot$), and were limited by the absence of simultaneous, multi-wavelength information. We present a new study of young star variability in the $\sim$1-2 Myr-old, massive Lagoon Nebula region. Our sample encompasses 278 young, late-B to K-type stars, monitored with Kepler/K2. Auxiliary $u,g,r,i,H\alpha$ time series photometry, simultaneous with K2, was acquired at the Paranal Observatory. We employed this comprehensive dataset and archival infrared photometry to determine individual stellar parameters, assess the presence of circumstellar disks, and tie the variability behaviors to inner disk dynamics. We found significant mass-dependent trends in variability properties, with B/A stars displaying substantially reduced levels of variability compared to G/K stars for any light curve morphology. These properties suggest different magnetic field structures at the surface of early-type and later-type stars. We also detected a dearth of some disk-driven variability behaviors, particularly dippers, among stars earlier than G. This indicates that their higher surface temperatures and more chaotic magnetic fields prevent the formation and survival of inner disk dust structures co-rotating with the star. Finally, we examined the characteristic variability timescales within each light curve, and determined that the day-to-week timescales are predominant over the K2 time series. These reflect distinct processes and locations in the inner disk environment, from intense accretion triggered by instabilities in the innermost disk regions, to variable accretion efficiency in the outer magnetosphere.

The INT Galactic Plane Survey (IGAPS) is the merger of the optical photometric surveys, IPHAS and UVEX, based on data from the Isaac Newton Telescope (INT) obtained between 2003 and 2018. Here, we present the IGAPS point source catalogue. It contains 295.4 million rows providing photometry in the filters, i , r , narrow-band H α , g , and U RGO . The IGAPS footprint fills the Galactic coordinate range, | b | < 5° and 30° < ℓ < 215°. A uniform calibration, referred to as the Pan-STARRS system, is applied to g , r , and i , while the H α calibration is linked to r and then is reconciled via field overlaps. The astrometry in all five bands has been recalculated in the reference frame of Gaia Data Release 2. Down to i ∼ 20 mag (Vega system), most stars are also detected in g , r , and H α . As exposures in the r band were obtained in both the IPHAS and UVEX surveys, typically a few years apart, the catalogue includes two distinct r measures, r I and r U . The r 10 σ limiting magnitude is approximately 21, with median seeing of 1.1 arcsec. Between approximately 13th and 19th mag in all bands, the photometry is internally reproducible to within 0.02 mag. Stars brighter than r = 19.5 mag are tested for narrow-band H α excess signalling line emission, and for variation exceeding | r I − r U | = 0.2 mag. We find and flag 8292 candidate emission line stars and over 53 000 variables (both at > 5 σ confidence).

PV Tel variables are extreme helium (EHe) stars known to be intrinsic light and velocity variable on characteristic timescales 0.1 - 2 d. With two exceptions, they are best described as irregular. Light curves have invariably been obtained from single-site terrestrial observatories. We present TESS observations of two bright EHe stars, Popper's star (V821 Cen) and Thackeray's star (PV Tel). PV Tel is variable on timescales previously reported. V821 Cen is proven to be variable for the first time. Neither light curve shows any evidence of underlying regularity. Implications are considered.

Kepler, K2, and Transiting Exoplanet Survey Satellite (TESS) have demonstrated the power of high-precision uninterrupted photometry. Combining data sets from these two observatories can extend the baseline of high precision photometry on a target. In addition, for some investigations, the differing passbands of the two telescopes may provide additional information about the causes of the observed variability. In order to facilitate studies combining these unique data sets, we present a list of all the 55,641 targets observed by K2 which fell within the TESS field of view during its first three years of observations.