Abstract
We report the discovery of TOI-1444b, a 1.4
R
⊕
super-Earth on a 0.47 day orbit around a Sun-like star discovered by TESS. Precise radial velocities from Keck/HIRES confirmed the planet and ...constrained the mass to be 3.87 ± 0.71
M
⊕
. The RV data set also indicates a possible nontransiting, 16 day planet (11.8 ± 2.9
M
⊕
). We report a tentative detection of phase-curve variation and a secondary eclipse of TOI-1444b in the TESS bandpass. TOI-1444b joins the growing sample of 17 ultra-short-period planets (USPs) with well-measured masses and sizes, most of which are compatible with an Earth-like composition. We take this opportunity to examine the expanding sample of ultra-short-period planets (<2
R
⊕
) and contrast them with the newly discovered sub-day ultrahot Neptunes (>3
R
⊕
, >2000
F
⊕
TOI-849 b, LTT9779 b, and K2-100). We find that (1) USPs have predominately Earth-like compositions with inferred iron core mass fractions of 0.32 ± 0.04 and have masses below the threshold of runaway accretion (∼10
M
⊕
), while ultrahot Neptunes are above the threshold and have H/He or other volatile envelopes. (2) USPs are almost always found in multi-planet systems consistent with a secular interaction formation scenario; ultrahot Neptunes (
P
orb
≲1 day) tend to be “lonely,” similar to longer-period hot Neptunes (
P
orb
1–10 days) and hot Jupiters. (3) USPs occur around solar-metallicity stars while hot Neptunes prefer higher metallicity hosts. (4) In all these respects, ultrahot Neptunes show more resemblance to hot Jupiters than the smaller USP planets, although ultrahot Neptunes are rarer than both USPs and hot Jupiters by 1–2 orders of magnitude.
Abstract
Giant stars as known exoplanet hosts are relatively rare due to the potential challenges in acquiring precision radial velocities and the small predicted transit depths. However, these giant ...host stars are also some of the brightest in the sky and so enable high signal-to-noise ratio follow-up measurements. Here, we report on new observations of the bright (
V
∼ 3.3) giant star
ι
Draconis (
ι
Dra), known to host a planet in a highly eccentric ∼511 day period orbit. TESS observations of the star over 137 days reveal asteroseismic signatures, allowing us to constrain the stellar radius, mass, and age to ∼2%, ∼6%, and ∼28%, respectively. We present the results of continued radial-velocity monitoring of the star using the Automated Planet Finder over several orbits of the planet. We provide more precise planet parameters of the known planet and, through the combination of our radial-velocity measurements with Hipparcos and Gaia astrometry, we discover an additional long-period companion with an orbital period of
∼
68
−
36
+
60
yr. Mass predictions from our analysis place this substellar companion on the border of the planet and brown dwarf regimes. The bright nature of the star combined with the revised orbital architecture of the system provides an opportunity to study planetary orbital dynamics that evolve as the star moves into the giant phase of its evolution.
Abstract
NASA’s Transiting Exoplanet Survey Satellite (TESS) mission is expected to discover hundreds of planets via single transits first identified in their light curves. Determining the orbital ...period of these single-transit candidates typically requires a significant amount of follow-up work to observe a second transit or measure a radial velocity (RV) orbit. In Yao et al., we developed simulations that demonstrated the ability to use archival photometric data in combination with TESS to “precover” the orbital period for these candidates with a precision of several minutes, assuming circular orbits. In this work, we incorporate updated models for TESS single transits, allowing for eccentric orbits, along with an updated methodology to improve the reliability of the results. Additionally, we explore how RV observations can be used to follow up single-transit events, using strategies distinct from those employed when the orbital period is known. We find that the use of an estimated period based on a circular orbit to schedule reconnaissance RV observations can efficiently distinguish eclipsing binaries from planets. For candidates that pass reconnaissance RV observations, we simulate RV monitoring campaigns that enable one to obtain an approximate orbital solution. We find that this method can regularly determine the orbital periods for planets more massive than 0.5
M
J
with orbital periods as long as 100 days.
ABSTRACT
We present BVRI and unfiltered (Clear) light curves of 70 stripped-envelope supernovae (SESNe), observed between 2003 and 2020, from the Lick Observatory Supernova Search follow-up program. ...Our SESN sample consists of 19 spectroscopically normal SNe Ib, 2 peculiar SNe Ib, six SNe Ibn, 14 normal SNe Ic, 1 peculiar SN Ic, 10 SNe Ic-BL, 15 SNe IIb, 1 ambiguous SN IIb/Ib/c, and 2 superluminous SNe. Our follow-up photometry has (on a per-SN basis) a mean coverage of 81 photometric points (median of 58 points) and a mean cadence of 3.6 d (median of 1.2 d). From our full sample, a subset of 38 SNe have pre-maximum coverage in at least one passband, allowing for the peak brightness of each SN in this subset to be quantitatively determined. We describe our data collection and processing techniques, with emphasis toward our automated photometry pipeline, from which we derive publicly available data products to enable and encourage further study by the community. Using these data products, we derive host-galaxy extinction values through the empirical colour evolution relationship and, for the first time, produce accurate rise-time measurements for a large sample of SESNe in both optical and infrared passbands. By modelling multiband light curves, we find that SNe Ic tend to have lower ejecta masses and lower ejecta velocities than SNe Ib and IIb, but higher 56Ni masses.
Abstract
More than 5000 exoplanets have been confirmed and among them almost 4000 were discovered by the transit method. However, few transiting exoplanets have an orbital period greater than 100 ...days. Here we report a transit detection of Kepler-167 e, a “Jupiter analog” exoplanet orbiting a K4 star with a period of 1071 days, using the Unistellar ground-based telescope network. From 2021 November 18 to 20, citizen astronomers located in nine different countries gathered 43 observations, covering the 16 hr long transit. Using a nested sampling approach to combine and fit the observations, we detected the midtransit time to be UTC 2021 November 19 17:20:51 with a 1
σ
uncertainty of 9.8 minutes, making it the longest-period planet to ever have its transit detected from the ground. This is the fourth transit detection of Kepler-167 e, but the first made from the ground. This timing measurement refines the orbit and keeps the ephemeris up to date without requiring space telescopes. Observations like this demonstrate the capabilities of coordinated networks of small telescopes to identify and characterize planets with long orbital periods.
Abstract We present an updated ephemeris, and physical parameters, for the exoplanet WASP-77 A b. In this effort, we combine 64 ground- and space-based transit observations, 6 space-based eclipse ...observations, and 32 radial velocity observations to produce this target's most precise orbital solution to date aiding in the planning of James Webb Space Telescope and Ariel observations and atmospheric studies. We report a new orbital period of 1.360029395 ± 5.7 × 10 −8 days, a new mid-transit time of 2459957.337860 ± 4.3 × 10 −5 Barycentric Julian Date in the Barycentric Dynamical Timescale (BJDTDB) and a new mid-eclipse time of 2459956.658192 ± 6.7 × 10 −5 BJDTDB. Furthermore, the methods presented in this study reduce the uncertainties in the planet's mass 1.6654 ± 4.5 × 10 −3 M Jup and orbital period 1.360029395 ± 5.7 × 10 −8 days by factors of 15.1 and 10.9, respectively. Through a joint fit analysis comparison of transit data taken by space-based and citizen science-led initiatives, our study demonstrates the power of including data collected by citizen scientists compared to a fit of the space-based data alone. Additionally, by including a vast array of citizen science data from ExoClock, Exoplanet Transit Database, and Exoplanet Watch, we can increase our observational baseline and thus acquire better constraints on the forward propagation of our ephemeris than what is achievable with Transiting Exoplanet Survey Satellite data alone.
The exoplanet HD 118203 b, orbiting a bright (V = 8.05) host star, was discovered using the radial velocity method by da Silva et al., but was not previously known to transit. Transiting Exoplanet ...Survey Satellite (TESS) photometry has revealed that this planet transits its host star. Nine planetary transits were observed by TESS, allowing us to measure the radius of the planet to be , and to calculate the planet mass to be . The host star is slightly evolved with an effective temperature of K and a surface gravity of . With an orbital period of days and an eccentricity of 0.314 0.017, the planet occupies a transitional regime between circularized hot Jupiters and more dynamically active planets at longer orbital periods. The host star is among the 10 brightest known to have transiting giant planets, providing opportunities for both planetary atmospheric and asteroseismic studies.
Abstract
We report the discovery of HIP-97166b (TOI-1255b), a transiting sub-Neptune on a 10.3 day orbit around a K0 dwarf 68 pc from Earth. This planet was identified in a systematic search of TESS ...Objects of Interest for planets with eccentric orbits, based on a mismatch between the observed transit duration and the expected duration for a circular orbit. We confirmed the planetary nature of HIP-97166b with ground-based radial-velocity measurements and measured a mass of
M
b
= 20 ± 2
M
⊕
along with a radius of
R
b
= 2.7 ± 0.1
R
⊕
from photometry. We detected an additional nontransiting planetary companion with
M
c
sin
i
= 10 ± 2
M
⊕
on a 16.8 day orbit. While the short transit duration of the inner planet initially suggested a high eccentricity, a joint RV-photometry analysis revealed a high impact parameter
b
= 0.84 ± 0.03 and a moderate eccentricity. Modeling the dynamics with the condition that the system remain stable over >10
5
orbits yielded eccentricity constraints
e
b
= 0.16 ± 0.03 and
e
c
< 0.25. The eccentricity we find for planet b is above average for the small population of sub-Neptunes with well-measured eccentricities. We explored the plausible formation pathways of this system, proposing an early instability and merger event to explain the high density of the inner planet at 5.3 ± 0.9 g cc
−1
as well as its moderate eccentricity and proximity to a 5:3 mean-motion resonance.
Over the past several decades, thousands of planets have been discovered outside our Solar System. These planets exhibit enormous diversity, and their large numbers provide a statistical opportunity ...to place our Solar System within the broader context of planetary structure, atmospheres, architectures, formation, and evolution. Meanwhile, the field of exoplanetary science is rapidly forging onward toward a goal of atmospheric characterization, inferring surface conditions and interiors, and assessing the potential for habitability. However, the interpretation of exoplanet data requires the development and validation of exoplanet models that depend on in situ data that, in the foreseeable future, are only obtainable from our Solar System. Thus, planetary and exoplanetary science would both greatly benefit from a symbiotic relationship with a two‐way flow of information. Here, we describe the critical lessons and outstanding questions from planetary science, the study of which are essential for addressing fundamental aspects for a variety of exoplanetary topics. We outline these lessons and questions for the major categories of Solar System bodies, including the terrestrial planets, the giant planets, moons, and minor bodies. We provide a discussion of how many of these planetary science issues may be translated into exoplanet observables that will yield critical insight into current and future exoplanet discoveries.
Plain Language Summary
Thousands of planets have been found outside our Solar System, called “exoplanets,” forging a new frontier of planetary exploration. However, studying these planets many light years away requires a deep understanding of the planets nearby so that we can accurately interpret the planetary processes that are occurring on these distant worlds. In this work, we provide a summary of advances in planetary science and describe how the various Solar System bodies enable us to unlock the secrets of exoplanets. These advances include new insights into planetary habitability, and we discuss how diagnosing the evolution of our nearest neighbors can further the search for life in the universe.
Key Points
Exoplanetary science is rapidly expanding toward characterization of atmospheres and interiors
Planetary science has similarly undergone rapid expansion of understanding planetary processes and evolution
Effective studies of exoplanets require models and in situ data derived from planetary science observations and exploration
Abstract
HD 106315 and GJ 9827 are two bright, nearby stars that host multiple super-Earths and sub-Neptunes discovered by K2 that are well suited for atmospheric characterization. We refined the ...planets’ ephemerides through Spitzer transits, enabling accurate transit prediction required for future atmospheric characterization through transmission spectroscopy. Through a multiyear high-cadence observing campaign with Keck/High Resolution Echelle Spectrometer and Magellan/Planet Finder Spectrograph, we improved the planets’ mass measurements in anticipation of Hubble Space Telescope transmission spectroscopy. For GJ 9827, we modeled activity-induced radial velocity signals with a Gaussian process informed by the Calcium II H&K lines in order to more accurately model the effect of stellar noise on our data. We measured planet masses of
M
b
= 4.87 ± 0.37
M
⊕
,
M
c
= 1.92 ± 0.49
M
⊕
, and
M
d
= 3.42 ± 0.62
M
⊕
. For HD 106315, we found that such activity radial velocity decorrelation was not effective due to the reduced presence of spots and speculate that this may extend to other hot stars as well (
T
eff
> 6200 K). We measured planet masses of
M
b
= 10.5 ± 3.1
M
⊕
and
M
c
= 12.0 ± 3.8
M
⊕
. We investigated all of the planets’ compositions through comparison of their masses and radii to a range of interior models. GJ 9827 b and GJ 9827 c are both consistent with a 50/50 rock-iron composition, GJ 9827 d and HD 106315 b both require additional volatiles and are consistent with moderate amounts of water or hydrogen/helium, and HD 106315 c is consistent with a ∼10% hydrogen/helium envelope surrounding an Earth-like rock and iron core.
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