Stars with hot Jupiters (HJs) tend to rotate faster than other stars of the same age and mass. This trend has been attributed to tidal interactions between the star and planet. A constraint on the ...dissipation parameter follows from the assumption that tides have managed to spin up the star to the observed rate within the age of the system. This technique was applied previously to HATS-18 and WASP-19. Here, we analyze the sample of all 188 known HJs with an orbital period <3.5 days and a "cool" host star (Teff < 6100 K). We find evidence that the tidal dissipation parameter ( ) increases sharply with forcing frequency, from 105 at 0.5 day−1 to 107 at 2 day−1. This helps to resolve a number of apparent discrepancies between studies of tidal dissipation in binary stars, HJs, and warm Jupiters. It may also allow for a HJ to damp the obliquity of its host star prior to being destroyed by tidal decay.
We provide evidence that the obliquities of stars with close-in giant planets were initially nearly random, and that the low obliquities that are often observed are a consequence of star-planet tidal ...interactions. The evidence is based on 14 new measurements of the Rossiter-McLaughlin effect (for the systems HAT-P-6, HAT-P-7, HAT-P-16, HAT-P-24, HAT-P-32, HAT-P-34, WASP-12, WASP-16, WASP-18, WASP-19, WASP-26, WASP-31, G1 436, and Kepler-8), as well as a critical review of previous observations. The low-obliquity (well-aligned) systems are those for which the expected tidal timescale is short, and likewise the high-obliquity (misaligned and retrograde) systems are those for which the expected timescale is long. At face value, this finding indicates that the origin of hot Jupiters involves dynamical interactions like planet-planet interactions or the Kozai effect that tilt their orbits rather than inspiraling due to interaction with a protoplanetary disk. We discuss the status of this hypothesis and the observations that are needed for a more definitive conclusion.
HAT-P-11 is a mid-K dwarf that hosts one of the first Neptune-sized planets found outside the solar system. The orbit of HAT-P-11b is misaligned with the star's spin-one of the few known cases of a ...misaligned planet orbiting a star less massive than the Sun. We find an additional planet in the system based on a decade of precision radial velocity (RV) measurements from Keck/High Resolution Echelle Spectrometer. HAT-P-11c is similar to Jupiter in its mass ( MJ) and orbital period ( year), but has a much more eccentric orbit (e = 0.60 0.03). In our joint modeling of RV and stellar activity, we found an activity-induced RV signal of ∼7 , consistent with other active K dwarfs, but significantly smaller than the 31 reflex motion due to HAT-P-11c. We investigated the dynamical coupling between HAT-P-11b and c as a possible explanation for HAT-P-11b's misaligned orbit, finding that planet-planet Kozai interactions cannot tilt planet b's orbit due to general relativistic precession; however, nodal precession operating on million year timescales is a viable mechanism to explain HAT-P-11b's high obliquity. This leaves open the question of why HAT-P-11c may have such a tilted orbit. At a distance of 38 pc, the HAT-P-11 system offers rich opportunities for further exoplanet characterization through astrometry and direct imaging.
Abstract
Hot Jupiters are a rare and interesting outcome of planet formation. Although more than 500 hot Jupiters (HJs) are known, most of them were discovered by a heterogeneous collection of ...surveys with selection biases that are difficult to quantify. Currently, our best knowledge of HJ demographics around FGK stars comes from the sample of ≈40 objects detected by the Kepler mission, which have a well-quantified selection function. Using the Kepler results, we simulate the characteristics of the population of nearby transiting HJs. A comparison between the known sample of nearby HJs and simulated magnitude-limited samples leads to four conclusions. (1) The known sample of HJs appears to be ≈75% complete for stars brighter than Gaia
G
≤ 10.5, falling to ≲50% for
G
≤ 12. (2) There are probably a few undiscovered HJs with host stars brighter than
G
≈ 10 located within 10° of the Galactic plane. (3) The period and radius distributions of HJs may differ for F-type hosts (which dominate the nearby sample) and
G
-type hosts (which dominate the Kepler sample). (4) To obtain a magnitude-limited sample of HJs that is larger than the Kepler sample by an order of magnitude, the limiting magnitude should be approximately
G
≈ 12.5. This magnitude limit is within the range for which NASA’s Transiting Exoplanet Survey Satellite can easily detect HJs, presenting the opportunity to greatly expand our knowledge of hot-Jupiter demographics.
ABSTRACT
We present a revised characterization of the previously discovered transiting planet systems HATS-34 and HATS-46. We make use of the newly available space-based light curves from the NASA ...TESS mission and high-precision parallax and absolute photometry measurements from the ESA Gaia mission to determine the mass and radius of the planets and host stars with dramatically increased precision and accuracy compared to published values, with the uncertainties in some parameters reduced by as much as a factor of 7. Using an isochrone-based fit, for HATS-34 we measure a revised host star mass and radius of $0.952_{-0.020}^{+0.040}$ $\, \mathrm{M}_\odot$ and 0.9381 ± 0.0080 $\, \mathrm{R}_\odot$, respectively, and a revised mass and radius for the transiting planet of 0.951 ± 0.050 MJ and 1.282 ± 0.064 RJ, respectively. Similarly, for HATS-46 we measure a revised mass and radius for the host star of 0.869 ± 0.023 $\, \mathrm{M}_\odot$ and 0.894 ± 0.010 $\, \mathrm{R}_\odot$, respectively, and a revised mass and radius for the planet of 0.158 ± 0.042 MJ and 0.951 ± 0.029 RJ, respectively. The uncertainties that we determine on the stellar and planetary masses and radii are also substantially lower than re-determinations that incorporate the Gaia results without performing a full re-analysis of the light curves and other observational data. We argue that, in light of Gaia and TESS, a full re-analysis of previously discovered transiting planets is warranted.
We revisit the issue of period variation of the recently claimed red nova precursor candidate KIC 9832227. By using the data gathered during the main mission of the Kepler satellite, and data ...collected by ground-based wide-field surveys and other monitoring programs (such as ASAS-SN), we find that the currently available timing data strongly support a model consisting of the known W UMa binary and a distant low-mass companion with an orbital period of ∼13.5 years. The period of the W UMa component exhibits a linear period decrease at a rate of (1.10 ± 0.05) × 10−6 days per year, within the range of many other similar systems. This rate of decrease is several orders of magnitude lower than that of V1309 Sco, the first (and so far the only) well-established binary precursor of a nova observed a few years before the outburst. The high-fidelity fit of the timing data and the conformity of the derived minimum mass of (0.38 ± 0.02) M⊙ of the outer companion from these data with the limit posed by the spectroscopic non-detection of this component are in agreement with the suggested hierarchical nature of this system.
Stellar-mass black holes are found in X-ray-emitting binary systems, where their mass can be determined from the dynamics of their companion stars. Models of stellar evolution have difficulty ...producing black holes in close binaries with masses more than ten times that of the Sun (>10; ref. 4), which is consistent with the fact that the most massive stellar black holes known so far all have masses within one standard deviation of 10. Here we report a mass of (15.65 +/- 1.45) for the black hole in the recently discovered system M 33 X-7, which is located in the nearby galaxy Messier 33 (M 33) and is the only known black hole that is in an eclipsing binary. To produce such a massive black hole, the progenitor star must have retained much of its outer envelope until after helium fusion in the core was completed. On the other hand, in order for the black hole to be in its present 3.45-day orbit about its (70.0 +/- 6.9) companion, there must have been a 'common envelope' phase of evolution in which a significant amount of mass was lost from the system. We find that the common envelope phase could not have occurred in M 33 X-7 unless the amount of mass lost from the progenitor during its evolution was an order of magnitude less than what is usually assumed in evolutionary models of massive stars.
Abstract
While secondary mass inferences based on single-lined spectroscopic binary (SB1) solutions are subject to
sin
i
degeneracies, this degeneracy can be lifted through the observations of ...eclipses. We combine the subset of Gaia Data Release 3 SB1 solutions consistent with brown dwarf-mass secondaries with the Transiting Exoplanet Survey Satellite (TESS) Object of Interest (TOI) list to identify three candidate transiting brown dwarf systems. Ground-based precision radial velocity follow-up observations confirm that TOI-2533.01 is a transiting brown dwarf with
M
=
72
−
3
+
3
M
Jup
=
0.069
−
0.003
+
0.003
M
⊙
orbiting TYC 2010-124-1 and that TOI-5427.01 is a transiting very low-mass star with
M
=
93
−
2
+
2
M
Jup
=
0.088
−
0.002
+
0.002
M
⊙
orbiting UCAC4 515-012898. We validate TOI-1712.01 as a very low-mass star with
M
=
82
−
7
+
7
M
Jup
=
0.079
−
0.007
+
0.007
M
⊙
transiting the primary in the hierarchical triple system BD+45 1593. Even after accounting for third light, TOI-1712.01 has a radius nearly a factor of 2 larger than predicted for isolated stars with similar properties. We propose that the intense instellation experienced by TOI-1712.01 diminishes the temperature gradient near its surface, suppresses convection, and leads to its inflated radius. Our analyses verify Gaia DR3 SB1 solutions in the low Doppler semiamplitude limit, thereby providing the foundation for future joint analyses of Gaia radial velocities and Kepler, K2, TESS, and PLAnetary Transits and Oscillations light curves for the characterization of transiting massive brown dwarfs and very low-mass stars.
We extract light curves for 4554 objects with 9 < G < 19 in the K2 superstamp observations of the globular cluster M4, including 3784 cluster members, and search for variability. Among cluster-member ...objects, we detect 66 variables, of which 52 are new discoveries. Among objects not belonging to the cluster, we detect 24 variables, of which 20 are new discoveries. We additionally discover 57 cluster-member suspected variables, 10 cluster-non-member suspected variables, and four variables with ambiguous cluster membership. Our light curves reach sub-millimagnitude precision for the cluster horizontal branch, permitting us to detect asteroseismic activity in six horizontal branch stars outside the instability strip and one inside the strip but with only ∼1 mmag amplitude variability. Nineteen additional stars along the red giant branch also have detected asteroseismic variability. Several eclipsing binaries are found in the cluster, including a 4.6 day detached eclipsing binary and an EW-class eclipsing binary, as well as an EW with uncertain cluster membership and three other candidate EWs. A 22 day detached eclipsing binary is also found outside the cluster. We identify a candidate X-ray binary that is a cluster member with quiescent and periodic ∼20 mmag optical variability. We also obtain high-precision light curves for 10 of the previously known RR Lyrae variables in the cluster and identify one as a candidate Blazhko variable with a Blazhko period in excess of 78 days. We make our light curves publicly available.
Sensitive signal processing methods are needed to detect transiting planets from ground-based photometric surveys. Caceres et al. show that the autoregressive planet search (ARPS) method-a ...combination of autoregressive integrated moving average (ARIMA) parametric modeling, a new transit comb filter (TCF) periodogram, and machine learning classification-is effective when applied to evenly spaced light curves from space-based missions. We investigate here whether ARIMA and TCF will be effective for ground-based survey light curves that are often sparsely sampled with high noise levels from atmospheric and instrumental conditions. The ARPS procedure is applied to selected light curves with strong planetary signals from the Kepler mission that have been altered to simulate the conditions of ground-based exoplanet surveys. Typical irregular cadence patterns are used from the Hungarian-made Automated Telescope Network-South (HATSouth) survey. We also evaluate recovery of known planets from HATSouth. Simulations test transit signal recovery as a function of cadence pattern and duration, stellar magnitude, planet orbital period, and transit depth. Detection rates improve for shorter periods and deeper transits. The study predicts that the ARPS methodology will detect planets with 0.1% transit depth and periods 40 days in HATSouth stars brighter than ∼15 mag. ARPS methodology is therefore promising for planet discovery from ground-based exoplanet surveys with sufficiently dense cadence patterns.
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