Long-period Companions Research Articles

Toward a Direct Measure of the Galactic Acceleration

Abstract High-precision spectrographs can enable not only the discovery of exoplanets, but can also provide a fundamental measurement in Galactic dynamics. Over about 10 year baselines, the expected change in the line-of-sight velocity due to the Galaxy’s gravitational field for stars at ∼kiloparsec scale distances above the Galactic midplane is ∼few tens of cm s−1, and may be detectable by the current generation of high-precision spectrographs. Here, we provide theoretical expectations for this measurement based on both static models of the Milky Way and isolated Milky Way simulations, as well from controlled dynamical simulations of the Milky Way interacting with dwarf galaxies. We simulate a population synthesis model to analyze the contribution of planets and binaries to the Galactic acceleration signal. We find that while low-mass, long-period planetary companions are a contaminant to the Galactic acceleration signal, their contribution is very small. Our analysis of ∼10 years of data from the Lick–Carnegie Exoplanet Survey HIRES/Keck precision radial-velocity (RV) survey shows that slopes of the RV curves of standard RV stars agree with expectations of the local Galactic acceleration near the Sun within the errors, and that the error in the slope scales inversely as the square root of the number of observations. Thus, we demonstrate that a survey of stars with low intrinsic stellar jitter at kiloparsec distances above the Galactic midplane for realistic sample sizes can enable a direct determination of the dark matter density.

Nearly polar orbit of the sub-Neptune HD 3167 c

Aims. We present the obliquity measurement, that is, the angle between the normal angle of the orbital plane and the stellar spin axis, of the sub-Neptune planet HD 3167 c, which transits a bright nearby K0 star. We study the orbital architecture of this multi-planet system to understand its dynamical history. We also place constraints on the obliquity of planet d based on the geometry of the planetary system and the dynamical study of the system. Methods. New observations obtained with HARPS-N at the Telescopio Nazionale Galileo (TNG) were employed for our analysis. The sky-projected obliquity was measured using three different methods: the Rossiter-McLaughlin anomaly, Doppler tomography, and reloaded Rossiter-McLaughlin techniques. We performed the stability analysis of the system and investigated the dynamical interactions between the planets and the star. Results. HD 3167 c is found to be nearly polar with sky-projected obliquity, λ = −97°± 23°. This misalignment of the orbit of planet c with the spin axis of the host star is detected with 97% confidence. The analysis of the dynamics of this system yields coplanar orbits of planets c and d. It also shows that it is unlikely that the currently observed system can generate this high obliquity for planets c and d by itself. However, the polar orbits of planets c and d could be explained by the presence of an outer companion in the system. Follow-up observations of the system are required to confirm such a long-period companion.

A Recommendation Algorithm to Predict Giant Exoplanet Host Stars Using Stellar Elemental Abundances

The presence of certain elements within a star, and by extension its planet, strongly impacts the formation and evolution of the planetary system. The positive correlation between a host star's iron-content and the presence of an orbiting giant exoplanet has been confirmed; however, the importance of other elements in predicting giant planet occurrence is less certain despite their central role in shaping internal planetary structure. We designed and applied a machine learning algorithm to the Hypatia Catalog (Hinkel et a. 2014) to analyze the stellar abundance patterns of known host stars to determine those elements important in identifying potential giant exoplanet host stars. We analyzed a variety of different elements ensembles, namely volatiles, lithophiles, siderophiles, and Fe. We show that the relative abundances of oxygen, carbon, and sodium, in addition to iron, are influential indicators of the presence of a giant planet. We demonstrate the predictive power of our algorithm by analyzing stars with known giant planets and found that they had median 75% prediction score. We present a list of ~350 stars with no currently discovered planets that have a $\geq$90% prediction probability likelihood of hosting a giant exoplanet. We investigated archival HARPS data and found significant trends that HIP62345, HIP71803, and HIP10278 host long-period giant planet companions with estimated minimum $M_p\sin(i)$ values of 3.7, 6.8, and 8.5 M$_{J}$, respectively. We anticipate that our findings will revolutionize future target selection, the role that elements play in giant planet formation, and the determination of giant planet interior structure models.

Long-period Giant Companions to Three Compact, Multiplanet Systems

Abstract Understanding the relationship between long-period giant planets and multiple smaller short-period planets is critical for formulating a complete picture of planet formation. This work characterizes three such systems. We present Kepler-65, a system with an eccentric (e = 0.28 ± 0.07) giant planet companion discovered via radial velocities (RVs) exterior to a compact, multiply transiting system of sub-Neptune planets. We also use precision RVs to improve mass and radius constraints on two other systems with similar architectures, Kepler-25 and Kepler-68. In Kepler-68 we propose a second exterior giant planet candidate. Finally, we consider the implications of these systems for planet formation models, particularly that the moderate eccentricity in Kepler-65's exterior giant planet did not disrupt its inner system.

Detection and characterization of an ultra-dense sub-Neptunian planet orbiting the Sun-like star K2-292

We present the discovery and characterization of a new transiting planet from Campaign 17 of the Kepler extended mission K2. The planet K2-292 b is a warm sub-Neptune on a 17 day orbit around a bright (V = 9.9 mag) solar-like G3 V star with a mass and radius of M⋆ = 1.00 ± 0.03 M⊙ and R⋆ = 1.09 ± 0.03 R⊙, respectively. We modeled simultaneously the K2 photometry and CARMENES spectroscopic data and derived a radius of Rp=2.63−0.10+0.12 R⊕ and mass of Mp=24.5−4.4+4.4 M⊕, yielding a mean density of ρp=7.4−1.5+1.6 g cm−3, which makes it one of the densest sub-Neptunian planets known to date. We also detected a linear trend in the radial velocities of K2-292 (γ˙RV = −0.40−0.07+0.07 m s−1 d−1) that suggests a long-period companion with a minimum mass on the order of 33 M⊕. If confirmed, it would support a formation scenario of K2-292 b by migration caused by Kozai-Lidov oscillations.

Truly eccentric – I. Revisiting eight single-eccentric planetary systems

We examine eight known single-eccentric planetary systems in light of recently released large data archives and new analysis techniques. For four of these systems (HD 7449, HD 65216, HD 89744, HD 92788) we find evidence for additional long-period companions. HD 65216c is a Jupiter analog, with a period of 14.7 yr, $e=0.18$, and m sin $i$ of 2M_Jup, whilst the remaining candidate companions move on as-yet-incomplete orbits. Our results highlight the importance of revisiting the analysis of known exoplanetary systems when new data become available, particularly given the possibility that poorly-sampled data might previously have led to the detection of a 'false-positive' single eccentric planet, when the system in question actually contains two (or more) planets on near-circular orbits.

The Orbital Eccentricity of Small Planet Systems

Abstract We determine the orbital eccentricities of individual small Kepler planets, through a combination of asteroseismology and transit light-curve analysis. We are able to constrain the eccentricities of 51 systems with a single transiting planet, which supplement our previous measurements of 66 planets in multi-planet systems. Through a Bayesian hierarchical analysis, we find evidence that systems with only one detected transiting planet have a different eccentricity distribution than systems with multiple detected transiting planets. The eccentricity distribution of the single-transiting systems is well described by the positive half of a zero-mean Gaussian distribution with a dispersion σ e = 0.32 ± 0.06, while the multiple-transit systems are consistent with . A mixture model suggests a fraction of of single-transiting systems have a moderate eccentricity, represented by a Rayleigh distribution that peaks at . This finding may reflect differences in the formation pathways of systems with different numbers of transiting planets. We investigate the possibility that eccentricities are self-excited in closely packed planetary systems, as well as the influence of long-period giant companion planets. We find that both mechanisms can qualitatively explain the observations. We do not find any evidence for a correlation between eccentricity and stellar metallicity, as has been seen for giant planets. Neither do we find any evidence that orbital eccentricity is linked to the detection of a companion star. Along with this paper, we make available all of the parameters and uncertainties in the eccentricity distributions, as well as the properties of individual systems, for use in future studies.

An Excess of Jupiter Analogs in Super-Earth Systems

Abstract We use radial velocity (RV) observations to search for long-period gas giant companions in systems hosting inner super-Earth (1–4 R ⊕, 1–10 M ⊕) planets to constrain formation and migration scenarios for this population. We consistently refit published RV data sets for 65 stars and find nine systems with statistically significant trends indicating the presence of an outer companion. We combine these RV data with AO images to constrain the masses and semi-major axes of these companions. We quantify our sensitivity to the presence of long-period companions by fitting the sample with a power-law distribution and find an occurrence rate of 39% ± 7% for companions 0.5–20 M Jup and 1–20 au. Half of our systems were discovered by the transit method, and half were discovered by the RV method. While differences in the RV baselines and number of data points between the two samples lead to different sensitivities to distant companions, we find that occurrence rates of gas giant companions in each sample are consistent at the 0.5σ level. We compare the frequency of Jupiter analogs in these systems to the equivalent rate from field star surveys and find that Jupiter analogs are more common around stars hosting super-Earths. We conclude that the presence of outer gas giants does not suppress the formation of inner super-Earths, and that these two populations of planets instead appear to be correlated. We also find that the stellar metallicities of systems with gas giant companions are higher than those without companions, in agreement with the well-established metallicity correlation from RV surveys of field stars.

Exploring the realm of scaled solar system analogues with HARPS

Context. The assessment of the frequency of planetary systems reproducing the solar system’s architecture is still an open problem in exoplanetary science. Detailed study of multiplicity and architecture is generally hampered by limitations in quality, temporal extension and observing strategy, causing difficulties in detecting low-mass inner planets in the presence of outer giant planets. Aims. We present the results of high-cadence and high-precision HARPS observations on 20 solar-type stars known to host a single long-period giant planet in order to search for additional inner companions and estimate the occurence rate fp of scaled solar system analogues – in other words, systems featuring lower-mass inner planets in the presence of long-period giant planets. Methods. We carried out combined fits of our HARPS data with literature radial velocities using differential evolution MCMC to refine the literature orbital solutions and search for additional inner planets. We then derived the survey detection limits to provide preliminary estimates of fp. Results. We generally find better constrained orbital parameters for the known planets than those found in the literature; significant updates can be especially appreciated on half of the selected planetary systems. While no additional inner planet is detected, we find evidence for previously unreported long-period massive companions in systems HD 50499 and HD 73267. We finally estimate the frequency of inner low mass (10–30 M⊕) planets in the presence of outer giant planets as fp < 9.84% for P < 150 days. Conclusions. Our preliminary estimate of fp is significantly lower than the literature values for similarly defined mass and period ranges; the lack of inner candidate planets found in our sample can also be seen as evidence corroborating the inwards-migration formation model for super-Earths and mini-Neptunes. Our results also underline the need for high-cadence and high-precision followup observations as the key to precisely determine the occurence of solar system analogues.

K2-99: a subgiant hosting a transiting warm Jupiter in an eccentric orbit and a long-period companion

We report the discovery from K2 of a transiting planet in an 18.25-d, eccentric (0.19$\pm$ 0.04) orbit around K2-99, an 11th magnitude subgiant in Virgo. We confirm the planetary nature of the companion with radial velocities, and determine that the star is a metal-rich ([Fe/H] = 0.20$\pm$0.05) subgiant, with mass $1.60^{+0.14}_{-0.10}~M_\odot$ and radius $3.1\pm 0.1~R_\odot$. The planet has a mass of $0.97\pm0.09~M_{\rm Jup}$ and a radius $1.29\pm0.05~R_{\rm Jup}$. A measured systemic radial acceleration of $-2.12\pm0.04~{\rm m s^{-1} d^{-1}}$ offers compelling evidence for the existence of a third body in the system, perhaps a brown dwarf orbiting with a period of several hundred days.

High-Contrast Imaging of Intermediate-Mass Giants with Long-Term Radial Velocity Trends.

A radial velocity (RV) survey for intermediate-mass giants has been operated for over a decade at Okayama Astrophysical Observatory (OAO). The OAO survey has revealed that some giants show long-term linear RV accelerations (RV trends), indicating the presence of outer companions. Direct imaging observations can help clarify what objects generate these RV trends. We present the results of high-contrast imaging observations of six intermediate-mass giants with long-term RV trends using the Subaru Telescope and HiCIAO camera. We detected co-moving companions to γ Hya , HD 5608 B (0.10 ± 0.01M ⊙), and HD 109272 B (0.28 ± 0.06M ⊙). For the remaining targets(ι Dra, 18 Del, and HD 14067) we exclude companions more massive than 30-60 M Jup at projected separations of 1''-7''. We examine whether these directly imaged companions or unidentified long-period companions can account for the RV trends observed around the six giants. We find that the Kozai mechanism can explain the high eccentricity of the inner planets ι Dra b, HD 5608 b, and HD 14067 b.

An extreme planetary system around HD 219828

With about 2000 extrasolar planets confirmed, the results show that planetary systems have a whole range of unexpected properties. We present a full investigation of the HD219828 system, a bright metal-rich star for which a hot neptune has previously been detected. We used a set of HARPS, SOPHIE, and ELODIE radial velocities to search for the existence of orbiting companions to HD219828. A dynamical analysis is also performed to study the stability of the system and to constrain the orbital parameters and planet masses. We announce the discovery of a long period (P=13.1years) massive (msini=15.1MJup) companion (HD219828c) in a very eccentric orbit (e=0.81). The same data confirms the existence of a hot-neptune, HD219828b, with a minimum mass of 21 MEarth and a period of 3.83days. The dynamical analysis shows that the system is stable. The HD219828 system is extreme and unique in several aspects. First, among all known exoplanet systems it presents an unusually high mass ratio. We also show that systems like HD219828, with a hot neptune and a long-period massive companion are more frequent than similar systems with a hot jupiter instead. This suggests that the formation of hot neptunes follows a different path than the formation of their hot jovian counterparts. The high mass, long period, and eccentricity of HD219828c also make it a good target for Gaia astrometry as well as a potential target for atmospheric characterisation, using direct imaging or high-resolution spectroscopy. Astrometric observations will allow us to derive its real mass and orbital configuration. If a transit of HD219828b is detected, we will be able to fully characterise the system, including the relative orbital inclinations. With a clearly known mass, HD219828c may become a benchmark object for the range in between giant planets and brown dwarfs.

STATISTICS OF LONG PERIOD GAS GIANT PLANETS IN KNOWN PLANETARY SYSTEMS

ABSTRACT We conducted a Doppler survey at Keck combined with NIRC2 K-band adaptive optics (AO) imaging to search for massive, long-period companions to 123 known exoplanet systems with one or two planets detected using the radial velocity (RV) method. Our survey is sensitive to Jupiter-mass planets out to 20 au for a majority of stars in our sample, and we report the discovery of eight new long-period planets, in addition to 20 systems with statistically significant RV trends that indicate the presence of an outer companion beyond 5 au. We combine our RV observations with AO imaging to determine the range of allowed masses and orbital separations for these companions, and account for variations in our sensitivity to companions among stars in our sample. We estimate the total occurrence rate of companions in our sample to be 52 ± 5% over the range 1–20 MJup and 5–20 au. Our data also suggest a declining frequency for gas giant planets in these systems beyond 3–10 au, in contrast to earlier studies that found a rising frequency for giant planets in the range 0.01–3 au. This suggests either that the frequency of gas giant planets peaks between 3 and 10 au, or that outer companions in these systems have a different semi-major axis distribution than the overall population of gas giant planets. Our results also suggest that hot gas giants may be more likely to have an outer companion than cold gas giants. We find that planets with an outer companion have higher average eccentricities than their single counterparts, suggesting that dynamical interactions between planets may play an important role in these systems.

MagAO IMAGING OF LONG-PERIOD OBJECTS (MILO). I. A BENCHMARK M DWARF COMPANION EXCITING A MASSIVE PLANET AROUND THE SUN-LIKE STAR HD 7449*

ABSTRACT We present high-contrast Magellan adaptive optics images of HD 7449, a Sun-like star with one planet and a long-term radial velocity (RV) trend. We unambiguously detect the source of the long-term trend from 0.6–2.15 μm at a separation of ∼0.″54. We use the object’s colors and spectral energy distribution to show that it is most likely an M4–M5 dwarf (mass ∼0.1–0.2 M ⊙ ?> ) at the same distance as the primary and is therefore likely bound. We also present new RVs measured with the Magellan/MIKE and Planet Finder Spectrograph spectrometers and compile these with archival data from CORALIE and HARPS. We use a new Markov chain Monte Carlo procedure to constrain both the mass ( > 0.17 ?> M ⊙ ?> at 99% confidence) and semimajor axis (∼18 AU) of the M dwarf companion (HD 7449B). We also refine the parameters of the known massive planet (HD 7449Ab), finding that its minimum mass is 1.09 − 0.19 + 0.52 ?> M J , its semimajor axis is 2.33 − 0.02 + 0.01 ?> AU, and its eccentricity is 0.8 − 0.06 + 0.08 ?> . We use N-body simulations to constrain the eccentricity of HD 7449B to ≲0.5. The M dwarf may be inducing Kozai oscillations on the planet, explaining its high eccentricity. If this is the case and its orbit was initially circular, the mass of the planet would need to be ≲1.5 M J . This demonstrates that strong constraints on known planets can be made using direct observations of otherwise undetectable long-period companions.

The SOPHIE search for northern extrasolar planets

Long-period brown dwarf companions detected in radial velocity surveys are important targets for direct imaging and astrometry to calibrate the mass-luminosity relation of substellar objects. Through a 20-year radial velocity monitoring of solar-type stars that began with ELODIE and was extended with SOPHIE spectrographs, giant exoplanets and brown dwarfs with orbital periods longer than ten years are discovered. We report the detection of five new potential brown dwarfs with minimum masses between 32 and 83 Jupiter mass orbiting solar-type stars with periods longer than ten years. An upper mass limit of these companions is provided using astrometric Hipparcos data, high-angular resolution imaging made with PUEO, and a deep analysis of the cross-correlation function of the main stellar spectra to search for blend effects or faint secondary components. These objects double the number of known brown dwarf companions with orbital periods longer than ten years and reinforce the conclusion that the occurrence of such objects increases with orbital separation. With a projected separation larger than 100 mas, all these brown dwarf candidates are appropriate targets for high-contrast and high angular resolution imaging.

TESTS OF IN SITU FORMATION SCENARIOS FOR COMPACT MULTIPLANET SYSTEMS

Kepler has identified over 600 multiplanet systems, many of which have several planets with orbital distances smaller than that of Mercury -- quite different from the Solar System. Because these systems may be difficult to explain in the paradigm of core accretion and disk migration, it has been suggested that they formed in situ within protoplanetary disks with high solid surface densities. The strong connection between giant planet occurrence and stellar metallicity is thought to be linked to enhanced solid surface densities in disks around metal-rich stars, so the presence of a giant planet can be a detectable sign of planet formation in a high solid surface density disk. I formulate quantitative predictions for the frequency of long-period giant planets in these in situ models of planet formation by translating the proposed increase in disk mass into an equivalent metallicity enhancement. I rederive the scaling of giant planet occurrence with metallicity as P_gp = 0.05_{-0.02}^{+0.02} x 10^{(2.1 +/- 0.4) [M/H]} = 0.08_{-0.03}^{+0.02} x 10^{(2.3 +/- 0.4) [Fe/H]} and show that there is significant tension between the frequency of giant planets suggested by the minimum mass extrasolar nebula scenario and the observational upper limits. This fact suggests that high-mass disks alone cannot explain the observed properties of the close-in Kepler multiplanet systems and that migration is still a necessary contributor to their formation. More speculatively, I combine the metallicity scaling of giant planet occurrence with recently published small planet occurrence rates to estimate the number of Solar System analogs in the Galaxy. I find that in the Milky Way there are perhaps 4 x 10^6 true Solar System analogs with an FGK star hosting both a terrestrial planet in the habitable zone and a long-period giant planet companion.

AN UNDERSTANDING OF THE SHOULDER OF GIANTS: JOVIAN PLANETS AROUND LATE K DWARF STARS AND THE TREND WITH STELLAR MASS

Analyses of exoplanet statistics suggest a trend of giant planet occurrence with host star mass, a clue to how planets like Jupiter form. One missing piece of the puzzle is the occurrence around late K dwarf stars (masses of 0.5-0.75Msun and effective temperatures of 3900-4800K). We analyzed four years of Doppler radial velocities data of 110 late K dwarfs, one of which hosts two previously reported giant planets. We estimate that 4.0+/-2.3% of these stars have Saturn-mass or larger planets with orbital periods <245d, depending on the planet mass distribution and RV variability of stars without giant planets. We also estimate that 0.7+/-0.5% of similar stars observed by Kepler have giant planets. This Kepler rate is significantly (99% confidence) lower than that derived from our Doppler survey, but the difference vanishes if only the single Doppler system (HIP 57274) with completely resolved orbits is considered. The difference could also be explained by the exclusion of close binaries (without giant planets) from the Doppler but not Kepler surveys, the effect of long-period companions and stellar noise on the Doppler data, or an intrinsic difference between the two populations. Our estimates for late K dwarfs bridge those for solar-type stars and M dwarfs and support a positive trend with stellar mass. Small sample size precludes statements about finer structure, e.g. a "shoulder" in the distribution of giant planets with stellar mass. Future surveys such as the Next Generation Transit Survey and the Transiting Exoplanet Satellite Survey will ameliorate this deficiency.

The HARPS search for southern extra-solar planets

(Abridged) Searching for planets around stars with different masses probes the outcome of planetary formation for different initial conditions. This drives observations of a sample of 102 southern nearby M dwarfs, using a fraction of our guaranteed time on the ESO/HARPS spectrograph (Feb. 11th, 2003 to Apr. 1st 2009). This paper makes available the sample's time series, presents their precision and variability. We apply systematic searches and diagnostics to discriminate whether the observed Doppler shifts are caused by stellar surface inhomogeneities or by the radial pull of orbiting planets. We recover the planetary signals corresponding to 9 planets already announced by our group (Gl176b, Gl581b, c, d & e, Gl674b, Gl433b, Gl 667Cb and c). We present radial velocities that confirm GJ 849 hosts a Jupiter-mass planet, plus a long-term radial-velocity variation. We also present RVs that precise the planetary mass and period of Gl 832b. We detect long-term RV changes for Gl 367, Gl 680 and Gl 880 betraying yet unknown long-period companions. We identify candidate signals in the radial-velocity time series and demonstrate they are most probably caused by stellar surface inhomogeneities. Finally, we derive a first estimate of the occurrence of M-dwarf planets as a function of their minimum mass and orbital period. In particular, we find that giant planets (m sin i = 100-1,000 Mearth) have a low frequency (e.g. f<1% for P=1-10 d and f=0.02^{+0.03}_{-0.01} for P=10-100 d), whereas super-Earths (m sin i = 1-10 Mearth) are likely very abundant (f=0.36^{+0.25}_{-0.10} for P=1-10 d and f=0.35^{+0.45}_{-0.11} for P=10-100 d). We also obtained eta_earth=0.41^{+0.54}_{-0.13}, the frequency of habitable planets orbiting M dwarfs (1<m sin i<10 Mearth). For the first time, eta_earth is a direct measure and not a number extrapolated from the statistic of more massive and/or shorter-period planets.

Long-term magnetic activity of a sample of M-dwarf stars from the HARPS program

Due to their low mass and luminosity, M dwarfs are ideal targets if one hopes to find low-mass planets similar to Earth by using the radial velocity (RV) method. However, stellar magnetic cycles could add noise or even mimic the RV signal of a long-period companion. Following our previous work that studied the correlation between activity cycles and long-term RV variations for K dwarfs we now expand that research to the lower-end of the main sequence. Our objective is to detect any correlations between long-term activity variations and the observed RV of a sample of M dwarfs. We used a sample of 27 M-dwarfs with a median observational timespan of 5.9 years. The cross-correlation function (CCF) with its parameters RV, bisector inverse slope (BIS), full-width-at-half- maximum (FWHM) and contrast have been computed from the HARPS spectrum. The activity index have been derived using the Na I D doublet. These parameters were compared with the activity level of the stars to search for correlations. We detected RV variations up to ~5 m/s that we can attribute to activity cycle effects. However, only 36% of the stars with long-term activity variability appear to have their RV affected by magnetic cycles, on the typical timescale of ~6 years. Therefore, we suggest a careful analysis of activity data when searching for extrasolar planets using long-timespan RV data.

All-sky search for periodic gravitational waves in the full S5 LIGO data

We report on an all-sky search for periodic gravitational waves in the frequency band 50-800 Hz and with the frequency time derivative in the range of 0 through -6e-9 Hz/s. Such a signal could be produced by a nearby spinning and slightly non-axisymmetric isolated neutron star in our galaxy. After recent improvements in the search program that yielded a 10x increase in computational efficiency, we have searched in two years of data collected during LIGO's fifth science run and have obtained the most sensitive all-sky upper limits on gravitational wave strain to date. Near 150 Hz our upper limit on worst-case linearly polarized strain amplitude $h_0$ is 1e-24, while at the high end of our frequency range we achieve a worst-case upper limit of 3.8e-24 for all polarizations and sky locations. These results constitute a factor of two improvement upon previously published data. A new detection pipeline utilizing a Loosely Coherent algorithm was able to follow up weaker outliers, increasing the volume of space where signals can be detected by a factor of 10, but has not revealed any gravitational wave signals. The pipeline has been tested for robustness with respect to deviations from the model of an isolated neutron star, such as caused by a low-mass or long-period binary companion.