The Dispersed Matter Planet Project Sample -- Detection limits, Occurrence Rates and New Planets

Abstract

DMPP is a radial-velocity survey that aims to detect planets around stars exhibiting anomalous activity signatures, consistent with the presence of close-in evaporating planets. Here, we report the discovery of 7 new planetary signals in 5 different systems: DMPP-2c & d, HD67200/DMPP-6b & c, HD118006/DMPP-7b, HD191122/DMPP-8b, and HD200133/DMPP-9b. We update the orbital parameters of the DMPP-1, DMPP-2, and DMPP-3 systems, along with those of the planetary systems orbiting HD181433, HD39194, and HD89839. We derive detection limits for all 24 targets in our sample with adequate observational coverage, and test the DMPP hypothesis by calculating the occurrence rates for planets in this configuration. We find that the occurrence rates of planets in our sample with orbital periods shorter than $50~\mathrm{d}$ and masses in the range $3$-$10$ M$_\oplus$ are $83.0^{+27.1}_{-24.4}\%$, for $10$-$30$ M$_\oplus$ are $27.0^{+15.0}_{-11.2}\%$, and for $30$-$100$ M$_\oplus$ are $13.9^{+11.8}_{-7.5}\%$. This is significantly higher than the occurrence rates reported by other radial velocity surveys, providing strong support for the DMPP hypothesis.

Figures (57)

• Figure 1: Detection limit plot for HD118006 / DMPP-7. The grey hexbin plot denotes the density of posterior samples obtained from kima runs on our HD118006 / DMPP-7 dataset, the darker the region the more samples are present. The blue line is the $99\%$ upper detection limit, with uncertainties denoted by the blue shaded region. The red line is the $99\%$ upper limit calculated on posterior samples with $e<0.1$, with associated uncertainty denoted by the red shaded region. Shaded uncertainties for the detection limits are present but small. The green point represents the detected planetary signal of HD118006 / DMPP-7 b.
• Figure 2: Completeness and planet abundance plot for the DMPP radial velocity survey of 24 targets with sub-basal activity, as a function of minimum mass and orbital period. The red contours indicate the completeness of the survey from $0\%$ (white) to $100\%$ (dark red) as in Figure 10 in Martin2019. The dark green circles show previously published planet signals present in our data, while the light green show signals found to pass our detection threshold in this work. Cyan open circles are the three candidate signals we identified with moderate statistical evidence, while the grey circles represent signals which we suspect arise from activity. The white lines delineate 11 boxes enclosing regions of parameter space within which we are able to constrain our planetary abundance. Box limits were chosen to be roughly equal in $\log$ space for short periods within our completeness, with mass limits on integer masses. The number in the centre of each box is a percentage indicating the planet abundance with its $1\sigma$ uncertainty, or the $2\sigma$ ($95\%$) upper limit on abundance where no planet detection was made. The white values in the lower right of each box is its mean completeness as a percentage.
• Figure 3: Detection limit plot for BD+03580. The grey hexbin plot denotes the density of 222,000 posterior samples obtained from kima runs. The blue line is the $99\%$ upper detection limit, with uncertainties denoted by the blue shaded region. The green line is the same $99\%$ upper limit calculated on posterior samples obtained from separate runs where $N_{\rm p}=2$, with associated uncertainty denoted by the green shaded region. Shaded uncertainties for the detection limits are present but small
• Figure 4: Phased Keplerian RV models of DMPP-2 b (top), DMPP-2 c (middle), and DMPP-2 d (bottom) with HARPS data post-fibre upgrade (blue) and its residuals after removing the planetary signals. The additional RV jitter term has been added to the plotted uncertainties and is shown by the grey error bars. No random samples are shown for these signals as their eccentricity is unconstrained and consistent with 0. The shaded regions display the repeating signal.
• Figure 5: Detection limit plot as in Figure \ref{['fig:HD118006_Det_lim']} for target HD191122 / DMPP-8 demonstrating the difference between the circular (red) detection limit and the standard (blue) detection limit.