arXiv subjects

J. -F. Lestrade

Publications and source records attributed to J. -F. Lestrade.

At least 73 records · Page 4Linked to original sources

arXiv2019

NIKA: a mm camera for Sunyaev-Zel'dovich science in clusters of galaxies

Clusters of galaxies, the largest bound objects in the Universe, constitute a cosmological probe of choice, which is sensitive to both dark matter and dark energy. Within this framework, the Sunyaev-Zel'dovich (SZ) effect has opened a new window for the detection of clusters of galaxies and for the characterization of their physical properties such as mass, pressure and temperature. NIKA, a KID-based dual band camera installed at the IRAM 30-m telescope, was particularly well adapted in terms of frequency, angular resolution, field-of-view and sensitivity, for the mapping of the thermal and kinetic SZ effect in high-redshift clusters. In this paper, we present the NIKA cluster sample and a review of the main results obtained via the measurement of the SZ effect on those clusters: reconstruction of the cluster radial pressure profile, mass, temperature and velocity.

astro-ph.CO↗

arXiv2019

GASTON: Galactic Star Formation with NIKA2: A new population of cold massive sources discovered

Understanding where and when the mass of stars is determined is one of the fundamental, mostly unsolved, questions in astronomy. Here, we present the first results of GASTON, the Galactic Star Formation with NIKA2 large programme on the IRAM 30m telescope, that aims to identify new populations of low-brightness sources to tackle the question of stellar mass determination across all masses. In this paper, we focus on the high-mass star formation part of the project, for which we map a $\sim2$ deg$^2$ region of the Galactic plane around $l=24^\circ$ in both 1.2 mm and 2.0 mm continuum. Half-way through the project, we reach a sensitivity of 3.7 mJy/beam at 1.2mm. Even though larger than our target sensitivity of 2 mJy, the current sensitivity already allows the identification of a new population of cold, compact sources that remained undetected in any (sub-)mm Galactic plane survey so far. In fact, about 25% of the $\sim 1600$ compact sources identified in the 1.2 mm GASTON image are new detections. We present a preliminary analysis of the physical properties of the GASTON sources as a function of their evolutionary stage, arguing for a potential evolution of the mass distribution of these sources with time.

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arXiv2019

Mapping the gas thermodynamic properties of the massive cluster merger MOO J1142$+$1527 at z = 1.2

We present the results of the analysis of the very massive cluster MOO J1142$+$1527 at a redshift $z = 1.2$ based on high angular resolution NIKA2 Sunyaev-Zel'dovich (SZ) and $Chandra$ X-ray data. This multi-wavelength analysis enables us to estimate the shape of the temperature profile with unprecedented precision at this redshift and to obtain a map of the gas entropy distribution averaged along the line of sight. The comparison between the cluster morphological properties observed in the NIKA2 and $Chandra$ maps together with the analysis of the entropy map allows us to conclude that MOO J1142$+$1527 is an on-going merger hosting a cool-core at the position of the X-ray peak. This work demonstrates how the addition of spatially-resolved SZ observations to low signal-to-noise X-ray data can bring valuable insights on the intracluster medium thermodynamic properties at $z>1$.

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arXiv2019

Unveiling the merger dynamics of the most massive MaDCoWS cluster at $z = 1.2$ from a multi-wavelength mapping of its intracluster medium properties

The characterization of the Intra-Cluster Medium (ICM) properties of high-redshift galaxy clusters is fundamental to our understanding of large-scale structure formation processes. We present the results of a multi-wavelength analysis of the very massive cluster MOO J1142$+$1527 at a redshift $z = 1.2$ discovered as part of the Massive and Distant Clusters of WISE Survey (MaDCoWS). This analysis is based on high angular resolution $Chandra$ X-ray and NIKA2 Sunyaev-Zel'dovich (SZ) data. Although the X-ray data have only about 1700 counts, we are able to determine the ICM thermodynamic radial profiles, namely temperature, entropy, and hydrostatic mass. These have been obtained with unprecedented precision at this redshift and up to $0.7R_{500}$, thanks to the combination of high-resolution X-ray and SZ data. The comparison between the galaxy distribution mapped in infrared by $Spitzer$ and the morphological properties of the ICM derived from the combined analysis of the $Chandra$ and NIKA2 data leads us to the conclusion that the cluster is an on-going merger. We measure the hydrostatic mass profile of the cluster in four angular sectors centered on the large-scale X-ray centroid. This allows us to estimate a systematic uncertainty on the cluster total mass that characterizes both the impact of the observed deviations from spherical symmetry and of the core dynamics on the mass profile. We further combine the X-ray and SZ data at the pixel level to obtain maps of the temperature and entropy distributions averaged along the line of sight. We find a relatively low entropy core at the position of the X-ray peak and high temperature regions located on its south and west sides. The increase in ICM temperature at the location of the SZ peak is expected given the merger dynamics. (abridged)

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arXiv2018

NIKA2 Performance and Cosmology Program with Galaxy Clusters

NIKA2 is a dual-band millimetric camera of thousands of Kinetic Inductance Detectors (KID) installed at the IRAM 30-meter telescope in the Spanish Sierra Nevada. The instrument commissioning was completed in September 2017, and NIKA2 is now open to the scientific community and will operate for the next decade. NIKA2 has well-adapted instrumental design and performance to produce high-resolution maps of the thermal Sunyaev-Zel'dovich (SZ) effect toward intermediate and high redshift galaxy clusters. Moreover, it benefits from a guaranteed time large program dedicated to mapping a representative sample of galaxy clusters via SZ and that includes X-ray follow-ups. The main expected outputs of the SZ large program are the constraints on the redshift evolution of the pressure profile and the mass-observable relation. The first SZ mapping of a galaxy cluster with NIKA2 was produced, as part of the SZ large program. We found a sizable impact of the intracluster medium dynamics on the integrated SZ observables. This shows NIKA2 capabilities for the precise characterisation of the mass-observable relation that is required for accurate cosmology with galaxy clusters.

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arXiv2018

First Sunyaev-Zel'dovich mapping with the NIKA2 camera: Implication of cluster substructures for the pressure profile and mass estimate

The complete characterization of the pressure profile of high-redshift galaxy clusters, from their core to their outskirts, is a major issue for the study of the formation of large-scale structures. It is essential to constrain a potential redshift evolution of both the slope and scatter of the mass-observable scaling relations used in cosmology studies based on cluster statistics. In this paper, we present the first thermal Sunyaev-Zel'dovich (tSZ) mapping of a cluster from the sample of the NIKA2 SZ large program that aims at constraining the redshift evolution of cluster pressure profiles and the tSZ-mass scaling relation. We have observed the galaxy cluster PSZ2 G144.83+25.11 at redshift $z=0.58$ with the NIKA2 camera, a dual-band (150 and 260 GHz) instrument operated at the IRAM 30-meter telescope. We identify a thermal pressure excess in the south-west region of PSZ2 G144.83+25.11 and a high redshift sub-millimeter point source that affect the intracluster medium (ICM) morphology of the cluster. The NIKA2 data are used jointly with tSZ data acquired by the MUSTANG, Bolocam and $Planck$ experiments in order to non-parametrically set the best constraints on the electronic pressure distribution from the cluster core ($\rm{R} \sim 0.02 \rm{R_{500}}$) to its outskirts ($\rm{R} \sim 3 \rm{R_{500}} $). We investigate the impact of the over-pressure region on the shape of the pressure profile and on the constraints on the integrated Compton parameter $\rm{Y_{500}}$. A hydrostatic mass analysis is also performed by combining the tSZ-constrained pressure profile with the deprojected electronic density profile from XMM-$Newton$. This allows us to conclude that the estimates of $\rm{Y_{500}}$ and $\rm{M_{500}}$ obtained from the analysis with and without masking the disturbed ICM region differ by 65 and 79% respectively. (abridged)

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arXiv2018

A NIKA view of two star-forming infrared dark clouds: Dust emissivity variations and mass concentration

The thermal emission of dust grains is a powerful tool for probing cold, dense regions of molecular gas in the ISM, and so constraining dust properties is key to obtaining accurate measurements of dust mass and temperature. By placing constraints on the dust emissivity spectral index, beta, towards two star-forming infrared dark clouds, SDC18.888 and SDC24.489, we evaluate the role of mass concentration in the associated star-formation activity. We exploit the simultaneous 1.2mm and 2.0mm imaging capability of NIKA on the IRAM 30m telescope to construct maps of beta for both clouds, and by incorporating Herschel observations, we create H2 column density maps with 13" resolution. While we find no significant systematic radial variations around the most massive clumps in either cloud on >0.1 pc scales, their mean beta values are significantly different, with beta = 2.07 +/- 0.09 (rand) +/- 0.25 (syst) for SDC18.888 and beta = 1.71 +/- 0.09 (rand) +/- 0.25 (syst) for SDC24.489. These differences could be a consequence of the very different environments in which both clouds lie, and we suggest that the proximity of SDC18.888 to the W39 HII region may raise beta on scales of 1 pc. We also find that the mass in SDC24.489 is more centrally concentrated and circularly symmetric than in SDC18.888, and is consistent with a scenario in which spherical globally-collapsing clouds concentrate a higher fraction of their mass into a single core than elongated clouds that will more easily fragment, distributing their mass into many cores. We demonstrate that beta variations towards interstellar clouds can be robustly constrained with high-SNR NIKA observations, providing more accurate estimates of their masses. The methods presented here will be applied to the Galactic Star Formation with NIKA2 (GASTON) large programme, extending our analysis to a statistically significant sample of star-forming clouds.

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arXiv2018

The NIKA2 instrument at 30-m IRAM telescope: performance and results

The New IRAM KID Arrays 2 (NIKA2) consortium has just finished installing and commissioning a millimetre camera on the IRAM 30 m telescope. It is a dual-band camera operating with three frequency multiplexed kilo-pixels arrays of Lumped Element Kinetic Inductance Detectors (LEKID) cooled at 150 mK, designed to observe the intensity and polarisation of the sky at 260 and 150 GHz (1.15 and 2 mm). NIKA2 is today an IRAM resident instrument for millimetre astronomy, such as Intra Cluster Medium from intermediate to distant clusters and so for the follow-up of Planck satellite detected clusters, high redshift sources and quasars, early stages of star formation and nearby galaxies emission. We present an overview of the instrument performance as it has been evaluated at the end of the commissioning phase.

astro-ph.IM↗

arXiv2017

Sub-structure and merger detection in resolved NIKA Sunyaev-Zel'dovich images of distant clusters

Sub-structures in the hot gas of galaxy clusters are related to their formation history and to the astrophysical processes at play in the intracluster medium (ICM). The thermal Sunyaev-Zel'dovich (tSZ) effect is directly sensitive to the line-of-sight integrated ICM pressure, and is thus particularly adapted to study ICM sub-structures. We apply structure-enhancement filtering algorithms to high resolution tSZ observations of distant clusters, in order to search for pressure discontinuities, compressions, as well as secondary peaks in the ICM. The same filters are applied to synthetic tSZ images extracted from RHAPSODY-G hydrodynamic simulations, in order to better interpret the extracted features. We also study the noise propagation trough the filters and quantify the impact of systematic effects, point source residuals being identified as the dominant potential contaminant. In 3 of our 6 NIKA clusters we identify features at high S/N that show clear evidence for merger events. In MACSJ0717 (z=0.55), three strong pressure gradients are observed on the E, SE and W sectors, and two main peaks in the pressure distribution are identified. We observe a lack of tSZ compact structure in the cool-core cluster PSZ1G045.85 (z=0.61), and a tSZ gradient ridge dominates in the SE. In the highest z cluster, CLJ1227 (z=0.89), we detect a ~45" (360 kpc) long ridge pressure gradient associated with a secondary pressure peak in the W region. Our results show that current tSZ facilities have now reached the angular resolution and sensitivity to allow an exploration of the details of pressure sub-structures in clusters, even at high z. This opens the possibility to quantify the impact of the dynamical state on the relation between the tSZ signal and the mass of clusters, which is important when using tSZ clusters to test cosmological models. This work also marks the first NIKA cluster sample data release.

astro-ph.CO↗

arXiv2017

A multi-instrument non-parametric reconstruction of the electron pressure profile in the galaxy cluster CLJ1226.9+3332

Context: In the past decade, sensitive, resolved Sunyaev-Zel'dovich (SZ) studies of galaxy clusters have become common. Whereas many previous SZ studies have parameterized the pressure profiles of galaxy clusters, non-parametric reconstructions will provide insights into the thermodynamic state of the intracluster medium (ICM). Aims: We seek to recover the non-parametric pressure profiles of the high redshift ($z=0.89$) galaxy cluster CLJ 1226.9+3332 as inferred from SZ data from the MUSTANG, NIKA, Bolocam, and Planck instruments, which all probe different angular scales. Methods: Our non-parametric algorithm makes use of logarithmic interpolation, which under the assumption of ellipsoidal symmetry is analytically integrable. For MUSTANG, NIKA, and Bolocam we derive a non-parametric pressure profile independently and find good agreement among the instruments. In particular, we find that the non-parametric profiles are consistent with a fitted gNFW profile. Given the ability of Planck to constrain the total signal, we include a prior on the integrated Compton Y parameter as determined by Planck. Results: For a given instrument, constraints on the pressure profile diminish rapidly beyond the field of view. The overlap in spatial scales probed by these four datasets is therefore critical in checking for consistency between instruments. By using multiple instruments, our analysis of CLJ 1226.9+3332 covers a large radial range, from the central regions to the cluster outskirts: $0.05 R_{500} < r < 1.1 R_{500}$. This is a wider range of spatial scales than is typical recovered by SZ instruments. Similar analyses will be possible with the new generation of SZ instruments such as NIKA2 and MUSTANG2.

astro-ph.CO↗

arXiv2016

ALMA observations of the $η$ Corvi debris disc: inward scattering of CO-rich exocomets by a chain of 3-30 M$_\oplus$ planets?

While most of the known debris discs present cold dust at tens of AU, a few young systems exhibit hot dust analogous to the Zodiacal dust. $η$ Corvi is particularly interesting as it is old and it has both, with its hot dust significantly exceeding the maximum luminosity of an in-situ collisional cascade. Previous work suggested that this system could be undergoing an event similar to the Late Heavy Bombardment (LHB) soon after or during a dynamical instability. Here we present ALMA observations of $η$ Corvi with a resolution of 1."2 (~22au) to study its outer belt. The continuum emission is consistent with an axisymmetric belt, with a mean radius of 152au and radial FWHM of 46au, which is too narrow compared to models of inward scattering of an LHB-like scenario. Instead, the hot dust could be explained as material passed inwards in a rather stable planetary configuration. We also report a 4sigma detection of CO at ~ 20au. CO could be released in situ from icy planetesimals being passed in when crossing the H$_2$O or CO$_2$ ice lines. Finally, we place constraints on hidden planets in the disc. If a planet is sculpting the disc's inner edge, this should be orbiting at 75-100au, with a mass of 3-30 M$_\oplus$ and an eccentricity < 0.08. Such a planet would be able to clear its chaotic zone on a timescale shorter than the age of the system and scatter material inwards from the outer belt to the inner regions, thus feeding the hot dust.

astro-ph.EP↗

arXiv2015

Dynamical masses of the low-mass stellar binary ABDoradusB

Context. ABDoradus is the main system of the ABDoradus moving group. It is a quadruple system formed by two widely separated binaries of pre-main-sequence (PMS) stars: ABDor A/C and ABDor Ba/Bb. The pair ABDor A/C has been extensively studied and its dynamical masses have been determined with high precision, thus making of ABDor C a benchmark for calibrating PMS stellar models. If the orbit and dynamical masses of the pair ABDor Ba/Bb can be determined, they could not only play a similar role to that of ABDor C in calibrating PMS models, but would also help to better understand the dynamics of the whole ABDoradus system. Aims. We aim to determine the individual masses of the pair ABDor Ba/Bb using VLBI observations and archive infrared data, as part of a larger program directed to monitor binary systems in the ABDoradus moving group. Methods. We observed the system ABDor B between 2007 and 2013 with the Australian Long Baseline Array (LBA), at a frequency of 8.4 GHz in phase-reference mode. Results. We detected, for the first time, compact radio emission from both stars in the binary, ABDor Ba and ABDor Bb. This result allowed us to determine the orbital parameters of both the relative and absolute orbits and, consequently, their individual dynamical masses: 0.28+/-0.05 Msun and 0.25+/-0.05 Msun, respectively. Conclusions. Comparisons of the dynamical masses with the prediction of PMS evolutionary models show that the models underpredict the dynamical masses of the binary components Ba and Bb by 10-30% and 10-40%, respectively, although they all still agree at the 2-sigma level. Some of stellar models considered favour an age between 50 and 100 Myr for this system, meanwhile others predict older ages. We also discuss the evolutionary status of ABDor Ba/Bb in terms of an earlier double-double star scenario that might explain the strong radio emission detected in both components.

astro-ph.SR↗

arXiv2015

Does the presence of planets affect the frequency and properties of extrasolar Kuiper Belts? Results from the Herschel DEBRIS and DUNES surveys

The study of the planet-debris disk connection can shed light on the formation and evolution of planetary systems, and may help predict the presence of planets around stars with certain disk characteristics. In preliminary analyses of the Herschel DEBRIS and DUNES surveys, Wyatt et al. (2012) and Marshall et al. (2014) identified a tentative correlation between debris and low-mass planets. Here we use the cleanest possible sample out these surveys to assess the presence of such a correlation, discarding stars without known ages, with ages < 1 Gyr and with binary companions <100 AU, to rule out possible correlations due to effects other than planet presence. In our sample of 204 FGK stars, we do not find evidence that debris disks are more common or more dusty around stars harboring high-mass or low-mass planets compared to a control sample without identified planets, nor that debris disks are more or less common (or more or less dusty) around stars harboring multiple planets compared to single-planet systems. Diverse dynamical histories may account for the lack of correlations. The data show the correlation between the presence of high-mass planets and stellar metallicity, but no correlation between the presence of low-mass planets or debris and stellar metallicity. Comparing the observed cumulative distribution of fractional luminosity to those expected from a Gaussian distribution, we find that a distribution centered on the Solar system's value fits well the data, while one centered at 10 times this value can be rejected. This is of interest in the context of future terrestrial planet characterization because it indicates that there are good prospects for finding a large number of debris disk systems (i.e. with evidence of harboring the building blocks of planets) with exozodiacal emission low enough to be appropriate targets for an ATLAST-type mission to search for biosignatures.

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arXiv2014

Correlations between the stellar, planetary and debris components of exoplanet systems observed by $\textit{Herschel}$

The $\textit{Herschel}$ DEBRIS, DUNES and GT programmes observed 37 exoplanet host stars within 25 pc at 70, 100 and 160 $μ$m with the sensitivity to detect far-infrared excess emission at flux density levels only an order of magnitude greater than that of the Solar system's Edgeworth-Kuiper belt. Here we present an analysis of that sample, using it to more accurately determine the (possible) level of dust emission from these exoplanet host stars and thereafter determine the links between the various components of these exoplanetary systems through statistical analysis. We have fitted the flux densities measured from recent \textit{Herschel} observations with a simple two parameter ($T_{d}$, $L_{\rm IR}/L_{\star}$) black body model (or to the 3-$σ$ upper limits at 100 $μ$m). From this uniform approach we calculate the fractional luminosity, radial extent, dust temperature and disc mass. We then plotted the calculated dust luminosity or upper limits against the stellar properties, e.g. effective temperature, metallicity, age, and identified correlations between these parameters. A total of eleven debris discs are identified around the 37 stars in the sample. An incidence of ten cool debris discs around the Sun-like exoplanet host stars (29 $\pm$ 9 %) is consistent with the detection rate found by DUNES (20.2 $\pm$ 2.0 %). For the debris disc systems, the dust temperatures range from 20 to 80 K, and fractional luminosities ($L_{\rm IR}/L_{\star}$) between 2.4 $\times$10$^{-6}$ and 4.1 $\times$10$^{-4}$. In the case of non-detections, we calculated typical 3-$σ$ upper limits to the dust fractional luminosities of a few $\times10^{-6}$. We recover the previously identified correlation between stellar metallicity and hot Jupiter planets in our data set. We find a correlation between the increased presence of dust, lower planet masses and lower stellar metallicities. (abridged)

astro-ph.EP↗

arXiv2013

Discovery of the Fomalhaut C debris disc

Fomalhaut is one of the most interesting and well studied nearby stars, hosting at least one planet, a spectacular debris ring, and two distant low-mass stellar companions (TW PsA and LP 876-10, a.k.a. Fomalhaut B & C). We observed both companions with Herschel, and while no disc was detected around the secondary, TW PsA, we have discovered the second debris disc in the Fomalhaut system, around LP 876-10. This detection is only the second case of two debris discs seen in a multiple system, both of which are relatively wide ($\gtrsim$3000 AU for HD 223352/40 and 158 kAU [0.77 pc] for Fomalhaut/LP 876-10). The disc is cool (24K) and relatively bright, with a fractional luminosity $L_{\rm disc}/L_\star = 1.2 \times 10^{-4}$, and represents the rare observation of a debris disc around an M dwarf. Further work should attempt to find if the presence of two discs in the Fomalhaut system is coincidental, perhaps simply due to the relatively young system age of 440 Myr, or if the stellar components have dynamically interacted and the system is even more complex than it currently appears.

astro-ph.EP↗

arXiv2013

Alignment in star-debris disc systems seen by Herschel

Many nearby main-sequence stars have been searched for debris using the far-infrared Herschel satellite, within the DEBRIS, DUNES and Guaranteed-Time Key Projects. We discuss here 11 stars of spectral types A to M where the stellar inclination is known and can be compared to that of the spatially-resolved dust belts. The discs are found to be well aligned with the stellar equators, as in the case of the Sun's Kuiper belt, and unlike many close-in planets seen in transit surveys. The ensemble of stars here can be fitted with a star-disc tilt of ~<10 degrees. These results suggest that proposed mechanisms for tilting the star or disc in fact operate rarely. A few systems also host imaged planets, whose orbits at tens of AU are aligned with the debris discs, contrary to what might be expected in models where external perturbers induce tilts.

astro-ph.SR↗

arXiv2012

A DEBRIS Disk Around The Planet Hosting M-star GJ581 Spatially Resolved with Herschel

Debris disks have been found primarily around intermediate and solar mass stars (spectral types A-K) but rarely around low mass M-type stars. We have spatially resolved a debris disk around the remarkable M3-type star GJ581 hosting multiple planets using deep PACS images at 70, 100 and 160 microns as part of the DEBRIS Program on the Herschel Space Observatory. This is the second spatially resolved debris disk found around an M-type star, after the one surrounding the young star AU Mic (12 Myr). However, GJ 581 is much older (2-8 Gyr), and is X-ray quiet in the ROSAT data. We fit an axisymmetric model of the disk to the three PACS images and found that the best fit model is for a disk extending radially from 25+/-12 AU to more than 60 AU. Such a cold disk is reminiscent of the Kuiper Belt but it surrounds a low mass star (0.3 M_sol) and its fractional dust luminosity L_dust/L_* of \sim 10^-4 is much higher. The inclination limits of the disk found in our analysis make the masses of the planets small enough to ensure the long-term stability of the system according to some dynamical simulations. The disk is collisionally dominated down to submicron-sized grains and the dust cannot be expelled from the system by radiation or wind pressures because of the low luminosity and low X-ray luminosity of GJ581. We suggest that the correlation between low-mass planets and debris disks recently found for G-type stars also applies to M-type stars.Finally, the known planets, of low masses and orbiting within 0.3 AU from the star, cannot dynamically perturb the disk over the age of the star, suggesting that an additional planet exists at larger distance that is stirring the disk to replenish the dust.

astro-ph.EP↗

arXiv2012

Herschel imaging of 61 Vir: implications for the prevalence of debris in low-mass planetary systems

This paper describes Herschel observations of the nearby (8.5pc) G5V multi-exoplanet host star 61 Vir at 70-500micron carried out by the DEBRIS survey. These reveal emission that is extended out to >15arcsec with a morphology that can be fitted by a nearly edge-on (77deg inclination) radially broad (from 30AU to >100AU) debris disk of fractional luminosity 2.7x10^-5, with two unrelated sources nearby that are more prominent at longer wavelengths. Chance alignment with a background object seen at 1.4GHz provides potential for confusion, but the star's 1.4"/yr proper motion allows Spitzer 70micron images to confirm that what we are interpreting as disk emission really is circumstellar. Although the exact shape of the disk's inner edge is not well constrained, the region inside 30AU must be significantly depleted in planetesimals. This is readily explained if there are additional planets in the 0.5-30AU region, but is also consistent with collisional erosion. We also find tentative evidence that the presence of detectable debris around nearby stars correlates with the presence of the lowest mass planets that are detectable in current radial velocity surveys. Out of an unbiased sample of the nearest 60 G stars, 11 are known to have planets, of which 6 (including 61 Vir) have planets that are all less massive than Saturn, and 4 of these have evidence for debris. The debris toward one of these planet-hosts (HD20794) is reported here for the first time. This fraction (4/6) is higher than that expected for nearby field stars (15%), and implies that systems that form low-mass planets are also able to retain bright debris disks. We suggest that this correlation could arise because such planetary systems are dynamically stable and include regions that are populated with planetesimals in the formation process where the planetesimals can remain unperturbed over Gyr timescales.

astro-ph.EP↗