The HOSTS survey for exozodiacal dust: Observational results from the complete survey
Steve Ertel, Denis Defrère, Philip M. Hinz, Bertrand Mennesson, Grant M. Kennedy, William C. Danchi, Christopher Gelino, John M. Hill, William F. Hoffmann, Joha… 展开作者
Steve Ertel, Denis Defrère, Philip M. Hinz, Bertrand Mennesson, Grant M. Kennedy, William C. Danchi, Christopher Gelino, John M. Hill, William F. Hoffmann, Johan Mazoyer, George Rieke, Andrew Shannon, Karl Stapelfeldt, Eckhart Spalding, Jordan M. Stone, Amali Vaz, Alycia J. Weinberger, Phil Willems, Olivier Absil, Paul Arbo, Vanessa P. Bailey, Charles Beichman, Geoffrey Bryden, Elwood C. Downey, Olivier Durney, Simone Esposito, Andras Gaspar, Paul Grenz, Chris A. Haniff, Jarron M. Leisenring, Lindsay Marion, Tom J. McMahon, Rafael Millan-Gabet, Oscar M. Montoya, Katie M. Morzinski, Saavidra Perera, Enrico Pinna, Jörg-Uwe Pott, Jennifer Power, Alfio Puglisi, Aki Roberge, Eugene Serabyn, Andrew J. Skemer, Kate Y. L. Su, Vidhya Vaitheeswaran, Mark C. Wyatt
The Large Binocular Telescope Interferometer (LBTI) enables nulling interferometric observations across the N band (8 to 13 um) to suppress a star's bright light and probe for faint circumstellar emission. We present and statistically analyze the results from the LBTI/HOSTS (Hunt for Observable Signatures of Terrestrial Systems) survey for exozodiacal dust. By comparing our measurements to model predictions based on the Solar zodiacal dust in the N band, we estimate a 1 sigma median sensitivity of 23 zodis for early type stars and 48 zodis for Sun-like stars, where 1 zodi is the surface density of habitable zone (HZ) dust in the Solar system. Of the 38 stars observed, 10 show significant excess. A clear correlation of our detections with the presence of cold dust in the systems was found, but none with the stellar spectral type or age. The majority of Sun-like stars have relatively low HZ dust levels (best-fit median: 3 zodis, 1 sigma upper limit: 9 zodis, 95% confidence: 27 zodis based on our N band measurements), while ~20% are significantly more dusty. The Solar system's HZ dust content is consistent with being typical. Our median HZ dust level would not be a major limitation to the direct imaging search for Earth-like exoplanets, but more precise constraints are still required, in particular to evaluate the impact of exozodiacal dust for the spectroscopic characterization of imaged exo-Earth candidates.
Hot exozodiacal dust emission was detected in recent surveys around two dozen main sequence stars at distances of less than $1\,\text{au}$ using H and K band interferometry. Due to the high contrast as well as the small angular distance between the circumstellar dust and the star, direct observation of this dust component is challenging. An alternative way to explore the hot exozodiacal dust is provided by mid-infrared interferometry. We analyze the L, M and N band interferometric signature of this emission in order to find stronger constraints for the properties and the origin of the hot exoz…
Future direct observations of extrasolar Earth-sized planets in the habitable zone could be hampered by a worrisome source of noise, starlight-reflecting exozodiacal dust. Mid-infrared surveys are currently underway to constrain the amount of exozodiacal dust in the habitable zones around nearby stars. However, at visible wavelengths another source of dust, invisible to these surveys, may dominate over exozodiacal dust. For systems observed near edge-on, a cloud of dust with face-on optical depth 10^-7 beyond ~5 AU can mimic the surface brightness of a cloud of exozodiacal dust with equal opti…
Planets embedded within debris disks gravitationally perturb nearby dust and can create clumpy, azimuthally asymmetric circumstellar ring structures that rotate in lock with the planet. The Earth creates one such structure in the solar zodiacal dust cloud. In an edge-on system, the dust "clumps" periodically pass in front of the star as the planet orbits, occulting and forward-scattering starlight. In this paper, we predict the shape and magnitude of the corresponding transit signal. To do so, we model the dust distributions of collisional, steady-state exozodiacal clouds perturbed by planetar…
[Abridged] Debris disks are extrasolar analogs to the solar system planetesimal belts. The star Fomalhaut harbors a cold debris belt at 140 AU as well as evidence of a warm dust component, which is suspected of being a bright analog to the solar system's zodiacal dust. Interferometric observations obtained with the VLTI and the KIN have identified near- and mid-infrared excesses attributed to hot and warm exozodiacal dust in the inner few AU of the star. We performed parametric modeling of the exozodiacal disk using the GRaTeR radiative transfer code to reproduce the interferometric data, comp…
For the first time we observed the emission of hot exozodiacal dust in L band. We used the new instrument MATISSE at the Very Large Telescope Interferometer to detect the hot dust around $κ$ Tuc with a significance of 3$σ$ to 6$σ$ at wavelengths between 3.37 and 3.85 $μ$m and a dust-to-star flux ratio of 5 to 7 %. We modelled the spectral energy distribution based on the new L band data alone and in combination with H band data published previously. In all cases we find 0.58 $μ$m grains of amorphous carbon to fit the $κ$ Tuc observations the best, however, also nanometre or micrometre grains a…
Recent interferometric surveys of nearby main-sequence stars show a faint but significant near-infrared excess in roughly two dozen systems, i.$\,$e. around $10\,\%$ to $30\,\%$ of stars surveyed. This excess is attributed to dust located in the immediate vicinity of the star, the origin of which is highly debated. We used previously published interferometric observations to constrain the properties and distribution of this hot dust. Considering both scattered radiation and thermal reemission, we modelled the observed excess in nine of these systems. We find that grains have to be sufficiently…
Planets embedded within dust disks may drive the formation of large scale clumpy dust structures by trapping dust into resonant orbits. Detection and subsequent modeling of the dust structures would help constrain the mass and orbit of the planet and the disk architecture, give clues to the history of the planetary system, and provide a statistical estimate of disk asymmetry for future exoEarth-imaging missions. Here we present the first search for these resonant structures in the inner regions of planetary systems by analyzing the light curves of hot Jupiter planetary candidates identified by…
The Hunt for Observable Signatures of Terrestrial planetary Systems (HOSTS) on the Large Binocular Telescope Interferometer will survey nearby stars for faint emission arising from ~300 K dust (exozodiacal dust), and aims to determine the exozodiacal dust luminosity function. HOSTS results will enable planning for future space telescopes aimed at direct spectroscopy of habitable zone terrestrial planets, as well as greater understanding of the evolution of exozodiacal disks and planetary systems. We lay out here the considerations that lead to the final HOSTS target list. Our target selection …
The HOSTS (Hunt for Observable Signatures of Terrestrial Systems) survey searches for dust near the habitable zones (HZs) around nearby, bright main sequence stars. We use nulling interferometry in N band to suppress the bright stellar light and to probe for low levels of HZ dust around the 30 stars observed so far. Our overall detection rate is 18%, including four new detections, among which are the first three around Sun-like stars and the first two around stars without any previously known circumstellar dust. The inferred occurrence rates are comparable for early type and Sun-like stars, bu…
Context. Detecting and characterizing circumstellar dust is a way to study the architecture and evolution of planetary systems. Cold dust in debris disks only traces the outer regions. Warm and hot exozodiacal dust needs to be studied in order to trace regions close to the habitable zone. Aims. We aim to determine the prevalence and to constrain the properties of hot exozodiacal dust around nearby main-sequence stars. Methods. We search a magnitude limited (H < 5) sample of 92 stars for bright exozodiacal dust using our VLTI visitor instrument PIONIER in the H-band. We derive statistics of the…
When observing an extrasolar planetary system, the most luminous component after the star itself is generally the light scattered and/or thermally emitted by a population of micron-sized dust grains. These grains are expected to be continuously replenished by the collisions and evaporation of larger bodies just as in our solar zodiacal cloud. Exozodiacal clouds ("exozodis") must therefore be seriously taken into account when attempting to directly image faint Earth-like planets (exoEarths, for short). This paper summarizes the oral contributions and discussions that took place during the Satel…
We report the results of high-angular-resolution observations that search for exozodiacal light in a sample of main sequence stars and sub-giants. Using the "jouvence" of the fiber linked unit for optical recombination (JouFLU) at the center for high angular resolution astronomy (CHARA) telescope array, we have observed a total of 44 stars. Out of the 44 stars, 33 are new stars added to the initial, previously published survey of 42 stars performed at CHARA with the fiber linked unit for optical recombiation (FLUOR). Since the start of the survey extension, we have detected a K-band circumstel…
(abridged) Context. The origin of hot exozodiacal dust and its connection with outer dust reservoirs remains unclear. Aims. We aim to explore the possible connection between hot exozodiacal dust and warm dust reservoirs (> 100 K) in asteroid belts. Methods. We use precision near-infrared interferometry with VLTI/PIONIER to search for resolved emission at H band around a selected sample of nearby stars. Results. Our observations reveal the presence of resolved near-infrared emission around 17 out of 52 stars, four of which are shown to be due to a previously unknown stellar companion. The 13 ot…
Interferometric Detection and Orbit Modeling of the Subcomponent in the Hot-dust System $κ$ Tuc A: A Low-mass Star on an Eccentric Orbit in a Hierarchical-quintuple System
The young (50-400 Myr) A3V star $β$ Leo is a primary target to study the formation history and evolution of extrasolar planetary systems as one of the few stars with known hot ($\sim$1600$^\circ$K), warm ($\sim$600$^\circ$K), and cold ($\sim$120$^\circ$K) dust belt components. In this paper, we present deep mid-infrared measurements of the warm dust brightness obtained with the Large Binocular Telescope Interferometer (LBTI) as part of its exozodiacal dust survey (HOSTS). The measured excess is 0.47\%$\pm$0.050\% within the central 1.5 au, rising to 0.81\%$\pm$0.026\% within 4.5 au, outside th…
(Abridged) Dust is expected to be ubiquitous in extrasolar planetary systems owing to the dynamical activity of minor bodies. Inner dust populations are, however, still poorly known because of the high contrast and small angular separation with respect to their host star. We aim to determine the level of near-infrared exozodiacal dust emission around a sample of 42 nearby main sequence stars with spectral types ranging from A to K and to investigate its correlation with various stellar parameters and with the presence of cold dust belts. We use high-precision K-band visibilities obtained with …
Although numerous white dwarf stars host dusty debris disks, the temperature distribution of these stars differs significantly from the white dwarf population as a whole. Dusty debris disks exist exclusively around white dwarfs cooler than 27,000 K. This is all the more enigmatic given that the formation processes of dusty debris disks should favor younger, hotter white dwarfs, which likely host more dynamically unstable planetary systems. Here we apply a sophisticated material sublimation model to white dwarf systems to show that these statistics are actually a natural result of the interplay…
The main goal of the EXOZODI survey is to detect and characterize circumstellar dust and to propose the first statistical study of exozodiacal disks in the near-infrared using telescopes in both hemispheres. For this purpose, Ertel et al. have conducted in 2012 a survey of nearby main sequence stars with VLTI/PIONIER to search for the presence of circumstellar dust. This survey, carried out during 12 nights, comprises about 100 stars. For each star, we obtained typically three OBs and we searched for circumstellar emission based on the measurement of squared visibilities at short baselines. A …
Dust in debris disks is produced by colliding or evaporating planetesimals, remnants of the planet formation process. Warm dust disks, known by their emission at < 24 micron, are rare (4% of FGK main sequence stars) and especially interesting because they trace material in the region likely to host terrestrial planets, where the dust has a very short dynamical lifetime. Statistical analyses of the source counts of excesses as found with the mid-IR Wide Field Infrared Survey Explorer (WISE) suggest that warm-dust candidates found for the Kepler transiting-planet host-star candidates can be expl…
The Keck Interferometer Nuller (KIN) was used to survey 25 nearby main sequence stars in the mid-infrared, in order to assess the prevalence of warm circumstellar (exozodiacal) dust around nearby solar-type stars. The KIN measures circumstellar emission by spatially blocking the star but transmitting the circumstellar flux in a region typically 0.1 - 4 AU from the star. We find one significant detection (eta Crv), two marginal detections (gamma Oph and alpha Aql), and 22 clear non-detections. Using a model of our own Solar System's zodiacal cloud, scaled to the luminosity of each target star, …
Depletion studies provide a way to understand the chemical composition of interstellar dust grains. We here examine 23 gamma-ray bursts (GRB) optical afterglow spectra (spanning 0.6<z<5.0) and compare their silicon and iron dust-phase column densities with different extinction curve parameters to study the composition of the interstellar dust grains in these high-redshift GRB host galaxies. The majority of our sample (87%) show featureless extinction curves and only vary in shape. We observe strong correlations (with >96% significance) between the total-to-selective extinction, R_V, and the du…
We present a substantial extension of the mm-wave continuum photometry catalog for Taurus circumstellar dust disks. Combining new Submillimeter Array data with measurements in the literature, we construct a mm-wave luminosity distribution for Class II disks that is statistically complete for stellar hosts with spectral types earlier than M8.5 and has a (3-sigma) depth of ~3 mJy. The resulting census eliminates a longstanding bias against disks with late-type hosts, and thereby reveals a strong correlation between L_mm and the host spectral type. We confirm that this corresponds to a statistica…
The environmental dependence of mid-IR luminous dusty Supernovae
Hebei University（河北大学）；Institute of Space Sciences (ICE, CSIC)（空间科学研究所（ICE，CSIC））；University of Szeged（塞格德大学）；Space Telescope Science Institute（太空望远镜科学研究所）；Carnegie Mellon University（卡内基梅隆大学）
Investigating interstellar (IS) dust properties in external galaxies is important not only to infer the intrinsic properties of astronomical objects but also to understand the star/planet formation in the galaxies. From the non-Milky-Way-like extinction and interstellar polarization (ISP) observed in reddened Type Ia supernovae (SNe), it has been suggested that their host galaxies contain dust grains whose properties are substantially different from the Milky-Way (MW) dust. It is important to investigate the universality of such non-MW-like dust in the universe. Here we report spectropolarimet…
A dust-free hierarchically nested supermassive-star model for James Webb Space Telescope Little Red Dots
Universitat Politècnica de València（瓦伦西亚理工大学）；Max Planck Institute for Extraterrestrial Physics（马克斯·普朗克地外物理研究所）；Kavli Institute for Astronomy and Astrophysics at Peking University（北京大学科维理天文与天体物理研究所）
