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Register a new userALMA 1.3 Millimeter Map of the HD 95086 System
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Planets and minor bodies such as asteroids, Kuiper-belt objects and comets are integral components of a planetary system. Interactions among them leave clues about the formation process of a planetary system. The signature of such interactions is most prominent through observations of its debris disk at millimeter wavelengths where emission is dominated by the population of large grains that stay close to their parent bodies. Here we present ALMA 1.3 mm observations of HD 95086, a young early-type star that hosts a directly imaged giant planet b and a massive debris disk with both asteroid- and Kuiper-belt analogs. The location of the Kuiper-belt analog is resolved for the first time. The system can be depicted as a broad ($Delta R/R sim$0.84), inclined (30arcdeg$pm$3arcdeg) ring with millimeter emission peaked at 200$pm$6 au from the star. The 1.3 mm disk emission is consistent with a broad disk with sharp boundaries from 106$pm$6 to 320$pm$20 au with a surface density distribution described by a power law with an index of --0.5$pm$0.2. Our deep ALMA map also reveals a bright source located near the edge of the ring, whose brightness at 1.3 mm and potential spectral energy distribution are consistent with it being a luminous star-forming galaxy at high redshift. We set constraints on the orbital properties of planet b assuming co-planarity with the observed disk.
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One of the defining properties of debris discs compared to protoplanetary discs used to be their lack of gas, yet small amounts of gas have been found around an increasing number of debris discs in recent years. These debris discs found to have gas tend to be both young and bright. In this paper we conduct a deep search for CO gas in the system HD 95086 - a 17 Myr old, known planet host that also has a debris disc with a high fractional luminosity of $1.5times10^{-3}$. Using the Atacama Large Millimeter/submillimeter Array (ALMA) we search for CO emission lines in bands 3, 6 and 7. By implementing a spectro-spatial filtering technique, we find tentative evidence for CO $J$=2-1 emission in the disc located at a velocity, 8.5$pm$0.2 km s$^{-1}$, consistent with the radial velocity of the star. The tentative detection suggests that the gas on the East side of the disc is moving towards us. In the same region where continuum emission is detected, we find an integrated line flux of 9.5$pm$3.6 mJy km s$^{-1}$, corresponding to a CO mass of (1.4-13)$times10^{-6}$ M$_oplus$. Our analysis confirms that the level of gas present in the disc is inconsistent with the presence of primordial gas in the system and is consistent with second generation production through the collisional cascade.
We present ALMA Band 6 observations (1.3 mm/233 GHz) of Fomalhaut and its debris disc. The observations achieve a sensitivity of 17 $mu$Jy and a resolution of 0.28 arcsec (2.1 au at a distance of 7.66 pc), which are the highest resolution observations to date of the millimetre grains in Fomalhauts main debris ring. The ring is tightly constrained to $139^{+2}_{-3}$ au with a FWHM of $13pm3$ au, following a Gaussian profile. The millimetre spectral index is constrained to $alpha_{mm} = -2.62pm0.12$. We explore fitting debris disc models in the image plane, as well as fitting models using visibility data directly. The results are compared and the potential advantages/disadvantages of each approach are discussed. The detected central emission is indistinguishable from a point source, with a most probable flux of $0.90pm 0.12$ mJy (including calibration uncertainties). This implies that any inner debris structure, as was inferred from far-Infrared observations, must contribute little to the total central emission. Moreover, the stellar flux is less than 70% of that predicted by extrapolating a black body from the constrained stellar photosphere temperature. This result emphasizes that unresolved inner debris components cannot be fully characterized until the behaviour of the host stars intrinsic stellar emission at millimetre wavelengths is properly understood.
We present astrometric monitoring of the young exoplanet HD 95086 b obtained with the Gemini Planet Imager between 2013 and 2016. A small but significant position angle change is detected at constant separation; the orbital motion is confirmed with literature measurements. Efficient Monte Carlo techniques place preliminary constraints on the orbital parameters of HD 95086 b. With 68% confidence, a semimajor axis of 61.7^{+20.7}_{-8.4} au and an inclination of 153.0^{+9.7}_{-13.5} deg are favored, with eccentricity less than 0.21. Under the assumption of a co-planar planet-disk system, the periastron of HD 95086 b is beyond 51 au with 68% confidence. Therefore HD 95086 b cannot carve the entire gap inferred from the measured infrared excess in the SED of HD 95086. We use our sensitivity to additional planets to discuss specific scenarios presented in the literature to explain the geometry of the debris belts. We suggest that either two planets on moderately eccentric orbits or three to four planets with inhomogeneous masses and orbital properties are possible. The sensitivity to additional planetary companions within the observations presented in this study can be used to help further constrain future dynamical simulations of the planet-disk system.
We present ALMA 1.3 mm (230 GHz) observations of the HD 32297 and HD 61005 debris disks, two of the most iconic debris disks due to their dramatic swept-back wings seen in scattered light images. These observations achieve sensitivities of 14 and 13 $mu$Jy beam$^{-1}$ for HD 32297 and HD 61005, respectively, and provide the highest resolution images of these two systems at millimeter wavelengths to date. By adopting a MCMC modeling approach, we determine that both disks are best described by a two-component model consisting of a broad ($Delta R/R> 0.4$) planetesimal belt with a rising surface density gradient, and a steeply falling outer halo aligned with the scattered light disk. The inner and outer edges of the planetesimal belt are located at $78.5pm8.1$ AU and $122pm3$ AU for HD 32297, and $41.9pm0.9$ AU and $67.0pm0.5$ AU for HD 61005. The halos extend to $440pm32$ AU and $188pm8$ AU, respectively. We also detect $^{12}$CO J$=2-1$ gas emission from HD 32297 co-located with the dust continuum. These new ALMA images provide observational evidence that larger, millimeter-sized grains may also populate the extended halos of these two disks previously thought to only be composed of small, micron-sized grains. We discuss the implications of these results for potential shaping and sculpting mechanisms of asymmetric debris disks.
VLT/NaCo angular differential imaging at L (3.8 microns) revealed a probable giant planet comoving with the young and early-type HD 95086 also known to harbor an extended debris disk. The discovery was based on the proper motion analysis of two datasets spanning 15 months. However, the second dataset suffered from bad atmospheric conditions, which limited the significance of the redetection at the 3 sigma level. In this Letter, we report new VLT/NaCo observations of HD 95086 obtained on 2013 June 26-27 at L to recover the planet candidate. We unambiguously redetect the companion HD 95086 b with multiple independent pipelines at a signal-to-noise ratio greater than or equal to 5. Combined with previously reported measurements, our astrometry decisively shows that the planet is comoving with HD 95086 and inconsistent with a background object. With a revised mass of 5 pm 2 Jupiter masses, estimated from its L photometry and hot-start models at 17 pm 4 Myr, HD 95086 b becomes a new benchmark for further physical and orbital characterization of young giant planets.
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