Debris Distribution in Hd 95086—a Young Analog of Hr 8799

Abstract

HD 95086 is a young early-type star that hosts (1) a 5 M J planet at the projected distance of 56 AU revealed by direct imaging, and (2) a prominent debris disk. Here we report the detection of 69 µm crystalline olivine feature from the disk using the Spitzer/MIPS-SED data covering 55-95 µm. Due to the low resolution of MIPS-SED mode, this feature is not spectrally resolved, but is consistent with the emission from crystalline forsterite contributing ∼5% of the total dust mass. We also present detailed analysis of the disk SED and re-analysis of resolved images obtained by Herschel. Our results suggest that the debris structure around HD 95086 consists of a warm (∼175 K) belt, a cold (∼55 K) disk, and an extended disk halo (up to ∼800 AU), and is very similar to that of HR 8799. We compare the properties of the three debris components, and suggest that HD 95086 is a young analog of HR 8799. We further investigate and constrain single-planet, two-planet, three-planet and four-planet architectures that can account for the observed debris structure and are compatible with dynamical stability constraints. We find that equal-mass four-planet configurations of geometrically spaced orbits, with each planet of mass ∼5 M J , could maintain the gap between the warm and cold debris belts, and also be just marginally stable for timescales comparable to the age of the system. Subject headings: circumstellar matter -infrared: stars, planetary systems -stars: individual (HD 95086)

ALMA 1.3 mm Map of the HD 95086 System

“…We adopted this value for further SED analysis. Using similar approaches and grain parameters as in Su et al (2015) (minimum and maximum grain sizes of ∼1.8 µm and 1000 µm, and a particle size distribution in a power law index of −3.5), a geometrically thin, constant surface density disk with a radial span of 106-320 au provides a good fit to the ALMA 1.3 mm flux and maximum allowable fluxes in the far infrared (gray squares in Figure 5). This cold disk SED model also agrees with the observed 7 mm flux (not shown in Figure 5) obtained by Ricci et al (2015b) within the uncertainty.…”

“…Based on the χ 2 , the Gaussian ring model gives a slightly better fit; however, the number of free parameters is different (7 vs. 8), and some of the parameters are correlated. Su et al (2015) examined the resolved disk images of HD 95086 from Herschel and argued, by a detailed SED analysis, that the system is likely to possess three debris structures. The three debris components are very similar to the ones of the HR 8799 system -(1) an inner warm emission representing the dust in an asteroid-belt analog, (2) an outer cold emission representing the dust in Su et al (2015).…”

“…Su et al (2015) examined the resolved disk images of HD 95086 from Herschel and argued, by a detailed SED analysis, that the system is likely to possess three debris structures. The three debris components are very similar to the ones of the HR 8799 system -(1) an inner warm emission representing the dust in an asteroid-belt analog, (2) an outer cold emission representing the dust in Su et al (2015). The estimated 1.3 mm disk flux from this study is shown as the orange square.…”

“…The photometry points from Herschel (purple diamonds) and APEX are likely contaminated by the point source detected in our ALMA map, therefore, the total model disk SED (dashed line) is lower than those values. The grey squares are the maximum allowable fluxes derived from the PACS data (details see Su et al 2015). …”

“…Analysis of its detailed infrared SED and re-analysis of the resolved images suggest that the debris structure around HD 95086 is very similar to that of HR 8799: a warm (∼170 K) belt, a cold (∼60 K) disk, and an extended disk halo (up to ∼800 AU) (Su et al 2015). Modeling the disk surface brightness distribution at 70 and 160 µm suggests that the extended emission seen in the far-infrared is largely from the small grains produced by frequent collisions due to dynamical stirring of planetesimals and launched from the system by stellar radiation in the form of a disk halo.…”