Subaru/SCExAO First-light Direct Imaging of a Young Debris Disk around HD 36546

Abstract

We present H-band scattered light imaging of a bright debris disk around the A0 star HD 36546 obtained from the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system with data recorded by the HiCIAO camera using the vector vortex coronagraph. SCExAO traces the disk from r∼0 3 to r∼1″ (34-114 au). The disk is oriented in a near east-west direction (PA∼75°), is inclined by i∼70°-75°, and is strongly forward-scattering (g>0.5). It is an extended disk rather than a sharp ring; a second, diffuse dust population extends from the disk's eastern side. While HD 36546 intrinsic properties are consistent with a wide age range (t∼1-250 Myr), its kinematics and analysis of coeval stars suggest a young age (3-10 Myr) and a possible connection to TaurusAuriga's star formation history. SCExAO's planet-to-star contrast ratios are comparable to the first-light Gemini Planet Imager contrasts; for an age of 10 Myr, we rule out planets with masses comparable to HR 8799 b beyond a projected separation of 23 au. A massive icy planetesimal disk or an unseen super-Jovian planet at r>20 au may explain the disk's visibility. The HD 36546 debris disk may be the youngest debris disk yet imaged, is the first newly identified object from the now-operational SCExAO extreme AO system, is ideally suited for spectroscopic follow-up with SCExAO/CHARIS in 2017, and may be a key probe of icy planet formation and planet-disk interactions.

An H-band Vector Vortex Coronagraph for the Subaru Coronagraphic Extreme Adaptive Optics System

“…Presented reduced images are normalized by the peak photometry of the primary. The bottom panel shows 5σ contrast curves for κAnd (median-combine ADI and ALOCI), as well as for HD 36546 on a deeper data set, also using the ALOCI algorithm (Currie et al 2017).…”

“…As seen on Figure 6, a basic ADI contrast (5-sigma) of about -· 8 10 5 is reached at 0 3, and -10 5 is achieved past 0 7 (see Table 3). Another one to two magnitudes ALOCI contrast gain can be obtained on deeper exposure ADI data sets with larger parallactic angle rotation (see e.g., Currie et al 2017). …”

“…At a magnitude ratio of ΔH=10.35 to the host star, the companion is detected with a S/N from 72 (median-combine ADI) to 107 (ALOCI), with its first Airy ring being visible. Using a ∼8.3 mas/pixel platescale for HiCIAO (Currie et al 2017), and in the absence of an astrometric field calibration frame, rough astrometry for kap And b obtained at this epoch yields an angular separation of 944 mas (∼48 au projected separation), and a PA of 39°.1 east of north. As seen on Figure 6, a basic ADI contrast (5-sigma) of about -· 8 10 5 is reached at 0 3, and -10 5 is achieved past 0 7 (see Table 3).…”

“…Figure 6 presents this final median-combined ADI image after derotation, as well as a few contrast curves: the basic ADI 5-σ contrast curve (adjusted for self-subtraction/throughput, but not for small sampling statistics Mawet et al 2014), an example of Adaptive LOCI (ALOCI, see Currie et al 2012) reduction (adjusted for throughput and small sample statistics), and the current best throughput-adjusted contrast obtained with the vortex on-sky (HD 36546 on 2016 October 5 UT Currie et al 2017), with about four times longer integration time and seven times larger position angle (PA) motion. At a magnitude ratio of ΔH=10.35 to the host star, the companion is detected with a S/N from 72 (median-combine ADI) to 107 (ALOCI), with its first Airy ring being visible.…”

VLT/SPHERE Multiwavelength High-contrast Imaging of the HD 115600 Debris Disk: New Constraints on the Dust Geometry and the Presence of Young Giant Planets

“…Planets can interact with the disk to produce large-scale structures (rings, warps, spirals, etc. ) that are often easier to observe than the planets themselves (e.g., Su et al 2013;Matthews et al 2017;Currie et al 2017). Thus, stars with debris disks are not only good places to look for exoplanets, but disk structures can also be used to predict and constrain unseen planets for possible future detections and studies.…”