Strategic Explorations of Exoplanets and Disks with Subaru

File:HR 8976 exoplanet.jpg, the Super-Jupiter exoplanet of 12.8 Jupiter masses discovered as part of the SEEDS survey]]

File:GJ 758 System - Labeled.jpg GJ 758 B and the candidate GJ 758 C, which was later found to be a background star]]The direct imaging survey was carried out with a suite of high-contrast instrumentation at the large Subaru 8.2 m telescope, including a second-generation adaptive optics (AO) system with 188 actuators (AO188) and a dedicated coronagraph instrument called HiCIAO. {{cite book |last=Tamura |first=Motohide |chapter=Concept and science of HiCIAO: High contrast instrument for the Subaru next generation adaptive optics |display-authors=etal |date=July 2006 |editor1-last=McLean |editor1-first=Ian S |editor2-last=Iye |editor2-first=Masanori |title=Ground-based and Airborne Instrumentation for Astronomy |chapter-url=http://optik2.mtk.nao.ac.jp/~hide/APRO/HiCIAOTamuraSPIE.pdf |journal=Proceedings of the SPIE |volume=6269 |pages=62690V |bibcode=2006SPIE.6269E..0VT |citeseerx=10.1.1.662.5117 |doi=10.1117/12.670742|s2cid=67780784 }}{{cite book |last=Hodapp |first=Klaus |chapter=HiCIAO: The Subaru Telescope's new high-contrast coronographic imager for adaptive optics |display-authors=etal |date=August 2008 |editor1-last=McLean |editor1-first=Ian S |editor2-last=Casali |editor2-first=Mark M |title=Ground-based and Airborne Instrumentation for Astronomy II |chapter-url=http://www.ifa.hawaii.edu/~hodapp/SPIE-2008-hodapp-HiCIAO.pdf |journal=Proceedings of the SPIE |volume=7014 |pages=42H |bibcode=2008SPIE.7014E..19H |doi=10.1117/12.788088|s2cid=3870419 }} Observations began in late October 2009 and were completed in early January 2015, having observed roughly 500 nearby stars (including duplicates). The survey was conducted in the H-band (1.65 micron) and once a planet/companion candidate was detected, it was also observed at other near-infrared wavelengths.

SEEDS has reported four candidate planets to date. The first one is GJ 758 b, with a mass around 10–30 Jupiter masses and orbiting around a Sun-like star. The projected distance from the central star to the companion is 29 AU at a distance of around 52 light years.{{cite journal |last=Thalmann |first=Christian |display-authors=etal |date=December 2009 |title=Discovery of the Coldest Imaged Companion of a Sun-Like Star |journal=Astrophysical Journal Letters |volume=707 |issue=2 |pages=L123–L127 |arxiv=0911.1127 |bibcode=2009ApJ...707L.123T |doi=10.1088/0004-637X/707/2/L123|s2cid=116823073 }}{{cite journal |last=Janson |first=Markus |display-authors=etal |date=January 2011 |title=Near-infrared Multi-band Photometry of the Substellar Companion GJ 758 B |journal=The Astrophysical Journal |volume=728 |issue=2 |pages=85 |arxiv=1011.5505 |bibcode=2011ApJ...728...85J |doi=10.1088/0004-637X/728/2/85|s2cid=119296265 }} The second discovery was of a very faint planet orbiting a Sun-like star named GJ 504.{{cite journal |last=Kuzuhara |first=Masayuki |display-authors=etal |date=August 2013 |title=Direct Imaging of a Cold Jovian Exoplanet in Orbit around the Sun-like Star GJ 504 |journal=Astrophysical Journal |volume=774 |issue=1 |pages=11 |arxiv=1307.2886 |bibcode=2013ApJ...774...11K |doi=10.1088/0004-637X/774/1/11|s2cid=53343537 }} The projected distance from the central star is 44 AU at a distance of 59 light years. The central star itself is bright, visible to the naked-eye (V ~ 5 mag), but the planet is very dim, 17–20 mag at infrared wavelengths. The planet mass is estimated to be only 3–4.5 Jupiter masses, estimated from its luminosity and age. It is one of the lightest-mass planets ever imaged.

The survey also discovered a likely superjovian-mass planet named Kappa Andromedae b, orbiting a young B-type star 2.8 times the mass of Sun.{{cite journal |last=Carson |first=Joseph |display-authors=etal |date=January 2013 |title=Direct Imaging Discovery of a 'Super-Jupiter' Around the late B-Type Star Kappa And |journal=Astrophysical Journal Letters |volume=763 |issue=2 |pages=32 |arxiv=1211.3744 |bibcode=2013ApJ...763L..32C |doi=10.1088/2041-8205/763/2/L32|s2cid=119253577 }} HD 100546 b was confirmed as a planet with a disk system around a very young star as part of the SEEDS survey. SEEDS has also reported the detection of three brown dwarfs in the Pleiades cluster as part of the Open Cluster category survey and several stellar or substellar companions around planetary systems, from the radial velocity detection. SEEDS has detected interesting fine-structures in disks around dozens of young stars. These disks exhibit gaps, spiral arms, rings, and other structures at similar radial distances where the outer planets are imaged. These structures can be considered to be "signposts" of planets. The results obtained on disks support the need for a new planet formation model.

Additional planet and disk discoveries include:

• New high resolution imaging of the AB Aurigae system{{cite journal|last=Hashimoto|first=Jun|display-authors=etal|title=Direct Imaging of Fine Structures in Giant Planet-forming Regions of the Protoplanetary Disk Around AB Aurigae|journal=Astrophysical Journal Letters|date=March 2011|volume=729|issue=2|pages=17|doi=10.1088/2041-8205/729/2/L17|bibcode = 2011ApJ...729L..17H |arxiv = 1102.4408 |s2cid=118665967 }}
• Detection of extended outer regions of the debris ring around HR 4796 A{{cite journal|last=Thalmann|first=Christian|display-authors=etal|title=Images of the Extended Outer Regions of the Debris Ring around HR 4796 A|journal=Astrophysical Journal Letters|date=December 2011|volume=743|issue=1|pages=6|doi=10.1088/2041-8205/743/1/L6|bibcode=2011ApJ...743L...6T|arxiv = 1110.2488 |s2cid=14131310 }}
• New reflected light imaging of the transitional disk gap around LkCa 15{{cite journal|last=Thalmann|first=Christian|display-authors=etal|title=Imaging of a Transitional Disk Gap in Reflected Light: Indications of Planet Formation Around the Young Solar Analog LkCa 15|journal=Astrophysical Journal|date=August 2010|volume=718|issue=2|pages=L87–L91|doi=10.1088/2041-8205/718/2/L87|bibcode = 2010ApJ...718L..87T |arxiv = 1005.5162 |s2cid=26500380 }}
• Explorations for outer massive bodies around the transiting planet system HAT-P-7{{cite journal|last=Narita|first=Norio|display-authors=etal|title=Search for Outer Massive Bodies around Transiting Planetary Systems: Candidates of Faint Stellar Companions around HAT-P-7|journal=Publications of the Astronomical Society of Japan|date=June 2010|volume=62|issue=3|pages=779–786|bibcode = 2010PASJ...62..779N |arxiv = 1004.2458|doi=10.1093/pasj/62.3.779}}
• Imaging discovery of the debris disk around HIP 79977{{cite journal|last=Thalmann|first=Christian|display-authors=etal|title=Imaging Discovery of the Debris Disk Around HIP 79977|journal=Astrophysical Journal Letters|date=February 2013|volume=763|issue=2|pages=29|doi=10.1088/2041-8205/763/2/L29|arxiv=1301.0625|bibcode=2013ApJ...763L..29T |s2cid=119259358 }}
• First infrared images of the inner gap in the 2MASS J16042165-2130284 transitional disk.{{cite journal|last=Mayama|first=Satoshi|display-authors=etal|title=Subaru Imaging of Asymmetric Features in a Transitional Disk in Upper Scorpius|journal=Astrophysical Journal Letters|date=December 2012|volume=760|issue=2|pages=26|doi=10.1088/2041-8205/760/2/L26|arxiv=1211.3284|bibcode=2012ApJ...760L..26M|s2cid=52998952 }}
• Direct imaging discovery of a large inner gap in the protoplanetary disk around PDS 70{{cite journal|last=Hashimoto|first=Jun|display-authors=etal|title=Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk around PDS 70: Observations of the Disk|journal=Astrophysical Journal Letters|date=October 2012|volume=758|issue=1|pages=19|doi=10.1088/2041-8205/758/1/L19|arxiv=1208.2075|bibcode=2012ApJ...758L..19H |s2cid=13691976 }}
• Discovery of spiral structures in the transitional disk around SAO 206462{{cite journal|last=Muto|first=Takayuki|display-authors=etal|title=Discovery of Small-scale Spiral Structures in the Disk of SAO 206462 (HD 135344B): Implications for the Physical State of the Disk from Spiral Density Wave Theory|journal=Astrophysical Journal Letters|date=April 2012|volume=748|issue=2|pages=22|doi=10.1088/2041-8205/748/2/L22|arxiv=1202.6139|bibcode=2012ApJ...748L..22M |s2cid=118374349 }}
• Discovery of a stellar companion to the extrasolar planet system HAT-P-7{{cite journal|last=Narita|first=Norio|display-authors=etal|title=A Common Proper Motion Stellar Companion to HAT-P-7|journal=Publications of the Astronomical Society of Japan|date=December 2012|volume=64|issue=2|pages=7|doi=10.1088/2041-8205/748/2/L22|arxiv=1209.4422|bibcode=2012PASJ...64L...7N |s2cid=118374349 }}
• Near-IR scattered light detection of the spiral-armed transitional disk of the star MWC 758{{cite journal|last=Grady|first=C.A.|display-authors=etal|title=Spiral Arms in the Asymmetrically Illuminated Disk of MWC 758 and Constraints on Giant Planets|journal=Astrophysical Journal|date=January 2013|volume=762|issue=1|pages=48|doi=10.1088/0004-637X/762/1/48|arxiv=1212.1466|bibcode=2013ApJ...762...48G |s2cid=54930830 }}
• Direct imaging of the UX Tau A pre-transitional disk revealing gap structures{{cite journal|last=Tanii|first=Ryoko|display-authors=etal|title=High-Resolution Near-Infrared Polarimetry of a Circumstellar Disk around UX Tau A|journal=Publications of the Astronomical Society of Japan|date=December 2012|volume=64|issue=6|pages=124|arxiv=1206.1215|bibcode=2012PASJ...64..124T|doi=10.1093/pasj/64.6.124}}
• Scattered light imaging of the MWC 80 protoplanetary disk at a historic minimum of the near-IR excess{{cite journal|last=Kusakabe|first=Nobuhiko|display-authors=etal|title=High-Contrast NIR Polarization Imaging of MWC480|journal=Astrophysical Journal|date=July 2012|volume=753|issue=2|pages=153|doi=10.1088/0004-637X/753/2/153|arxiv=1205.3159|bibcode=2012ApJ...753..153K|s2cid=119114993 }}
• High-contrast imaging discovery of architecture in the LkCa 15 transitional disk{{cite journal|last=Thalmann|first=Christian|display-authors=etal|title=The architecture of the LkCa 15 transitional disk revealed by high-contrast imaging|journal=Astronomy & Astrophysics|date=Feb 2014|volume=566|pages=23|doi=10.1051/0004-6361/201322915|arxiv=1402.1766|bibcode = 2014A&A...566A..51T |s2cid=34485844 }}
• Submillimeter and near-infrared observation of the transitional disk around Sz 91{{cite journal|last=Tsukagoshi|first=Takashi|display-authors=etal|title=High-Resolution Submillimeter and Near-Infrared Studies of the Transition Disk around Sz 91|journal=Astrophysical Journal|date=Feb 2014|volume=783|issue=2|pages=90|doi=10.1088/0004-637X/783/2/90|arxiv=1402.1538|bibcode=2014ApJ...783...90T|s2cid=49393475 }}
• First high resolution infrared images of circumstellar disk around SU Aur revealing tidal-like tails{{Cite journal|title = Near-IR High-Resolution Imaging Polarimetry of the SU Aur Disk: Clues for Tidal Tails?|journal = The Astrophysical Journal|date = 2015-06-04|issn = 2041-8213|pages = L10|volume = 806|issue = 1|doi = 10.1088/2041-8205/806/1/L10|first1 = Jerome|last1 = de Leon|first2 = Michihiro|last2 = Takami|first3 = Jennifer L.|last3 = Karr|first4 = Jun|last4 = Hashimoto|first5 = Tomoyuki|last5 = Kudo|first6 = Michael|last6 = Sitko|first7 = Satoshi|last7 = Mayama|first8 = Nobuyuki|last8 = Kusakabe|first9 = Eiji|last9 = Akiyama|arxiv = 1505.03610 |bibcode = 2015ApJ...806L..10D | s2cid=22225752 }}

• Definition of 'Extrasolar planet'
• Direct imaging of extrasolar planets
• List of extrasolar planets
• List of planet types

{{Reflist|30em}}

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