Strategic Explorations of Exoplanets and Disks with Subaru

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The Subaru Telescope at the Mauna Kea Observatory on Hawaii. MaunaKea Subaru.jpg
The Subaru Telescope at the Mauna Kea Observatory on Hawaii.

Strategic Explorations of Exoplanets and Disks with Subaru (SEEDS) is a multi-year survey that used the Subaru Telescope on Mauna Kea, Hawaii in an effort to directly image extrasolar planets and protoplanetary/debris disks around hundreds of nearby stars. [1] SEEDS is a Japanese-led international project. It consists of some 120 researchers from a number of institutions in Japan, the U.S. and the EU. [2] The survey's headquarters is at the National Astronomical Observatory of Japan (NAOJ) and led by Principal Investigator Motohide Tamura. The goals of the survey are to address the following key issues in the study of extrasolar planets and disks: the detection and census of exoplanets in the regions around solar-mass and massive stars; the evolution of protoplanetary disks and debris disks; and the link between exoplanets and circumstellar disks. [1]

Contents

Observations and Results

Kappa Andromedae b, the Super-Jupiter exoplanet of 12.8 Jupiter masses discovered as part of the SEEDS survey HR 8976 exoplanet.jpg
Kappa Andromedae b, the Super-Jupiter exoplanet of 12.8 Jupiter masses discovered as part of the SEEDS survey
The confirmed brown dwarf GJ 758 B and the candidate GJ 758 C, which was later found to be a background star GJ 758 System - Labeled.jpg
The confirmed brown dwarf 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. [3] [4] 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. [2]

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. [5] [6] The second discovery was of a very faint planet orbiting a Sun-like star named GJ 504. [7] 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. [2]

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. [8] 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. [2] [9]

Additional planet and disk discoveries include:

See also

Related Research Articles

<span class="mw-page-title-main">Protoplanet</span> Large planetary embryo

A protoplanet is a large planetary embryo that originated within a protoplanetary disk and has undergone internal melting to produce a differentiated interior. Protoplanets are thought to form out of kilometer-sized planetesimals that gravitationally perturb each other's orbits and collide, gradually coalescing into the dominant planets.

<span class="mw-page-title-main">Rogue planet</span> Planetary objects without a planetary system

A rogueplanet, also termed a free-floating planet (FFP) or an isolated planetary-mass object (iPMO), is an interstellar object of planetary mass which is not gravitationally bound to any star or brown dwarf.

<span class="mw-page-title-main">2M1207b</span> Planetary-mass object orbiting the brown dwarf 2M1207

2M1207b is a planetary-mass object orbiting the brown dwarf 2M1207, in the constellation Centaurus, approximately 170 light-years from Earth. It is one of the first candidate exoplanets to be directly observed. It was discovered in April 2004 by the Very Large Telescope (VLT) at the Paranal Observatory in Chile by a team from the European Southern Observatory led by Gaël Chauvin. It is believed to be from 5 to 6 times the mass of Jupiter and may orbit 2M1207 at a distance roughly as far from the brown dwarf as Pluto is from the Sun.

<span class="mw-page-title-main">Kappa Andromedae</span> Star in the constellation of Andromeda

Kappa Andromedae, Latinized from κ Andromedae, is the Bayer designation for a bright star in the northern constellation of Andromeda. It is visible to the naked eye with an apparent visual magnitude of 4.1. Based on the star's ranking on the Bortle Dark-Sky Scale, it is luminous enough to be visible from the suburbs and from urban outskirts, but not from brightly lit inner city regions. Parallax measurements made during the Hipparcos mission place it at a distance of approximately 168 light-years from the Sun. It is drifting closer with a radial velocity of −15 km/s, and there is a high likelihood (86%) that it is a member of the Beta Pictoris moving group. The star has one known companion exoplanet, Kappa Andromedae b.

<span class="mw-page-title-main">TW Hydrae</span> T Tauri star in the constellation Hydra

TW Hydrae is a T Tauri star approximately 196 light-years away in the constellation of Hydra. TW Hydrae is about 80% of the mass of the Sun, but is only about 5-10 million years old. The star appears to be accreting from a face-on protoplanetary disk of dust and gas, which has been resolved in images from the ALMA observatory. TW Hydrae is accompanied by about twenty other low-mass stars with similar ages and spatial motions, comprising the "TW Hydrae association" or TWA, one of the closest regions of recent "fossil" star-formation to the Sun.

<span class="mw-page-title-main">HD 100546</span> Star in the constellation Musca

HD 100546, also known as KR Muscae, is a pre-main sequence star of spectral type B8 to A0 located 353 light-years from Earth in the southern constellation of Musca. The star is surrounded by a circumstellar disk from a distance of 0.2 to 4 AU, and again from 13 AU out to a few hundred AU, with evidence for a protoplanet forming at a distance of around 47 AU.

<span class="mw-page-title-main">HR 8799</span> Star in the constellation Pegasus

HR 8799 is a roughly 30 million-year-old main-sequence star located 133.3 light-years away from Earth in the constellation of Pegasus. It has roughly 1.5 times the Sun's mass and 4.9 times its luminosity. It is part of a system that also contains a debris disk and at least four massive planets. Those planets, along with Fomalhaut b, were the first exoplanets whose orbital motion was confirmed by direct imaging. The star is a Gamma Doradus variable: its luminosity changes because of non-radial pulsations of its surface. The star is also classified as a Lambda Boötis star, which means its surface layers are depleted in iron peak elements. It is the only known star which is simultaneously a Gamma Doradus variable, a Lambda Boötis type, and a Vega-like star.

<span class="mw-page-title-main">Fomalhaut b</span> Extrasolar object orbiting Fomalhaut

Fomalhaut b, formally named Dagon, is a directly imaged extrasolar object and former candidate planet observed near the A-type main-sequence star Fomalhaut, approximately 25 light-years away in the constellation of Piscis Austrinus. The object's discovery was initially announced in 2008 and confirmed in 2012 via images taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. Under the working hypothesis that the object was a planet, it was reported in January 2013 that it had a highly elliptical orbit with a period of 1,700 Earth years. The planetary hypothesis has since fallen out of favor; more recently gathered data suggests a dust or debris cloud is far more likely, and more recent analysis placed the object on an escape trajectory.

<span class="mw-page-title-main">HR 8799 b</span> Jovian planet orbiting HR 8799

HR 8799 b is an extrasolar planet located approximately 129 light-years away in the constellation of Pegasus, orbiting the 6th magnitude Lambda Boötis star HR 8799. It has a mass between 4 and 7 Jupiter masses and a radius from 10 to 30% larger than Jupiter's. It orbits at 68 AU from HR 8799 with an unknown eccentricity and a period of 460 years, and is the outermost known planet in the HR 8799 system. Along with two other planets orbiting HR 8799, the planet was discovered on November 13, 2008 by Marois et al., using the Keck and Gemini observatories in Hawaii. These planets were discovered using the direct imaging technique.

<span class="mw-page-title-main">HR 8799 c</span> Exoplanet orbiting HR 8799

HR 8799 c is an extrasolar planet located approximately 129 light-years away in the constellation of Pegasus, orbiting the 6th magnitude Lambda Boötis star HR 8799. This planet has a mass between 5 and 10 Jupiter masses and a radius from 20 to 30% larger than Jupiter's. It orbits at 38 AU from HR 8799 with an unknown eccentricity and a period of 190 years; it is the 2nd planet discovered in the HR 8799 system. Along with two other planets orbiting HR 8799, this planet was discovered on November 13, 2008, by Marois et al., using the Keck and the Gemini observatories in Hawaii. These planets were discovered using the direct imaging technique. In January 2010, HR 8799 c became the 3rd exoplanet to have a portion of its spectrum directly observed, confirming the feasibility of direct spectrographic studies of exoplanets.

<span class="mw-page-title-main">Kappa Andromedae b</span> Astronomical object orbiting Kappa Andromedae

Kappa Andromedae b is a directly imaged substellar object and likely superjovian-mass planet orbiting Kappa Andromedae, a young B9IV star in the Andromeda constellation, about 170 light-years away. The companion's mass is roughly 13 times the mass of Jupiter. As early history on Kappa And b is filled with debate over whether it is an exoplanet or a brown dwarf, some scientists have broadly described it as a "super-Jupiter" object.

<span class="mw-page-title-main">HD 95086 b</span> Exoplanet orbiting the young HD 95086

HD 95086 b, formally named Levantes, is a confirmed, directly imaged exoplanet orbiting the young, 17 Myr A-class pre-main-sequence star HD 95086. It is roughly 5 times as massive as Jupiter and orbits about 70 AU away from the parent star. It was detected at thermal infrared wavelengths (3.8 μm) through direct imaging, using the NACO instrument on the VLT. A debris disk has been detected in this system at submillimeter wavelengths and has been resolved in the far-infrared from data obtained with the Herschel Space Observatory.

<span class="mw-page-title-main">Gliese 504 b</span> Planetary mass object orbiting Gliese 504

Gliese 504 b is a Jovian planet or brown dwarf located in the system of the solar analog 59 Virginis, discovered by direct imaging using HiCIAO instrument and AO188 adaptive optics system on the 8.2-meter Subaru Telescope of Mauna Kea Observatory, Hawaii by Kuzuhara et al. Visually, GJ 504 b would have a dull magenta color.

<span class="mw-page-title-main">HD 106906 b</span> Candidate exoplanet in the constellation Crux

HD 106906 b is a directly imaged planetary-mass companion and candidate exoplanet orbiting the star HD 106906, in the constellation Crux at about 336 ± 13 light-years (103 ± 4 pc) from Earth. It is estimated to be about eleven times the mass of Jupiter and is located about 738 AU away from its host star. HD 106906 b is an oddity; while its mass estimate is nominally consistent with identifying it as an exoplanet, it appears at a much wider separation from its parent star than thought possible for in-situ formation from a protoplanetary disk.

<span class="mw-page-title-main">Spectro-Polarimetric High-Contrast Exoplanet Research</span>

Spectro-Polarimetric High-contrast Exoplanet REsearch (VLT-SPHERE) is an adaptive optics system and coronagraphic facility at the Very Large Telescope (VLT). It provides direct imaging as well as spectroscopic and polarimetric characterization of exoplanet systems. The instrument operates in the visible and near infrared, achieving exquisite image quality and contrast over a small field of view around bright targets.

<span class="mw-page-title-main">LkCa 15</span> Star system in the constellation Taurus

LkCa 15 is a T Tauri star in the Taurus Molecular Cloud. These types of stars are relatively young pre-main-sequence stars that show irregular variations in brightness. It has a mass that is about 97% of the Sun, an effective temperature of 4370 K, and is slightly cooler than the Sun. Its apparent magnitude is 11.91, meaning it is not visible to the naked eye.

<span class="mw-page-title-main">PDS 70</span> T Tauri-type star in the constellation Centaurus

PDS 70 is a very young T Tauri star in the constellation Centaurus. Located 370 light-years from Earth, it has a mass of 0.76 M☉ and is approximately 5.4 million years old. The star has a protoplanetary disk containing two nascent exoplanets, named PDS 70b and PDS 70c, which have been directly imaged by the European Southern Observatory's Very Large Telescope. PDS 70b was the first confirmed protoplanet to be directly imaged.

<span class="mw-page-title-main">Circumplanetary disk</span> Accumulation of matter around a planet

A circumplanetary disk is a torus, pancake or ring-shaped accumulation of matter composed of gas, dust, planetesimals, asteroids or collision fragments in orbit around a planet. Around the planets, they are the reservoirs of material out of which moons may form. Such a disk can manifest itself in various ways.

References

  1. 1 2 Tamura, Motohide (August 2009). "Subaru Strategic Exploration of Exoplanets and Disks with HiCIAO/AO188 (SEEDS)". AIP Conference Proceedings. 1158 (1): 11–16. Bibcode:2009AIPC.1158...11T. doi:10.1063/1.3215811.
  2. 1 2 3 4 TAMURA, Motohide (2016-02-10). "SEEDS — Strategic explorations of exoplanets and disks with the Subaru Telescope —". Proceedings of the Japan Academy. Series B, Physical and Biological Sciences. 92 (2): 45–55. Bibcode:2016PJAB...92...45T. doi:10.2183/pjab.92.45. ISSN   0386-2208. PMC   4906811 . PMID   26860453.
  3. ↑ Tamura, Motohide; et al. (July 2006). McLean, Ian S; Iye, Masanori (eds.). "Concept and science of HiCIAO: high contrast instrument for the Subaru next generation adaptive optics" (PDF). Proceedings of the SPIE. Ground-based and Airborne Instrumentation for Astronomy. 6269: 62690V. Bibcode:2006SPIE.6269E..0VT. CiteSeerX   10.1.1.662.5117 . doi:10.1117/12.670742. S2CID   67780784.
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  9. 1 2 Thalmann, Christian; et al. (December 2011). "Images of the Extended Outer Regions of the Debris Ring around HR 4796 A". Astrophysical Journal Letters. 743 (1): 6. arXiv: 1110.2488 . Bibcode:2011ApJ...743L...6T. doi:10.1088/2041-8205/743/1/L6. S2CID   14131310.
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  11. ↑ Thalmann, Christian; et al. (August 2010). "Imaging of a Transitional Disk Gap in Reflected Light: Indications of Planet Formation Around the Young Solar Analog LkCa 15". Astrophysical Journal. 718 (2): L87–L91. arXiv: 1005.5162 . Bibcode:2010ApJ...718L..87T. doi:10.1088/2041-8205/718/2/L87. S2CID   26500380.
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  15. ↑ Hashimoto, Jun; et al. (October 2012). "Polarimetric Imaging of Large Cavity Structures in the Pre-transitional Protoplanetary Disk around PDS 70: Observations of the Disk". Astrophysical Journal Letters. 758 (1): 19. arXiv: 1208.2075 . Bibcode:2012ApJ...758L..19H. doi:10.1088/2041-8205/758/1/L19. S2CID   13691976.
  16. ↑ Muto, Takayuki; et al. (April 2012). "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". Astrophysical Journal Letters. 748 (2): 22. arXiv: 1202.6139 . Bibcode:2012ApJ...748L..22M. doi:10.1088/2041-8205/748/2/L22. S2CID   118374349.
  17. ↑ Narita, Norio; et al. (December 2012). "A Common Proper Motion Stellar Companion to HAT-P-7". Publications of the Astronomical Society of Japan. 64 (2): 7. arXiv: 1209.4422 . Bibcode:2012PASJ...64L...7N. doi:10.1088/2041-8205/748/2/L22. S2CID   118374349.
  18. ↑ Grady, C.A.; et al. (January 2013). "Spiral Arms in the Asymmetrically Illuminated Disk of MWC 758 and Constraints on Giant Planets". Astrophysical Journal. 762 (1): 48. arXiv: 1212.1466 . Bibcode:2013ApJ...762...48G. doi:10.1088/0004-637X/762/1/48. S2CID   54930830.
  19. ↑ Tanii, Ryoko; et al. (December 2012). "High-Resolution Near-Infrared Polarimetry of a Circumstellar Disk around UX Tau A". Publications of the Astronomical Society of Japan. 64 (6): 124. arXiv: 1206.1215 . Bibcode:2012PASJ...64..124T. doi:10.1093/pasj/64.6.124.
  20. ↑ Kusakabe, Nobuhiko; et al. (July 2012). "High-Contrast NIR Polarization Imaging of MWC480". Astrophysical Journal. 753 (2): 153. arXiv: 1205.3159 . Bibcode:2012ApJ...753..153K. doi:10.1088/0004-637X/753/2/153. S2CID   119114993.
  21. ↑ Thalmann, Christian; et al. (Feb 2014). "The architecture of the LkCa 15 transitional disk revealed by high-contrast imaging". Astronomy & Astrophysics. 566: 23. arXiv: 1402.1766 . Bibcode:2014A&A...566A..51T. doi:10.1051/0004-6361/201322915. S2CID   34485844.
  22. ↑ Tsukagoshi, Takashi; et al. (Feb 2014). "High-Resolution Submillimeter and Near-Infrared Studies of the Transition Disk around Sz 91". Astrophysical Journal. 783 (2): 90. arXiv: 1402.1538 . Bibcode:2014ApJ...783...90K. doi:10.1088/0004-637X/783/2/90. S2CID   49393475.
  23. ↑ de Leon, Jerome; Takami, Michihiro; Karr, Jennifer L.; Hashimoto, Jun; Kudo, Tomoyuki; Sitko, Michael; Mayama, Satoshi; Kusakabe, Nobuyuki; Akiyama, Eiji (2015-06-04). "Near-IR High-Resolution Imaging Polarimetry of the SU Aur Disk: Clues for Tidal Tails?". The Astrophysical Journal. 806 (1): L10. arXiv: 1505.03610 . Bibcode:2015ApJ...806L..10D. doi:10.1088/2041-8205/806/1/L10. ISSN   2041-8213. S2CID   22225752.
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