Engineering topics

Konishi, Mihoko

Publications and source records attributed to Konishi, Mihoko.

3 records

DOE OSTI2020

Accretion Properties of PDS 70b with MUSE

We report a new evaluation of the accretion properties of PDS 70b obtained with the Very Large Telescope/Multi Unit Spectroscopic Explorer. The main difference from the previous studies of Haffert et al. and Aoyama & Ikoma is in the mass accretion rate. Simultaneous multiple line observations, such as Hα and Hβ, can better constrain the physical properties of an accreting planet. While we clearly detected Hα emissions from PDS 70b, no Hβ emissions were detected. We estimate the line flux of Hβ with a 3σ upper limit to be 2.3 × 10{sup −16} erg s{sup −1} cm{sup −2}. The flux ratio F {sub Hβ}/F {sub Hα} for PDS 70b is <0.28. Numerical investigations by Aoyama et al. suggest that F {sub Hβ}/F {sub Hα} should be close to unity if the extinction is negligible. We attribute the reduction of the flux ratio to the extinction, and estimate the extinction of Hα (A {sub Hα}) for PDS 70b to be >2.0 mag using the interstellar extinction value. By combining with the Hα linewidth and the dereddening line luminosity of Hα, we derive the PDS 70b mass accretion rate to be ≳5 × 10{sup −7} M {sub Jup} yr{sup −1}. The PDS 70b mass accretion rate is an order of magnitude larger than that of PDS 70. We found that the filling factor f {sub f} (the fractional area of the planetary surface emitting Hα) is ≳0.01, which is similar to the typical stellar value. The small value of f {sub f} indicates that the Hα emitting areas are localized at the surface of PDS 70b.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS2016

A Substellar Companion to Pleiades HII 3441

We find a new substellar companion to the Pleiades member star, Pleiades HII 3441, using the Subaru telescope with adaptive optics. The discovery is made as part of the high-contrast imaging survey to search for planetary-mass and substellar companions in the Pleiades and young moving groups. The companion has a projected separation of 0". 49+/-0". 02 (66+/-2 au) and a mass of 68+/-5M(sub J) based on three observations in the J-, H-, and K(sub s)-bands. The spectral type is estimated to be M7 (approx. 2700 K), and thus no methane absorption is detected in the H band. Our Pleiades observations result in the detection of two substellar companions including one previously reported among 20 observed Pleiades stars, and indicate that the fraction of substellar companions in the Pleiades is about 10.0+26.1 −8.8 %. This is consistent with multiplicity studies of both the Pleiades stars and other open clusters.

Pleiades HII 3441↗

NASA NTRS2016

Discovery of an Inner Disk Component Around HD 141569 A

We report the discovery of a scattering component around the HD 141569 A circumstellar debris system, interior to the previously known inner ring. The discovered inner disk component, obtained in broadband optical light with Hubble Space Telescope/Space Telescope Imaging Spectrograph coronagraphy, was imaged with an inner working angle of 0 25 arcseconds, and can be traced from 0 4 seconds (approximately 46 atomic units) to 1.0 arcseconds (approximately 116 atomic units) after deprojection using inclination = 55 degrees. The inner disk component is seen to forward scatter in a manner similar to the previously known rings, has a pericenter offset of approximately 6 atomic units, and break points where the slope of the surface brightness changes. It also has a spiral arm trailing in the same sense as other spiral arms and arcs seen at larger stellocentric distances. The inner disk spatially overlaps with the previously reported warm gas disk seen in thermal emission. We detect no point sources within 2 arcseconds (approximately 232 atomic units), in particular in the gap between the inner disk component and the inner ring. Our upper limit of 9 plus or minus 3 mass Jupiter (M (sub J)) is augmented by a new dynamical limit on single planetary mass bodies in the gap between the inner disk component and the inner ring of 1 mass Jupiter, which is broadly consistent with previous estimates.

pericenter offset↗