Direct Imaging Confirmation and Characterization of a Dust-Enshrouded Candidate Exoplanet Orbiting Fomalhaut

We present Subaru/IRCS J band data for Fomalhaut and a (re)reduction of archival 2004--2006 HST/ACS data first presented by Kalas et al. (2008). We confirm the existence of a candidate exoplanet, Fomalhaut b, in both the 2004 and 2006 F606W data sets at a high signal-to-noise. Additionally, we confirm the detection at F814W and present a new detection in F435W. Fomalhaut b's space motion may be consistent with it being in an apsidally-aligned, non debris ring-crossing orbit, although new astrometry is required for firmer conclusions. We cannot confirm that Fomalhaut b exhibits 0.7-0.8 mag variability cited as evidence for planet accretion or a semi-transient dust cloud. The new, combined optical SED and IR upper limits confirm that emission identifying Fomalhaut b originates from starlight scattered by small dust, but this dust is most likely associated with a massive body. The Subaru and IRAC/4.5 micron upper limits imply M < 2 Mj, still consistent with the range of Fomalhaut b masses needed to sculpt the disk. Fomalhaut b is very plausibly "a planet identified from direct imaging" even if current images of it do not, strictly speaking, show thermal emission from a directly imaged planet.Comment: 13 pages, 3 figures; ApJ Letters in press. Fixed one outdated reference and a few typo

Deep Thermal Infrared Imaging of HR 8799 bcde: New Atmospheric Constraints and Limits on a Fifth Planet

We present new $L^\prime$ (3.8 $\mu m$) and Br-$\alpha$ (4.05 $\mu m$) data and reprocessed archival $L^\prime$ data for the young, planet-hosting star HR 8799 obtained with Keck/NIRC2, VLT/NaCo and Subaru/IRCS. We detect all four HR 8799 planets in each dataset at a moderate to high signal-to-noise (SNR $\gtrsim$ 6-15). We fail to identify a fifth planet, "HR 8799 f", at $r$ $<$ 15 $AU$ at a 5-$\sigma$ confidence level: one suggestive, marginally significant residual at 0.2" is most likely a PSF artifact. Assuming companion ages of 30 $Myr$ and the Baraffe (Spiegel \& Burrows) planet cooling models, we rule out an HR 8799 f with mass of 5 $M_{J}$ (7 $M_{J}$), 7 $M_{J}$ (10 $M_{J}$), and 12 $M_{J}$ (13 $M_{J}$) at $r_{proj}$ $\sim$ 12 $AU$, 9 $AU$, and 5 $AU$, respectively. All four HR 8799 planets have red early T dwarf-like $L^\prime$ - [4.05] colors, suggesting that their SEDs peak in between the $L^\prime$ and $M^\prime$ broadband filters. We find no statistically significant difference in HR 8799 cde's colors. Atmosphere models assuming thick, patchy clouds appear to better match HR 8799 bcde's photometry than models assuming a uniform cloud layer. While non-equilibrium carbon chemistry is required to explain HR 8799 bc's photometry/spectra, evidence for it from HR 8799 de's photometry is weaker. Future, deep IR spectroscopy/spectrophotometry with the Gemini Planet Imager, SCExAO/CHARIS, and other facilities may clarify whether the planets are chemically similar or heterogeneous.Comment: 18 pages, 6 Tables, and 9 Figures. Fig. 1a is the key figure. Accepted for publication in Ap

A Combined VLT and Gemini Study of the Atmosphere of the Directly-Imaged Planet, beta Pictoris b

We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet $\beta$ Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While $\beta$ Pic b's near-IR colors mimick that of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects -- i.e. $\kappa$ And b and 1RXJ 1609B -- match $\beta$ Pic b's $JHK_{s}L^\prime$ photometry, and its 3.1 $\mu m$ and 5 $\mu m$ photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large ($\sim$ 60 $\mu m$) dust grains fail to reproduce the $\beta$ Pic b spectrum. However, models incorporating thick clouds similar to those found for HR 8799 bcde but also with small (a few microns) modal particle sizes yield fits consistent with the data within uncertainties. Assuming solar abundance models, thick clouds, and small dust particles ($$ = 4 $\mu m$) we derive atmosphere parameters of log(g) = 3.8 $\pm$ 0.2 and $T_{eff}$ = 1575--1650 $K$, an inferred mass of 7$^{+4}_{-3}$ $M_{J}$, and a luminosity of log(L/L$_{\odot}$) $\sim$ -3.80 $\pm$ 0.02. The best-estimated planet radius, $\approx$ 1.65 $\pm$ 0.06 $R_{J}$, is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges with constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if $\beta$ Pic b is younger than $\approx$ 7 Myr, consistent with a late formation, well after its host star's birth $\sim$ 12$^{+8}_{-4}$ Myr ago.Comment: 24 pages, minor changes from previous version, Accepted for publication in Ap

A Combined Very Large Telescope and Gemini Study of the Atmosphere of the Directly Imaged Planet, Beta Pictoris b

We analyze new/archival VLT/NaCo and Gemini/NICI high-contrast imaging of the young, self-luminous planet Beta Pictoris b in seven near-to-mid IR photometric filters, using advanced image processing methods to achieve high signal-to-noise, high precision measurements. While Beta Pic b's near-IR colors mimic those of a standard, cloudy early-to-mid L dwarf, it is overluminous in the mid-infrared compared to the field L/T dwarf sequence. Few substellar/planet-mass objects-i.e., And b and 1RXJ 1609B-match Beta Pic b's JHKsL photometry and its 3.1 micron and 5 micron photometry are particularly difficult to reproduce. Atmosphere models adopting cloud prescriptions and large (approx. 60 micron)dust grains fail to reproduce the Beta Pic b spectrum. However, models incorporating thick clouds similar to those found forHR8799 bcde, but also with small (a fewmicrons) modal particle sizes, yield fits consistent with the data within the uncertainties. Assuming solar abundance models, thick clouds, and small dust particles (a = 4 micron), we derive atmosphere parameters of log(g) = 3.8 +/- 0.2 and Teff = 1575-1650 K, an inferred mass of 7+4 3 MJ, and a luminosity of log(L/L) approx. 3.80 +/- 0.02. The best-estimated planet radius, is approx. equal to 1.65 +/- 0.06 RJ, is near the upper end of allowable planet radii for hot-start models given the host star's age and likely reflects challenges constructing accurate atmospheric models. Alternatively, these radii are comfortably consistent with hot-start model predictions if Beta Pic b is younger than is approx. equal to 7 Myr, consistent with a late formation well after its host star's birth approx. 12+8 4 Myr ago

A Combined Subaru/VLT/MMT 1--5 Micron Study of Planets Orbiting HR 8799: Implications for Atmospheric Properties, Masses, and Formation

We present new 1--1.25 micron (z and J band) Subaru/IRCS and 2 micron (K band) VLT/NaCo data for HR 8799 and a rereduction of the 3--5 micron MMT/Clio data first presented by Hinz et al. (2010). Our VLT/NaCo data yields a detection of a fourth planet at a projected separation of ~ 15 AU -- "HR 8799e". We also report new, albeit weak detections of HR 8799b at 1.03 microns and 3.3 microns. Empirical comparisons to field brown dwarfs show that at least HR 8799b and HR8799c, and possibly HR 8799d, have near-to-mid IR colors/magnitudes significantly discrepant from the L/T dwarf sequence. Standard cloud deck atmosphere models appropriate for brown dwarfs provide only (marginally) statistically meaningful fits to HR 8799b and c for unphysically small radii. Models with thicker cloud layers not present in brown dwarfs reproduce the planets' SEDs far more accurately and without the need for rescaling the planets' radii. Our preliminary modeling suggests that HR 8799b has log(g) = 4--4.5, Teff = 900K, while HR 8799c, d, and (by inference) e have log(g) = 4--4.5, Teff = 1000--1200K. Combining results from planet evolution models and new dynamical stability limits implies that the masses of HR 8799b, c, d, and e are 6--7 Mj, 7--10 Mj, 7--10 Mj and 7--10 Mj. 'Patchy" cloud prescriptions may provide even better fits to the data and may lower the estimated surface gravities and masses. Finally, contrary to some recent claims, forming the HR 8799 planets by core accretion is still plausible, although such systems are likely rare.Comment: 27 pages, 15 figures, Accepted for publication in The Astrophysical Journa

Identification of CD73 as the Antigen of an Antigen-Unknown Monoclonal Antibody Established by Exosome Immunization, and Its Antibody&ndash;Drug Conjugate Exerts an Antitumor Effect on Glioblastoma Cell Lines

Development of antibodies against the native structure of membrane proteins with multiple transmembrane domains is challenging because it is difficult to prepare antigens with native structures. Previously, we successfully developed a monoclonal antibody against multi-pass membrane protein TMEM180 by exosome immunization in rats. This approach yielded antibodies that recognized cancer-specific antigens on the exosome. In this study, we performed immunoprecipitation using magnetic beads to identify the antigen of one of the rat antibody clones, 0614, as CD73. We then converted antibody 0614 to human chimeric antibody 0614-5. Glioblastoma (GB) was the cancer type with the highest expression of CD73 in the tumor relative to healthy tissue. An antibody&ndash;drug conjugate (ADC) of 0614-5 exerted an antitumor effect on GB cell lines according to expression of CD73. The 0614-5-ADC has potential to be used to treat cancers with high CD73 expression. In addition, our strategy could be used to determine the antigen of any antibody produced by exosome immunization, which may allow the antibody to advance to new antibody therapies