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Register a new userClio: a 3-5 micron AO planet-finding camera
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Clio is an adaptive-optics camera mounted on the 6.5 meter MMT optimized for diffraction-limited L and M-band imaging over a ~15 field. The instrument was designed from the ground up with a large well-depth, fast readout thermal infrared (~3-5 micron) 320 by 256 pixel InSb detector, cooled optics, and associated focal plane and pupil masks (with the option for a coronograph) to minimize the thermal background and maximize throughput. When coupled with the MMTs adaptive secondary AO (two warm reflections) systems low thermal background, this instrument is in a unique position to image nearby warm planets, which are the brightest in the L and M-band atmospheric windows. We present the current status of this recently commissioned instrument that performed exceptionally during first light. Our instrument sensitivities are impressive and are sky background limited: for an hour of integration, we obtain an L-band 5 sigma detection limit of of 17.0 magnitudes (Strehl ~80%) and an M-band limit of 14.5 (Strehl ~90%). Our M-band sensitivity is lower due to the increase in thermal sky background. These sensitivities translate to finding relatively young planets five times Jupiter mass at 10 pc within a few AU of a star. Presently, a large Clio survey of nearby stellar systems is underway including a search for planets around solar-type stars, M dwarfs, and white dwarfs. Even with a null result, we can place strong constraints on planet distribution models.
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Young giant exoplanets are a unique laboratory for understanding cool, low-gravity atmospheres. A quintessential example is the massive extrasolar planet $beta$ Pic b, which is 9 AU from and embedded in the debris disk of the young nearby A6V star $beta$ Pictoris. We observed the system with first light of the Magellan Adaptive Optics (MagAO) system. In Paper I we presented the first CCD detection of this planet with MagAO+VisAO. Here we present four MagAO+Clio images of $beta$ Pic b at 3.1 $mu$m, 3.3 $mu$m, $L^prime$, and $M^prime$, including the first observation in the fundamental CH$_4$ band. To remove systematic errors from the spectral energy distribution (SED), we re-calibrate the literature photometry and combine it with our own data, for a total of 22 independent measurements at 16 passbands from 0.99--4.8 $mu$m. Atmosphere models demonstrate the planet is cloudy but are degenerate in effective temperature and radius. The measured SED now covers $>$80% of the planets energy, so we approach the bolometric luminosity empirically. We calculate the luminosity by extending the measured SED with a blackbody and integrating to find log($L_{bol}$/$L_{Sun}$) $= -3.78pm0.03$. From our bolometric luminosity and an age of 23$pm$3 Myr, hot-start evolutionary tracks give a mass of 12.7$pm$0.3 $M_{Jup}$, radius of 1.45$pm$0.02 $R_{Jup}$, and $T_{eff}$ of 1708$pm$23 K (model-dependent errors not included). Our empirically-determined luminosity is in agreement with values from atmospheric models (typically $-3.8$ dex), but brighter than values from the field-dwarf bolometric correction (typically $-3.9$ dex), illustrating the limitations in comparing young exoplanets to old brown dwarfs.
We present the results of infrared L-band (3-4 micron) and M-band (4-5 micron) VLT-ISAAC spectroscopy of five bright Ultraluminous InfraRed Galaxies (ULIRGs) hosting an AGN. From our analysis we distinguish two types of sources: ULIRGs where the AGN is unobscured (with a flat continuum and no absorption features at 3.4 micron and 4.6 micron), and those with highly obscured AGNs (with a steep, reddened continuum and absorption features due to hydrocarbons and CO). Starburst activity is also present in all of the sources as inferred from the 3.3 micron PAH emission line. A strong correlation is found between continuum slope and CO optical depth, which suggests that deep carbon monoxide absorption is a common feature of highly obscured ULIRG AGN. Finally we show that the AGN dominates the 3-4 micron emission, even if its contribution to the bolometric luminosity is small.
Images obtained with NIRI on the Gemini North telescope are used to investigate the photometric properties of the central regions of M31 in the 3 - 5 micron wavelength range. The light distribution in the central arcsecond differs from what is seen in the near-infrared in the sense that the difference in peak brigh tness between P1 and P2 is larger in M than in K; no obvious signature of P3 is dete cted in M. These results can be explained if there is a source of emission that contributes ~ 20% of the peak M light of P1 and has an effective temperature of no more than a few hundred K that is located between P1 and P2. Based on the red K-M color of this source, it is suggested that the emission originates in a circumstellar dust shell surrounding a single bright AGB star. A similar bright source that is ~ 8 arcsec from the center of the galaxy is also detected in M. Finally, the (L, K-L) color-magnitude diagram of unblended stars shows a domin ant AGB population with photometric characteristics that are similar to those of the most luminous M giants in the Galactic bulge.
We present 3-5 micron spectroscopy of the interacting system NGC 6240, showing the presence of two active galactic nuclei. The brightest (southern) nucleus shows up with a starburst-like emission, with a prominent 3.3 micron emission feature. However, the presence of an AGN is revealed by the detection of a broad Br alpha emission line, with a width of ~1,800 km/s. The spectrum of the faintest (northern) nucleus shows typical AGN features, such as a steep continuum and broad absorption features in the M-band. We discuss the physical properties of the dusty absorbers/emitters, and show that in both nuclei the AGN is dominant in the 3-5 micron band, but its contribution to the total luminosity is small (a few percent of the starburst emission).
Like the miniaturization of modern computers, next-generation radial velocity instruments will be significantly smaller and more powerful than their predecessors.
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