The 2 Micron All-Sky Survey (2MASS)will observe over one-million galaxies and extended Galactic sources covering the entire sky at wavelenghts between 1 and 2 m. Most of these galaxies, from 70 to 80%, will be newly catalogued objetcs.

https://iopscience.iop.org/article/10.1086/301330/pdf

2MASS Extended Source Catalog: Overview and Algorithms

We propose that coronagraphic imaging in combination with moderate to high spectral resolution from the outset may prove more effective in both detecting extrasolar planets and characterizing them than a standard coronagraphic imaging approach. We envisage an integral-field spectrograph coupled to a coronagraph to produce a data cube of two space dimensions and one wavelength. For the idealized case where the spectrum of the star is well known and unchanging across the field, we discuss the utility of cross-correlation to seek the extrasolar planet signal and describe a mathematical approach to completely eliminate stray light from the host star (although not its Poisson noise). For the case where the point-spread function (PSF) is dominated by diffraction and scattering effects and comprises a multitude of speckles within an Airy pattern, typical of a space-based observation, we turn the wavelength dependence of the PSF to advantage and present a general way to eliminate the contribution from the star while preserving both the flux and spectrum of the extrasolar planet. We call this method spectral deconvolution. We illustrate the dramatic gains by showing an idealized simulation that results in a 20 ? detection of a Jovian planet at 2 pc with a 2 m coronagraphic space telescope, even though the planet's peak flux is only 1% that of the PSF wings of the host star. This scales to detection of a terrestrial extrasolar planet at 2 pc with an 8 m coronagraphic Terrestrial Planet Finder in ~7 hr (or less with appropriate spatial filtering). Data on the spectral characteristics of the extrasolar planet and hence on its atmospheric constituents and possible biomarkers are naturally obtained as part of this process.

http://iopscience.iop.org/article/10.1086/342401/pdf

Imaging Spectroscopy for Extrasolar Planet Detection

Coronagraphic imaging in combination with moderate to high spectral resolution may prove more effective in both detecting extrasolar planets and characterizing them than a standard coronagraphic imaging approach. We envisage an integral-field spectrograph coupled to a coronagraph to produce a 3D datacube. For the idealised case where the spectrum of the star is well-known and unchanging across the field, we discuss the utility of cross-correlation to seek the extrasolar planet signal, and describe a mathematical approach to completely eliminate stray light from the host star (although not its Poisson noise). For the case where the PSF is dominated by diffraction and scattering effects, and comprises a multitude of speckles within an Airy pattern typical of a space-based observation, we turn the wavelength dependence of the PSF to advantage and present a general way to eliminate the contribution from the star while preserving both the flux and spectrum of the extrasolar planet. We call this method `spectral deconvolution'. We illustrate the dramatic gains by showing an idealized simulation that results in a 20-sigma detection of a Jovian planet at 2 pc with a 2-m coronagraphic space telescope, even though the planet's peak flux is only 1% that of the PSF wings of the host star. This scales to detection of a terrestrial extrasolar planet at 2 pc with an 8-m coronagraphic Terrestrial Planet Finder (TPF) in ~7 hr (or less with appropriate spatial filtering). Data on the spectral characteristics of the extrasolar planet and hence on its atmospheric constituents and possible biomarkers are obtained naturally as part of this process.

We present the discovery of 11 new T dwarfs, found during the course of a photometric survey for mid-to-late T dwarfs in the 2MASS Point Source Catalog and from a proper-motion-selected sample of ultracool dwarfs in the 2MASS Working Database. Using the NASA Infrared Telescope Facility SpeX spectrograph, we obtained low-resolution (R ~ 150) spectroscopy, allowing us to derive near-infrared spectral types of T2-T8. We also present improved signal-to-noise ratio SpeX low-resolution spectroscopy of the near-infrared T0 standard SDSS J120747.17+024424.8 and T1 standard SDSSp J083717.22-000018.3. One of these new T dwarfs, 2MASS J13243559+6358284, was also discovered independently by Metchev et al. This object is spectroscopically peculiar and possibly a binary and/or very young (<300 Myr). We specifically attempted to model the spectrum of this source as a composite binary to reproduce its peculiar spectral characteristics. The latest type object in our sample is a T8 dwarf, 2MASS J07290002-3954043, now one of the four latest type T dwarfs known. All 11 T dwarfs are nearby given their spectrophotometric distance estimates, with one T dwarf within 10 pc and eight additional T dwarfs within 25 pc, if single. These new additions increase the 25 pc census of T dwarfs by ~14%. Their proximity offers an excellent opportunity to probe for companions at separations closer than are possible for more distant T dwarfs.

/pdf/discovery-of-11-new-t-dwarfs-in-the-two-micron-all-sky-gimmbz9lqo.pdf

Discovery of 11 new t dwarfs in the two micron all sky survey, including a possible l/t transition binary

We have obtained long-slit spectra of NGC 253 in the J, H, K, and N bands, broadband images in the J, H, and Ks bands, narrowband images centered at the wavelengths of BrGamma and H2(1,0)S(1), and imaging spectroscopy centered on [NeII](12.8um). We use these data and data from the literature in a comprehensive re-assessment of the starburst in this galaxy. We derive the supernova rate from the strength of the infrared [FeII] lines. We find that most of the H2 infrared luminosity is excited by fluorescence in low density gas. We derive a strong upper limit of ~37,000K for the stars exciting the emission lines. We use velocity-resolved infrared spectra to determine the mass in the starburst region. Most of this mass appears to be locked up in the old, pre-existing stellar population. Using these constraints and others to build an evolutionary synthesis model, we find that the IMF originally derived to fit the starburst in M 82 (similar to a Salpeter IMF) also accounts for the properties of NGC 253. The models indicate that rapid massive star formation has been ongoing for 20-30 million years in NGC 253---that is, it is in a late phase of its starburst. We model the optical emission line spectrum expected from a late phase starburst and demonstrate that it reproduces the observed HII/weak-[OI] LINER characteristics.

The Nuclear Starburst in NGC 253

An improved K-band (2.0-2.4 μm) spectrum of the planetary nebula Hubble 12 has been obtained at a position near where Dinerstein et al. found the H 2 line emission to be fluorescent. The new spectrum is consistent with the conclusion of Dinerstein et al. and, in addition, provides further evidence that the emission is essentially purely fluorescent, through the presence of several weak H 2 lines of higher excitation than have been detected previously and a measured ortho/para ratio of 1.7. Analysis of the spectrum demonstrates that the gas density is ∼ 10 4 -10 5 cm −3

/pdf/pure-fluorescent-h2-emission-from-hubble-12-5ae5t3l7x1.pdf

Pure fluorescent H2 emission from Hubble 12

We present 1-2.5 μm spectra of the atmosphere above Mauna Kea. The emission in this region is chiefly non-thermal radiation from excited molecules in the upper atmosphere, but above ∼ 2.3 μm the thermal contribution from the telescope and surroundings dominates. The most important component of the non-thermal emission is from vibrational-rotational transitions of the hydroxyl radical, OH − . In addition to identifying these lines we examine the temporal and spatial variation of this emission, comparing the results with theories of the origin of the variation

/pdf/non-thermal-emission-in-the-atmosphere-above-mauna-kea-xu9kgzm1o3.pdf

Non-thermal emission in the atmosphere above Mauna Kea

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Pure fluorescent H2 emission from Hubble 12

Non-thermal emission in the atmosphere above Mauna Kea