The size of NGC 4151 at 11.2 µm

The size of the emission region of NGC 4151 at 11.2 µm has been measured to be 0.16" + 0.04" (lσ). This size is in agreement with that expected from thermal emission from dust grains heated by a central luminosity source, but is inconsistent with nonthermal emission

The dust enshrouded quasar in the ultraluminous galaxy Markarian 463 - Radio, near-infrared, and optical imaging

New radio continuum, near-infrared, and optical images are presented for the infrared ultraluminous galaxy Mrk 463, which prior optical work has shown to be an interacting/merging system containing two Seyfert 2 nuclei separated by 4" (4 kpc). The eastern nucleus, Mrk 463E, has a steep-spectrum (ƒ_v ∝ v^(-1) radio core with a luminosity density that is characteristic of a quasar or radio galaxy. Imaging at 20 cm reveals previously unknown components 4" north and 18" south of Mrk 463E, and a source 10" to the northwest which is apparently linked to the nuclear region. The western nucleus, Mrk 463W, has been detected at 6 and 20 cm (ƒ_v ∝ v^(-0 5); it has a radio luminosity comparable to that of a moderately luminous Seyfert galaxy or a highly luminous starburst galaxy. Near-infrared images at wavelengths less than 2.3 µm show the two nuclei; only Mrk 463E has been detected at 3.7 µm Mrk 463E has an extremely red V— K color of 6.8 mag. Brightness profiles of Mrk 463E are unresolved at K and L ' but extended at J; this is likely due to the effects of extinction and centrally concentrated hot dust emission. Radio continuum components 4-18 kpc from the nucleus are aligned with previously known 0.05-1.5 kpc radio structure and extended, conical [O III] emission. This suggests that Mrk 463E is powering weak radio lobes and may therefore exemplify a transition between the confined linear sources in Seyfert galaxies and the extended lobes in classical quasars and radio galaxies. Mrk 463E has a 3.7 µm luminosity and K — L' color comparable to PG quasars, suggesting that dust obscures an embedded quasar. These data are consistent with recent spectropolarimetry observations of Miller & Goodrich [ApJ, 355, 456 (1990)] that reveal a Seyfert 1 nucleus in Mrk 463E. We suggest that Mrk 463 represents the genesis of a classical quasar or radio galaxy

A search for infrared pulsations from PSR 1951 + 32

Observations have been conducted on the recently discovered short period pulsar PSR 1951+32 in the radio nebula CTB 80 in an attempt to detect pulsed infrared emission. A strong upper limit is placed on any pulsed, infrared component below that expected from a formally proposed optical candidate for the pulsar. This limit is consistent with proposed scaling laws for high-energy emission

Infrared photometry and spectroscopy of the brown dwarf candidate PC0025+0447

We have obtained I, J, H, Kf and L' photometry and infrared spectroscopy (λ/Δλ ≃ 100) from 1.2-2.4 µm of the unusual emission line M star PC0025+0447. The near infrared photometry shows that this star has infrared colors which are comparable to the latest M dwarf stars such as LHS 2924 and LHS 2065. The infrared colors of PC0025+0447 establish that this star is a dwarf and not a distant giant. The infrared spectrum is dominated by strong H_2O absorption bands, and these bands are the strongest measured in any dwarf. Since H_2O band strength increases with decreasing temperature it is very likely that PC0025-f 0447 is substantially cooler than any of the stars calibrated by Berriman & Reid [MNRAS, 227, 315 (1987)], i.e. T_(eff) 10^9 yr) H burning star, with M ≃ 0.08 M_☉, or a younger brown dwarf

Near-infrared observations of the Z about 2.3 IRAS source FSC 10214 + 4724

Near-infrared imaging and spectroscopy of the extremely luminous IRAS source FSC 10214+4724 have been obtained using the Cassegrain infrared camera on the 200 inch (5.08 m) Hale Telescope. A low-resolution spectrumm (⋋/d⋋ ~ 100) in the 2.0-2.4 μm atmospheric window shows a very strong Hɑ line at the optically determined redshift z = 2.286. The observed rest-frame equivalent width of Hɑ is 0.07 ± 0.02 μm, consistent with the largest values found in quasars. The images show an unresolved source, while the near-infrared colors are somewhat redder than the mean colors of quasars observed at the same redshift. The reddening inferred is A_v ~ 1.5 mag, with an upper limit of ~ 3.0 mag. The observations presented here cannot distinguish between starburst and quasar models for this source. Starburst models require -10^(12) M_☉ of stars to have been formed over 10^7-10^8 yr. If FSC 10214+4724 is a quasar, the reddening-corrected bolometric luminosity is approximately equal to the observed infrared luminosity

Near-infrared images of MG 1131+0456 with the W. M. Keck telescope: Another dusty gravitational lens?

Images of the gravitational lens system MG 1131+0456 taken with the near-infrared camera on the W. M. Keck telescope in the J and Ks bands show that the infrared counterparts of the compact radio structure are exceedingly red, with J - K greater than 4.2 mag. The J image reveals only the lensing galaxy, while the Ks image shows both the lens and the infrared counterparts of the compact radio components. After subtracting the lensing galaxy from the Ks image, the position and orientation of the compact components agree with their radio counterparts. The broad-band spectrum and observed brightness of the lens suggest a giant galaxy at a redshift of approximately 0.75, while the color of the quasar images suggests significant extinction by dust in the lens. There is a significant excess of faint objects within 20 sec of MG 1131+0456. Depending on their mass and redshifts, these objects could complicate the lensing potential considerably

Deep imaging of the field of the Z = 4.9 quasar PC 1247+3406, and faint galaxy counts in the K band with the Keck telescope

We present deep images in the K. band of the field of the quasar PC 1247 + 3406 at z = 4.897, obtained using the near-infrared camera on the W. M. Keck telescope. A number of faint sources have been detected, some of which appear to be quite red. Their nature and redshifts remain uncertain at this time. These data are combined with deep Keck infrared images of five additional fields and present galaxy counts reaching down to K_s = 22 mag, comparable to the deepest K-band surveys to date. The data presented here are in good agreement with the Hawaii Deep Survey and represent the first independent verification of those results. The slope of the log N-log S relation derived from these data agrees well with the Hawaii Deep Survey, while the counts are slightly higher, especially at the faintest levels probed here. This may be due to a presence of groups or clusters around the target objects at high redshifts

Near-infrared imaging of FSC 10214+4724 with the W. M. Keck Telescope

Near-infrared observations of the z = 2.286 IRAS source FSC 10214+4724, made with the near-infrared camera on the W. M. Keck Telescope, are reported. Deep broad-band images at 2.15 and 1.27 micrometers, and narrow-band images at 2.165 and 2.125 µm with 0.”6 to 0.”9 seeing show that FSC 10214+4724 consists of at least three distinct components in a compact group of galaxies. The source of the infrared luminosity appears to be in a strongly interacting galaxy that has a luminosity of ~100 times that of a present-day L* galaxy. The interaction suggests and 'age' of this galaxy of ≃ 10^9 yr. The Hα emission is resolved as a source of diameter ≃ 5 kpc, suggesting that a starburst contributes to the observed Hα emission. There is an excess of objects in the FSC 10214+4724 field that could represent galaxies in an associated cluster

Spectral modeling of gaseous metal disks around DAZ white dwarfs

We report on our attempt for the first non-LTE modeling of gaseous metal disks around single DAZ white dwarfs recently discovered by Gaensicke et al. and thought to originate from a disrupted asteroid. We assume a Keplerian rotating viscous disk ring composed of calcium and hydrogen and compute the detailed vertical structure and emergent spectrum. We find that the observed infrared CaII emission triplet can be modeled with a hydrogen-deficient gas ring located at R=1.2 R_sun, inside of the tidal disruption radius, with Teff about 6000 K and a low surface mass density of about 0.3 g/cm**2. A disk having this density and reaching from the central white dwarf out to R=1.2 R_sun would have a total mass of 7 10**21 g, corresponding to an asteroid with about 160 km diameter.Comment: Proceedings, 16th European White Dwarf Workshop, Barcelona, 200