Near-Infrared Camera And Multiobject Spectrograph Research Articles

THE HUBBLE SPACE TELESCOPE TREASURY PROGRAM ON THE ORION NEBULA CLUSTER ,

The Hubble Space Telescope (HST) Treasury Program on the Orion Nebula Cluster has used 104 orbits of HST time to image the Great Orion Nebula region with the Advanced Camera for Surveys (ACS), the Wide-Field/Planetary Camera 2 (WFPC2) and the Near Infrared Camera and Multi Object Spectrograph (NICMOS) instruments in 11 filters ranging from the U-band to the H-band equivalent of HST. The program has been intended to perform the definitive study of the stellar component of the ONC at visible wavelengths, addressing key questions like the cluster IMF, age spread, mass accretion, binarity and cirumstellar disk evolution. The scanning pattern allowed to cover a contiguous field of approximately 600 square arcminutes with both ACS and WFPC2, with a typical exposure time of approximately 11 minutes per ACS filter, corresponding to a point source depth AB(F435W) = 25.8 and AB(F775W)=25.2 with 0.2 magnitudes of photometric error. We describe the observations, data reduction and data products, including images, source catalogs and tools for quick look preview. In particular, we provide ACS photometry for 3399 stars, most of them detected at multiple epochs, WFPC2 photometry for 1643 stars, 1021 of them detected in the U-band, and NICMOS JH photometry for 2116 stars. We summarize the early science results that have been presented in a number of papers. The final set of images and the photometric catalogs are publicly available through the archive as High Level Science Products at the STScI Multimission Archive hosted by the Space Telescope Science Institute.

Transit infrared spectroscopy of the hot Neptune around GJ 436 with the Hubble Space Telescope

Abstract The nearby transiting system GJ 436b offers a unique opportunity to probe the structure and atmosphere of an extrasolar ‘hot Neptune’. In this Letter, we present the main results of observations covering two transit events with the Near Infrared Camera and Multi Object Spectrograph (NICMOS) camera on the Hubble Space Telescope (HST). The data consist in high-cadence time series of grism spectra covering the 1.1–1.9 µm spectral range. We find Rpl= 4.04 ± 0.10 R⊕ and R*= 0.446 ± 0.011 R⊙ for the planet and star radius, confirming and improving earlier measurements with a ground-based photometry and a Spitzer light curve at 8 µm, as opposed to a much higher value obtained with the Fine Guidance Sensor on the HST. We measure no departure from strict periodicity in the transits to the level of ∼7 s. This strongly disfavours the proposed explanation of the orbital eccentricity of GJ 436b in terms of the perturbation by another close-by planet. We measure a flat transmission spectrum at the level of a few parts per 10 000 in flux, with no significant signal in the 1.4-µm water band to a level comparable to the maximum amplitude of the effect predicted by planetary atmosphere models.

CATS: OPTICAL TO NEAR-INFRARED COLORS OF THE BULGE AND DISK OF TWOz= 0.7 GALAXIES USINGHUBBLE SPACE TELESCOPEAND KECK LASER ADAPTIVE OPTICS IMAGING

We have employed laser guide star (LGS) adaptive optics (AO) on the Keck II telescope to obtain near-infrared (NIR) images in the Extended Groth Strip deep galaxy survey field. This is a continuation of our Center for Adaptive Optics Treasury Survey program of targeting 0.5 < z < 1 galaxies where existing images with the Hubble Space Telescope (HST) are already in hand. Our AO field has already been imaged by the Advanced Camera for Surveys and the Near Infrared Camera and Multiobject Spectrograph (NICMOS). Our AO images at 2.2 ?m (K') are comparable in depth to those from the HST, have Strehl ratios up to 0.4, and full width at half-maximum resolutions superior to that from NICMOS. By sampling the field with the LGS at different positions, we obtain better quality AO images than with an immovable natural guide star. As examples of the power of adding LGS AO to HST data, we study the optical to NIR colors and color gradients of the bulge and disk of two galaxies in the field with z = 0.7.

Hubble Space Telescope Near‐Infrared Snapshot Survey of 3CR Radio Source Counterparts at Low Redshift

We present newly acquired images of the near-infrared counterpart of 3CR radio sources. All the sources were selected to have a redshift of less than 0.3 to allow us to obtain the highest spatial resolution. The observations were carried out as a snapshot program using the Near-Infrared Camera and Multiobject Spectrograph (NICMOS) on-board the Hubble Space Telescope (HST). In this paper we describe 69 radio galaxies observed for the first time with NICMOS during HST cycle 13. All the objects presented here are elliptical galaxies. However, each of them has unique characteristics such as close companions, dust lanes, unresolved nuclei, arclike features, globular clusters, and jets clearly visible from the images or with basic galaxy subtraction.

Spectrophotometric Standards from the Far-Ultraviolet to the Near-Infrared: STIS and NICMOS Fluxes

With photometric repeatability in the 0.2%–0.4% range and wavelength coverage from 1150 to 10,200 A, the Space Telescope Imaging Spectrograph (STIS) low-dispersion spectrophotometry provides excellent absolute flux standards. STIS observations of 19 stars are used to update the database of Hubble Space Telescope standard stars with absolute fluxes that are based on the white dwarf pure hydrogen scale. Uncertainties in the STIS absolute flux calibration range from 4% in the far-UV to 2% at longer wavelengths. The relative and absolute fluxes of our composite standards in the IR are verified by the Near Infrared Camera and Multi-Object Spectrograph (NICMOS) observations and by ground-based IR photometry.

Star Formation in Galaxies between Redshifts of 0.7 and 1.8

We present an analysis of the star formation rate in galaxies with redshifts in the range 0.7 < z < 1.8 using Near Infrared Camera and Multi-Object Spectrograph (NICMOS) grism spectral observations. We detect 163 galaxies in an area of ~4.4 arcmin2, 37 of which show possible H? emission. We extend the observed H? luminosity function (LF) in this redshift range to luminosities a factor of 2 fainter than earlier work and are consistent in the region of overlap. Using the H? LF, we estimate a star formation rate (SFR) density in this redshift range of 0.166 M? yr-1 Mpc-3 (H0 = 75 km s-1 Mpc-1), consistent with other estimates based on emission lines and supporting the order-of-magnitude increase in SFR density between z = 0 and z = 1. Our measurement of SFR density is a factor of ?2?3 greater than that estimated from UV data, comparable to the factor observed locally, implying little evolution in the relative extinctions between UV and H? out to z ? 1.3.

Bright Spot on a Centaur

PLANETARY SCIENCE Centaurs are primitive icy objects that are tens of kilometers in diameter that reside for a few million years in chaotic orbits between Jupiter and Neptune. Centaurs may originate in the Kuiper Belt, which is a zone of icy objects on the edge of the solar system beyond Neptune. They can provide clues to the composition of the original solar nebula, but observing these small distant objects is difficult, and there has been controversy about their size, shape, and composition. Kern et al. now present two long-exposure spectra from two regions of the Centaur 8405 Asbolus from the near-infrared camera and multiobject spectrograph (NICMOS) on the Hubble Space Telescope. They conclude that Asbolus is a spherical object that rotates with a period of about 4 hours (instead of the previously estimated 9 hours) and that has an impact crater on one side. The spectrum for this side shows absorption features that they attribute to an exposed deeper water-ice layer against a darkened weathered surface. The spectrum for the other side is featureless. Asbolus may have been ejected from the Kuiper Belt by a collision that produced the observed crater, and this collision may have increased its rotation rate. The chemical and structural heterogeneity of Asbolus may help explain discrepant observations of other centaurs, some of which were thought to be homogeneous objects. — LR Astrophys. J . 542 , L155 (2000).

Photometry and Photometric Redshifts of Faint Galaxies in the Hubble Deep Field South NICMOS Field

We present a catalog of photometry and photometric redshifts of 335 faint objects in the Hubble Deep Field South near-infrared camera and multiobject spectrograph (NICMOS) —eld. The analysis is based on (1) infrared images obtained with the Hubble Space Telescope (HST ) using the NICMOS with the F110W, F160W, and F222M —lters; (2) an optical image obtained with HST using the Space Telescope Imaging Spectrograph with no —lter; and (3) optical images obtained with the European Southern Observatory Very Large Telescope with U, B, V , R, and I —lters. The primary utility of the catalog of photometric redshifts is as a survey of faint galaxies detected in the NICMOS F160W and F222M images. The sensitivity of the survey varies signi—cantly with position, reaching a limiting depth of AB(16000) B 28.7 and covering 1.01 arcmin2 to AB(16000) 27 and 1.05 arcmin2 to AB(16000) 26.5. The catalog of photometric redshifts identi—es 21 galaxies (or 6% of the total) of redshift z ( 5, eight galaxies (or 2% of the total) of redshift z ( 10, and 11 galaxies (or 3% of the total) of best-—t spectral type E/S0, of which —ve galaxies (or 1% of the total) are of redshift z ( 1. Subject headings: cosmology: observationsgalaxies: distances and redshifts ¨ galaxies: photometrygalaxies: statistics

The first galaxies: structure and stellar populations

The Hubble deep fields (HDFs) continue to be a valuable resource for studying the distant Universe, particularly at z > 2 where their comoving volume becomes large enough to encompass several hundred L * galaxies or their progenitors. Here, I present recent results from a near-infrared (NIR) imaging survey of the HDFnorth with the Near Infrared Camera and Multi–Object Spectrograph (NICMOS), which provides structural and photometric information in the optical rest frame (λλ24000–5500 A) for hundreds of ‘ordinary’ galaxies at 2 12. The space density of UV–bright galaxies in the HDF appears to thin out toward larger redshifts, although surface–brightness selection effects may play an important role.

Hubble Space TelescopeNear‐infrared and Optical Imaging of Faint Radio Sources in the Distant Cluster Cl 0939+4713

We present deep Hubble Space Telescope Near-Infrared Camera and Multiobject Spectrograph (NICMOS) and Wide Field and Planetary Camera 2 (WFPC2) optical imaging of a small region in the core of the distant rich cluster Cl 0939+4713 (z = 0.41). We compare the optical and near-infrared morphologies of cluster members and find apparent small-scale optical structures within the galaxies that are absent in the near-infrared. We conclude that strong dust obscuration is a common feature in the late-type galaxies in distant clusters. We then concentrate on a sample of 10 faint radio galaxies lying within our NICMOS field and selected from a very deep 1.4 GHz VLA map of the cluster with a 1 σ flux limit of 9 μJy. Using published data we focus on the spectral properties of the eight radio-selected cluster members and show that these comprise a large fraction of the poststarburst population in the cluster. The simplest interpretation of the radio emission from these galaxies is that they are currently forming massive stars, contradicting their classification as poststarburst systems based on the optical spectra. We suggest that this star formation is hidden from view in the optical by the same obscuring dust that is apparent in our comparison on the optical and near-infrared morphologies of these galaxies. We caution that even in the rest-frame optical the effects of dust cannot be ignored when comparing samples of distant galaxies to low-redshift systems, particularly if dust is as prevalent in distant galaxies as appears to be the case in our study.

NICMOS Narrowband Images of OMC‐1

We present images of a 90in. x 90in. field centered on BN in OMC-1, taken with the Near-Infrared Camera and MultiObject Spectrograph (NICMOS) aboard the Hubble Space Telescope. The observed lines are H2 1-0 S(l), Pa, [FeII] 1.64 pm, and the adjacent continua. The region is rich in interesting structures. The most remarkable are the streamers or of H2 emission which extend from 15in. to 50in. from IRc2, seen here in unprecedented detail. Unlike the northern H2 fingers, the inner fingers do not exhibit significant [FeII] emission at theirdips, which we suggest is due to lower excitation. These observations also show that the general morphology of the Pa and [FeII] emission (both imaged for the first time in this region) bears a striking resemblance to that of the Ha and [SII] emission previously observed with WFPC2. This implies that these IR and optical lines are produced by radiative excitation on the surface of the molecular cloud. The Pa morphology of HH 202 is also very similar to its H a and [OIII] emission, again suggesting that the Pa in this object is photo-excited by the Trapezium, as has been suggested for the optical emission. We find evidence of shock-excited [FeII] in HH 208, where it again closely follows the morphology of [SII]. There is also H2 coincident with the [SII] and [FeII] emission, which may be associated with HH 208. Finally, we note some interesting continuum features: diffuse tails trailing from IRc3 and IRc4, more extensive observations of the crescent found by Stolovy, et al. (1998), and new observations of a similar oval object nearby. We also find a V-shaped region which may be the boundary of a cavity being cleared by IRc2.

Morphological differences between optical and infrared images of the spiral galaxy NGC309

THE morphological classification of spiral galaxies into various types is suspected to be highly dependent on the wavelength of observation1, because optical images emphasize young population I stars at the expense of other stellar types, as well as ionized gas and dust. Extension of the classification of galaxies out to wavelengths of a few micrometres has had to await the development of large-format near-infrared array cameras. We present here images at 2.1 μm wavelength of NGC309, one of the largest 'grand design' (type ScI) spiral galaxies, obtained with the 256x256 array camera developed for the NICMOS (near-infrared camera and multiobject spectrograph) instrument, designed for installation on the Hubble Space Telescope. Optically, NGC309 presents a classic multi-arm morphology, but at 2.1 μm we see a two-arm spiral and the appearance of a prominent central bar; it resembles the SBa galaxy NGC1358. These studies underscore existing indications2 that the disk structure of spiral galaxies may be unrelated to the Hubble type assigned from the transient population I morphology.