- ID:
- ivo://CDS.VizieR/J/ApJ/756/171
- Title:
- HST far-UV survey of H2 emission of T Tau stars
- Short Name:
- J/ApJ/756/171
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The formation timescale and final architecture of exoplanetary systems are closely related to the properties of the molecular disks from which they form. Observations of the spatial distribution and lifetime of the molecular gas at planet-forming radii (a<10AU) are important for understanding the formation and evolution of exoplanetary systems. Toward this end, we present the largest spectrally resolved survey of H_2_ emission around low-mass pre-main-sequence stars compiled to date. We use a combination of new and archival far-ultraviolet spectra from the Cosmic Origins Spectrograph and Space Telescope Imaging Spectrograph instruments on the Hubble Space Telescope to sample 34 T Tauri stars (27 actively accreting Classical T Tauri Stars and 7 non-accreting Weak-lined T Tauri Stars) with ages ranging from ~1 to 10Myr. We observe fluorescent H_2_emission, excited by Ly{alpha} photons, in 100% of the accreting sources, including all of the transitional disks in our sample (CS Cha, DM Tau, GM Aur, UX Tau A, LkCa 15, HD 135344B, and TW Hya). The spatial distribution of the emitting gas is inferred from spectrally resolved H_2_ line profiles. Some of the emitting gas is produced in outflowing material, but the majority of H_2_ emission appears to originate in a rotating disk. For the disk-dominated targets, the H_2_ emission originates predominately at a<~3AU. The emission line widths and inner molecular radii are found to be roughly consistent with those measured from mid-IR CO spectra.
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- ID:
- ivo://CDS.VizieR/J/ApJ/835/152
- Title:
- HST FGS-1r parallaxes for 8 metal-poor stars
- Short Name:
- J/ApJ/835/152
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hubble Space Telescope (HST) fine guidance sensor observations were used to obtain parallaxes of eight metal-poor ([Fe/H]< -1.4) stars. The parallaxes of these stars determined by the new Hipparcos reduction average 17% accuracy, in contrast to our new HST parallaxes, which average 1% accuracy and have errors on the individual parallaxes ranging from 85 to 144{mu}as. These parallax data were combined with HST Advanced Camera for Surveys photometry in the F606W and F814W filters to obtain the absolute magnitudes of the stars with an accuracy of 0.02-0.03 mag. Six of these stars are on the main sequence (MS) (with -2.7<[Fe/H]< -1.8) and are suitable for testing metal-poor stellar evolution models and determining the distances to metal-poor globular clusters (GCs). Using the abundances obtained by O'Malley+ (2017ApJ...838...90O), we find that standard stellar models using the VandenBerg & Clem (2003AJ....126..778V) color transformation do a reasonable job of matching five of the MS stars, with HD 54639 ([Fe/H]=-2.5) being anomalous in its location in the color-magnitude diagram. Stellar models and isochrones were generated using a Monte Carlo analysis to take into account uncertainties in the models. Isochrones that fit the parallax stars were used to determine the distances and ages of nine GCs (with -2.4{<=}[Fe/H]{<=}-1.9). Averaging together the age of all nine clusters led to an absolute age of the oldest, most metal-poor GCs of 12.7+/-1.0Gyr, where the quoted uncertainty takes into account the known uncertainties in the stellar models and isochrones, along with the uncertainty in the distance and reddening of the clusters.
6553. HST FOS spectral atlas
- ID:
- ivo://CDS.VizieR/J/ApJS/140/143
- Title:
- HST FOS spectral atlas
- Short Name:
- J/ApJS/140/143
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyzed the absorption line spectra of all quasars observed with the high-resolution gratings of the Faint Object Spectrograph on board the Hubble Space Telescope. We examined 788 spectra for 334 quasars and present line lists and identifications of absorption lines in the spectra of 271 of them. Analysis of the statistics of the Ly{alpha} and metal absorption systems are presented in companion papers. The data and several analysis products are available on the authors' Web site, http://lithops.as.arizona.edu/~jill/QuasarSpectra .
- ID:
- ivo://CDS.VizieR/J/MNRAS/444/268
- Title:
- HST Frontier Fields clusters
- Short Name:
- J/MNRAS/444/268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extending over three Hubble Space Telescope (HST) cycles, the Hubble Frontier Fields (HFF) initiative constitutes the largest commitment ever of HST time to the exploration of the distant Universe via gravitational lensing by massive galaxy clusters. Here, we present models of the mass distribution in the six HFF cluster lenses, derived from a joint strong- and weak-lensing analysis anchored by a total of 88 multiple-image systems identified in existing HST data. The resulting maps of the projected mass distribution and of the gravitational magnification effectively calibrate the HFF clusters as gravitational telescopes. Allowing the computation of search areas in the source plane, these maps are provided to the community to facilitate the exploitation of forthcoming HFF data for quantitative studies of the gravitationally lensed population of background galaxies. Our models of the gravitational magnification afforded by the HFF clusters allow us to quantify the lensing-induced boost in sensitivity over blank-field observations and predict that galaxies at z>10 and as faint as m(AB)=32 will be detectable, up to 2mag fainter than the limit of the Hubble Ultra Deep Field.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/1626
- Title:
- HST Frontier Fields Herschel sources
- Short Name:
- J/MNRAS/459/1626
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a complete census of all Herschel-detected sources within the six massive lensing clusters of the HST Frontier Fields (HFF). We provide a robust legacy catalogue of 263 sources with Herschel fluxes, primarily based on imaging from the Herschel Lensing Survey and PEP/HerMES Key Programmes. We optimally combine Herschel, Spitzer and WISE infrared (IR) photometry with data from HST, VLA and ground-based observatories, identifying counterparts to gain source redshifts. For each Herschel-detected source we also present magnification factor ({mu}), intrinsic IR luminosity and characteristic dust temperature, providing a comprehensive view of dust-obscured star formation within the HFF. We demonstrate the utility of our catalogues through an exploratory overview of the magnified population, including more than 20 background sub-LIRGs unreachable by Herschel without the assistance gravitational lensing.
- ID:
- ivo://CDS.VizieR/J/ApJ/840/30
- Title:
- HST/Gemini proper motions for Pyxis
- Short Name:
- J/ApJ/840/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a proper motion measurement for the halo globular cluster Pyxis, using Hubble Space Telescope/ACS data as the first epoch and GeMS/GSAOI Adaptive Optics data as the second, separated by a baseline of ~5 years. This is both the first measurement of the proper motion of Pyxis and the first calibration and use of Multi-Conjugate Adaptive Optics data to measure an absolute proper motion for a faint, distant halo object. Consequently, we present our analysis of the Adaptive Optics data in detail. We obtain a proper motion of {mu}_{alpha}_cos({delta})=1.09+/-0.31mas/yr and {mu}_{delta}_=0.68+/-0.29mas/yr. From the proper motion and line-of-sight velocity, we find that the orbit of Pyxis is rather eccentric, with its apocenter at more than 100kpc and its pericenter at about 30kpc. We also investigate two literature-proposed associations for Pyxis with the recently discovered ATLAS stream and the Magellanic system. Combining our measurements with dynamical modeling and cosmological numerical simulations, we find it unlikely Pyxis is associated with either system. We examine other Milky Way satellites for possible association using the orbit, eccentricity, metallicity, and age as constraints and find no likely matches in satellites down to the mass of Leo II. We propose that Pyxis probably originated in an unknown galaxy, which today is fully disrupted. Assuming that Pyxis is bound and not on a first approach, we derive a 68% lower limit on the mass of the Milky Way of 0.95x10^12^M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/ApJ/859/38
- Title:
- HST grism obs. of CARLA galaxy cluster candidates
- Short Name:
- J/ApJ/859/38
- Date:
- 08 Mar 2022 13:56:29
- Publisher:
- CDS
- Description:
- We report spectroscopic results from our 40-orbit Hubble Space Telescope slitless grism spectroscopy program observing the 20 densest Clusters Around Radio-Loud AGN (CARLA) candidate galaxy clusters at 1.4<z<2.8. These candidate rich structures, among the richest and most distant known, were identified on the basis of [3.6]-[4.5] color from a 408hr multi-cycle Spitzer program targeting 420 distant radio-loud AGN. We report the spectroscopic confirmation of 16 distant structures at 1.4<z<2.8 associated with the targeted powerful high-redshift radio-loud AGN. We also report the serendipitous discovery and spectroscopic confirmation of seven additional structures at 0.87<z<2.12 not associated with the targeted radio-loud AGN. We find that 10^10^-10^11^M_{sun}_ member galaxies of our confirmed CARLA structures form significantly fewer stars than their field counterparts at all redshifts within 1.4<=z<=2. We also observe higher star-forming activity in the structure cores up to z=2, finding similar trends as cluster surveys at slightly lower redshifts (1.0<z<1.5). By design, our efficient strategy of obtaining just two grism orbits per field only obtains spectroscopic confirmation of emission line galaxies. Deeper spectroscopy will be required to study the population of evolved, massive galaxies in these (forming) clusters. Lacking multi-band coverage of the fields, we adopt a very conservative approach of calling all confirmations "structures," although we note that a number of features are consistent with some of them being bona fide galaxy clusters. Together this survey represents a unique and large homogenous sample of spectroscopically confirmed structures at high redshifts, potentially more than doubling the census of confirmed, massive clusters at z>1.4.
- ID:
- ivo://CDS.VizieR/J/MNRAS/442/1049
- Title:
- HST gz magnitude of NGC 1023 star clusters
- Short Name:
- J/MNRAS/442/1049
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Faint fuzzies (FFs) are a relatively new class of star cluster, first found in the nearby S0 galaxy NGC 1023 by Larsen & Brodie (2000AJ....120.2938L) using Wide Field Planetary Camera 2 (WFPC2) images from the Hubble Space Telescope (HST). Here, we investigate the star cluster system of NGC 1023 using an eight pointing mosaic of Advanced Camera for Surveys (ACS) images from HST. We identify blue and red normal globular clusters (two of which are particularly luminous and dense) and two ultracompact dwarf objects (with effective radius ~10pc). With our more complete spatial coverage, we also find 81 red and 27 blue FFs. We confirm the association of the red FFs with the disc of NGC 1023, consistent with them being long-lived open clusters. Half of the blue FFs appear to be associated with the dwarf satellite galaxy NGC 1023A (which was largely absent from the original HST/WFPC2 coverage), while the remainder are spatially coincident with the densest HI gas that surrounds NGC 1023. The blue FFs have colours that are consistent with young (few 100Myr old) star clusters that formed during the most recent interaction between NGC 1023 and its satellite NGC 1023A.
6559. HST Hot Star Library
- ID:
- ivo://CDS.VizieR/J/A+A/615/A115
- Title:
- HST Hot Star Library
- Short Name:
- J/A+A/615/A115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Libraries of stellar spectra find many uses in astrophysics, from photometric calibration to stellar population synthesis. We present low resolution spectra of 40 stars from 0.2 micrometers (ultraviolet) to 1.0 micrometers (near infrared) with excellent fluxing. The stars include normal O-type stars, helium-burning stars, and post-asymptotic giant branch (PAGB) stars. Spectra were obtained with the Space Telescope Imaging Spectrograph (STIS) installed in the Hubble Space Telescope (HST) using three low resolution gratings, G230LB, G430L, and G750L. Cosmic ray hits and fringing in the red were corrected. A correction for scattered light was applied, significant only for our coolest stars. Cross-correlation was used to bring the spectra to a common, final, zero velocity wavelength scale. Finally, synthetic stellar spectra were used to estimate line of sight dust extinction to each star, and a five-parameter dust extinction model was fit, or a one-parameter fit in the case of low extinction. These spectra dovetail with the similar Next Generation Stellar Library (NGSL) spectra, extending the NGSL's coverage of stellar parameters, and extending to helium burning stars and stars that do not fuse. The fitted dust extinction model showed considerable variation from star to star, indicating variations in dust properties for different lines of sight. Interstellar absorption lines are present in most stars, notably MgII.
- ID:
- ivo://CDS.VizieR/J/ApJ/595/685
- Title:
- HST imaging in Chandra Deep Field-South
- Short Name:
- J/ApJ/595/685
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present quantitative morphological analyses of 37 Hubble Space Telescope (HST)/WFPC2 counterparts of X-ray sources in the 1Ms Chandra Deep Field South (CDFS, Cat. <J/ApJS/139/369>). We investigate (1) one-dimensional surface brightness profiles via isophotal ellipse fitting; (2) two-dimensional, point-spread function convolved, bulge+disk+nucleus profile fitting; (3) asymmetry and concentration indices compared with all ~3000 sources in our three WFPC2 fields; and (4) near-neighbor analyses comparing local environments of X-ray sources versus the field control sample. Significant nuclear point-source optical components appear in roughly half of the resolved HST/WFPC2 counterparts, showing a narrow range of FX/Fopt, nuc consistent with the several HST-unresolved X-ray sources (putative type 1 active galactic nuclei [AGNs]) in our fields.