Larry Ramsey

SparsePak: A Formatted Fiber Field Unit for the WIYN Telescope Bench Spectrograph. I. Design, Construction, and Calibration

ABSTRACT We describe the design and construction of a formatted fiber field unit, SparsePak, and characterize its optical and astrometric performance. This array is optimized for spectroscopy of low surface brightness extended sources in the visible and near‐infrared. SparsePak contains 82, 4 documentclass{aastex} usepackage{amsbsy} usepackage{amsfonts} usepackage{amssymb} usepackage{bm} usepackage{mathrsfs} usepackage{pifont} usepackage{stmaryrd} usepackage{textcomp} usepackage{portland,xspace} usepackage{amsmath,amsxtra} usepackage[OT2,OT1]{fontenc} newcommandcyr{ renewcommandrmdefault{wncyr} renewcommandsfdefault{wncyss} renewcommandencodingdefault{OT2} normalfont selectfont} DeclareTextFontCommand{textcyr}{cyr} pagestyle{empty} DeclareMathSizes{10}{9}{7}{6} begin{document} landscape

The Chandra Deep Survey of the Hubble Deep Field-North Area. II. Results from the Caltech Faint Field Galaxy Redshift Survey Area*

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ROTATIONAL VELOCITIES FOR M DWARFS

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A Planetary-Mass Companion to the K0 Giant HD 17092

We present results from a 221.9 ks Chandra exposure of the HDF-N and its vicinity, concentrating on the 8.6 X 8.7 area covered by the Caltech Faint Field Galaxy Redshift Survey (the `Caltech area). The minimum detectable fluxes in the 0.5-2 keV and 2-8 keV bands are 1.3e-16 cgs and 6.5e-16 cgs, respectively and a total of 82 sources are detected. More than 80% of the extragalactic X-ray background in the 2-8 keV band is resolved. Redshifts are available for 96% of the sources with R<23; the redshift range is 0.1-3.5 with most sources having z<1.5. Eight of the X-ray sources are located in the HDF-N itself, including two not previously reported. A population of X-ray faint, optically bright, nearby galaxies emerges at soft-band fluxes of ~<3e-16 cgs. We set the tightest constraints to date on the X-ray emission properties of microJy radio sources, mid-infrared sources detected by ISO, and very red (R-K_s>5.0) objects. Where both the infrared and the X-ray coverage are deepest, 75% of the X-ray sources are detected by ISO; the high X-ray to infrared matching rate bodes well for future sensitive infrared observations of faint X-ray sources. Four of the 33 very red objects that have been identified in the Caltech area by Hogg et al. (2000) are detected in X-rays; these four are among our hardest Chandra sources, and we argue that they contain moderately luminous obscured AGN. Overall, however, the small Chandra detection fraction suggests a relatively small AGN content in the optically selected very red object population. (Abridged)A deep X-ray survey of the Hubble Deep Field-North (HDF-N) and its environs is performed using data collected by the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory. Currently a 221.9 ks exposure is available, the deepest ever presented, and here we give results on X-ray sources located in the 86 × 87 area covered by the Caltech Faint Field Galaxy Redshift Survey (the Caltech area). This area has (1) deep photometric coverage in several optical and near-infrared bands; (2) extensive coverage at radio, submillimeter, and mid-infrared wavelengths; and (3) some of the deepest and most complete spectroscopic coverage ever obtained. It is also where the X-ray data have the greatest sensitivity; the minimum detectable fluxes in the 0.5-2 keV (soft) and 2-8 keV (hard) bands are ≈1.3 × 10-16 and ≈6.5 × 10-16 ergs cm-2 s-1, respectively. More than ≈80% of the extragalactic X-ray background in the hard band is resolved. The 82 Chandra sources detected in the Caltech area are correlated with more than 25 multiwavelength source catalogs, and the results of these correlations as well as spectroscopic follow-up results obtained with the Keck and Hobby-Eberly Telescopes are presented. All but nine of the Chandra sources are detected optically with R 26.5. Redshifts are available for 39% of the Chandra sources, including 96% of the sources with R 5.0) objects. A total of 16 of the 67 1.4 GHz μJy sources in the Caltech area are detected in the X-ray band, and the detection rates for starburst-type and AGN-candidate μJy sources are comparable. Only two of the 17 red, optically faint (I > 25) μJy sources are detected in X-rays. While many of the starburst-type μJy sources appear to contain obscured active galactic nuclei (AGNs), the Chandra data are consistent with the majority of the μJy radio sources being powered by star formation. A total of 11 of the ≈100 ISO mid-infrared sources found in and near the HDF-N are detected in X-rays. In the HDF-N itself, where both the infrared coverage and the X-ray coverage are deepest, it is notable that six of the eight Chandra sources are detected by ISO; most of these are known to be AGNs where the X-ray and infrared detections reveal both the direct and indirect accretion power being generated. The high X-ray-to-infrared matching rate bodes well for future sensitive infrared observations of faint X-ray sources. Four of the 33 very red objects that have been identified in the Caltech area are detected in X-rays; these four are among our hardest Chandra sources, and we argue that they contain moderately luminous obscured AGNs. Overall, however, the small Chandra detection fraction suggests a relatively small AGN content in the optically selected very red object population. A stacking analysis of the very red objects not detected individually by Chandra yields a soft-band detection with an average soft-band X-ray flux of ≈1.9 × 10-17 ergs cm-2 s-1; the observed emission may be associated with the hot interstellar media of moderate-redshift elliptical galaxies. Constraints on AGN candidates, extended X-ray sources, and Galactic objects in the Caltech area are also presented.

Observations of Faint, Hard-Band X-Ray Sources in the Field of CRSS J0030.5+2618 with the Chandra X-Ray Observatory and the Hobby-Eberly Telescope

We present spectroscopic rotation velocities (v sin i) for 56 M dwarf stars using high-resolution Hobby-Eberly Telescope High Resolution Spectrograph red spectroscopy. In addition, we have also determined photometric effective temperatures, masses, and metallicities ([Fe/H]) for some stars observed here and in the literature where we could acquire accurate parallax measurements and relevant photometry. We have increased the number of known v sin i values for mid M stars by around 80% and can confirm a weakly increasing rotation velocity with decreasing effective temperature. Our sample of v sin is peak at low velocities (~3 km s–1). We find a change in the rotational velocity distribution between early M and late M stars, which is likely due to the changing field topology between partially and fully convective stars. There is also a possible further change in the rotational distribution toward the late M dwarfs where dust begins to play a role in the stellar atmospheres. We also link v sin i to age and show how it can be used to provide mid-M star age limits. When all literature velocities for M dwarfs are added to our sample, there are 198 with v sin i ≤ 10 km s–1 and 124 in the mid-to-late M star regime (M3.0-M9.5) where measuring precision optical radial velocities is difficult. In addition, we also search the spectra for any significant Hα emission or absorption. Forty three percent were found to exhibit such emission and could represent young, active objects with high levels of radial-velocity noise. We acquired two epochs of spectra for the star GJ1253 spread by almost one month and the Hα profile changed from showing no clear signs of emission, to exhibiting a clear emission peak. Four stars in our sample appear to be low-mass binaries (GJ1080, GJ3129, Gl802, and LHS3080), with both GJ3129 and Gl802 exhibiting double Hα emission features. The tables presented here will aid any future M star planet search target selection to extract stars with low v sin i.

The habitable zone planet finder: a proposed high-resolution NIR spectrograph for the Hobby Eberly Telescope to discover low-mass exoplanets around M dwarfs

We report the discovery of a substellar-mass companion to the K0 giant HD 17092 with the Hobby-Eberly Telescope. In the absence of any correlation of the observed 360 day periodicity with the standard indicators of stellar activity, the observed radial velocity variations are most plausibly explained in terms of a Keplerian motion of a planetary-mass body around the star. As the estimated stellar mass is 2.3 M_⊙, the minimum mass of the planet is 4.6 M_J. The planets orbit is characterized by a mild eccentricity of e = 0.17 and a semimajor axis of 1.3 AU. This is the tenth published detection of a planetary companion around a red giant star. Such discoveries add to our understanding of planet formation around intermediate-mass stars, and they provide dynamical information on the evolution of planetary systems around post-main-sequence stars.

A Pathfinder Instrument for Precision Radial Velocities in the Near-Infrared

We present results from a study of 2–8 keV X-ray sources detected by the Advanced CCD Imaging Spectrometer on the Chandra X-Ray Observatory in the field of the z = 0.516 cluster CRSS J0030.5+2618. In our 63.5 arcmin2 search area, we detect 10 sources with 2–8 keV fluxes down to ≈4 × 10-15 ergs cm-2 s-1; our lowest flux sources are ≈10 times fainter than those previously available for study in this band. Our derived source density is about an order of magnitude larger than previous source counts above 2 keV, although this density may be enhanced somewhat because of the presence of the cluster. We detail our methods for source detection and characterization, and we show that the resulting source list and parameters are robust. We have used the Marcario Low-Resolution Spectrograph on the Hobby-Eberly Telescope to obtain optical spectra for several of our sources; by combining these spectra with archival data, we find that the sources appear to be active galaxies, often with narrow permitted lines, red optical continua, or hard X-ray spectra. Four of the X-ray sources are undetected to R = 21.7; if they reside in L* galaxies they must have z > 0.55–0.75 and hard X-ray luminosities of L2–8 4 × 1042 ergs s-1. We detect all but one of our 2–8 keV sources in the 0.2–2 keV band as well. This result extends to significantly lower fluxes the constraints on any large, completely new population of X-ray sources that appears above 2–3 keV.

The Low-Resolution Spectrograph of the Hobby-Eberly Telescope. II. Observations of quasar candidates from the Sloan Digital Sky Survey

The Habitable Zone Planet Finder (HZPF) is a proposed instrument for the 10m class Hobby Eberly telescope that will be capable of discovering low mass planets around M dwarfs. HZPF will be fiber-fed, provide a spectral resolution R~ 50,000 and cover the wavelength range 0.9-1.65μm, the Y, J and H NIR bands where most of the flux is emitted by midlate type M stars, and where most of the radial velocity information is concentrated. Enclosed in a chilled vacuum vessel with active temperature control, fiber scrambling and mechanical agitation, HZPF is designed to achieve a radial velocity precision < 3m/s, with a desire to obtain <1m/s for the brightest targets. This instrument will enable a study of the properties of low mass planets around M dwarfs; discover planets in the habitable zones around these stars, as well serve as an essential radial velocity confirmation tool for astrometric and transit detections around late M dwarfs. Radial velocity observation in the near-infrared (NIR) will also enable a search for close in planets around young active stars, complementing the search space enabled by upcoming high-contrast imaging instruments like GPI, SPHERE and PALM3K. Tests with a prototype Pathfinder instrument have already demonstrated the ability to recover radial velocities at 7-10 m/s precision from integrated sunlight and ~15-20 m/s precision on stellar observations at the HET. These tests have also demonstrated the ability to work in the NIR Y and J bands with an un-cooled instrument. We will also discuss lessons learned about calibration and performance from our tests and how they impact the overall design of the HZPF.

The Pathfinder Testbed: Exploring Techniques for Achieving Precision Radial Velocities in the Near-Infrared

Original article can be found at : http://www.journals.uchicago.edu/ Copyright Astronomical Society of the Pacific

Precision radial velocity spectrograph

ABSTRACT This paper describes spectra of quasar candidates acquired during the commissioning phase of the Low‐Resolution Spectrograph of the Hobby‐Eberly Telescope. The objects were identified as possible quasars from multicolor image data from the Sloan Digital Sky Survey. The 10 sources had typical r documentclass{aastex} usepackage{amsbsy} usepackage{amsfonts} usepackage{amssymb} usepackage{bm} usepackage{mathrsfs} usepackage{pifont} usepackage{stmaryrd} usepackage{textcomp} usepackage{portland,xspace} usepackage{amsmath,amsxtra} usepackage[OT2,OT1]{fontenc} newcommandcyr{ renewcommandrmdefault{wncyr} renewcommandsfdefault{wncyss} renewcommandencodingdefault{OT2} normalfont selectfont} DeclareTextFontCommand{textcyr}{cyr} pagestyle{empty} DeclareMathSizes{10}{9}{7}{6} begin{document} landscape