- ID:
- ivo://CDS.VizieR/J/AJ/162/187
- Title:
- IRTF spectral indices for giant stars
- Short Name:
- J/AJ/162/187
- Date:
- 15 Mar 2022
- Publisher:
- CDS
- Description:
- We present infrared spectral indices (1.0-2.3{mu}m) of Galactic late-type giants and red supergiants (RSGs). We used existing and new spectra obtained at resolution power R=2000 with SpeX on the IRTF telescope. While a large CO equivalent width (EW), at 2.29{mu}m ([CO,2.29]>~45{AA}) is a typical signature of RSGs later than spectral type M0, [CO] of K-type RSGs and giants are similar. In the [CO,2.29] versus [MgI,1.71] diagram, RSGs of all spectral types can be distinguished from red giants because the MgI line weakens with increasing temperature and decreasing gravity. We find several lines that vary with luminosity, but not temperature: SiI (1.59{mu}m), Sr (1.033{mu}m), Fe+Cr+Si+CN (1.16{mu}m), Fe+Ti (1.185{mu}m), Fe+Ti (1.196{mu}m), Ti+Ca (1.28{mu}m), and Mn (1.29{mu}m). Good markers of CN enhancement are the Fe+Si+CN line at 1.087{mu}m and CN line at 1.093{mu}m. Using these lines, at the resolution of SpeX, it is possible to separate RSGs and giants. Contaminant O-rich Mira and S-type AGBs are recognized by strong molecular features due to water vapor features, TiO band heads, and/or ZrO absorption. Among the 42 candidate RSGs that we observed, all but one were found to be late types. Twenty-one have EWs consistent with those of RSGs, 16 with those of O-rich Mira AGBs, and one with an S-type AGB. These infrared results open new, unexplored, potential for searches at low resolution of RSGs in the highly obscured innermost regions of the Milky Way.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/826/209
- Title:
- IRX-{beta} relation of HII regions in NGC628
- Short Name:
- J/ApJ/826/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has been found that the infrared-to-ultraviolet luminosity ratio (IRX) and ultraviolet spectral slope ({beta}) have a tight correlation in starburst galaxies, while in normal galaxies the relation is deviated and has a much larger scatter. Star formation regions are much simpler in both morphology and physical properties than galaxies, so their photometric and spectroscopic properties are more easily and accurately determined. We have used the integral field spectroscopy and multiband photometric images to study the IRX-{beta} relation of HII regions in a nearby galaxy, NGC 628. There are obvious correlations between the D_n_ (4000), stellar population age, star formation rate, especially H{alpha} equivalent width EW(H{alpha}), and deviation distance d_p_ from the starburst IRX-{beta} relation. However, there is little correlation between the Balmer decrement, metallicity, and d_p_. It is much more complicated than expected, so that we cannot introduce a single second parameter to describe the scatter and deviation of the HII region IRX-{beta} relation.
- ID:
- ivo://CDS.VizieR/III/242
- Title:
- ISO Astrophysical Spectroscopic Database
- Short Name:
- III/242
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This database will eventually contain all the published infrared lines observed by ISO, the Infrared Space Observatory. At this stage only a few percent of the total content is included but it is increasing steadily. Thus what is presented at this stage is a beta-version of the final product. ISO - the Infrared Space Observatory - was operational during about 28 months, between November 1995 and May 1998, until its cooling fluid (liquid helium) burnt out (Kessler et al. 1996A&A...315L..27K). It was the first far-infrared satellite equipped with two medium and high resolution spectrometers, SWS (Short Wavelength Spectrometer, 2.38-45.2{mu}m, de Graauw et al. 1996A&A...315L..49D) and LWS (Long Wavelength Spectrometer, 43-197{mu}m, Clegg et al. 1996A&A...315L..38C). Both spectrometers could be operated in grating or Fabry-Perot mode. In addition, the two other ISO instruments also provided spectroscopic data: ISOCAM (the ISO Camera, Cesarsky et al. 1996A&A...315L..32C) had a CVF (Circular Variable Filter) mode in 3 bands covering the range 2.3-17.3{mu}m, and ISOPHOT (The Imaging Photo-Polarimeter, Lemke et al. 1996A&A...315L..64L) had a dual grating spectrometer (PHOT-S) with resolving power of order 90 in two bands (2.5-4.9{mu}m and 5.8-11.6{mu}m). Detailed information about ISO and its four ISO instruments can be found in "The ISO Handbook" available on-line at http://www.iso.vilspa.esa.es/ The novelty, the richness and the unicity of the ISO spectroscopic data is what motivated us in compiling this data in a systematic and homogeneous way in order to make it available to the whole astronomical community. No other past, current or foreseen space project will overwrite this data, hence the importance of this compilation. In addition, queries on the database content will be a useful tool for the preparation of follow-up observations with other space, airborne or ground-based observatories such as Herschel, SOFIA, ALMA, VLT and more. In this early version, the database is very incomplete. It contains about 3000 lines which represents only a few percent of the total. Each observed and published ISO spectroscopic line corresponds to a physical line in IASD with up to 39 parameter/information fields. The description of the various columns is given below.
- ID:
- ivo://CDS.VizieR/J/ApJS/150/343
- Title:
- ISOCAM CVF spectrometer 2.2-16.5{mu}m spectra
- Short Name:
- J/ApJS/150/343
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present all ISOCAM Circular Variable Filter (CVF) spectra that cover more than one-third of the 2.2-16.5{mu}m spectral range of the instrument. The 364 spectra have been classified according to the classification system of Kraemer et al. (2002ApJS..140..389K), as modified by Hodge et al. (2004, Cat. <J/ApJS/151/299>) to account for the shorter wavelength range. Prior to classification, the spectra were processed and recalibrated to create a uniform database. Aperture photometry was performed at each wavelength centered on the brightest position in each image field and the various spectral segments merged into a single spectrum. The aperture was the same for all scale sizes of the images. Since this procedure differs fundamentally from that used in the initial ISOCAM calibration, a recalibration of the spectral response of the instrument was required for the aperture photometry. The recalibrated spectra and the software used to create them are available to the community on-line via the ISO Data Archive.
- ID:
- ivo://CDS.VizieR/J/AJ/123/2070
- Title:
- ISO deep asteroid search
- Short Name:
- J/AJ/123/2070
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A total of six deep exposures (using the astronomical observation template CAM01 with a 6" pixel field of view) through the ISOCAM LW10 filter (IRAS band 1, i.e., 12{mu}m) were obtained on a ~15' square field centered on the ecliptic plane. Point sources were extracted using the technique described in 1999 by Deert et al. Twoknown asteroids appear in these frames, and 20 sources moving with velocities appropriate for main-belt asteroids are present. Most of the asteroids detected have flux densities less than 1 mJy, that is, between 150 and 350 times fainter than any of the asteroids observed by IRAS. These data provide the first direct measurement of the 12{mu}m sky-plane density for asteroids on the ecliptic equator. The median zodiacal foreground, as measured by ISOCAM during this survey, is found to be 22.1+/-1.5mJy/pixel, i.e. 26.2+/-1.7MJy/sr. The results presented here imply that the actual number of kilometer-sized asteroids may be higher than several recent estimates based upon observations at visual wavelengths and are in reasonable agreement with the statistical asteroid model. Using results from the observations presented here, together with three other recent population estimates, we conclude that the cumulative number of main-belt asteroids with diameters greater than 1km is (1.2+/-0.5)x10^6^.
- ID:
- ivo://CDS.VizieR/J/ApJS/136/631
- Title:
- IUE absorption toward 164 early-type stars
- Short Name:
- J/ApJS/136/631
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present measurements of Galactic interstellar AlIII, SiIV, and CIV absorption recorded in high-resolution archival ultraviolet spectra of 164 hot early-type stars observed by the International Ultraviolet Explorer (IUE) satellite. The objects studied were drawn from the list of hot stars scheduled to be observed with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite as part of observing programs designed to investigate absorption by OVI in the Galactic disk and halo. Multiple IUE echelle-mode integrations have been combined to produce a single ultraviolet (1150-1900{AA}) spectrum of each star with a spectral resolution of ~25km/s (FWHM). Selected absorption-line profiles are presented for each star along with plots of the apparent column density per unit velocity for each line of the AlIII, SiIV, and CIV doublets. We report absorption-line equivalent widths, absorption velocities, and integrated column densities based on the apparent optical depth method of examining interstellar absorption lines. We also determine column densities and Doppler parameters from single-component curve-of-growth analyses. The scientific analysis of these observations will be undertaken after the FUSE satellite produces similar measurements for absorption by interstellar OIV, FeIII, SIII, and other ions.
- ID:
- ivo://CDS.VizieR/III/188
- Title:
- IUE Atlas of B-Type Stellar Spectra
- Short Name:
- III/188
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The IUE Atlas of B-type Stellar Spectra is an atlas of B-type spectra consisting of short-wavelength, high-resolution data from the International Ultraviolet Explorer archive, designed to complement the widely used O-star atlas from the same source (Walborn, Nichols-Bohlin, & Panek 1985, NASA Reference Publication 1155, catalog <III/115>). The atlas presented here completes the OB natural group, i.e., to spectral type B3 for the main sequence and giants, type B5 at class Ib, and B8 at Ia, which is also the most relevant domain for stellar-wind effects among normal B-type spectra.
- ID:
- ivo://CDS.VizieR/III/115
- Title:
- IUE Atlas of O-Type Stellar Spectra
- Short Name:
- III/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The International Ultraviolet Explorer Atlas of O-Type Spectra From 1200 to 1900 A (Walborn et el. 1985) lists normalized fluxes and flux quality factors, splice points, and identifying information (star name/number, spectral type, SWP number, and name of the principal investigator) on 101 spectrograms of 98 O-type stars. The primary purpose of this work is to investigate the existence of systematic trends in the ultraviolet line spectra of the O stars, including the prominent stellar wind features, and the degree to which they correlate with the optical spectral classifications. A subsidiary objective is to identify ultraviolet features which may themselves prove useful as classifications criteria.
- ID:
- ivo://CDS.VizieR/J/ApJS/147/305
- Title:
- IUE atlas of pre-main-sequence stars
- Short Name:
- J/ApJS/147/305
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We identified 137 T Tauri stars (TTS) and 97 Herbig Ae/Be (HAEBE) stars observed by IUE in the wavelength interval 1900-3200{AA}. Each low-resolution (R~6{AA}) spectrum was visually inspected for source contamination and data quality, and then all usable spectra were combined to form a single time averaged spectrum for each star. For sources with multiple observations, we characterized variability and compared with previously published amplitudes at shorter wavelengths. We combined several co-added spectra of diskless TTS to produce a pair of intrinsic stellar spectra unaffected by accretion. We then fitted spectra of TTS with the reddened sum of an intrinsic spectrum and a schematic veiling continuum, measuring emission line fluxes from the residuals. We used extinction and distance estimates from the literature to convert measured Mg II line fluxes into intrinsic line luminosities, noting that the IUE detection limit introduces a sample bias such that intrinsic line luminosity is correlated with extinction. This sample bias complicates any physical interpretation of TTS intrinsic luminosities. We measured extinction toward HAEBE stars by fitting our co-added IUE spectra with reddened spectra of main-sequence stars and also from V band minus 3000{AA} color excess. We measured excess line emission and absorption in spectra of HAEBE stars divided by fitted spectra of main-sequence stars, noting that HAEBE stars with an infrared excess indicating circumstellar material typically also have anomalous UV line strengths. In the latter situation, Mg II is usually shallower than in a main-sequence star of the same spectral class, whereas Fe II lines are equally likely to be deeper or shallower. Our co-added spectra of TTS, HAEBE stars, and main-sequence templates are available electronically, in FITS and ASCCI format, at http://archive.stsci.edu/prepds/iuepms/ .
- ID:
- ivo://CDS.VizieR/J/ApJS/119/207
- Title:
- IUE echelle spectra of hot white dwarfs
- Short Name:
- J/ApJS/119/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper summarizes the results obtained from a comprehensive analysis of all of the SWP echelle spectra of the white dwarf stars contained in the IUE Final Archive. A total of 209 NEWSIPS spectra of 55 degenerate stars of various types have been systematically reduced and analyzed. These include, in addition to conventional white dwarfs, several examples of the hot planetary nebula central stars such as NGC 246, which represent the initial stages of He-rich degenerate evolution. A representative summary of the stellar, circumstellar, and interstellar features found to be present in these spectra is presented. For 33 of the 55 stars, multiple spectra of sufficient quality exist so that co-added spectra with improved signal-to-noise ratio can be constructed. Much previously unrecognized detail and many new features are evident in these data. In addition, it was found necessary to apply several corrections to the NEWSIPS extracted spectra. These corrections, involving the wavelength scale and flux uncertainty vector, are described.
