- ID:
- ivo://CDS.VizieR/III/44
- Title:
- Atlas of Stellar Spectra
- Short Name:
- III/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There are exactly 8192 spectral elements (points) in each spectrum, regularly spaced in terms of frequency. The first point corresponds to spectral frequency 0, while point number 8193 (not included) corresponds to the laser frequency. The 632.8nm laser frequency was doubled, producing an effective laser wavelength of about 316.4nm. Tentatively, it may be assumed that the exact laser wavelength is 316.43nm. The spectra have been normalized so that the bluest stars are approximately level from 480 to 1000nm. The spectra are linear in intensity with zero intensity at tabulated zero. It was not possible to make satisfactory atmospheric extinction corrections throughout all of the atmospheric bands; at places where corrections could not be made, the spectra were set (exactly) to zero. Some of these spectra have been published already (H.L. Johnson, Rev. Mex. Astron. Astrof. 2, 71, 1977); the remainder will be published soon (Rev. Mex. Astron. Astrofis., 4, 3). These published spectral plots contain in graphical form the information needed to evaluate the signal-to-noise ratios of the spectra on this tape. (From Harold L. Johnson, Dec. 13, 1977)
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/549/A8
- Title:
- Atmospheric extinction properties above Mauna Kea
- Short Name:
- J/A+A/549/A8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new atmospheric extinction curve for Mauna Kea spanning 3200-9700{AA}. It is the most comprehensive to date, being based on some 4285 standard star spectra obtained on 478 nights spread over a period of 7 years obtained by the Nearby SuperNova Factory using the SuperNova Integral Field Spectrograph. This mean curve and its dispersion can be used as an aid in calibrating spectroscopic or imaging data from Mauna Kea, and in estimating the calibration uncertainty associated with the use of a mean extinction curve. Our method for decomposing the extinction curve into physical components, and the ability to determine the chromatic portion of the extinction even on cloudy nights, is described and verified over the wide range of conditions sampled by our large dataset. We demonstrate good agreement with atmospheric science data obtain at nearby Mauna Loa Observatory, and with previously published measurements of the extinction above Mauna Kea.
- ID:
- ivo://CDS.VizieR/J/AJ/112/628
- Title:
- BATC Color Survey of M67
- Short Name:
- J/AJ/112/628
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The authors present nine color CCD intermediate-band spectrophotometry of a two square degree field centered on the old open cluster M67, from 3890 Angstroms to nearly 1 micron. These observations are taken as a part of the BATC (Beijing-Arizona-Taipei-Connecticut) Color Survey of the Sky, for both scientific and calibration reasons. The BATC program uses a dedicated 60/90 cm Schmidt telecope with a 2048 x 2048 CCD and 15 specially-designed intermediate-band filters to be applied to both galactic and extragalactic studies. Nine-band spectrophotometry of 6558 stars is presented.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A30
- Title:
- B stars in 4 open clusters
- Short Name:
- J/A+A/610/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar physical properties of star clusters are poorly known and the cluster parameters are often very uncertain. Our goals are to perform a spectrophotometric study of the B star population in open clusters to derive accurate stellar parameters, search for the presence of circumstellar envelopes, and discuss the characteristics of these stars. The BCD spectrophotometric system is a powerful method to obtain stellar fundamental parameters from direct measurements of the Balmer discontinuity. To this end, we wrote the interactive code MIDE3700. The BCD parameters can also be used to infer the main properties of open clusters: distance modulus, color excess, and age. Furthermore, we inspected the Balmer discontinuity to provide evidence for the presence of circumstellar disks and identify Be star candidates. We used an additional set of high-resolution spectra in the H{alpha} region to confirm the Be nature of these stars. We provide Teff, logg, Mv, Mbol, and spectral types for a sample of 68 stars in the field of the open clusters NGC6087, NGC6250, NGC6383, and NGC6530, as well as the cluster distances, ages, and reddening. Then, based on a sample of 230 B stars in the direction of the 11 open clusters studied along this series of three papers, we report 6 new Be stars, 4 blue straggler candidates, and 15 B-type stars (called Bdd) with a double Balmer discontinuity, which indicates the presence of circumstellar envelopes. We discuss the distribution of the fraction of B, Be, and Bdd star cluster members per spectral subtype. The majority of the Be stars are dwarfs and present a maximum at the spectral type B2-B4 in young and intermediate-age open clusters (<40Myr). Another maximum of Be stars is observed at the spectral type B6-B8 in open clusters older than 40Myr, where the population of Bdd stars also becomes relevant. The Bdd stars seem to be in a passive emission phase. Our results support previous statements that the Be phenomenon is present along the whole main sequence band and occurs in very different evolutionary states.We find clear evidence of an increase of stars with circumstellar envelopes with cluster age. The Be phenomenon reaches its maximum in clusters of intermediate age (10-40Myr) and the number of B stars with circumstellar envelopes (Be plus Bdd stars) is also high for the older clusters (40-100Myr).
- ID:
- ivo://CDS.VizieR/J/A+A/539/A129
- Title:
- BVRI light curves of 3 eclipsing binaries
- Short Name:
- J/A+A/539/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We aim to derive the absolute parameters of the components of AD And, AL Cam, and V338 Her, interpret their orbital period changes and discuss their evolutionary status. New and complete multi-filter light curves of the eclipsing binaries AD And, AL Cam, and V338 Her were obtained and analysed with modern methods. Using all reliably observed times of minimum light, we examined orbital period irregularities using the least squares method. In addition, we acquired new spectroscopic observations during the secondary eclipses for AL Cam and V338 Her. For AL Cam and V338 Her, we derive reliable spectral types for their primary stars. Statistical checks of orbital period analysis for all systems are very reassuring in the cases of V338 Her and AD And, although less so for AL Cam. The LIght-Time Effect (LITE) results are checked by inclusion of a third light option in the photometric analyses. Light curve solutions provide the means to calculate the absolute parameters of the components of the systems and reliably estimate their present evolutionary status. AL Cam and V338 Her are confirmed as classical Algols of relatively low mass in similar configurations. Unlike AL Cam, however, V338 Her is still transferring matter between its components, raising interest in the determinability of the evolutionary histories of Algols. AD And is found to be a detached system in which both close stars are of age 10^9^yr and is probably a "non-classical" young triple, at an interesting stage of its dynamical evolution.
- ID:
- ivo://CDS.VizieR/J/AJ/157/229
- Title:
- CALSPEC: WFC3 infrared grism spectrophotometry
- Short Name:
- J/AJ/157/229
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The collections of spectral energy distributions (SEDs) in the Hubble Space Telescope (HST) CALSPEC database are augmented by 19 infrared (IR) SEDs from Wide Field Camera 3 (WFC3) IR grism spectra. Together, the two IR grisms, G102 and G141, cover the 0.8-1.7 {mu}m range with resolutions of R=200 and 150, respectively. These new WFC3 SEDs overlap existing CALSPEC Space Telescope Imaging Spectrograph (STIS) standard star flux distributions at 0.8-1 {mu}m with agreement to ~<1%. Some CALSPEC standards already have near-IR camera and multi-object spectrogragh (NICMOS) SEDs; but in their overlap region at 0.8-1.7 {mu}m, the WFC3 data have better wavelength accuracy, better spectral resolution, better repeatability, and, consequently, better flux distributions of ~1% accuracy in our CALSPEC absolute flux SEDs versus ~2% for NICMOS. With the improved SEDs in the WFC3 range, the modeled extrapolations to 32 {mu}m for the James Webb Space Telescope flux standards begin to lose precision longward of the 1.7 {mu}m WFC3 limit, instead of at the 1.0-{mu}m-long wavelength limit for STIS. For example, the extrapolated IR flux longward of 1.7 {mu}m for 1808347 increases by ~1% for the model fit to the data with WFC3, instead of just to the STIS SED alone.
- ID:
- ivo://CDS.VizieR/J/MNRAS/286/500
- Title:
- Classification of Late Type Stars
- Short Name:
- J/MNRAS/286/500
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Energy distributions for 33 galactic (super)giants situated mostly in the southern Milky Way in the range from 4800 to 7700 Angstroems with an effective resolution of 10 Angstroems are presented here. The observations and reductions are described in the paper. The errors of the absolute and relative flux calibration are 0.028 and 0.021 mag, respectively. The S/N ratio is at least 80 for each star. Cross references, MK classifications and spectral indices one may find in the paper. Further informations are available at M.O.Oestreicher (mio@astro.ruhr-uni-bochum.de). The data are given in three files: 1) stars.dat A list of the programme stars listing the HD/HDE numbers, MK types and positions related to J2000 2) absolute.dat A list of absolute fluxes for each star observed under photometric conditions (18 stars). The fluxes are given in magnitudes according to the system of Hayes & Latham (1975). A monochromatic magnitude of 0.00 corresponds to a flux of 3.5x10^-20^ erg.cm-2.s-1.Hz-1, (3.5x10^-23^ W/m2/Hz), i.e. the fluxes are related to FREQUENCY INTERVALS. 3) relative.dat A list of relative fluxes for each star observed in nights of low quality (15 stars). The fluxes are normalized to 1 at 5555 Angstr. and are related to WAVELENGTH INTERVALS.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A12
- Title:
- Clustering the Orion B giant molecular cloud
- Short Name:
- J/A+A/610/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Previous attempts at segmenting molecular line maps of molecular clouds have focused on using position-position-velocity data cubes of a single molecular line to separate the spatial components of the cloud. In contrast, wide field spectral imaging over a large spectral bandwidth in the (sub)mm domain now allows one to combine multiple molecular tracers to understand the different physical and chemical phases that constitute giant molecular clouds (GMCs). We aim at using multiple tracers (sensitive to different physical processes and conditions) to segment a molecular cloud into physically/ chemically similar regions (rather than spatially connected components), thus disentangling the different physical/chemical phases present in the cloud. We use a machine learning clustering method, namely the Meanshift algorithm, to cluster pixels with similar molecular emission, ignoring spatial information. Clusters are defined around each maximum of the multidimensional probability density function (PDF) of the line integrated intensities. Simple radiative transfer models were used to interpret the astrophysical information uncovered by the clustering analysis. A clustering analysis based only on the J=1-0 lines of three isotopologues of CO proves sufficient to reveal distinct density/column density regimes (n_H_~100cm^-3^, ~500cm^-3^, and >1000cm^-3^), closely related to the usual definitions of diffuse, translucent and high-column-density regions. Adding two UV-sensitive tracers, the J=1-0 line of HCO^+^ and the N=1-0 line of CN, allows us to distinguish two clearly distinct chemical regimes, characteristic of UV-illuminated and UV-shielded gas. The UV-illuminated regime shows overbright HCO^+^ and CN emission, which we relate to a photochemical enrichment effect. We also find a tail of high CN/HCO^+^ intensity ratio in UV-illuminated regions. Finer distinctions in density classes (n_H_~710^3^cm^-3^, ~410^4^cm^-3^) for the densest regions are also identified, likely related to the higher critical density of the CN and HCO^+^ (1-0) lines. These distinctions are only possible because the high-density regions are spatially resolved. Molecules are versatile tracers of GMCs because their line intensities bear the signature of the physics and chemistry at play in the gas. The association of simultaneous multi-line, wide-field mapping and powerful machine learning methods such as the Meanshift clustering algorithm reveals how to decode the complex information available in these molecular tracers.
- ID:
- ivo://CDS.VizieR/III/77
- Title:
- Copernicus 0.2-A Resolution Far-UV Stellar Spectra
- Short Name:
- III/77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is a subset comprising data for 60 O- and B-type stars observed by the Copernicus satellite. For each star a FITS file was created of the observed spectrum. Each spectrum has 2250 photometric data points. The wavelength range is from 1000 to 1450 Angstroems in 0.2-Angstrom steps. The data were acquired with photomultiplier U2, which had a nominal bandpass of 0.2 Angstrom (A) and scanned the spectrum with a 0.2 A step length, integrating for 13.6 sec at each wavelength position.
- ID:
- ivo://CDS.VizieR/J/A+A/566/A95
- Title:
- C-rich giants synthetic spectrophotometry. IV
- Short Name:
- J/A+A/566/A95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The evolution and spectral properties of stars on the asymptotic giant branch (AGB) are significantly affected by massloss through dusty stellar winds. Dynamic atmosphere and wind models are an essential tool for studying these evolved stars, both individually and as members of stellar populations, to understand their contribution to the integrated light and chemical evolution of galaxies. This paper is part of a series with the purpose of testing state-of-the-art atmosphere and wind models of C-type AGB stars against observations, and making them available to the community for use in various theoretical and observational studies. We have computed low-resolution spectra and photometry (in the wavelength range 0.35-25um) for a grid of 540 dynamic models with stellar parameters typical of solar-metallicity C-rich AGB stars and with a range of pulsation amplitudes. The models cover the dynamic atmosphere and dusty outflow (if present), assuming spherical symmetry, and taking opacities of gas-phase species and dust grains consistently into account. To characterize the time-dependent dynamic and photometric behaviour of the models in a concise way we defined a number of classes for models with and without winds.Results. Comparisons with observed data in general show a quite satisfactory agreement for example regarding mass-loss rates vs. (J-K) colours or K magnitudes vs. (J-K) colours. Some exceptions from the good overall agreement, however, are found and attributed to the range of input parameters (e.g. relatively high carbon excesses) or intrinsic model assumptions (e.g. small particle limit for grain opacities). While current results indicate that some changes in model assumptions and parameter ranges should be made in the future to bring certain synthetic observables into better agreement with observations, it seems unlikely that these pending improvements will significantly affect the mass-loss rates of the models.
