- ID:
- ivo://CDS.VizieR/J/MNRAS/411/705
- Title:
- Spectrophotometric distances of HII regions
- Short Name:
- J/MNRAS/411/705
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a near-infrared study of the stellar content of 35 HII regions in the Galactic plane, 24 of which have been classified as giant H ii regions. We have selected these optically obscured star-forming regions from the catalogues of Russeil (2003, Cat. J/A+A/397/133), Conti & Crowther (2004MNRAS.355..899C) and Bica et al. (2003, Cat. J/A+A/404/223). In this paper, we have used the near-infrared domain J-, H- and Ks-band colour images to visually inspect the sample. Also, we have used colour-colour and colour-magnitude diagrams to indicate ionizing star candidates, as well as the presence of young stellar objects such as classical T Tauri stars and massive young stellar objects (MYSOs). We have obtained Spitzer Infrared Array Camera images for each region to help further characterize them. Spitzer and near-infrared morphology were used to place each cluster in an evolutionary phase of development. Spitzer photometry was also used to classify the MYSOs.
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- ID:
- ivo://CDS.VizieR/J/A+A/366/68
- Title:
- Spectrophotometric indices from galaxy bulges
- Short Name:
- J/A+A/366/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured Mg_2_, Fe5270 and Fe5335 spectrophotometric indices (LICK system) in the bulge of 89 galaxies, mostly spirals from the Heraudeau sample. The indices are reduced to a null velocity dispersion and normalized to an aperture of 0.2h^-1^kpc. The mean errors are 0.009 mag on Mg_2_, and 0.3{AA} on the iron indices. These measurements almost double the amount of similar data already available on spiral galaxies. Our data confirm the existence of the relation between Mg_2_ and sigma_0_, the central stellar velocity dispersion; and we find an even tighter relation between Mg_2_ and Vmaxrot, the maximum rotational velocity of the galaxy, deduced from HI observations. For the most massive bulges these correlations may be interpreted as a mass-metallicity relation. However, the presence of young stellar populations, traced by the detection of [OIII]{lambda}500.7nm emission, provides a clear evidence that age effects play a role. Since the contribution of the young population is anti-correlated with the mass of the galaxy, it continues the Mg_2_ vs. sigma_0_ relation toward the low sigma_0_ and globally increases its slope. We present also evidence for a new positive correlation between Fe indices and sigma_0_ and for a significant correlation between the line strength indices and the total or disk luminosity. We propose to model the whole sequence of bulges within the following framework: Bulges are composed of a primary population formed prior to the disk during the initial collapse and a secondary population formed along the evolution. The whole family of bulges can be classified in three classes: (A) The bulges dominated by a young population are generally small, have ionized gas, low velocity dispersion and low line strengths. (B) The bulges dominated by the primary population lie along the mass metallicity sequence defined for elliptical galaxies. (C) The bulges where the secondary population is significant are less Mg-overabundant than B-type bulges and deviate from the Mg_2_ vs. sigma_0_ relation of elliptical galaxies. The original data are available in Hypercat: http://www-obs.univ-lyon1.fr/hypercat The tables of measurements and the extracted 1D spectra are also available in the present archive set.
- ID:
- ivo://CDS.VizieR/J/AJ/158/147
- Title:
- Spectrophotometric parallaxes with linear models
- Short Name:
- J/AJ/158/147
- Date:
- 07 Jan 2022 11:19:14
- Publisher:
- CDS
- Description:
- With contemporary infrared spectroscopic surveys like APO Galactic Evolution Experiment (APOGEE), red-giant stars can be observed to distances and extinctions at which Gaia parallaxes are not highly informative. Yet the combination of effective temperature, surface gravity, composition, and age-all accessible through spectroscopy - determines a giant's luminosity. Therefore spectroscopy plus photometry should enable precise spectrophotometric distance estimates. Here we use the overlap of APOGEE, Gaia, the Two Micron All Sky Survey (2MASS), and the Wide-field Infrared Survey Explorer (WISE) to train a data-driven model to predict parallaxes for red-giant branch stars with 0<logg=<2.2 (more luminous than the red clump). We employ (the exponentiation of) a linear function of APOGEE spectral pixel intensities and multiband photometry to predict parallax spectrophotometrically. The model training involves no logarithms or inverses of the Gaia parallaxes, and needs no cut on the Gaia parallax signal-to-noise ratio. It includes an L1 regularization to zero out the contributions of uninformative pixels. The training is performed with leave-out subsamples such that no star's astrometry is used even indirectly in its spectrophotometric parallax estimate. The model implicitly performs a reddening and extinction correction in its parallax prediction, without any explicit dust model. We assign to each star in the sample a new spectrophotometric parallax estimate; these parallaxes have uncertainties of less than 15%, depending on data quality, which is more precise than the Gaia parallax for the vast majority of targets, and certainly any stars more than a few kiloparsec distance. We obtain 10% distance estimates out to heliocentric distances of 20 kpc, and make global maps of the Milky Way's disk.
- ID:
- ivo://CDS.VizieR/J/ApJ/668/839
- Title:
- Spectrophotometric redshifts for 1308 HUDF galaxies
- Short Name:
- J/ApJ/668/839
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of spectrophotometric redshifts for 1308 galaxies from the Grism ACS Program for Extragalactic Science (GRAPES) observations with the Hubble Space Telescope. These low-resolution spectra between 6000{AA} and 9500{AA} are supplemented with U, J, H, and Ks data from various facilities, resulting in redshifts computed with ~40 spectral bins per galaxy. For 75 galaxies in the range 0.5<z<1.5 with spectroscopic redshifts, the standard deviation in the fractional error in 1+z is 0.037. With this catalog, we compute the B-band luminosity function in this redshift range from 72 galaxies. Due to the depth of the GRAPES survey, we are able to accurately constrain the faint-end slope by going to MB~-18mag at z=1.0+/-0.2, nearly 2mag fainter than previous studies. The faint-end slope is alpha=-1.32+/-0.07. When compared to numerous published values at various redshifts, we find strong evidence for a steepening of the faint-end slope with redshift, which is expected in the hierarchical formation scenario of galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/157
- Title:
- Spectrophotometric redshifts of GOODS galaxies
- Short Name:
- J/ApJ/883/157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the accuracy of 4000{AA}/Balmer-break based redshifts by combining Hubble Space Telescope (HST) grism data with photometry. The grism spectra are from the Probing Evolution And Reionization Spectroscopically survey with HST using the G800L grism on the Advanced Camera for Surveys. The photometric data come from a compilation by the 3D-HST collaboration of imaging from multiple surveys (notably, the Cosmic Assembly Near-infrared Deep Extragalactic Survey (CANDELS) and 3D-HST). We show evidence that spectrophotometric redshifts (SPZs) typically improve the accuracy of photometric redshifts by ~17%-60%. Our SPZ method is a template-fitting-based routine that accounts for correlated data between neighboring points within grism spectra via the covariance matrix formalism and also accounts for galaxy morphology along the dispersion direction. We show that the robustness of the SPZ is directly related to the fidelity of the D4000 measurement. We also estimate the accuracy of continuum-based redshifts, i.e., for galaxies that do not contain strong emission lines, based on the grism data alone ({sigma}_{Delta}z/(1+z)_^NMAD^<~0.06). Given that future space-based observatories like Wide Field InfraRed Survey Telescope and Euclid will spend a significant fraction of time on slitless spectroscopic observations, we estimate number densities for objects with |{Delta}z/(1+z_s_)|<=0.02. We predict ~700-4400 galaxies degree^-2^ for galaxies with D4000>1.1 and |{Delta}z/(1+z_s_)|<=0.02 to a limiting depth of i_AB_=24mag. This is especially important in the absence of an accompanying rich photometric data set like the existing one for the CANDELS fields, where redshift accuracy from future surveys will rely only on the presence of a feature like the 4000{AA}/Balmer breaks or the presence of emission lines within the grism spectra.
17206. Spectrophotometric Scans
- ID:
- ivo://CDS.VizieR/III/48B
- Title:
- Spectrophotometric Scans
- Short Name:
- III/48B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This data set contains 937 sets of spectrophotometric observations of stellar continua made in the 320-1200nm region. The data were transformed to the Hayes and Latham (1975ApJ...197..593H) calibration of {alpha} Lyr. Bandpasses vary between 1 and 10nm. Note that scans of the southern stars observed by Gutierrez-Moreno et al. (1968SanS....4...49G) are NOT corrected for the right ascension effects discussed in Breger (1976).
- ID:
- ivo://CDS.VizieR/J/MNRAS/501/2848
- Title:
- Spectrophotometric standard cand. photometry
- Short Name:
- J/MNRAS/501/2848
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Johnson-Kron-Cousins BVRI photometry of 228 candidate spectrophotometric standard stars for the external (absolute) flux calibration of Gaia data. The data were gathered as part of a 10-yr observing campaign with the goal of building the external grid of flux standards for Gaia and we obtained absolute photometry, relative photometry for constancy monitoring, and spectrophotometry. Preliminary releases of the flux tables were used to calibrate the first two Gaia releases. This paper focuses on the imaging frames observed in good sky conditions (about 9100). The photometry will be used to validate the ground-based flux tables of the Gaia spectrophotometric standard stars and to correct the spectra obtained in non-perfectly photometric observing conditions for small zero-point variations. The absolute photometry presented here is tied to the Landolt standard stars system to ~1 per cent or better, depending on the photometric band. Extensive comparisons with various literature sources show an overall ~1 per cent agreement, which appears to be the current limit in the accuracy of flux calibrations across various samples and techniques in the literature. The Gaia photometric precision is presently of the order of 0.1 per cent or better, thus various ideas for the improvement of photometric calibration accuracy are discussed.
17208. Spectrophotometric Standards
- ID:
- ivo://CDS.VizieR/III/209
- Title:
- Spectrophotometric Standards
- Short Name:
- III/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog contains energy distribution data of 82 stars of 7-8mag belonging to spectral types A0-G2. Spectral energy distribution is presented in the range 3400-7500{AA} with 50{AA} step. The observations were made in the period 1991-1996 by means of the spectrophotometer working at the regime of the photon counting. Scanner was installed at the 60-cm Zeiss reflector of the Sternberg Institute Crimean Station. Eight early type stars were used as spectrophotometic standards: {beta} Ari, {gamma} Ori, {beta} Tau, {alpha} Leo, {eta} UMa, {alpha} Lyr, {alpha} Aql and {alpha} Peg. The accuracy of the monochromatic fluxes is about 2% in the ultraviolet, 1% in the visual range an 1.5-2% for {lambda}>7000{AA}. The energy distribution data are expressed in erg/(cm^2^.s.cm)*10^-6^.
17209. Spectrophotometric Standards
- ID:
- ivo://CDS.VizieR/III/116
- Title:
- Spectrophotometric Standards
- Short Name:
- III/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observers at the National Optical Astronomy Observatories have provided spectrophotometry for 25 stars in the visual magnitude range 7.5 to 16.6. This document describes the machine-readable version of their results as received from P. Massey. The magnitudes are on the Hayes-Latham system and cover the wavelength range from 3200 to 8100 angstroms at approximately two angstrom intervals.
- ID:
- ivo://CDS.VizieR/J/AZh/78/1135
- Title:
- Spectrophotometric standards near DE=+40{deg}
- Short Name:
- J/AZh/78/1135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The second stage to compile a list of regional intermediate-brightness spectrophotometric standards has been completed. It includes the spectral energy distribution for 24 stars with magnitudes 7.0-8.5 near +40{deg} declination. The range 3100-7600{AA} was studied with a spectral resolution of 50{AA}. All the stars are referenced to a single standard the circumpolar star HD 221525. The energy distributions were used to compute color indices in the UBV, WBVR, and UPXYZVS systems,as well as in the system (BT,VT) of the TYCHO catalog.