- ID:
- ivo://CDS.VizieR/J/MNRAS/446/369
- Title:
- Colour and spectral index from the SLUGGS survey
- Short Name:
- J/MNRAS/446/369
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of the SAGES Legacy Unifying Globulars and GalaxieS (SLUGGS) survey, we stack 1137 Keck DEIMOS (Deep Imaging Multi-Object Spectrograph) spectra of globular clusters from 10 galaxies to study their stellar populations in detail. The stacked spectra have median signal-to-noise ratios of ~90 {AA}^-1^. Besides the calcium triplet, we study weaker sodium, magnesium, titanium and iron lines as well as the H{alpha} and higher order Paschen hydrogen lines. In general, the stacked spectra are consistent with old ages and a Milky Way-like initial mass function. However, we see different metal line index strengths at fixed colour and magnitude, and differences in the calcium triplet-colour relation from galaxy to galaxy. We interpret this as strong evidence for variations in the globular cluster colour-metallicity relation between galaxies. Two possible explanations for the colour-metallicity relation variations are that the average ages of globular clusters vary from galaxy to galaxy or that the average abundances of light elements (i.e. He, C, N and O) differ between galaxies. Stacking spectra by magnitude, we see that the colours become redder and metal line indices stronger with brighter magnitudes. These trends are consistent with the previously reported `blue tilts' being mass-metallicity relations.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/894/142
- Title:
- Column densities from HST/COS SiIV AGN sight lines
- Short Name:
- J/ApJ/894/142
- Date:
- 19 Jan 2022 13:10:08
- Publisher:
- CDS
- Description:
- We develop a kinematical model for the Milky Way SiIV-bearing gas to determine its density distribution and kinematics. This model is constrained by a column density line-shape sample extracted from the Hubble Space Telescope/Cosmic Origins Spectrograph archival data, which contains 186 active galactic nucleus sight lines. We find that the SiIV ion density distribution is dominated by an extended disk along the z-direction (above or below the midplane), i.e., n(z)=n_0_exp(-(z/z_0_)^0.82^), where z_0_ is the scale height of 6.3_-1.5_^+1.6^kpc (northern hemisphere) and 3.6_-0.9_^+1.0^kpc (southern hemisphere). The density distribution of the disk in the radial direction shows a sharp edge at 15-20kpc given by, n(r_XY_)=n_0_exp(-(r_XY_/r_0_)^3.36^), where r_0_~12.5+/-0.6kpc. The difference of density distributions over r_XY_ and z directions indicates that the warm gas traced by SiIV is mainly associated with disk processes (e.g., feedback or cycling gas) rather than accretion. We estimate the mass of the warm gas (within 50kpc) is log(M(50kpc)/M_{sun}_)~8.1 (assuming Z~0.5Z_{sun}_), and a 3{sigma} upper limit of log(M(250kpc)/M_{sun}_)~9.1 (excluding the Magellanic system). Kinematically, the warm gas disk is nearly co-rotating with the stellar disk at v_rot_=215+/-3km/s, which lags the midplane rotation by about 8km/s/kpc (within 5kpc). Meanwhile, we note that the warm gas in the northern hemisphere has significant accretion with vacc of 69+/-7km/s at 10kpc (an accretion rate of -0.60_-0.13_^+0.11^M_{sun}_/yr), while in the southern hemisphere, there is no measurable accretion, with an upper limit of 0.4M_{sun}_/yr.
- ID:
- ivo://CDS.VizieR/J/ApJ/883/78
- Title:
- Column densities of CGM absorption lines
- Short Name:
- J/ApJ/883/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the geometric distribution of gas metallicities in the circumgalactic medium (CGM) around 47, z<0.7 galaxies from the "Multiphase Galaxy Halos" Survey. Using a combination of quasar spectra from Hubble Space Telescope (HST)/COS and from Keck/HIRES or Very Large Telescope/UVES, we measure column densities of, or determine limits on, CGM absorption lines. We then use a Markov Chain Monte Carlo approach with Cloudy to estimate the metallicity of cool (T~10^4^K) CGM gas. We also use HST images to determine host-galaxy inclination and quasar-galaxy azimuthal angles. Our sample spans a HI column density range of 13.8cm^-2^<logN_HI_<19.9cm^-2^. We find (1) while the metallicity distribution appears bimodal, a Hartigan dip test cannot rule out a unimodal distribution (0.4{sigma}). (2) CGM metallicities are independent of halo mass, spanning three orders of magnitude at a fixed halo mass. (3) The CGM metallicity does not depend on the galaxy azimuthal and inclination angles regardless of HI column density, impact parameter, and galaxy color. (4) The ionization parameter does not depend on azimuthal angle. We suggest that the partial Lyman limit metallicity bimodality is not driven by a spatial azimuthal bimodality. Our results are consistent with simulations where the CGM is complex and outflowing, accreting, and recycled gas are well-homogenized at z<0.7. The presence of low-metallicity gas at all orientations suggests that cold streams of accreting filaments are not necessarily aligned with the galaxy plane at low redshifts or intergalactic transfer may dominate. Finally, our results support simulations showing that strong metal absorption can mask the presence of low-metallicity gas in integrated line-of-sight CGM metallicities.
- ID:
- ivo://CDS.VizieR/J/A+AS/141/449
- Title:
- Coma cluster early-type galaxies
- Short Name:
- J/A+AS/141/449
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Table 1 describes the photometric properties (R-band magnitude, effective radius, surface brightness, a_4_, ellipticity) of all 35 Coma cluster galaxies, which are investigated spectroscopically in this work. Besides the galaxy numbers given by Godwin et al. (1983, Cat. <VII/42>, GMP83), we also list the NGC/IC numbers as well as Dressler's numbers given in Dressler et al. (1987ApJ...313...42D, D87). Additionally the galaxy type as well as there distance to the clusters center are given. Table 5 to Table 12 (photom.dat) give the results from surface brightness and isophotal shape analysis (local surface brightness, ellipticity, position angle and Fourier coefficients along the major axis) for 8 galaxies of the sample derived from Kron Cousins R band photometry. Table 13 to Table 47 (kinema.dat) give spatially resolved kinematic parameter (v, sigma, H_3_, H_4_) for all 35 galaxies while in Table 48 to Table 82 (indice1.dat and indice2.dat) we list the radial profiles of the measured line indices (H_beta_, Mg, Fe, NaD) of these galaxies. Table 4 contains the results from the comparison of our mean data within the circular standard aperture (see paper) with the mean values given by Joergensen (1999MNRAS.306..607J, J99).
- ID:
- ivo://CDS.VizieR/J/A+A/407/423
- Title:
- Coma cluster early-type galaxies. III.
- Short Name:
- J/A+A/407/423
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on Paper I of this series (Mehlert et al., 2000, Cat. <J/A+AS/141/449>), we derive central values and logarithmic gradients for the Hbeta, Mg and Fe indices of 35 early-type galaxies in the Coma cluster. We find that pure elliptical galaxies have on average slightly higher velocity dispersions, lower Hbeta, and higher metallic line-strengths than galaxies with disks (S0).
- ID:
- ivo://CDS.VizieR/J/MNRAS/411/2558
- Title:
- Coma cluster galaxies absorption-line indices
- Short Name:
- J/MNRAS/411/2558
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper we study the stellar populations of 356 bright, Mr<=-19, Coma cluster members located in a 2{deg} field centred on the cluster core using Sloan Digital Sky Survey (SDSS) Data Release 7 (DR7) spectroscopy. We find ~31 per cent of the sample have significant emission in H{beta}, [OIII]5007, H{alpha} or [NII]6585, due to star formation or active galactic nuclei (AGN)/LINER activity. The remaining portion of the sample we describe as passive or quiescent.
- ID:
- ivo://CDS.VizieR/J/AJ/156/68
- Title:
- Comet C/2017 E4 composition with iSHELL at NASA/IRTF
- Short Name:
- J/AJ/156/68
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In 2017 April, we acquired comprehensive high-resolution spectra of newly discovered comet C/2017 E4 (Lovejoy) as it approached perihelion, and before its disintegration. We detected many cometary emission lines in the range (2.8-5.3) {mu}m, in four customized instrument settings (L1-c, L3, Lp1-c, and M1) of iSHELL - the new near-IR high-resolution immersion echelle spectrograph at NASA/IRTF (Maunakea, Hawaii). We identified 12 molecular species: nine primary volatiles (H_2_O, HCN, NH_3_, CO, C_2_H_2_, C_2_H_6_, CH_4_, CH_3_OH, H_2_CO) and three product species (CN, NH_2_, OH). We detected 85 H_2_O emission lines from 12 water vibrational bands across L1-c and M1 settings. The many detected water emission lines enabled retrieval of accurate measures for ortho- and para-H_2_O independently, thereby reducing systematic uncertainty in the derived ortho-para ratio and nuclear spin temperature. Excitation analyses and emission profile analyses were performed for all species, and molecular abundance ratios relative to water are compared with values found for other Oort Cloud comets in our infrared database. Abundance ratios are consistent for most species, with the exception of underabundant methanol and overabundant ammonia in E4.
- ID:
- ivo://CDS.VizieR/J/A+A/656/A160
- Title:
- Comet C/2020 F3 (NEOWISE) emission lines
- Short Name:
- J/A+A/656/A160
- Date:
- 21 Mar 2022 09:16:33
- Publisher:
- CDS
- Description:
- Comet C/2020 F3 (NEOWISE) is considered to be the brightest comet observed in the northern hemisphere since the passage of comet C/1995 O1 (Hale-Bopp) in 1997. Since the study of comets offers a unique opportunity to investigate the early stages of the formation and evolution of our Sun and the Solar System, we obtained high-resolution optical spectra (R={lambda}/{Delta}{lambda}=115000) of comet NEOWISE. The unique passage and its brightness yielded spectra with a large number of emission lines, providing information on the coma composition and the physical and chemical processes occurring in the nucleus. The spectra have been used to generate a catalog of emission lines to be used for future studies of comets since there are no catalogs in the literature with such a high spectral resolution. Two high-resolution spectra of comet NEOWISE were obtained, on 26 July 2020 (geocentric distance of 0.7au) and 5 August 2020 (geocentric distance of 0.89au), with the High Accuracy Radial velocity Planet Searcher for the Northern hemisphere (HARPS-N) echelle spectrograph installed on the 360cm Telescopio Nazionale Galileo (TNG). The spectra cover the range between 383 and 693nm, and have been extracted using the HARPS-N Data Reduction Pipeline. To analyze the spectra and compile the high-resolution catalog, we collected several laboratory molecular line lists that cover the same wavelength range as that of our spectra. To validate the final identification, we compared our catalog with other atlases that resulted from the spectral analysis of other comets. We generate a high-spectral-resolution catalog of emission lines observed in comet NEOWISE, providing the identification for 4488 lines. We found cometary lines due to CN, CH, C_2_, C_3_, and NH_2_ and atomic lines due to NaI and [OI].
- ID:
- ivo://CDS.VizieR/J/A+A/367/1049
- Title:
- Comet C/1995 O1 (Hale-Bopp) emission lines
- Short Name:
- J/A+A/367/1049
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High-resolution and high signal-to-noise ratio spectra of Comet C/1995 O1 (Hale-Bopp), which provided continuous wavelength coverage from 5500{AA} to 8500{AA} and partial coverage from 4000{AA} to 5500{AA}, were obtained with the Coude Echelle Spectrograph at Beijing Astronomical Observatory on March 26, 28 and April 22, 1997. In the spectra we found 532 emission features, among which 459 lines from H, O, Na, C_2_, C_3_, CN, CH, NH_2_ and H_2_O^+^ were identified. The intensity of sodium emission lines at 5890 {AA} and 5896 {AA} on April 22 increased about 5 fold compared to that recorded on March 26 and 28. The intensity ratio I_{lambda}5577_/(I_{lambda}6300_+I_{lambda}6364_) of [O I] is consistent with the formation of excited O atoms from the photodissociation of H_2_O.
- ID:
- ivo://CDS.VizieR/J/A+A/619/A127
- Title:
- Comet C/2016 R2 (PanSTARRS) IRAM spectra
- Short Name:
- J/A+A/619/A127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength study of comet C/2016 R2 (PanSTARRS). This comet was observed on 23-24 January 2018 with the IRAM 30m telescope, and in January to March 2018 with the Nancay radio telescope. Visible spectroscopy was performed in December 2017 and February 2018 with small amateur telescopes. We report on measurements of CO, CH_3_OH, H_2_CO and HCN production rates, and on the determination of the N2/CO abundance ratio. Several other species, especially OH, were searched for but not detected. The inferred relative abundances, including upper limits for sulfur species, are compared to those measured in other comets at about the same heliocentric distance of ~2.8AU. The coma composition of comet C/2016 R2 is very different from all other comets observed so far, being rich in N2 and CO and dust poor. This suggests that this comet might belong to a very rare group of comets formed beyond the N_2_ ice line. Alternatively, comet C/2016 R2 (PanSTARRS) could be the fragment of a large and differentiated transneptunian object, with properties characteristic of volatile-enriched layers.
