- ID:
- ivo://CDS.VizieR/J/AJ/132/1796
- Title:
- Spectroscopy in nearby group cores
- Short Name:
- J/AJ/132/1796
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used V and I CCD photometry to search for low surface brightness dwarf galaxies in the central (<0.5h^-1^Mpc) region of the groups NGC 6868, NGC 5846, HCG 42, and the poor cluster IC 4765. We used the exponential profile fit parameters to identify 80 low surface brightness dwarf galaxy candidates with 17mag<V<22mag (-16.7>MV>-11.4), V-I<1.5mag, {mu}_0_>22.5Vmag/arcsec^2^, h>1.5", and diameters larger than 1.2h^-1^kpc. Twenty of these galaxies are extended low surface brightness galaxies that were detected only on smoothed images, after masking all high surface brightness objects. The completeness in the sample detection is ~80% for V~<20 and 22.5Vmag/arcsec^2^<{mu}_0_<24.5Vmag/arcsec^2^. For galaxies with V>20mag and {mu}_0_>24.5Vmag/arcsec^2^, the completeness is below 50% but increases to ~80% when we search for galaxies in smoothed images.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/148/83
- Title:
- Spectroscopy in NGC 2360, NGC 3680, and NGC 5822
- Short Name:
- J/AJ/148/83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Binary stars in open clusters are very useful targets in constraining the nucleosynthesis process. The luminosities of the stars are known because the distances of the clusters are also known, so chemical peculiarities can be linked directly to the evolutionary status of a star. In addition, binary stars offer the opportunity to verify a relationship between them and the straggler population in both globular and open clusters. We carried out a detailed spectroscopic analysis to derive the atmospheric parameters for 16 red giants in binary systems and the chemical composition of 11 of them in the open clusters NGC 2360, NGC 3680, and NGC 5822. We obtained abundances of C, N, O, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, and Nd. The atmospheric parameters of the studied stars and their chemical abundances were determined using high-resolution optical spectroscopy. We employ the local thermodynamic equilibrium model atmospheres of Kurucz and the spectral analysis code MOOG. The abundances of the light elements were derived using the spectral synthesis technique. We found that the stars NGC 2360-92 and 96, NGC 3680-34, and NGC 5822-4 and 312 are yellow straggler stars. We show that the spectra of NGC 5822-4 and 312 present evidence of contamination by an A-type star as a secondary star. For the other yellow stragglers, evidence of contamination is given by the broad wings of the H{alpha}. Detection of yellow straggler stars is important because the observed number can be compared with the number predicted by simulations of binary stellar evolution in open clusters. We also found that the other binary stars are not s-process enriched, which may suggest that in these binaries the secondary star is probably a faint main-sequence object. The lack of any s-process enrichment is very useful in setting constraints for the number of white dwarfs in the open cluster, a subject that is related to the birthrate of these kinds of stars in open clusters and also to the age of a cluster. Finally, rotational velocities were also determined and their values were compared with those already determined for field giant stars.
- ID:
- ivo://CDS.VizieR/J/AJ/129/363
- Title:
- Spectroscopy in Orion Nebula Cluster
- Short Name:
- J/AJ/129/363
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from high-resolution spectra of 237 stars in the Orion Nebula cluster (ONC) obtained during two engineering runs with the Hectochelle multifiber echelle spectrograph on the 6.5m MMT. The ONC is the nearest populous young (age ~1Myr) cluster and is therefore an important object for studies of the evolution of protoplanetary disks. Using the high spectral resolution of Hectochelle, we are able to distinguish stellar accretion and wind emission-line profiles from nebular emission lines and identify accreting members of the cluster from H{alpha} profiles with greater accuracy than previously possible. We find 15 new members on the basis of Li {lambda}6707 absorption and H{alpha} emission. Line profiles of H{alpha} of some objects that are not too contaminated by nebular emission show features characteristic of mass inflow and ejection. We also present rotational velocities as part of an initial investigation into angular momentum evolution of very young stars, confirming a difference between classical T Tauri stars and weak-line T Tauri stars that had been found from period analysis. Finally, we present an initial study of the radial velocity dispersion of the brighter stars in the central cluster. The very small dispersion derived, 1.8km/s, is in good agreement with estimates from proper motions.
- ID:
- ivo://CDS.VizieR/J/MNRAS/381/1035
- Title:
- Spectroscopy in Shapley supercluster
- Short Name:
- J/MNRAS/381/1035
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new optical spectroscopy for 342 R<18 galaxies in the Shapley supercluster (and 198 supplementary galaxies), obtained from 8-h integrations with the AAOmega facility at the Anglo-Australian Telescope. We describe the observations and measurements of central velocity dispersion {sigma}, emission-line equivalent widths and absorption-line indices. The distinguishing characteristic of the survey is its coverage of a very wide baseline in velocity dispersion (90 per cent range {sigma}=40-230km/s), while achieving high signal-to-noise ratio throughout (median 60{AA}^-1^ at 5000{AA}). The data quality will enable estimates of Balmer-line ages to better than 20 per cent precision even for the faintest galaxies in the sample. Significant emission at H{alpha} was detected in ~30 per cent of the supercluster galaxies, including ~20 per cent of red-sequence members. Using line-ratio diagnostics, we find that the emission is LINER (low ionization nuclear emission region) like at high luminosity, but driven by star formation in low-luminosity galaxies. To characterize the absorption lines, we use the classical Lick indices in the spectral range 4000-5200{AA}. We introduce a new method for applying resolution corrections to the line-strength indices. We define a subset of galaxies with very low emission contamination, based on the H{alpha} line, and fit the index relations for this subset. The final sample analysed in this paper comprises 232 NFPS-selected galaxies meeting both the emission and the redshift criteria, of which 198 have measured velocity dispersions (i.e. are not unresolved).
- ID:
- ivo://CDS.VizieR/J/ApJ/661/1119
- Title:
- Spectroscopy in the 25 Ori group
- Short Name:
- J/ApJ/661/1119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report here on the photometric and kinematic properties of a well-defined group of nearly 200 low-mass pre-main-sequence stars, concentrated within ~1{deg} of the early-B star 25 Ori, in the Orion OB1a subassociation. We refer to this stellar aggregate as the 25 Orionis group. The group also harbors the Herbig Ae/Be star V346 Ori and a dozen other early-type stars with photometry, parallaxes, and some with IR excess emission, indicative of group membership.
- ID:
- ivo://CDS.VizieR/J/AJ/159/24
- Title:
- Spectroscopy & Kepler data of the EB star V404 Lyr
- Short Name:
- J/AJ/159/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first high-resolution spectra for the eclipsing binary V404Lyr showing {gamma}Dor pulsations, which we use to study its absolute properties. By fitting models to the disentangling spectrum of the primary star, we found that it has an effective temperature of T_eff,1_=7330{+/-}150K and a rotational velocity of v_1_sini=148{+/-}18km/s. The simultaneous analysis of our double-lined radial velocities and the pulsation-subtracted Kepler data gives us accurate stellar and system parameters of V404Lyr. The masses, radii, and luminosities are M1=2.17{+/-}0.06M_{sun}_, R1=1.91{+/-}0.02R_{sun}_, and L1=9.4{+/-}0.8L_{sun}_ for the primary, and M2=1.42{+/-}0.04M_{sun}_, R2=1.79{+/-}0.02R_{sun}_, and L2=2.9{+/-}0.2L_{sun}_ for the secondary. The tertiary component orbiting the eclipsing pair has a mass of M_3b_=0.71{+/-}0.15M_{sun}_ in an orbit of P_3b_=642{+/-}3d, e_3b_=0.21{+/-}0.04, and a_3b_=509{+/-}2R_{sun}_. The third light of l_3_=4.1{+/-}0.2% could be partly attributable to the K-type circumbinary object. By applying a multiple frequency analysis to the eclipse-subtracted light residuals, we detected 45 frequencies with signal-to-noise amplitude ratios larger than 4.0. Identified as independent pulsation modes, seven frequencies (f_1_-f_6_, f_9_), their new pulsation constants, and the location in the Hertzsprung-Russell diagram indicate that the pulsating primary is a {gamma}Dor-type variable star.
- ID:
- ivo://CDS.VizieR/J/MNRAS/395/855
- Title:
- Spectroscopy (310-1040nm) of HH 202
- Short Name:
- J/MNRAS/395/855
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results of deep echelle spectrophotometry of the brightest knot of the Herbig-Haro object HH 202 in the Orion Nebula - HH 202-S - using the Ultraviolet Visual Echelle Spectrograph in the spectral range from 3100 to 10400{AA} The high spectral resolution of the observations has permitted to separate the component associated with the ambient gas from that associated with the gas flow. We derive electron densities and temperatures from different diagnostics for both components, as well as the chemical abundances of several ions and elements from collisionally excited lines, including the first determinations of Ca^+^ and Cr^+^ abundances in the Orion Nebula. We also calculate the He+, C^2+^, O+ and O^2+^ abundances from recombination lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/834/9
- Title:
- Spectroscopy obs. of LeoA, Aqr & Sgr dwarf gal.
- Short Name:
- J/ApJ/834/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Keck/DEIMOS spectroscopy of individual stars in the relatively isolated Local Group dwarf galaxies Leo A, Aquarius, and the Sagittarius dwarf irregular galaxy. The three galaxies-but especially Leo A and Aquarius-share in common delayed star formation histories (SFHs) relative to many other isolated dwarf galaxies. The stars in all three galaxies are supported by dispersion. We found no evidence of stellar velocity structure, even for Aquarius, which has rotating HI gas. The velocity dispersions indicate that all three galaxies are dark-matter-dominated, with dark-to-baryonic mass ratios ranging from 4.4_-0.8_^+1.0^ (SagDIG) to 9.6_-1.8_^+2.5^ (Aquarius). Leo A and SagDIG have lower stellar metallicities than Aquarius, and they also have higher gas fractions, both of which would be expected if Aquarius were further along in its chemical evolution. The metallicity distribution of Leo A is inconsistent with a closed or leaky box model of chemical evolution, suggesting that the galaxy was pre-enriched or acquired external gas during star formation. The metallicities of stars increased steadily for all three galaxies, but possibly at different rates. The [{alpha}/Fe] ratios at a given [Fe/H] are lower than that of the Sculptor dwarf spheroidal galaxy, which indicates more extended SFHs than Sculptor, consistent with photometrically derived SFHs. Overall, the bulk kinematic and chemical properties for the late-forming dwarf galaxies do not diverge significantly from those of less delayed dwarf galaxies, including dwarf spheroidal galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJ/853/36
- Title:
- Spectroscopy obs. of 20 Planck gal. cluster cand.
- Short Name:
- J/ApJ/853/36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Gemini and Keck spectroscopic redshifts and velocity dispersions for 20 clusters detected via the Sunyaev-Zel'dovich (SZ) effect by the Planck space mission, with estimated masses in the range 2.3x10^14^M_{sun}_<M_500_^Pl^<9.4x10^14^M_{sun}_. Cluster members were selected for spectroscopic follow-up with Palomar, Gemini, and Keck optical and (in some cases) infrared imaging. Seven cluster redshifts were measured for the first time with this observing campaign, including one of the most distant Planck clusters confirmed to date, at z=0.782+/-0.010, PSZ2 G085.95+25.23. The spectroscopic redshift catalogs of members of each confirmed cluster are included as online tables. We show the galaxy redshift distributions and measure the cluster velocity dispersions. The cluster velocity dispersions obtained in this paper were used in a companion paper to measure the Planck mass bias and to constrain the cluster velocity bias.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/174
- Title:
- Spectroscopy obs. of RAVE J094921.8-161722
- Short Name:
- J/ApJ/862/174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a high-resolution (R~35000), high signal-to-noise ratio (S/N>200) Magellan/MIKE spectrum of the star RAVE J094921.8-161722, a bright (V=11.3) metal-poor red giant star with [Fe/H]=-2.2, identified as a carbon-enhanced metal-poor (CEMP) star from the RAVE survey. We report its detailed chemical abundance signature of light fusion elements and heavy neutron-capture elements. We find J0949-1617 to be a CEMP star with s-process enhancement that must have formed from gas enriched by a prior r-process event. Light neutron-capture elements follow a low-metallicity s-process pattern, while the heavier neutron-capture elements above Eu follow an r-process pattern. The Pb abundance is high, in line with an s-process origin. Thorium is also detected, as expected from an r-process origin, as Th is not produced in the s-process. We employ nucleosynthesis model predictions that take an initial r-process enhancement into account, and then determine the mass transfer of carbon and s-process material from a putative more massive companion onto the observed star. The resulting abundances agree well with the observed pattern. We conclude that J0949-1617 is the first bonafide CEMP-r+s star identified. This class of objects has previously been suggested to explain stars with neutron-capture element patterns that originate from neither the r- nor the s-process alone. We speculate that J0949-1617 formed in an environment similar to those of ultra-faint dwarf galaxies like TucanaIII and ReticulumII, which were enriched in r-process elements by one or multiple neutron star mergers at the earliest times.