- ID:
- ivo://CDS.VizieR/J/AJ/147/85
- Title:
- Solar neighborhood. XXXIII. 45 M dwarfs
- Short Name:
- J/AJ/147/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present basic observational data and association membership analysis for 45 young and active low-mass stellar systems from the ongoing Research Consortium On Nearby Stars photometry and astrometry program at the Cerro Tololo Inter-American Observatory. Most of these systems have saturated X-ray emission (log(L_X_/L_bol_)>-3.5) based on X-ray fluxes from the ROSAT All-Sky Survey, and many are significantly more luminous than main-sequence stars of comparable color. We present parallaxes and proper motions, Johnson-Kron-Cousins VRI photometry, and multiplicity observations from the CTIOPI program on the CTIO 0.9m telescope. To this we add low-resolution optical spectroscopy and line measurements from the CTIO 1.5m telescope, and interferometric binary measurements from the Hubble Space Telescope Fine Guidance Sensors. We also incorporate data from published sources: JHK_S_ photometry from the Two Micron All Sky Survey point source catalog, X-ray data from the ROSAT All-Sky Survey, and radial velocities from literature sources. Within the sample of 45 systems, we identify 21 candidate low-mass pre-main-sequence members of nearby associations, including members of {beta} Pictoris, TW Hydrae, Argus, AB Doradus, two ambiguous {approx}30Myr old systems, and one object that may be a member of the Ursa Major moving group. Of the 21 candidate young systems, 14 are newly identified as a result of this work, and six of those are within 25pc of the Sun.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/887/115
- Title:
- Spectra of 28 stars in Price-Whelan 1 association
- Short Name:
- J/ApJ/887/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report spectroscopic measurements of stars in the recently discovered young stellar association Price-Whelan 1 (PW1), which was found in the vicinity of the Leading Arm (LA) of the Magellanic Stream (MS). We obtained Magellan+MIKE high-resolution spectra of the 28 brightest stars in PW 1 and used The Cannon to determine their stellar parameters. We find that the mean metallicity of PW1 is [Fe/H]=-1.23 with a small scatter of 0.06dex and the mean RV is V_hel_=276.7km/s with a dispersion of 11.0km/s. Our results are consistent in T_eff_, logg, and [Fe/H] with the young and metal-poor characteristics (116Myr and [Fe/H]=-1.1) determined for PW1 from our discovery paper. We find a strong correlation between the spatial pattern of the PW1 stars and the LA II gas with an offset of -10.15{deg} in L_MS_ and +1.55{deg} in B_MS_. The similarity in metallicity, velocity, and spatial patterns indicates that PW1 likely originated in LA II. We find that the spatial and kinematic separation between LA II and PW1 can be explained by ram pressure from Milky Way (MW) gas. Using orbit integrations that account for the LMC and MW halo and outer disk gas, we constrain the halo gas density at the orbital pericenter of PW1 to be n_halo_(17kpc)=2.7_-2.0_^+3.4^x10^-3^atoms/cm^3^ and the disk gas density at the midplane at 20kpc to be n_disk_(20kpc,0)=6.0_-2.0_^+1.5^x10^-2^atoms/cm^3^. We, therefore, conclude that PW 1 formed from the LA II of the MS, making it a powerful constraint on the MW-Magellanic interaction.
- ID:
- ivo://CDS.VizieR/J/MNRAS/412/1741
- Title:
- Spectroscopic obs. of 3 spiral galaxies
- Short Name:
- J/MNRAS/412/1741
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The correlation between the breaks in the metallicity distribution and the corotation radius of spiral galaxies has been already advocated in the past and is predicted by a chemodynamical model of our Galaxy that effectively introduces the role of spiral arms in the star formation rate. In this work, we present photometric and spectroscopic observations made with the Gemini Telescope for three of the best candidates of spiral galaxies to have the corotation inside the optical disc: IC 0167, NGC 1042 and NGC 6907. We observed the most intense and well-distributed HII regions of these galaxies, deriving reliable galactocentric distances and oxygen abundances by applying different statistical methods. From these results, we confirm the presence of variations in the gradients of metallicity of these galaxies that are possibly correlated with the corotation resonance.
- ID:
- ivo://CDS.VizieR/J/ApJ/793/39
- Title:
- Spectroscopic properties of BOSS compact galaxies
- Short Name:
- J/ApJ/793/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Massive compact systems at 0.2<z<0.6 are the missing link between the predominantly compact population of massive quiescent galaxies at high redshift and their analogs and relics in the local volume. The evolution in number density of these extreme objects over cosmic time is the crucial constraining factor for the models of massive galaxy assembly. We select a large sample of ~200 intermediate-redshift massive compacts from the Baryon Oscillation Spectroscopic Survey (BOSS) spectroscopy by identifying point-like Sloan Digital Sky Survey photometric sources with spectroscopic signatures of evolved redshifted galaxies. A subset of our targets have publicly available high-resolution ground-based images that we use to augment the dynamical and stellar population properties of these systems by their structural parameters. We confirm that all BOSS compact candidates are as compact as their high-redshift massive counterparts and less than half the size of similarly massive systems at z~0. We use the completeness-corrected numbers of BOSS compacts to compute lower limits on their number densities in narrow redshift bins spanning the range of our sample. The abundance of extremely dense quiescent galaxies at 0.2<z<0.6 is in excellent agreement with the number densities of these systems at high redshift. Our lower limits support the models of massive galaxy assembly through a series of minor mergers over the redshift range 0<z<2.
- 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/A+A/395/753
- Title:
- Spectroscopy of Coma early-type galaxies. II.
- Short Name:
- J/A+A/395/753
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present minor axis, offset major axis and one diagonal long slit spectra for 10 E and S0 galaxies of the Coma cluster drawn from a magnitude-limited sample studied before. We derive rotation curves, velocity dispersion profiles and the H_3_ and H_4_ coefficients of the Hermite decomposition of the line of sight velocity distribution. Moreover, we derive the line index profiles of Mg, Fe and Hbeta line indices and assess their errors. The data will be used to construct dynamical models of the galaxies and study their stellar populations.
- ID:
- ivo://CDS.VizieR/J/AJ/146/45
- Title:
- Spectroscopy of 6 early-type galaxies
- Short Name:
- J/AJ/146/45
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Adaptive optics assisted SINFONI observations of the central regions of 10 early-type galaxies are presented. Based primarily on the SINFONI kinematics, 10 black hole (BH) masses occupying the high-mass regime of the M_BH_-{sigma} relation are derived using three-integral Schwarzschild models. The effect of dark matter (DM) inclusion on the BH mass is explored. The omission of a DM halo in the model results in a higher stellar mass-to-light ratio, especially when extensive kinematic data are used in the model. However, when the diameter of the sphere of influence--computed using the BH mass derived without a dark halo--is at least 10 times the point-spread function FWHM during the observations, it is safe to exclude a DM component in the dynamical modeling, i.e., the change in BH mass is negligible. When the spatial resolution is marginal, restricting the mass-to-light ratio to the right value returns the correct M_BH_ although a dark halo is not present in the model. Compared to the M_BH_-{sigma} and M_BH_-L relations of McConnell et al., the 10 BHs are all more massive than expected from the luminosities and 7 BH masses are higher than expected from the stellar velocity dispersions of the host bulges. Using new fitted relations, which include the 10 galaxies, we find that the space density of the most massive BHs (M_BH_>~10^9^M_{sun}_) estimated from the M_BH_-L relation is higher than the estimate based on the M_BH_-{sigma} relation and the latter is higher than model predictions based on quasar counts, each by about an order of magnitude.
- ID:
- ivo://CDS.VizieR/J/AJ/116/2738
- Title:
- Spectroscopy of early-type galaxies
- Short Name:
- J/AJ/116/2738
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present central velocity dispersion measurements for 325 early-type galaxies in eight clusters and groups of galaxies, including new observations for 212 galaxies. The clusters and groups are the A262, A1367, Coma (A1656), A2634, Cancer, and Pegasus Clusters and the NGC 383 and NGC 507 Groups. The new measurements were derived from medium-dispersion spectra that cover 600{AA} centered on the Mg I b triplet at {lambda}~5175{AA}. Velocity dispersions were measured using the Tonry & Davis (1979AJ.....84.1511T) cross-correlation method, with a typical accuracy of 6%. A detailed comparison with other data sources is made.
- ID:
- ivo://CDS.VizieR/J/AJ/144/78
- Title:
- Spectroscopy of early-type galaxies in A262
- Short Name:
- J/AJ/144/78
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new radially resolved spectroscopy of eight early-type galaxies in the A262 cluster. The measurements include stellar rotation, velocity dispersion, H_3_ and H_4_coefficients of the line-of-sight velocity distribution along the major and minor axes and an intermediate axis as well as line-strength index profiles of Mg, Fe, and H{beta}. The ionized-gas velocity and velocity dispersion is measured for six sample galaxies along different axes. We derive dynamical mass-to-light ratios and dark matter densities from orbit-based dynamical models, complemented by the galaxies' ages, metallicities, and {alpha}-element abundances from single stellar-population models. The ionized-gas kinematics give a valuable consistency check for the model assumptions about orientation and intrinsic shape of the galaxies. Four galaxies have a significant detection of dark matter and their halos are about 10 times denser than in spirals of the same stellar mass. By calibrating dark matter densities to cosmological simulations we find assembly redshifts of z_DM_{approx}1-3, as previously reported for the Coma Cluster. The dynamical mass that follows the light is larger than expected for a Kroupa stellar initial mass function (IMF), especially in galaxies with high velocity dispersion {sigma}_eff_ inside the effective radius r_eff_. This could indicate a "massive" IMF in massive galaxies. Alternatively, some of the dark matter in massive galaxies could follow the light very closely. In combination with our comparison sample of Coma early-type galaxies, we now have 5 of 24 galaxies where (1) mass follows light to 1-3r_eff_, (2) the dynamical mass-to-light ratio of all the mass that follows the light is large ({approx}8-10 in the Kron-Cousins R band), and (3) the dark matter fraction is negligible to 1-3r_eff_. Unless the IMF in these galaxies is particularly "massive" and somehow coupled to the dark matter content, there seems to be a significant degeneracy between luminous and dark matter in at least some early-type galaxies. The role of violent relaxation is briefly discussed.
- ID:
- ivo://CDS.VizieR/J/AJ/154/251
- Title:
- Spectroscopy of galaxies in z=0.2-0.9 clusters
- Short Name:
- J/AJ/154/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of stellar populations in passive galaxies in seven massive X-ray clusters at z=0.19-0.89. Based on absorption-line strengths measured from our high signal-to-noise spectra, the data support primarily passive evolution of the galaxies. We use the scaling relations between velocity dispersions and the absorption-line strengths to determine representative mean line strengths for the clusters. From the age determinations based on the line strengths (and stellar population models), we find a formation redshift of z_form_=1.96_-0.19_^+0.24^. Based on line strength measurements from high signal-to-noise composite spectra of our data, we establish the relations between velocity dispersions, ages, metallicities [M/H], and abundance ratios [{alpha}/Fe] as a function of redshift. The [M/H]-velocity dispersion and [{alpha}/Fe]-velocity dispersion relations are steep and tight. The age-velocity dispersion relation is flat, with zero-point changes reflecting passive evolution. The scatter in all three parameters is within 0.08-0.15 dex at fixed velocity dispersions, indicating a large degree of synchronization in the evolution of the galaxies. We find an indication of cluster-to-cluster differences in metallicities and abundance ratios. However, variations in stellar populations with the cluster environment can only account for a very small fraction of the intrinsic scatter in the scaling relations. Thus, within these very massive clusters, the main driver of the properties of the stellar populations in passive galaxies appears to be the galaxy velocity dispersion.
