- ID:
- ivo://CDS.VizieR/J/MNRAS/440/2265
- Title:
- Spectroscopy of NGC3310 HII regions
- Short Name:
- J/MNRAS/440/2265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Numerical simulations of minor mergers predict little enhancement in the global star formation activity. However, it is still unclear the impact they have on the chemical state of the whole galaxy and on the mass build-up in the galaxy bulge and disc. We present a two-dimensional analysis of NCG 3310, currently undergoing an intense starburst likely caused by a recent minor interaction, using data from the PPAK Integral Field Spectroscopy Nearby Galaxies Survey (PINGS). With data from a large sample of about a hundred HII regions identified throughout the disc and spiral arms, we derive, using strong-line metallicity indicators and direct derivations, a rather flat gaseous abundance gradient. Thus, metal mixing processes occurred, as in observed galaxy interactions. Spectra from PINGS data and additional multiwavelength imaging were used to perform a spectral energy distribution fitting to the stellar emission and a photoionization modelling of the nebulae. The ionizing stellar population is characterized by single populations with a narrow age range (2.5-5Myr) and a broad range of masses (10^4^-6x10^6^M_{sun}_). The effect of dust grains in the nebulae is important, indicating that 25-70% of the ultraviolet photons can be absorbed by dust. The ionizing stellar population within the Hii regions represents typically a few per cent of the total stellar mass. This ratio, a proxy to the specific star formation rate, presents a flat or negative radial gradient. Therefore, minor interactions may indeed play an important role in the mass build-up of the bulge.
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- ID:
- ivo://CDS.VizieR/J/A+A/574/A109
- Title:
- Spectroscopy of Planetary Nebulae in NGC 5128
- Short Name:
- J/A+A/574/A109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Planetary nebulae (PNe) are excellent tracers of the common low mass stars through their strong and narrow emission lines. The velocities of large numbers of PNe are excellent tracers of galaxy kinematics. NGC 5128, the nearest large early-type galaxy offers the possibility to gather a large PN sample. Imaging and spectroscopic observations of PNe in NGC 5128 were obtained to find PNe and measure their velocities. Combined with literature data, a large sample of high quality kinematic probes is assembled for dynamical studies in NGC 5128. NTT Imaging was obtained in 15 fields in NGC 5128 over 1 degree with EMMI and [OIII] and off-band filters. Newly detected emission sources, combined with literature PN, were used as input for FLAMES multi-fibre spectroscopy in MEDUSA mode. Spectra of the 4600-5100{AA} region were analysed and velocities were measured based on [OIII]4959,5007{AA} and often H{beta}. The chief results are catalogues of 1118 PN candidates and 1267 spectroscopically confirmed PNe in NGC 5128. The catalogue of PN candidates contains 1060 potential PNe discovered with NTT EMMI imaging and 58 from literature surveys. The spectroscopically confirmed PN catalogue has FLAMES radial velocity and emission line measurements for 1135 PNe, of which 486 are newly confirmed here. An additional 132 PN radial velocities are available from the literature. For 629 PNe observed with FLAMES, H-beta was measured in addition to the [OIII] emission lines. Nine targets show double-lined or more complex profiles (19 components in total), and their possible origin is discussed. FLAMES spectra of 48 globular clusters were also targetted, and 11 had emission lines detected (two with multiple components), but only 3 are PNe likely to belong to the host globular. Conclusions. The total of 1267 confirmed PNe in NGC 5128 with radial velocity measurements, of which 1135 have small velocity errors, is the largest such collection of individual kinematic probes in an early-type galaxy. This PN dataset, as well as the catalogue of 1118 PN candidates, are valuable resources for detailed investigation of the kinematics and stellar population of NGC 5128.
- ID:
- ivo://CDS.VizieR/J/ApJ/902/17
- Title:
- Spectroscopy of quiescent gal. in 9 lensing clusters
- Short Name:
- J/ApJ/902/17
- Date:
- 03 Mar 2022 11:35:20
- Publisher:
- CDS
- Description:
- We measure the central stellar velocity dispersion function for quiescent galaxies in a set of nine northern clusters in the redshift range 0.18<z<0.29 and with strong lensing arcs in Hubble Space Telescope images. The velocity dispersion function links galaxies directly to their dark matter halos. From dense SDSS and MMT/Hectospec spectroscopy, we identify 222-463 spectroscopic members in each cluster. We derive physical properties of cluster members including redshift, D_n_4000, and central stellar velocity dispersion and we include a table of these measurements for 3419 cluster members. We construct the velocity dispersion functions for quiescent galaxies with D_n_4000>1.5 and within R200. The cluster velocity dispersion functions all show excesses at {sigma}>~250km/s compared to the field velocity dispersion function. The velocity dispersion function slope at large velocity dispersion ({sigma}>160km/s) is steeper for more massive clusters, consistent with the trend observed for cluster luminosity functions. The spatial distribution of galaxies with large velocity dispersion at radii larger than R200 further underscores the probable major role of dry mergers in the growth of massive cluster galaxies during cluster assembly.
- ID:
- ivo://CDS.VizieR/J/ApJ/808/95
- Title:
- Spectroscopy of Reticulum II
- Short Name:
- J/ApJ/808/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Magellan/M2FS, Very Large Telescope/GIRAFFE, and Gemini South/GMOS spectroscopy of the newly discovered Milky Way satellite Reticulum II. Based on the spectra of 25 Ret II member stars selected from Dark Energy Survey imaging, we measure a mean heliocentric velocity of 62.8+/-0.5km/s and a velocity dispersion of 3.3+/-0.7km/s. The mass-to-light ratio of Ret II within its half-light radius is 470+/-210M_{sun}_/L_{sun}_, demonstrating that it is a strongly dark matter-dominated system. Despite its spatial proximity to the Magellanic Clouds, the radial velocity of Ret II differs from that of the LMC and SMC by 199 and 83km/s, respectively, suggesting that it is not gravitationally bound to the Magellanic system. The likely member stars of Ret II span 1.3dex in metallicity, with a dispersion of 0.28+/-0.09dex, and we identify several extremely metal-poor stars with [Fe/H]<-3. In combination with its luminosity, size, and ellipticity, these results confirm that Ret II is an ultra-faint dwarf galaxy. With a mean metallicity of [Fe/H]=-2.65+/-0.07, Ret II matches Segue 1 as the most metal-poor galaxy known. Although Ret II is the third-closest dwarf galaxy to the Milky Way, the line-of-sight integral of the dark matter density squared is log_10_(J)=18.8+/-0.6GeV^2^/cm^5^ within 0.2{deg}, indicating that the predicted gamma-ray flux from dark matter annihilation in Ret II is lower than that of several other dwarf galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/156/257
- Title:
- Spectroscopy of RGB stars in Draco & Ursa Minor
- Short Name:
- J/AJ/156/257
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measuring the frequency of binary stars in dwarf spheroidal galaxies (dSphs) requires data taken over long time intervals. We combine radial velocity measurements from five literature sources taken over the course of ~30 years to yield the largest multi-epoch kinematic sample for stars in the dSphs Draco and Ursa Minor. With this data set, we are able to implement an improved version of the Bayesian technique described in Spencer et al. (2017, J/AJ/153/254) to evaluate the binary fraction of red giant stars in these dwarf galaxies. Assuming Duquennoy & Mayor (1991A&A...248..485D) period and mass ratio distributions, the binary fractions in Draco and Ursa Minor are 0.50_-0.06_^+0.04^ and 0.78_-0.08_^+0.09^, respectively. We find that a normal mass ratio distribution is preferred over a flat distribution, and that log-normal period distributions centered on long periods ({mu}_logP_>3.5) are preferred over distributions centered on short ones. We reanalyzed the binary fractions in Leo II, Carina, Fornax, Sculptor, and Sextans, and find that there is <1% chance that binary fraction is a constant quantity across all seven dwarfs, unless the period distribution varies greatly. This indicates that the binary populations in Milky Way dSphs are not identical in regard to their binary fractions, period distributions, or both. We consider many different properties of the dwarfs (e.g., mass, radius, luminosity, etc.) and find that binary fraction might be larger in dwarfs that formed their stars quickly and/or have high velocity dispersions.
- ID:
- ivo://CDS.VizieR/J/AJ/144/168
- Title:
- Spectroscopy of Scl 1019417 and UMi 20103
- Short Name:
- J/AJ/144/168
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The most metal-poor stars in dwarf spheroidal galaxies (dSphs) can show the nucleosynthetic patterns of one or a few supernovae (SNe). These SNe could have zero metallicity, making metal-poor dSph stars the closest surviving links to Population III stars. Metal-poor dSph stars also help to reveal the formation mechanism of the Milky Way (MW) halo. We present the detailed abundances from Keck/HIRES spectroscopy for two very metal-poor stars in two MW dSphs. One star, in the Sculptor dSph, has [FeI/H]=-2.40. The other star, in the Ursa Minor dSph, has [FeI/H]=-3.16. Both stars fall in the previously discovered low-metallicity, high-[{alpha}/Fe] plateau. Most abundance ratios of very metal-poor stars in these two dSphs are largely consistent with very metal-poor halo stars. However, the abundances of Na and some r-process elements lie at the lower end of the envelope defined by inner halo stars of similar metallicity. We propose that the metallicity dependence of SN yields is the cause. The earliest SNe in low-mass dSphs have less gas to pollute than the earliest SNe in massive halo progenitors. As a result, dSph stars at -3<[Fe/H]<-2 sample SNe with [Fe/H]{Lt}-3, whereas halo stars in the same metallicity range sample SNe with [Fe/H]~-3. Consequently, enhancements in [Na/Fe] and [r/Fe] were deferred to higher metallicity in dSphs than in the progenitors of the inner halo.
3377. Spectroscopy of Segue 1
- ID:
- ivo://CDS.VizieR/J/ApJ/692/1464
- Title:
- Spectroscopy of Segue 1
- Short Name:
- J/ApJ/692/1464
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Keck/DEIMOS spectroscopy of Segue 1, an ultra-low-luminosity (M_V_=-1.5^+0.6^_-0.8_) Milky Way satellite companion. While the combined size and luminosity of Segue 1 are consistent with either a globular cluster or a dwarf galaxy, we present spectroscopic evidence that this object is a dark matter-dominated dwarf galaxy. We identify 24 stars as members of Segue 1 with a mean heliocentric recession velocity of 206+/-1.3km/s. Although Segue 1 spatially overlaps the leading arm of the Sagittarius stream, its velocity is 100km/s different from that predicted for recent Sagittarius tidal debris at this position. Using spectral synthesis modeling, we derive a metallicity for the single red giant branch star in our sample of [Fe/H]=-3.3+/-0.2dex. We conclude that Segue 1 is the least luminous of the ultra-faint galaxies recently discovered around the Milky Way, and is thus the least-luminous known galaxy.
- ID:
- ivo://CDS.VizieR/J/ApJS/132/37
- Title:
- Spectroscopy of Southern warm IR galaxies
- Short Name:
- J/ApJS/132/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present high-resolution optical spectra and optical classifications from our large sample of 285 warm infrared galaxies 10^8^<L_IR_<10^12.5^L_{sun}_. We have classified these galaxies using new theoretical lines on the standard optical diagnostic diagrams. We use a theoretical extreme mixing line between the starburst and AGN regions to classify LINER galaxies and we define a theoretical boundary separating AGNs from starbursts. We find that many galaxies previously classified as LINERs appear to lie on a mixing sequence between starburst and AGN type galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/143/98
- Title:
- Spectroscopy of star-forming regions in NGC 4194
- Short Name:
- J/AJ/143/98
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of long-slit spectroscopy at position angles 68{deg}, 131{deg}, and 164{deg} for the minor-merger NGC 4194, a luminous infrared starburst galaxy. The mass within 1.2kpc of the dynamical center is estimated to be 4.8*109 to 1.7*1010 M{sun}, depending on the assumed inclination to the plane of the sky. The star formation rate (SFR) in the areas sampled is 8 M{sun}/yr. The metallicity, log(O/H)+12, ranges from ~8.8 to >9.0 in regions of significant star formation, suggesting that the metallicity has been enhanced by the current star formation. The star-forming regions range in age from 5 to 9Myr, with the youngest ages occurring in the regions of high SFR. Electron temperatures and the location of the spectra in emission line diagnostic diagrams suggest the presence of shock waves, presumably due to the presence of supernovae, winds from massive stars, and/or collisions of clouds due to the merger. The presence of massive stars and supernovae is consistent with the ages determined for the star-forming regions. The ages of the continua produced by the stellar population are estimated to range from 10Myr to 5Gyr. Much of the stellar population represented in the continua was probably formed before the merger and represents the progenitor galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A107
- Title:
- Spectroscopy of the Eri 2 cluster
- Short Name:
- J/A+A/635/A107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It has been shown that the ultra-faint dwarf galaxy Eridanus 2 may host a stellar cluster in its centre. If this cluster is shown to exist, it can be used to set constraints on the mass and abundance of massive astrophysical compact halo objects (MACHOs) as a form of dark matter. Previous research has shown promising expectations in the mass range of 10-100M_{sun}_, but lacked spectroscopic measurements of the cluster. We aim to provide spectroscopic evidence regarding the nature of the putative star cluster in Eridanus 2 and to place constraints on MACHOs as a constituent of dark matter. We present spectroscopic observations of the central square arcminute of Eridanus 2 from MUSE-Faint, a survey of ultrafaint dwarf galaxies with the Multi Unit Spectroscopic Explorer on the Very Large Telescope. We derived line-of-sight velocities for possible member stars of the putative cluster and for stars in the centre of Eridanus 2. We discuss the existence of the cluster and determine new constraints for MACHOs using the Fokker-Planck diffusion approximation. Out of 182 extracted spectra, we identify 26 member stars of Eridanus 2, seven of which are possible cluster members. We find intrinsic mean line-of-sight velocities of 79.7^+3.1^_3.8_km/s and 76.0^+3.2^_3.7_km/s for the cluster and the bulk of Eridanus 2, respectively, as well as intrinsic velocity dispersions of <7.6km/s (68-% upper limit) and 10.3^+3.9^_3.2_km/s, respectively. This indicates that the cluster most likely exists as a distinct dynamical population hosted by Eridanus 2 and that it does not have a surplus of dark matter over the background distribution. Among the member stars in the bulk of Eridanus 2, we find possible carbon stars, alluding to the existence of an intermediate-age population.We derived constraints on the fraction of dark matter that can consist of MACHOs with a given mass between 1-10^5^M_{sun}_. For dark matter consisting purely of MACHOs, the mass of the MACHOs must be less than 7.6M_{sun}_ and 44M_{sun}_ at a 68- and 95-% confidence level, respectively.
