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- ID:
- ivo://CDS.VizieR/J/A+A/382/488
- Title:
- Stellar and ionized gas kinematics in NGC 2855
- Short Name:
- J/A+A/382/488
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present major and minor-axis kinematics of stars and ionized gas as well as narrow and broad-band surface photometry of the Sa spiral NGC 2855. In the nuclear regions of this unbarred and apparently undisturbed spiral galaxy the gas is rotating perpendicularly to the galaxy disk. We suggest that this kinematically-decoupled component is the signature of an acquisition process in the history of this galaxy.
- ID:
- ivo://CDS.VizieR/J/A+A/360/439
- Title:
- Stellar and ionized gas kinematics in NGC 4672
- Short Name:
- J/A+A/360/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the case of the early-type disk galaxy NGC 4672 as a new example of a galaxy characterized by the orthogonal geometrical decoupling between bulge and disk. The morphological features of this galaxy are discussed as well as the velocity curves and velocity dispersion profiles of stars and ionized gas along both its major and minor axis. We conclude that NGC 4672 has structural (i.e. a bulge elongated perpendicularly to the disk) and kinematical (i.e. a stellar core rotating perpendicularly to the disk) properties similar to those of the Sa NGC 4698. The presence of the isolated core suggests that the disk component is the end result of the acquisition of external material in polar orbits around a pre-existing oblate spheroid as in the case of the ring component of AM 2020-504, the prototype of polar ring ellipticals.
- ID:
- ivo://CDS.VizieR/J/MNRAS/477/4711
- Title:
- Stellar angular momentum for ManGa galaxies
- Short Name:
- J/MNRAS/477/4711
- Date:
- 17 Jan 2022 00:26:35
- Publisher:
- CDS
- Description:
- We measure {lambda}_Re_, a proxy for galaxy specific stellar angular momentum within one effective radius, and the ellipticity, {epsilon}, for about 2300 galaxies of all morphological types observed with integral field spectroscopy as part of the Mapping Nearby Galaxies at Apache Point Observatory survey, the largest such sample to date. We use the ({lambda}_Re_, {epsilon}) diagram to separate early-type galaxies into fast and slow rotators. We also visually classify each galaxy according to its optical morphology and two-dimensional stellar velocity field. Comparing these classifications to quantitative {lambda}_Re_ measurements reveals tight relationships between angular momentum and galaxy structure. In order to account for atmospheric seeing, we use realistic models of galaxy kinematics to derive a general approximate analytic correction for {lambda}_Re_. Thanks to the size of the sample and the large number of massive galaxies, we unambiguously detect a clear bimodality in the ({lambda}_Re_, {epsilon}) diagram which may result from fundamental differences in galaxy assembly history. There is a sharp secondary density peak inside the region of the diagram with low {lambda}_Re_ and {epsilon}<0.4, previously suggested as the definition for slow rotators. Most of these galaxies are visually classified as non-regular rotators and have high velocity dispersion. The intrinsic bimodality must be stronger, as it tends to be smoothed by noise and inclination. The large sample of slow rotators allows us for the first time to unveil a secondary peak at +/-90{deg} in their distribution of the misalignments between the photometric and kinematic position angles. We confirm that genuine slow rotators start appearing above M>=2x10^11^M_{sun}_ where a significant number of high-mass fast rotators also exist.
- ID:
- ivo://CDS.VizieR/J/AJ/140/379
- Title:
- Stellar associations in M51
- Short Name:
- J/AJ/140/379
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using data acquired as part of a unique Hubble Heritage imaging program of broadband colors of the interacting spiral system M51/NGC5195, we have conducted a photometric study of the stellar associations across the entire disk of the galaxy in order to assess trends in size, luminosity, and local environment associated with the recent star formation (SF) activity in the system. Starting with a sample of over 900 potential associations, we have produced color-magnitude and color-color diagrams for the 120 associations that were deemed to be single-aged.
- ID:
- ivo://CDS.VizieR/J/A+A/392/741
- Title:
- Stellar Catalogue in the Chandra DFS
- Short Name:
- J/A+A/392/741
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar catalogues in five passbands (UBVRI) over an area of approximately 0.3{deg}^2^, comprising about 1200 objects, and in seven passbands (UBVRIJK) over approximately 0.1{deg}^2^, comprising about 400 objects, in the direction of the Chandra Deep Field South are presented. The 90% completeness level of the number counts is reached at approximately U=23.8, B=24.0, V=23.5, R=23.0, I=21.0, J=20.5, K=19.0. These multi-band catalogues have been produced from publicly available, single passband catalogues. A scheme is presented to select point sources from these catalogues, by combining the SExtractor parameter CLASS_STAR from all available passbands. Probable QSOs and unresolved galaxies are identified by using the previously developed {chi}^2^-technique (Hatziminaoglou et al., 2002, Cat. <J/A+A/384/81>), that fits the overall spectral energy distributions to template spectra and determines the best fitting template. Approximately 15% of true galaxies are misclassified as stars by the {chi}^2^ method. The number of unresolved galaxies and QSOs identified by the {chi}^2^-technique, allows us to estimate that the remaining level of contamination by such objects is at the level of 2.4% of the number of stars. The fraction of missing stars being incorrectly removed as QSOs or unresolved galaxies is estimated to be similar. The resulting stellar catalogues and the objects identified as likely QSOs and unresolved galaxies with coordinates, observed magnitudes with errors and assigned spectral types by the {chi}^2^-technique are presented and are publicly available.
- ID:
- ivo://CDS.VizieR/J/MNRAS/396/2295
- Title:
- Stellar cluster dynamical masses in NGC2903
- Short Name:
- J/MNRAS/396/2295
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gas and star velocity dispersions have been derived for four circumnuclear star-forming regions (CNSFRs) and the nucleus of the spiral galaxy NGC 2903 using high-resolution spectroscopy in the blue and far red. Stellar velocity dispersions have been obtained from the CaII triplet lines at {lambda}{lambda} 8494, 8542, 8662{AA}, using cross-correlation techniques, while gas velocity dispersions have been measured by Gaussian fits to the H{beta} {lambda} 4861{AA} line.
- ID:
- ivo://CDS.VizieR/J/MNRAS/402/1005
- Title:
- Stellar cluster dynamical masses in NGC3310
- Short Name:
- J/MNRAS/402/1005
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gas and star velocity dispersions have been derived for eight circumnuclear star-forming regions (CNSFRs) and the nucleus of the spiral galaxy NGC 3310 using high-resolution spectroscopy in the blue and far red. Stellar velocity dispersions have been obtained from the CaII triplet in the near-IR, using cross-correlation techniques, while gas velocity dispersions have been measured by Gaussian fits to the H{beta} {lambda}4861{AA} and [OIII] {lambda}5007{AA} emission lines.
- ID:
- ivo://CDS.VizieR/J/A+A/657/A41
- Title:
- Stellar halo of NGC 5128 (Centaurus A)
- Short Name:
- J/A+A/657/A41
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- The extended stellar halos of galaxies contain important clues for investigating their assembly history and evolution. We investigate the resolved stellar content and the extended halo of NGC 5128 as a function of galactocentric distance, and trace the halo outward to its currently detectable limits. We used Hubble Space Telescope images obtained with the WFPC2, ACS, and WFC3 cameras equipped with F606W and F814W filters to resolve individual red giant branch (RGB) stars in 28 independent pointings across the halo of NGC 5128. The stellar halo analysis for 14 of these pointings is presented here for the first time. Star counts from deep VI color-magnitude diagrams reaching at least 1.5mag below the tip of the RGB are used to derive the surface density distribution of the halo. The contamination by Milky Way stars is assessed with a new control field, with models, and by combining optical and near-IR photometry. We present a new calibration of the WFC3 F606W + F814W photometry to the ground-based VI photometric system. The photometry shows that the stellar halo of NGC 5128 is dominated by old RGB stars that are present in all fields. The V-band surface brightness of fields changes from 23 to 32mag/arcsec^2^ between the innermost field only 8.3kpc from the galaxy center to our outermost halo fields, which are located 140 kpc away from the center along the major axis and 92 kpc along the minor axis. Within the inner ~30kpc, we also find evidence for a 2-3Gyr old population traced by asymptotic giant branch stars that are brighter than the tip of the RGB. This population contributes only up to 10% in total stellar mass if it is 2Gyr old, but a larger fraction of 30-40% is required if its age is 3Gyr. The stellar surface density profile is well fit by a classic r^1/4^ curve or a simple power-law form ~r^-3.1^ over the full radial range, with no obvious break in the slope, but with large field-to-field scatter. The ellipticity measured from integrated-light photometry in the inner parts, e=(b/a)=0.77, flattens to e=0.54+/-0.02 beyond 30kpc. Considering the flattening of the outer halo, the projection of the elliptical isophote on the semimajor axis for our most distant field reaches nearly 30 effective radii.
- ID:
- ivo://CDS.VizieR/J/ApJ/786/L10
- Title:
- Stellar IMF mass normalization for z~1 galaxies
- Short Name:
- J/ApJ/786/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar initial mass function (IMF) is a key parameter for studying galaxy evolution. Here we measure the IMF mass normalization for a sample of 68 field galaxies in the redshift range 0.7-0.9 within the Extended Groth Strip. To do this we derive the total (stellar + dark matter) mass-to-light [(M/L)] ratio using axisymmetric dynamical models. Within the region where we have kinematics (about one half-light radius), the models assume (1) that mass follows light, implying negligible differences between the slope of the stellar and total density profiles, (2) constant velocity anisotropy ({beta}_z_=1-{sigma}_z_^2^/{sigma}_R_^2^=0.2), and (3) that galaxies are seen at the average inclination for random orientations (i.e., i=60{deg}, where i=90{deg} represents edge-on). The dynamical models are based on anisotropic Jeans equations, constrained by Hubble Space Telescope/Advanced Camera for Surveys imaging and the central velocity dispersion of the galaxies, extracted from good-quality spectra taken by the DEEP2 survey. The population (M/L) are derived from full-spectrum fitting of the same spectra with a grid of simple stellar population models. Recent dynamical modeling results from the ATLAS^3D^ project and numerical simulations of galaxy evolution indicate that the dark matter fraction within the central regions of our galaxies should be small. This suggests that our derived total (M/L) should closely approximate the stellar M/L. Our comparison of the dynamical (M/L) and the population (M/L) then implies that for galaxies with stellar mass M_*_>~10^11^ M_{sun}_, the average normalization of the IMF is consistent with a Salpeter slope, with a substantial scatter. This is similar to what is found within a similar mass range for nearby galaxies.
