- ID:
- ivo://CDS.VizieR/J/A+A/327/1177
- Title:
- Kinematics and electron temperatures in Orion A
- Short Name:
- J/A+A/327/1177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A map of the core of Orion A, with a 42" resolution in the 64{alpha} recombination line of hydrogen, covering ~5' by ~5', is presented. The V_lsr_ distribution shows a complex variation about the center of the ionized gas emission: From {DELTA}{alpha}=-200" to +300", the V_lsr_ varies from -5km/s to +2km/s then to -4km/s, finally rising to +3km/s. A search for cold (T_e_~3000K) ionized gas toward the KL nebula has revealed no measurable differences in T_e_ between this region and other parts of Orion A. The average T_e_ from our data is 8300+/-200K. We find no significant difference between T_e_ values determined from radio recombination lines and those determined from forbidden optical lines of [O III], although the T_e_ value from Balmer decrement data is markedly lower. The turbulent velocity varies by <5% over the region mapped. On the basis of our 2.45' resolution, high dynamic range 6cm continuum map, we find that the emission falls off faster in the East than in the West. We find support for the model in which Orion A is ionization bounded in the East but density bounded in the West. The ionized gas in the West is flowing in the direction of the Sun, while the more positive V_lsr_ values in the east may be caused by the flow of ionized gas off the foreground Dark Bay. This ionized region may have little fine scale structure, since there is little continuum emission in interferometer maps.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/404/913
- Title:
- Kinematics and HR Diagrams of Southern Young Stars
- Short Name:
- J/A+A/404/913
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the spatial distribution, the space velocities and age distribution of the pre-main sequence (PMS) stars belonging to Ophiuchus, Lupus and Chamaeleon star-forming regions (SFRs), and of the young early-type star members of the Scorpius-Centaurus (Sco-Cen) OB association. These young stellar associations extend over the galactic longitude range from 280 to 360 degrees, and are at a distance interval of around 100 and 200pc. We present a compilation of PMS and early-type stars members of the investigated SFRs and OB associations. For these lists of stars we give the data used for the study of kinematic properties: positions, adopted distances, proper motions and radial velocities (whenever available), and the basic stellar data, used for the construction of Hertzsprung-Russel diagrams. All data have been taken from the literature. We also present the derived XYZ positions on the Galactic system, UVW components of the space velocities, visual extinction, and bolometric luminosity.
- ID:
- ivo://CDS.VizieR/J/A+A/424/447
- Title:
- Kinematics in 17 nearby spiral galaxies
- Short Name:
- J/A+A/424/447
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ionized gas and stellar kinematics have been measured along the major axes of seventeen nearby spiral galaxies of intermediate to late morphological type. We discuss the properties of each sample galaxy, distinguishing between those characterized by regular or peculiar kinematics. In most of the observed galaxies, ionized gas rotates more rapidly than stars and has a lower velocity dispersion, as is to be expected if the gas is confined in the disc and supported by rotation while the stars are mostly supported by dynamical pressure. In a few objects, gas and stars show almost the same rotational velocity and low velocity dispersion, suggesting that their motion is dominated by rotation. Incorporating the spiral galaxies studied by Bertola et al. (1996ApJ...458L..67B), Corsini et al. (1999, Cat. <J/A+A/342/671>, 2003, Cat. <J/A+A/408/873>) and Vega Beltran et al. (2001, Cat. <J/A+A/374/394>) we have compiled a sample of 50 S0/a-Scd galaxies, for which the major-axis kinematics of the ionized gas and stars have been obtained with the same spatial (~1") and spectral (~50km/s) resolution, and measured with the same analysis techniques.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/670
- Title:
- Kinematics in the M32 nucleus
- Short Name:
- J/ApJ/725/670
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using adaptive optics assisted Gemini/NIFS data, I study the present and past gas accretion in the central 3" of the M32 nucleus. From changes in the spectral slope and CO line depths near the center, I find evidence for unresolved dust emission resulting from black hole (BH) accretion. With a luminosity of ~2x10^38^erg/s, this dust emission appears to be the most luminous tracer of current BH accretion, 2 orders of magnitude more luminous than previously detected X-ray emission. These observations suggest that using high-resolution infrared data to search for dust emission may be an effective way to detect other nearby, low-luminosity BHs, such as those in globular clusters. I also examine the fossil evidence of gas accretion contained in the kinematics of the stars in the nucleus. The higher order moments (h3 and h4) of the line-of-sight velocity distribution show patterns that are remarkably similar to those seen on larger scales in elliptical galaxies and in gas-rich merger simulations. The kinematics suggests the presence of two components in the M32 nucleus, a dominant disk overlying a pressure supported component.
- ID:
- ivo://CDS.VizieR/J/ApJ/870/32
- Title:
- Kinematics in young star clusters & associations
- Short Name:
- J/ApJ/870/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia mission has opened a new window into the internal kinematics of young star clusters at the sub-km/s level, with implications for our understanding of how star clusters form and evolve. We use a sample of 28 clusters and associations with ages from ~1-5Myr, where lists of members are available from previous X-ray, optical, and infrared studies. Proper motions from Gaia DR2 reveal that at least 75% of these systems are expanding; however, rotation is only detected in one system. Typical expansion velocities are on the order of ~0.5km/s, and in several systems, there is a positive radial gradient in expansion velocity. Systems that are still embedded in molecular clouds are less likely to be expanding than those that are partially or fully revealed. One-dimensional velocity dispersions, which range from {sigma}_1D_=1 to 3km/s, imply that most of the stellar systems in our sample are supervirial and that some are unbound. In star-forming regions that contain multiple clusters or subclusters, we find no evidence that these groups are coalescing, implying that hierarchical cluster assembly, if it occurs, must happen rapidly during the embedded stage.
- ID:
- ivo://CDS.VizieR/J/A+A/555/A91
- Title:
- Kinematics of bulge red clump stars
- Short Name:
- J/A+A/555/A91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Galactic bulge is X-shaped, caused by the two southern arms of the X both crossing the lines of sight, producing a double red clump (one bright and one faint) in the color magnitude diagram. In this paper the authors measure the radial velocities and proper motions for a sample of 454 individual bulge giant stars, roughly equally distributed between the two red clumps to determine how such a structure could be formed from bar instabilities. The radial velocity distribution of stars in the bright red clump, which traces the closer overdensity of bulge stars, shows an excess of stars moving towards the Sun. Similarly, an excess of stars receding from the Sun is seen in the more distant overdensity, which is traced by faint red clump stars. This can be explained by the presence of stars on elongated orbits, which are most likely streaming along the arms of the X-shaped bulge. Proper motions for these stars are consistent with qualitative predictions of dynamical models of peanut-shaped bulges. Surprisingly, stars on elongated orbits have preferentially metal-poor (subsolar) metallicities, while the metal rich ones, in both overdensities, are preferentially found in more axisymmetric orbits.
- ID:
- ivo://CDS.VizieR/J/AJ/106/1273
- Title:
- Kinematics of dense clusters of galaxies
- Short Name:
- J/AJ/106/1273
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured redshifts in the fields of the 31 R>=1 Abell clusters with 0.02<z<0.05 and |bII|>30{deg}, from medium resolution spectra (5 or 7{AA}). At least ten of the fields are severely contaminated by superimposed velocity peaks. We derive the mean velocities and velocity dispersions of the 25 dense peaks in the sample. The abundance of peaks, 6.6x10^-6^h^3^ Mpc^-3^, is consistent with the mean number density of R>1 Abell clusters (Bahcall & Soneira 1983ApJ...270...20B). The range of velocity dispersions is 304-1346 km/s. The median dispersion is 718 km/s. The subset of eight systems with cD galaxies has a median velocity dispersion of 792 km/s, close to that of non-cD systems (626 km/s). When these data are combined with 16 cD cluster velocity dispersions from our previous study (Zabludoff et al. 1990ApJS...74....1Z, and Dunn [Proceedings of NATO Conf. 1991]), eight of 25 cD galaxies have peculiar motions larger than half the cluster velocity dispersions. These findings further support the conclusions of Beers & Geller (1983ApJ...274..491B), and Dunn (1991), who argue that cD galaxies do not lie in the global kinematic center, but in local potential minima. If so, systems with speeding cD's are probably a guide to substructure in dynamically evolving systems.
- ID:
- ivo://CDS.VizieR/J/MNRAS/421/3362
- Title:
- Kinematics of galactic red clump stars
- Short Name:
- J/MNRAS/421/3362
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate radial and vertical metallicity gradients for a sample of red clump stars from the RAdial Velocity Experiment (RAVE) Data Release 3. We select a total of 6781 stars, using a selection of colour, surface gravity and uncertainty in the derived space motion, and calculate for each star a probabilistic (kinematic) population assignment to a thin or thick disc using space motion and additionally another (dynamical) assignment using stellar vertical orbital eccentricity.
- ID:
- ivo://CDS.VizieR/J/AJ/139/1871
- Title:
- Kinematics of globulars in NGC 5128
- Short Name:
- J/AJ/139/1871
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New radial velocity measurements for previously known and newly confirmed globular clusters (GCs) in the nearby massive galaxy NGC 5128 are presented. We have obtained spectroscopy from LDSS-2/Magellan, VIMOS/Very Large Telescope, and HYDRA/Cerro Tololo Inter-American Observatory from which we have measured the radial velocities of 218 known, and identified 155 new, GCs. The current sample of confirmed GCs in NGC 5128 is now 605 with 563 of these having radial velocity measurements, the second largest kinematic database for any galaxy. We have performed a new kinematic analysis of the GC system that extends out to 45' in galactocentric radius. We have examined the systemic velocity, projected rotation amplitude and axis, and the projected velocity dispersion of the GCs as functions of galactocentric distance and metallicity.
- ID:
- ivo://CDS.VizieR/J/PAZh/32/906
- Title:
- Kinematics of Gould Belt Based on Open Clusters
- Short Name:
- J/PAZh/32/906
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have redetermined kinematic parameters of the Gould Belt using currently available data on the motion of nearby young (logt<7.91) open clusters, OB associations, and moving stellar groups. Our modeling shows that the residual velocities reach their maximum values of -4km/s for rotation (in the direction of Galactic rotation) and +4km/s for expansion at a distance from the kinematic center of 300pc. We have taken the following parameters of the Gould Belt center: R_0_=150pc and l_0_=128{deg}. The whole structure is shown to move relative to the local standard of rest at a velocity of 10.7+/-0.7km/s in the direction l=274+/-4{deg} and b=-1+/-3{deg}. Using the derived rotation velocity, we have estimated the virial mass of the Gould Belt to be 1.5 million solar masses.
