- ID:
- ivo://CDS.VizieR/J/A+A/578/A64
- Title:
- Velocity curve of {tau} Boo A
- Short Name:
- J/A+A/578/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We observed the tau Boo system with the HARPS-N spectrograph in order to test a new observational strategy aimed to jointly study asteroseismology, the planetary orbit and star-planet magnetic interaction. We collected high-cadence observations on 11 nearly consecutive nights, and for each night averaged the raw FITS files using dedicated software in order to obtain high S/N spectra to study the variation of the CaII H&K lines and radial velocity values free from stellar oscillations without losing this latter information. Specific software was written to build a new custom mask used to refine the RV determination with the HARPS-N pipeline and to perform the spectroscopic analysis. We updated the planetary ephemeris and proved the acceleration due to the stellar binary companion. The study of stellar activity variation suggests the presence of an high-latitude plage during the time span of our observations. The correlation between the chromospheric activity and the planetary orbital phase remains unclear. Solar-like oscillations are detected in the radial velocity time series: we estimate asteroseismic quantities finding good agreement with theoretical predictions. With the stellar model built we find for tau Boo an age of 0.9+/-0.5Gyr, and could further constrain the value of the stellar mass to 1.38+/-0.05M_{sun}_.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/146/107
- Title:
- Velocity curves of 10 cataclysmic binaries
- Short Name:
- J/AJ/146/107
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on ground-based optical observations of 10 cataclysmic binaries that were discovered through their X-ray emission. Time-resolved radial velocity spectroscopy yields unambiguous orbital periods for eight objects and ambiguous results for the remaining two. The orbital periods range from 87 minutes to 9.38 hr. We also obtained time-series optical photometry for six targets, four of which have coherent pulsations. These periods are 1218s for 1RXSJ045707.4+452751, 628s for AXJ1740.2-2903, 477s for AXJ1853.3-0128, and 935s for IGRJ19267+1325. A total of seven of the sources have coherent oscillations in X-rays or optical, indicating that they are intermediate polars (DQ Herculis stars). Time-resolved spectroscopy of one object, SwiftJ2218.4+1925, shows that it is an AM Herculis star, or polar, and IGRJ19552+0044 may also be in that class. For another object, SwiftJ0746.2-1611, we find an orbital period of 9.384 hr and detect the spectrum of the secondary star. The secondary's spectral contribution implies a distance of 900 (+190, -150)pc, where the error bars are estimated using a Monte Carlo technique to account for correlated uncertainties.
- ID:
- ivo://CDS.VizieR/J/AJ/126/2268
- Title:
- Velocity dispersions and Mg2 index of galaxies
- Short Name:
- J/AJ/126/2268
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present central velocity dispersions and Mg_2_ line indices for an all-sky sample of 1175 elliptical and S0 galaxies, of which 984 had no previous measures. This sample contains the largest set of homogeneous spectroscopic data for a uniform sample of elliptical galaxies in the nearby universe. These galaxies were observed as part of the ENEAR (Redshift-Distance Survey of Nearby Early-Type Galaxies) project, designed to study the peculiar motions and internal properties of the local early-type galaxies. Using 523 repeated observations of 317 galaxies obtained during different runs, the data are brought to a common zero point. These multiple observations, taken during the many runs and different instrumental setups employed for this project, are used to derive statistical corrections to the data and are found to be relatively small, typically <~5% of the velocity dispersion and 0.01mag in the Mg_2_ line strength. Typical errors are about 8% in velocity dispersion and 0.01mag in Mg_2_, in good agreement with values published elsewhere.
- ID:
- ivo://CDS.VizieR/J/ApJS/201/29
- Title:
- Velocity dispersions in active galaxies
- Short Name:
- J/ApJS/201/29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We derive spatially resolved stellar kinematics for a sample of 84 out of 104 observed local (0.02<z<0.09) galaxies hosting type-1 active galactic nuclei (AGNs), based on long-slit spectra obtained at the 10m W. M. Keck-1 Telescope. In addition to providing central stellar velocity dispersions, we measure major axis rotation curves and velocity dispersion profiles using three separate wavelength regions, including the prominent Ca H&K, MgIb, and CaII NIR stellar features. In this paper, we compare kinematic measurements of stellar velocity dispersion obtained for different apertures, wavelength regions, and signal-to-noise ratios, and provide recipes to cross-calibrate the measurements reducing systematic effects to the level of a few percent. We also provide simple recipes based on readily observable quantities such as global colors and Ca H&K equivalent width that will allow observers of high-redshift AGN hosts to increase the probability of obtaining reliable stellar kinematic measurements from unresolved spectra in the region surrounding the Ca H&K lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/724/714
- Title:
- Velocity dispersions of MS1054-03 & Coma galaxies
- Short Name:
- J/ApJ/724/714
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured velocity dispersions ({sigma}) for a sample of 36 galaxies with J<21.2 or M_r_<-20.6mag in MS 1054-03, a massive cluster of galaxies at z=0.83. Our data are of uniformly high quality down to our selection limit, our 16h exposures typically yielding errors of only {delta}({sigma})~10% for L* and fainter galaxies. By combining our measurements with data from the literature, we have 53 cluster galaxies with measured dispersions, and HST/ACS-derived sizes, colors and surface brightness. This sample is complete for the typical L^*^ galaxy at z~1, unlike most previous z~1 cluster samples which are complete only for the massive cluster members (>10^11^M_{sun}_). We find no evidence for a change in the tilt of the fundamental plane (FP).
- ID:
- ivo://CDS.VizieR/J/A+A/633/A108
- Title:
- Velocity field of the Lyra complex
- Short Name:
- J/A+A/633/A108
- Date:
- 02 Nov 2021 11:15:00
- Publisher:
- CDS
- Description:
- The formation of cosmic structures culminates with the assembly of galaxy clusters, a process that is quite different from cluster to cluster. We present the study of the structure and dynamics of the Lyra complex, consisting of the two clusters RXC J1825.3+3026 and CIZA J1824.1+3029, which was very recently studied by using both X-ray and radio data. This is the first analysis based on the kinematics of member galaxies. New spectroscopic data for 285 galaxies were acquired at the Italian Telescopio Nazionale Galileo and were used in combination with PanSTARRS photometry. The result of our member selection is a sample of 198 galaxies. For RXCJ1825 and CIZAJ1824 we report the redshifts, z=0.0645 and z=0.0708, the first estimates of velocity dispersion, sigma_v_=995_-125_^+131^km/s and sigma_v_=700+/-50km/s, and of dynamical mass, M_200_=1.1+/-0.4x10^15^M_[sun}_ and M_200_=4+/-0.110^14^M_{sun}_. The past assembly of RXCJ1825 is traced by the two dominant galaxies, which are both aligned with the major axis of the galaxy distribution along the east-west direction, and by a minor northeast substructure. We also detect a quite peculiar high velocity field in the southwest region of the Lyra complex. This feature is likely related to a very luminous galaxy, which is characterized by a high velocity. This galaxy is suggested to be the central galaxy of a group that is in interaction with RXCJ1825 according to very recent studies based on X-ray and radio data. The redshift of the whole Lyra complex is z=0.067. Assuming that the redshift difference between RXCJ1825 and CIZAJ1824 is due to the relative kinematics, the projected distance between the cluster centers is D~1.3Mpc and the line-of-sight velocity difference is ~1750km/s. A dynamical analysis of the system shows that the two clusters are likely to be gravitationally bound in a pre-merger phase, and that CIZAJ1824 is moving toward RXCJ1825. Our results corroborate a picture where the Lyra region is the place of a very complex scenario of cluster assembly.
- ID:
- ivo://CDS.VizieR/J/ApJ/733/46
- Title:
- Velocity measurements in Segue 1
- Short Name:
- J/ApJ/733/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a comprehensive Keck/DEIMOS spectroscopic survey of the ultra-faint Milky Way satellite galaxy Segue 1. We have obtained velocity measurements for 98.2% of the stars within 67pc (10', or 2.3 half-light radii) of the center of Segue 1 that have colors and magnitudes consistent with membership, down to a magnitude limit of r=21.7. Based on photometric, kinematic, and metallicity information, we identify 71 stars as probable Segue 1 members, including some as far out as 87pc. After correcting for the influence of binary stars using repeated velocity measurements, we determine a velocity dispersion of 3.7^+1.4^_-1.1_km/s. The mass within the half-light radius is 5.8^+8.2^_-3.1_x10^5^M_{sun}_. The stellar kinematics of Segue 1 require very high mass-to-light ratios unless the system is far from dynamical equilibrium, even if the period distribution of unresolved binary stars is skewed toward implausibly short periods. With a total luminosity less than that of a single bright red giant and a V-band mass-to-light ratio of 3400M_{sun}_/L_{sun}_, Segue 1 is the darkest galaxy currently known.
- ID:
- ivo://CDS.VizieR/J/ApJ/853/114
- Title:
- Vertical population gradients in NGC 891. I.
- Short Name:
- J/ApJ/853/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have measured vertical and radial stellar population gradients in NGC 891. We compare these gradients to those known for the Milky Way from studies of resolved stars. Optical spectroscopic measurements extend spatially from the disk midplane up to 2.6kpc in height and out to a radius of 12kpc on both sides of the galaxy. Data were acquired with {nabla}Pak, a variable-pitch fiber integral field unit (IFU) on the WIYN telescope. We describe the laboratory and on-sky performance of {nabla}Pak, as well as modifications to the standard observational and analysis procedures necessary to calibrate data taken with this unique IFU. {nabla}Pak has a mean throughput of 80% at 5500{AA}. To achieve an estimated precision of 10% in light-weighted mean age and metallicity, we define a set of spatial apertures in radius and height in which spectra are binned to achieve a signal-to-noise ratio of ~20{AA}^-1^. We use spectral indices to measure age, metallicity, and abundance, indicating that NGC 891's stellar populations have 0.2<Z/Z_{sun}_<1 and +0.2dex {alpha}-enhancement on average. We find a clear transition from young (<3-5Gyr) to old (>7Gyr) stellar populations at 0.4kpc, roughly the scale height of the thin disk. We also find a slight trend toward younger populations at larger radii, consistent with flaring in an inside-out disk formation scenario. The vertical age gradient in NGC 891 is in remarkable qualitative agreement with a model for disk heating tuned to studies of the Milk Way's solar cylinder.
- ID:
- ivo://CDS.VizieR/J/ApJ/765/26
- Title:
- Very low-z SDSS galaxies with H{alpha} emission
- Short Name:
- J/ApJ/765/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Strong H{alpha} emitters (HAEs) dominate the z~4 Lyman-break galaxy (LBG) population. We have identified local analogs of these HAEs using the Sloan Digital Sky Survey. At z<0.4, only 0.04% of the galaxies are classified as HAEs with H{alpha} equivalent widths (>~500{AA}) comparable to that of z~4 HAEs. Local HAEs have lower stellar mass and lower ultraviolet (UV) luminosity than z~4 HAEs, yet the H{alpha}-to-UV luminosity ratio, as well as their specific star formation rate, is consistent with that of z~4 HAEs, indicating that they are scaled-down versions of high-z star-forming galaxies. Compared to the previously studied local analogs of LBGs selected using rest-frame UV properties, local HAEs show similar UV luminosity surface density, weaker D_n_(4000) break, lower metallicity, and lower stellar mass. This implies that the local HAEs are less evolved galaxies than the traditional Lyman break analogs. In the stacked spectrum, local HAEs show a significant He II{lambda}4686 emission line suggesting a population of hot, massive stars similar to that seen in some Wolf-Rayet galaxies. Low [N II]/[O III] line flux ratios imply that local HAEs are inconsistent with being systems that host bright active galactic nuclei. Instead, it is highly likely that local HAEs are galaxies with an elevated ionization parameter, either due to a high electron density or large escape fraction of hydrogen ionizing photons as in the case of Wolf-Rayet galaxies.
- ID:
- ivo://CDS.VizieR/J/A+AS/127/521
- Title:
- Very luminous IRAS galaxies spectra.
- Short Name:
- J/A+AS/127/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents the results of spectral observations for the largest complete sample of very luminous IRAS galaxies obtained to date. The sample consists of those 73 objects for which log(L_IR_/L_sun_)>=11.5 (H0=50 km/s/Mpc, q0=0.5) and mag<=15.5, and was extracted from the 2Jy IRAS redshift catalog (Cat. <II/174>). All spectra were obtained using 2.16m telescope of Beijing Astronomical Observatory during the years 1994-1996. A total of 123 galaxy spectra were obtained with spectral ranges of 4400A to 7100A and 3500A to 8100A at resolutions of 11.2A and 9.3A respectively. In addition to the 73 spectra for sample galaxies, we also present spectra for ten non-sample galaxies and a further 40 for the companions of sample galaxies. The data presented include nuclear spectrum and the parameters describing the emission lines, absorption lines and continua as well as DSS images and environmental parameters.