- ID:
- ivo://CDS.VizieR/J/A+AS/129/87
- Title:
- ROSAT RASS II observations of IRAS galaxies
- Short Name:
- J/A+AS/129/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 120000 X-ray sources detected in the RASS II processing of the ROSAT All-Sky Survey are correlated with the 14315 IRAS galaxies selected from the IRAS Point Source Catalogue: 372 IRAS galaxies show X-ray emission within a distance of 100 arcsec from the infrared position. By inspecting the structure of the X-ray emission in overlays on optical images we quantify the likelihood that the X-rays originate from the IRAS galaxy. For 197 objects the soft X-ray emission is very likely associated with the IRAS galaxy. Their soft X-ray properties are determined and compared with their far-infrared emission.
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- ID:
- ivo://CDS.VizieR/J/AJ/135/209
- Title:
- Rotational and radial velocities 761 HIP giants
- Short Name:
- J/AJ/135/209
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present rotational and radial velocities for a sample of 761 giants selected from the Hipparcos Catalogue to lie within 100pc of the Sun. Our original goal was to examine stellar rotation in field giants using spectroscopic line broadening to look for evidence of excess rotation that could be attributed to planets that were engulfed as the parent stars expanded.
- ID:
- ivo://CDS.VizieR/J/AJ/147/138
- Title:
- Rotational and radial velocities of red giants
- Short Name:
- J/AJ/147/138
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study presents the rotational distribution of red giant (RG) stars in 11 old to intermediate age open clusters. The masses of these stars are all above the Kraft break, so they lose negligible amounts of their birth angular momentum (AM) during the main-sequence (MS) evolution. However, they do span a mass range with quite different AM distributions imparted during formation, with the stars less massive than ~1.6M_{sun}_ arriving on the MS with lower rotation rates than the more massive stars. The majority of RGs in this study are slow rotators across the entire red giant branch regardless of mass, supporting the picture that intermediate-mass stars rapidly spin down when they evolve off the MS and develop convection zones capable of driving a magnetic dynamo. Nevertheless, a small fraction of RGs in open clusters show some level of enhanced rotation, and faster rotators are as common in these clusters as in the field RG population. Most of these enhanced rotators appear to be red clump stars, which is also true of the underlying stellar sample, while others are clearly RGs that are above or below the clump. In addition to rotational velocities, the radial velocities (RVs) and membership probabilities of individual stars are also presented. Cluster heliocentric RVs for NGC 6005 and Pismis 18 are reported for the first time.
- ID:
- ivo://CDS.VizieR/J/ApJ/648/580
- Title:
- Rotational velocities in 19 open clusters
- Short Name:
- J/ApJ/648/580
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters offer us the means to study stellar properties in samples with well-defined ages and initial chemical composition. Here we present a survey of projected rotational velocities for a large sample of mainly B-type stars in young clusters to study the time evolution of the rotational properties of massive stars. The survey is based on moderate-resolution spectra made with the WIYN 3.5m and CTIO 4m telescopes and Hydra multi-object spectrographs, and the target stars are members of 19 young open clusters with an age range of approximately 673Myr. We made fits of the observed lines HeI {lambda}{lambda}4026, 4387, 4471, and MgII {lambda}4481, using model theoretical profiles to find projected rotational velocities for a total of 496 OB stars.
- ID:
- ivo://CDS.VizieR/J/AJ/150/41
- Title:
- Rotational velocities of 136 B stars from ALS
- Short Name:
- J/AJ/150/41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have determined projected rotational velocities, vsini, from Magellan/MIKE echelle spectra for a sample of 136 early B-type stars having large Galactocentric distances. The target selection was done independently of their possible membership in clusters, associations or field stars. We subsequently examined the literature and assigned each star as Field, Association, or Cluster. Our vsini results are consistent with a difference in aggregate vsini with stellar density. We fit bimodal Maxwellian distributions to the Field, Association, and Cluster subsamples representing sharp-lined and broad-lined components. The first two distributions, in particular, for the Field and Association are consistent with strong bimodality in vsini. Radial velocities are also presented, which are useful for further studies of binarity in B-type stars, and we also identify a sample of possible new double-lined spectroscopic binaries. In addition, we find 18 candidate Be stars showing emission at H{alpha}.
- ID:
- ivo://CDS.VizieR/J/A+AS/127/277
- Title:
- Rotation and binary rate among giant F stars
- Short Name:
- J/A+AS/127/277
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have tested the hypothesis of Berthet (1991A&A...251..171B) which foresees that Am stars become giant metallic A and F stars (defined by an enhanced value of the blanketing parameter {delta}m2 of the Geneva photometry) when they evolved. If this hypothesis is right, Am and metallic A-FIII stars need to have the same rate of binaries and a similar distribution of vsini. From our new spectroscopic data and from vsini and radial velocities in the literature, we show that it is not the case. The metallic giant stars are often fast rotators with vsini larger than 100 km/s, while the maximum rotational velocity for Am stars is about 100 km/s. The rate of tight binaries with periods less than 1000 days is less than 30 % among metallic giants, which is incompatible with the value of 75 % for Am stars (Abt & Levy, 1985ApJS...59..229A). Therefore, the simplest way to explain the existence of giant metallic F stars is to suggest that all normal A and early F stars might go through a short "metallic" phase when they are finishing their life on the main sequence. Besides, it is shown that only giant stars with spectral type comprised between F0 and F6 may have a really enhanced {delta}m2 value, while all A-type giants seem to be normal.
- ID:
- ivo://CDS.VizieR/J/A+AS/113/35
- Title:
- Rotation curves of galaxies in DC 1842-63
- Short Name:
- J/A+AS/113/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- H {alpha} maps, velocity contour maps and rotation curves are presented for nine galaxies in the Southern cluster DC 1842-63. These data have been obtained from the two-dimensional H {alpha} observations at the 3.60m ESO Telescope equipped with CIGALE, a scanning Fabry-Perot interferometer.
- ID:
- ivo://CDS.VizieR/J/ApJ/733/115
- Title:
- Rotation periods and membership in M34
- Short Name:
- J/ApJ/733/115
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a 5 month photometric time-series survey for stellar rotation periods combined with a 4 year radial-velocity survey for membership and binarity in the 220Myr open cluster M34. We report surface rotation periods for 120 stars, 83 of which are kinematic and photometric late-type cluster members. A comparison to previous work serves to illustrate the importance of high-cadence long baseline photometric observations and membership information. The new M34 periods are less biased against slow rotation and cleaned for non-members. The rotation periods of the cluster members span over more than an order of magnitude from 0.5 days up to 11.5 days, and trace two distinct rotational sequences -fast (C) and moderate-to-slow (I)- in the color-period diagram. The sequences represent two different states (fast and slow) in the rotational evolution of the late-type cluster members. We use the color-period diagrams for M34 and for younger and older clusters to estimate the timescale for the transition from the C to the I sequence and find <~150Myr, ~150-300Myr, and ~300-600 Myr for G, early-mid K, and late K dwarfs, respectively. The small number of stars in the gap between C and I suggests a quick transition. We determine a gyrochronology age of 240Myr for M34.
- ID:
- ivo://CDS.VizieR/J/AJ/117/2941
- Title:
- Rotation periods of Orion PMS stars
- Short Name:
- J/AJ/117/2941
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report rotation periods for 254 stars in an area 40'x80' centered on the Orion Nebula. We show that these stars are likely members of the young (~10^6^yr) Orion OBIc/d association. The rotation period distribution we determine, which is sensitive to periods 0.1<P<8days, shows a sharp cutoff for periods P<0.5days, corresponding to breakup velocity for these stars. Above 0.5days the distribution is consistent with a uniform distribution; we do not find evidence for a "gap" of periods at 4-5days. We find signatures of active accretion among stars at all periods; active accretion does not occur preferentially among slow rotators in our sample. We find no correlation between rotation period and near-IR signatures of circumstellar disks. In addition, we show that the distribution of vsini among stars in our sample bears striking resemblance to that of low-mass Pleiades stars. We discuss the implications of our findings for the evolution of stellar angular momentum during the pre-main-sequence phase. We argue that all stars in our sample must still deplete angular momentum by factors of roughly 5-10, if they are to preserve their vsini distribution over approximately the next 100Myr. We consider in detail whether our findings are consistent with disk-regulated stellar rotation. We do not find observational evidence that magnetic disk-locking is the dominant mechanism in angular momentum evolution during the premain-sequence phase.
- ID:
- ivo://CDS.VizieR/J/ApJS/249/30
- Title:
- R-Process Alliance: metal-poor star spectroscopy
- Short Name:
- J/ApJS/249/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This compilation is the fourth data release from the R-Process Alliance (RPA) search for r-process-enhanced stars and the second release based on "snapshot" high-resolution (R~30000) spectra collected with the du Pont 2.5m Telescope. In this data release, we propose a new delineation between the r-I and r-II stellar classes at [Eu/Fe]=+0.7, instead of the empirically chosen [Eu/Fe]=+1.0 level previously in use, based on statistical tests of the complete set of RPA data released to date. We also statistically justify the minimum level of [Eu/Fe] for definition of the r-I stars, [Eu/Fe]>+0.3. Redefining the separation between r-I and r-II stars will aid in the analysis of the possible progenitors of these two classes of stars and determine whether these signatures arise from separate astrophysical sources at all. Applying this redefinition to previous RPA data, the number of identified r-II and r-I stars changes to 51 and 121, respectively, from the initial set of data releases published thus far. In this data release, we identify 21 new r-II, 111 new r-I (plus 3 re-identified), and 7 new (plus 1 re-identified) limited-r stars out of a total of 232 target stars, resulting in a total sample of 72 new r-II stars, 232 new r-I stars, and 42 new limited-r stars identified by the RPA to date.
