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5651. Rosette globulettes and shells in the IR
ID:
ivo://CDS.VizieR/J/A+A/567/A108
Title:
Rosette globulettes and shells in the IR
Short Name:
J/A+A/567/A108
Date:
21 Oct 2021
Publisher:
CDS
Description:
The compressed molecular shells around the central clusters in HII regions break up into morphologically distinct fragments due to the UV light from the central OB stars. Tiny, dense, sub-solar mass clumps called globulettes are one of such distinct features. The objective of this study is to study the globulettes and the shells in the Rosette Nebula. Their extinction, surface brightness in the cores and rims, and density have been estimated through NIR observations. The star-formation activity has also been studied. The NIR JHKs photometry is used in creating visual extinction maps and studying the density of individual globulettes.
5652. Rosette Nebula globules
ID:
ivo://CDS.VizieR/J/A+A/605/A82
Title:
Rosette Nebula globules
Short Name:
J/A+A/605/A82
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Rosette nebula is an HII region ionized mainly by the stellar cluster NGC 2244. Elephant trunks, globules, and globulettes are seen at the interface where the HII region and the surrounding molecular shell meet. We have observed a field in the northwestern part of the Rosette nebula where we study the small globules protruding from the shell. Our aim is to measure their properties and study their star-formation history in continuation of our earlier study of the features of the region. We imaged the region in broadband near-infrared (NIR) JsHKs filters and narrowband H_2_ 1-0 S(1), P{beta}, and continuum filters using the SOFI camera at the ESO/NTT. The imaging was used to study the stellar population and surface brightness, create visual extinction maps, and locate star formation. Mid-infrared (MIR) Spitzer IRAC and WISE and optical NOT images were used to further study the star formation and the structure of the globules. The NIR and MIR observations indicate an outflow, which is confirmed with CO observations made with APEX.
5653. Rotating models of A and F stars
ID:
ivo://CDS.VizieR/J/A+A/346/586
Title:
Rotating models of A and F stars
Short Name:
J/A+A/346/586
Date:
21 Oct 2021
Publisher:
CDS
Description:
Magnitude differences between rotating and non-rotating copartners for a grid of models with solar metallicity are tabulated here. The results are expressed in terms of the dimensionless angular velocity w-bar- defined in Eq.(1) of the paper, the angle of inclination i and the atmospheric parameters T_e_ and g_e_ defined in Eqs.(22) and (21), respectively. To obtain the absolute magnitudes for a given rotating model, the magnitudes of a non-rotating model with T_eff_=T_e_, g=g_e_ and the same intrinsic luminosity must be added. Results are given for the filters in the Geneva, Johnson and Stroemgren systems. Eq (1): w-bar = {Omega}/{Omega}_c_, where {Omega} is the angular velocity of the star, and {Omega}_c_^2^=8GM/(27R^3^_p_), where M is the mass and R_p_ the polar radius.
5654. Rotational periods in Cygnus OB2
ID:
ivo://CDS.VizieR/J/A+A/603/A106
Title:
Rotational periods in Cygnus OB2
Short Name:
J/A+A/603/A106
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of a near-infrared time-series photometry study in the field of Cygnus OB2 association (RA~20.55h, DE~41.2{deg}). Observations were carried out in the JHK bands at the WFCAM/UKIRT telescope over 112 observed nights. We investigated the occurrence of periodicity in the time-series and we found reliable periods for 894 candidate members.
5655. Rotation of field stars from CoRoT data
ID:
ivo://CDS.VizieR/J/MNRAS/424/11
Title:
Rotation of field stars from CoRoT data
Short Name:
J/MNRAS/424/11
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present period measurements of a large sample of field stars in the solar neighbourhood, observed by the COnvection ROtation and planetary Transits (CoRoT) satellite in two different directions of the Galaxy. The presence of a period was detected using the Lomb-Scargle normalized periodogram technique and the autocorrelation analysis. The assessment of the results has been performed through a consistency verification supported by the folded light-curve analysis. The data analysis procedure has discarded a non-negligible fraction of light curves due to instrumental artefacts; however, it has allowed us to identify pulsators and binaries among a large number of field stars. We measure a wide range of periods, from 0.25 to 100d, most of which are rotation periods. The final catalogue includes 1978 periods, with 1727 of them identified as rotational periods, 169 as pulsations and 82 as orbital periods of binary systems.
5656. Rotation periods and membership in M34
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.
5657. Rotation periods for 171 Gaia members of NGC 6811
ID:
ivo://CDS.VizieR/J/ApJ/879/49
Title:
Rotation periods for 171 Gaia members of NGC 6811
Short Name:
J/ApJ/879/49
Date:
21 Oct 2021
Publisher:
CDS
Description:
Stellar rotation was proposed as a potential age diagnostic that is precise, simple, and applicable to a broad range of low-mass stars (<=1M_{sun}_). Unfortunately, rotation period (P_rot_) measurements of low-mass members of open clusters have undermined the idea that stars spin down with a common age dependence (i.e., P_rot{propto}age^0.5^): K dwarfs appear to spin down more slowly than F and G dwarfs. Agueros+ (2018, J/ApJ/862/33) interpreted data for the ~1.4Gyr-old cluster NGC 752 differently, proposing that after having converged onto a slow-rotating sequence in their first 600-700Myr (by the age of Praesepe), K dwarf P_rot_ stall on that sequence for an extended period of time. We use data from Gaia DR2 to identify likely single-star members of the ~1Gyr-old cluster NGC 6811 with Kepler light curves. We measure P_rot_ for 171 members, more than doubling the sample relative to the existing catalog and extending the mass limit from ~0.8 to ~0.6M_{sun}_. We then apply a gyrochronology formula calibrated with Praesepe and the Sun to 27 single G dwarfs in NGC 6811 to derive a precise gyrochronological age for the cluster of 1.04+/-0.07Gyr. However, when our new low-mass rotators are included, NGC 6811's color-P_rot_ sequence deviates away from the naive 1Gyr projection down to T_eff_~4295K (K5V, 0.7M_{sun}), where it clearly overlaps with Praesepe's. Combining these data with P_rot_ for other clusters, we conclude that the assumption that mass and age are separable dependencies is invalid. Furthermore, the cluster data show definitively that stars experience a temporary epoch of reduced braking efficiency where P_rot_ stall, and that the duration of this epoch lasts longer for lower-mass stars.
5658. Rotation periods for NGC 3532
ID:
ivo://CDS.VizieR/J/A+A/652/A60
Title:
Rotation periods for NGC 3532
Short Name:
J/A+A/652/A60
Date:
22 Feb 2022
Publisher:
CDS
Description:
A very rich cluster intermediate in age between the Pleiades (150Myr) and the Hyades (600Myr) is needed to probe the rotational evolution, especially the transition between fast and slow rotation that occurs between the two ages. We study the rich 300Myr-old open cluster NGC 3532 to probe this important transition and to provide constraints on angular momentum loss. Measuring the rotation periods builds on our prior work of providing spectroscopic membership information for the cluster, and it supports the chromospheric activity measurements of cluster stars that we provide in a companion paper. Using 42d-long photometric time series observations obtained with the Yale 1m telescope at CTIO, we measured rotation periods for members of NGC 3532 and compared them with the predictions of angular momentum evolution models. We directly measured 176 photometric rotation periods for the cluster members. An additional 113 photometric rotation periods were identified using activity information, described fully in the companion paper, resulting in a total sample containing 279 rotation periods for FGKM stars in NGC 3532. The colour-period diagram constructed from this rich data set shows a well-populated and structured slow rotator sequence, and a fast rotator sequence evolved beyond zero-age main sequence age whose stars are in transition from fast to slow rotation. The slow rotator sequence itself is split into slightly slower and faster rotators, a feature we trace to photometric binary status. We also identify an extended slow rotator sequence extending to P~32d, apparently the analogue of the one we previously identified in NGC 2516. We compare our period distribution to rotational isochrones in colour-period space and find that all considered models have certain shortcomings. Using more detailed spin-down models, we evolve the rotation periods of the younger NGC 2516 forward in time and find that the spindown of the models is too aggressive with respect to the slow rotators. In contrast, stars on the evolved fast rotator sequence are not spun down strongly enough by these models. Our observations suggest a shorter crossing time for the rotational gap, one we estimate to be ~80Myr for early-K dwarfs.
5659. Rotation periods from the K2 Campaign 9
ID:
ivo://CDS.VizieR/J/ApJS/255/4
Title:
Rotation periods from the K2 Campaign 9
Short Name:
J/ApJS/255/4
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Kepler mission is a powerful tool for the study of different types of astrophysical objects or events in the distant universe. However, the spacecraft also provides an opportunity to study solar system objects passing in the telescope's field of view. The aim of this paper is to determine, for the first time, the rotation periods of a number of asteroids observed by the K2 satellite during the K2 Campaign 9. Using publicly available data from the Kepler mission, we have used the Modified Causal Pixel Model code to perform the aperture-like and point-response function-like photometry of 1026 asteroids. The results allowed us to determine the rotation periods for 188 asteroids. For asteroids with rotation periods that were previously measured, we compared the results and found very good agreement. There are an additional 20 asteroids for which we obtained lower limits on rotation periods and in all cases these limits are at least 100hr.
5660. Rotation periods of asteroids using iPTF
ID:
ivo://CDS.VizieR/J/ApJS/227/20
Title:
Rotation periods of asteroids using iPTF
Short Name:
J/ApJS/227/20
Date:
21 Oct 2021
Publisher:
CDS
Description:
In order to look for large super-fast rotators, in late 2014 and early 2015, five dedicated surveys covering ~188deg^2^ in the ecliptic plane have been carried out in the R-band, with ~10min cadence using the intermediate Palomar Transient Factory. Among 1029 reliable rotation periods obtained from the surveys, we discovered 1 new large super-fast rotator, (40511) 1999 RE88, and 18 other candidates. (40511) 1999 RE88 is an S-type inner main-belt asteroid with a diameter of D=1.9+/-0.3km, a rotation period of P=1.96+/-0.01hr, and a light curve amplitude of {Delta}m~1.0mag. To maintain such fast rotation, an internal cohesive strength of ~780Pa is required. Combining all known large super-fast rotators, their cohesive strengths all fall in the range of 100-1000Pa of lunar regolith. However, the number of large super-fast rotators seems to be far less than the whole asteroid population. This might indicate a peculiar asteroid group for them. Although the detection efficiency for a long rotation period is greatly reduced due to our two-day observation time span, the spin-rate distributions of this work show consistent results with Chang+ (2015, J/ApJS/219/27), after considering the possible observational bias in our surveys. It shows a number decrease with an increase of spin rate for asteroids with a diameter of 3<=D<=15km, and a number drop at a spin rate of f=5rev/day for asteroids with D<=3km.