Positions for a total of 3487 stars, scattered over 14 regions, have been determined using the Danish 1.5-m telescope at La Silla. The 14 regions are centred on one of the southern galactic clusters NGC 1981, 2287, 2437, 2451, 2516, 2546, 2547, 2548, 3114, 3532, IC 2391, 2395, 2602 and Trumpler 10. Combining the Ritchey-Chretien reflector optics with a single element Schmidt-type corrector, gives a considerably enlarged flat field (radius about 25 minutes of arc, or 95mm) with stellar images of excellent definition. With the exception of distortion, which can be allowed for, the effect of the primary aberrations is negligible. A frame of reference has been established for each region using ESO Schmidt plates centred on the clusters, each plate containing from 20 to 35 measurable Perth 70 stars. These objects have served for determining positions of some 200 to 400 fainter stars within a central field of 25 minutes of arc radius, covering the corresponding 1.5-m plates. The fainter stars serve as a secondary standard. Based on three 1.5-m plates for each region, taken on different nights, an internal mean error in one plate position in the range 0.030 to 0.048 seconds of arc has been derived.
We present a comprehensive analysis of the spatial, kinematic and chemical properties of stars and globular clusters (GCs) in the 'ordinary' elliptical galaxy NGC 4494 using data from the Keck and Subaru telescopes. We derive galaxy surface brightness and colour profiles out to large galactocentric radii. We compare the latter to metallicities derived using the near-infrared Calcium Triplet. We obtain stellar kinematics out to ~3.5 effective radii.
We have identified stellar and substellar members in the nearby star cluster Coma Berenices, using photometry, proper motions, and distances of a combination of 2MASS, UKIDSS, URAT1, and Gaia/DR2 data. Those with Gaia/DR2 parallax measurements provide the most reliable sample to constrain the distance, averaging 86.7pc with a dispersion of 7.1pc, and age of ~800Myr, of the cluster. This age is older than the 400-600 Myr commonly adopted in the literature. Our analysis, complete within 5{deg} of the cluster radius, leads to identification of 192 candidates, among which, after field contamination is considered, about 148 are true members. The members have J~3mag to ~17.5mag, corresponding to stellar masses 2.3-0.06M_{sun}_. The mass function of the cluster peaks around 0.3M_{sun},_ and in the sense of dN/dm=m^-{alpha}^, where N is the number of members and m is stellar mass, with a slope {alpha}~=0.49+/-0.03 in the mass range 0.3-2.3M_{sun}_. This is much shallower than that of the field population in the solar neighborhood. The slope {alpha}=-1.69+/-0.14 from 0.3M_{sun}_ to 0.06M_{sun}_, the lowest mass in our sample. The cluster is mass-segregated and has a shape elongated toward the Galactic plane. Our list contains nine substellar members, including three new discoveries of an M8, an L1, and an L4 brown dwarfs, extending from the previously known coolest members of late-M types to even cooler types.
We present the results of a photometric BVI survey of 0.9deg^2^ around the Wolf-Rayet binary gamma^2^ Vel and its early-type common proper motion companion gamma^1^ Vel (together referred to as the gamma Vel system). Several hundred pre-main-sequence (PMS) stars are identified and the youth of a subset of these is spectroscopically confirmed by the presence of lithium in their atmospheres, Halpha emission and high levels of X-ray activity. We show that the PMS stars are kinematically coherent and spatially concentrated around gamma Vel. The PMS stars have similar proper motions to gamma Vel, to main-sequence (MS) stars around gamma Vel and to early-type stars of the wider Vela OB2 association of which gamma^2^ Vel is the brightest member.
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.
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.
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.
Stellar clusters from UKIDSS Galactic Plane Survey
Short Name:
J/A+A/542/A3
Date:
21 Oct 2021
Publisher:
CDS
Description:
Data mining techniques must be developed and applied to analyse the large public data bases containing hundreds to thousands of millions entries. We develop methods for locating previously unknown stellar clusters from the UKIDSS Galactic Plane Survey (GPS) catalogue data.
This directory contains movies in mpeg format which show models for the time evolution of the Hertzsprung-Russell diagram of a very young open cluster between 0 and 30Myr. Four different star formation scenario's are considered, (a) instantaneous star formation, (b) constant rate of star formation with time, (c) increasing rate of star formation, and (d) decreasing rate of star formation. For the latter three scenario's, models for a duration of the star formation episode {delta}t of 0.1, 1.0 and 10Myr are computed.
We present CCD photometry and spectroscopy for stars in Lucke-Hodge 9 and 10, two adjacent OB association in the northwest corner of the LMC. Our catalog contains UBV photometry (complete to ~18mag in all three filters) for 795 stars and BV-only photometry (complete to ~19mag in both filters) for an additional 434 stars.
