- ID:
- ivo://CDS.VizieR/J/A+A/584/A26
- Title:
- Cosmography of OB stars in the solar neighbourhood
- Short Name:
- J/A+A/584/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct a 3D map of the spatial density of OB stars within 500pc from the Sun using the Hipparcos catalogue and find three large-scale stream-like structures that allow a new view on the solar neighbourhood. The spatial coherence of these blue streams and the monotonic age sequence over hundreds of parsecs suggest that they are made of young stars, similar to the young streams that are conspicuous in nearby spiral galaxies. The three streams are 1) the Scorpius to Canis Majoris stream, covering 350pc and 65Myr of star formation history; 2) the Vela stream, encompassing at least 150pc and 25Myr of star formation history; and 3) the Orion stream, including not only the well-known Orion OB1abcd associations, but also a large previously unreported foreground stellar group lying only 200pc from the Sun. The map also reveals a remarkable and previously unknown nearby OB association, between the Orion stream and the Taurus molecular clouds, which might be responsible for the observed structure and star formation activity in this cloud complex. This new association also appears to be the birthplace of Betelgeuse, as indicated by the proximity and velocity of the red giant. If this is confirmed, it would solve the long-standing puzzle of the origin of Betelgeuse. The well-known nearby star-forming low-mass clouds, including the nearby T and R associations Lupus, Cha, Oph, CrA, Taurus, Vela R1, and various low-mass cometary clouds in Vela and Orion, appear in this new view of the local neighbourhood to be secondary star formation episodes that most likely were triggered by the feedback from the massive stars in the streams. We also recover well-known star clusters of various ages that are currently cruising through the solar neighbourhood. Finally, we find no evidence of an elliptical structure such as the Gould belt, a structure we suggest is a 2D projection effect, and not a physical ring.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/501/585
- Title:
- CT1 photometry in five LMC star clusters
- Short Name:
- J/A+A/501/585
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aims: We present CCD photometry in the Washington system C and T1 passbands down to T1~22.5 in the fields of NGC 1697, SL 133, NGC 1997, SL 663, and OHSC 28, five mostly unstudied star clusters in the LMC. Methods: Cluster radii were estimated from star counts in appropriate-sized boxes distributed throughout the entire observed fields. We perform a detailed analysis of the field star contamination and derive cluster colour-magnitude diagrams (CMDs). Based on the best fits of isochrones computed by the Padova group to the (T1, C-T_1_) CMDs, the {delta}(T1) index and the Standard Giant Branch procedure, we derive metallicities and ages for the five clusters. We combine our sample with clusters with ages and metallicities on a similar scale and examine relationships between position in the LMC, age and metallicity. Results: With the exception of NGC 1697 (age=0.7Gyr, [Fe/H]=0.0dex), the remaining four clusters are of intermediate-age (from 2.2 to 3.0Gyr) and relatively metal-poor ([Fe/H]=0.7dex). The cluster and field age-metallicty realtions show evidence for a metallicity offset but do overlap, particularly on the upper envelope side of the cluster age-metallicity relation. Conclusions: We confirm previous results that clusters younger than ~1Gyr were formed during an outside-in process; this occurred after a bust of cluster formation that took place mainly in the outer disk and peaked at ~2Gyr ago.
- ID:
- ivo://CDS.VizieR/J/MNRAS/377/300
- Title:
- CT1 photometry in 6 SMC star clusters
- Short Name:
- J/MNRAS/377/300
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry in the Washington C and T1 filters for six star clusters (B 34, NGC 256, NGC 265, NGC 294, IC 1611 and NGC 376) in the Small Magellanic Cloud (SMC) and their surrounding fields. The resultant colour-magnitude diagrams (CMDs) extend from T1~14 to as faint as T1~22 revealing the main-sequence turnoffs of the clusters. Adopting a metallicity of Z=0.004, we compare our cluster photometry with theoretical isochrones in the Washington system in order to derive ages. To facilitate age determination of the surrounding fields, we use the magnitude difference between the helium-burning red clump stars and the main-sequence turnoff. Finally, we estimate mean metallicities for the field stars by comparing the location of the field red giant branch with standard giant branches for Galactic globular clusters of known abundance, corrected for age effects. Combining these results with our previous work, we find a clear trend of younger clusters being located closer to the centre of the SMC. In addition, there is a tendency for the mean metallicity and its dispersion to be greater inside 4{deg} of the SMC's centre as compared to outside this radius. As far as the properties of the field stars are concerned, we find little correlation between the ages of the clusters and those of the field stars against which they are projected. Clearly, more work needs to be done to clarify these trends.
- ID:
- ivo://CDS.VizieR/J/PASP/123/519
- Title:
- C,T1 photometry of 6 LMC clusters
- Short Name:
- J/PASP/123/519
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of an ongoing project to investigate the cluster formation and chemical evolution history in the Large Magellanic Cloud (LMC), we have used the CTIO 0.9m telescope to obtain CCD imaging in the Washington system of NGC 2161, SL 874, and KMHK 1719 - three unstudied star clusters located in the outer region of the LMC. We measured T1 magnitudes and C-T1 colors for a total of 9611 stars distributed throughout cluster areas of 13.6x13.6arcmin^2^. Cluster radii were estimated from star counts distributed throughout the entire observed fields. Careful attention was paid to setting apart the cluster and field star distributions so that statistically cleaned color-magnitude diagrams (CMDs) were obtained. Based on the best fits of isochrones computed by the Padova group to the (T1, C-T1) CMDs, the {delta}T1 index, and the standard giant branch procedure, ages and metallicities were derived for the three clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/358/1215
- Title:
- CT1 photometry of 10 SMC clusters
- Short Name:
- J/MNRAS/358/1215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Colour-magnitude diagrams (CMDs) are presented for the first time for 10 star clusters projected on to the Small Magellanic Cloud (SMC). The photometry was carried out in the Washington system C and T1 filters allowing the determination of ages by means of the magnitude difference between the red giant clump and the main-sequence turnoff (MSTO), and metallicities from the red giant branch (RGB) locus.
- ID:
- ivo://CDS.VizieR/J/MNRAS/381/L84
- Title:
- CT1 photometry of 3 SMC old clusters
- Short Name:
- J/MNRAS/381/L84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results on the age and metallicity estimates of the Small Magellanic Cloud (SMC) clusters L 110, L 112 and L 113 obtained from CCD Washington CT_1_ photometry. We confirm L 113 as a relatively old and metal-poor cluster, and report for the first time that L 110 and 112 are also relatively old clusters (t~6.5Gyr) . Their derived ages and metallicities reinforce previous suggestions that the farther a cluster is from the centre of the galaxy, the older and more metal-poor it is, with some dispersion. In addition, the bursting star formation model still appears to be the most probable paradigm to describe the SMC's star formation history. We call attention to a second possible burst at ~6-7Gyr, besides the known burst at ~3Gyr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/382/1203
- Title:
- CT1 photometry of 5 SMC star clusters
- Short Name:
- J/MNRAS/382/1203
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Colour-magnitude diagrams in the Washington system are presented for the first time for five star clusters projected on to the outer region of the Small Magellanic Cloud (SMC). The clusters are found to have ages in the range 0.1-1.0Gyr, as derived from the fit of isochrones with Z=0.004. This sample increases substantially the number of young clusters in the outer SMC - particularly in the south-east quadrant - with well-derived parameters. We combine our results with those for other clusters in the literature to derive as large and homogeneous a data base as possible (totalling 49 clusters) in order to study global effects.
- ID:
- ivo://CDS.VizieR/J/MNRAS/389/429
- Title:
- CT1 photometry of 7 young SMC star clusters
- Short Name:
- J/MNRAS/389/429
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry in the Washington system C and T1 passbands down to T1~22 in the fields of L35, L45, L49, L50, L62, L63 and L85, seven poorly studied star clusters in the inner region of the Small Magellanic Cloud (SMC). We measured T1 magnitudes and C-T1 colours for a total of 114826 stars distributed throughout cluster areas of 13.7x13.7arcmin^2^ each. Cluster radii were estimated from star counts distributed throughout the entire observed fields.
- ID:
- ivo://CDS.VizieR/J/MNRAS/417/1559
- Title:
- CT1T2 photometry in 14 SMC star clusters
- Short Name:
- J/MNRAS/417/1559
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present CCD photometry in the Washington system C, T1 and T2 passbands down to T1~23 in the fields of L3, L28, HW 66, L100, HW 79, IC 1708, L106, L108, L109, NGC 643, L112, HW 84, HW 85 and HW 86, 14 Small Magellanic Cloud (SMC) clusters, most of them poorly studied objects. We measured T1 magnitudes and C-T1 and T1-T2 colours for a total of 213 516 stars spread throughout cluster areas of 14.7x14.7arcmin^2^ each. We carried out an in-depth analysis of the field star contamination of the colour-magnitude diagrams (CMDs) and statistically cleaned the cluster CMDs.
- ID:
- ivo://CDS.VizieR/J/A+A/540/A58
- Title:
- CT1T2 photometry of 26 LMC cluster
- Short Name:
- J/A+A/540/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- With the aim of enlarging the number of studied LMC clusters in the age range 8.0~<log(t)~<9.0, we focus here on a sample of mostly unstudied cluster candidates. We present, for the first time, CCD Washington CT1T2 photometry of stars in the field of 26 LMC clusters. The studied clusters turned out to be small angular size objects with ages within the age range 8.0~<log(t)~< 9.0, which are projected or immersed in dense star fields.
