scholarly journals The Color‐Magnitude Diagram in Baade's Window Revisited

1997 ◽  
Vol 485 (2) ◽  
pp. 611-617 ◽  
Author(s):  
Marcin Kiraga ◽  
Bohdan Paczyński ◽  
Krzysztof Z. Stanek
Keyword(s):  
Magnitude Diagram

scholarly journals Gaia DR1 completeness within 250 pc & star formation history of the Solar neighbourhood

2017 ◽  
Vol 12 (S330) ◽  
pp. 148-151 ◽  
Author(s):  
Edouard J. Bernard
Keyword(s):  
Star Formation ◽  
Star Formation History ◽  
Solar Neighbourhood ◽  
The Sun ◽  
Thick Disc ◽  
Formation History ◽  
Magnitude Diagram ◽  
History Of

AbstractWe took advantage of the Gaia DR1 to combine TGAS parallaxes with Tycho-2 and APASS photometry to calculate the star formation history (SFH) of the solar neighbourhood within 250 pc using the colour-magnitude diagram fitting technique. We present the determination of the completeness within this volume, and compare the resulting SFH with that calculated from the Hipparcos catalogue within 80 pc of the Sun. We also show how this technique will be applied out to ~5 kpc thanks to the next Gaia data releases, which will allow us to quantify the SFH of the thin disc, thick disc and halo in situ, rather than extrapolating based on the stars from these components that are today in the solar neighbourhood.

scholarly journals Infrared Observations of Giant Elliptical Galaxies: (V-K) Colors and the Infrared Hubble Diagram

1980 ◽  
Vol 92 ◽  
pp. 269-277
Author(s):  
Gary L. Grasdalen
Keyword(s):  
Elliptical Galaxies ◽  
Cosmological Models ◽  
Hubble Diagram ◽  
Infrared Observations ◽  
Color Evolution ◽  
Magnitude Diagram ◽  
Luminosity Evolution

The (V-K) colors of giant elliptical galaxies as a function of redshift are discussed. Present data are consistent with mild color evolution at z ~ 0.45. An infrared Hubble (redshift-magnitude) diagram is given. Cosmological models with qo = 0 and no luminosity evolution are clearly excluded by the present data. A wide variety of models including those with qo = 0 are permissible if luminosity evolution is included. Instrumental and programmatic implications of these results are summarized.

scholarly journals Evidence for feedback and stellar-dynamically regulated bursty star cluster formation: the case of the Orion Nebula Cluster

2018 ◽  
Vol 612 ◽  
pp. A74 ◽  
Author(s):  
Pavel Kroupa ◽  
Tereza Jeřábková ◽  
František Dinnbier ◽  
Giacomo Beccari ◽  
Zhiqiang Yan
Keyword(s):  
Molecular Cloud ◽  
Massive Stars ◽  
Cluster Formation ◽  
Life Time ◽  
Molecular Gas ◽  
Orion Nebula ◽  
Main Sequence Stars ◽  
Sequence Of Events ◽  
Proposed Model ◽  
Magnitude Diagram

A scenario for the formation of multiple co-eval populations separated in age by about 1 Myr in very young clusters (VYCs, ages less than 10 Myr) and with masses in the range 600–20 000 M⊙ is outlined. It rests upon a converging inflow of molecular gas building up a first population of pre-main sequence stars. The associated just-formed O stars ionise the inflow and suppress star formation in the embedded cluster. However, they typically eject each other out of the embedded cluster within 106 yr, that is before the molecular cloud filament can be ionised entirely. The inflow of molecular gas can then resume forming a second population. This sequence of events can be repeated maximally over the life-time of the molecular cloud (about 10 Myr), but is not likely to be possible in VYCs with mass <300 M⊙, because such populations are not likely to contain an O star. Stellar populations heavier than about 2000 M⊙ are likely to have too many O stars for all of these to eject each other from the embedded cluster before they disperse their natal cloud. VYCs with masses in the range 600–2000 M⊙ are likely to have such multi-age populations, while VYCs with masses in the range 2000–20 000 M⊙ can also be composed solely of co-eval, mono-age populations. More massive VYCs are not likely to host sub-populations with age differences of about 1 Myr. This model is applied to the Orion Nebula Cluster (ONC), in which three well-separated pre-main sequences in the colour–magnitude diagram of the cluster have recently been discovered. The mass-inflow history is constrained using this model and the number of OB stars ejected from each population are estimated for verification using Gaia data. As a further consequence of the proposed model, the three runaway O star systems, AE Aur, μ Col and ι Ori, are considered as significant observational evidence for stellar-dynamical ejections of massive stars from the oldest population in the ONC. Evidence for stellar-dynamical ejections of massive stars in the currently forming population is also discussed.

Detection of extended Red Clump in the SMC cluster Kron 3

2019 ◽  
Vol 14 (S351) ◽  
pp. 135-138
Author(s):  
P. K. Nayak ◽  
A. Subramaniam ◽  
S. Subramanian ◽  
S. Sahu ◽  
C. Mondal ◽  
...  
Keyword(s):  
Intrinsic Property ◽  
Field Star ◽  
Magnitude Diagram ◽  
Red Clump ◽  
Optical Color ◽  
First Time

AbstractFor the first time, we report the identification of NUV bright red clump (RC) stars and the extension of RC stars over two magnitudes both in color and magnitude axis in NUV vs (NUV – optical) color magnitude diagram. We find that the extension of RC is not due to photometric uncertainties. We suggest that the extension could be an effect of field star contamination. We also suggest that if it is an intrinsic property of the cluster then age and/or metallicity spread within the cluster could be the possible reasons for extended RC.

scholarly journals Gemini/Phoenix H-band analysis of the globular cluster AL 3

2021 ◽  
Vol 648 ◽  
pp. A16
Author(s):  
B. Barbuy ◽  
H. Ernandes ◽  
S. O. Souza ◽  
R. Razera ◽  
T. Moura ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Wavelength Range ◽  
Globular Cluster ◽  
Spectral Region ◽  
Wavelength Region ◽  
Individual Stars ◽  
Synthetic Spectra ◽  
Cool Stars ◽  
Magnitude Diagram ◽  
The Phoenix

Context. The globular cluster AL 3 is old and located in the inner bulge. Three individual stars were observed with the Phoenix spectrograph at the Gemini South telescope. The wavelength region contains prominent lines of CN, OH, and CO, allowing the derivation of C, N, and O abundances of cool stars. Aims. We aim to derive C, N, O abundances of three stars in the bulge globular cluster AL 3, and additionally in stars of NGC 6558 and HP 1. The spectra of AL 3 allows us to derive the cluster’s radial velocity. Methods. For AL 3, we applied a new code to analyse its colour-magnitude diagram. Synthetic spectra were computed and compared to observed spectra for the three clusters. Results. We present a detailed identification of lines in the spectral region centred at 15 555 Å, covering the wavelength range 15 525–15 590 Å. C, N, and O abundances are tentatively derived for the sample stars.

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