Further mid-infrared study of the rho Ophiuchi cloud young stellar population: Luminosities and masses of pre-main-sequence stars

1994 ◽  
Vol 434 ◽  
pp. 614 ◽  
Author(s):  
Thomas P. Greene ◽  
Bruce A. Wilking ◽  
Philippe Andre ◽  
Erick T. Young ◽  
Charles J. Lada
Keyword(s):  
Stellar Population ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Infrared Study ◽  
Mid Infrared ◽  
Rho Ophiuchi

scholarly journals IPHAS A-type Stars with Mid-IR Excesses in Spitzer Surveys

2009 ◽  
Vol 5 (H15) ◽  
pp. 815-815
Author(s):  
Antonio S. Hales ◽  
Michael J. Barlow ◽  
Janet E. Drew ◽  
Yvonne C. Unruh ◽  
Robert Greimel ◽  
...  
Keyword(s):  
Cross Correlation ◽  
Main Sequence ◽  
Terrestrial Planet ◽  
Circumstellar Disks ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
Mid Infrared ◽  
Isaac Newton ◽  
Intermediate Mass Stars ◽  
Dust Disks

AbstractThe Isaac Newton Photometric H-Alpha Survey (IPHAS) provides (r′-Hα)-(r′-i′) colors, which can be used to select AV0-5 Main Sequence star candidates (age~20-200 Myr). By combining a sample of 23050 IPHAS-selected A-type stars with 2MASS, GLIMPSE and MIPSGAL photometry we searched for mid-infrared excesses attributable to dusty circumstellar disks. Positional cross-correlation yielded a sample of 2692 A-type stars, of which 0.6% were found to have 8-μm excesses above the expected photospheric values. The low fraction of main sequence stars with mid-IR excesses found in this work indicates that dust disks in the terrestrial planet zone of Main Sequence intermediate mass stars are rare. Dissipation mechanisms such as photo-evaporation, grain growth, collisional grinding or planet formation could possibly explain the depletion of dust detected in the inner regions of these disks.

scholarly journals Observations of blue straggler stars in globular clusters

2006 ◽  
Vol 2 (14) ◽  
pp. 438-439
Author(s):  
Francesco R. Ferraro ◽  
Barbara Lanzoni
Keyword(s):  
Globular Clusters ◽  
Binary Systems ◽  
Stellar Population ◽  
Main Sequence ◽  
Formation Mechanisms ◽  
Main Sequence Stars ◽  
Blue Stragglers ◽  
Photometric And Spectroscopic Observations ◽  
Blue Straggler ◽  
Dynamical Simulations

AbstractBlue stragglers stars (BSS) define a sparsely populated sequence extending to higher luminosity than the turnoff point of normal main sequence stars in the color magnitude diagrams of stellar aggregates, thus mimicking a rejuvenated (more massive) stellar population. The nature of these stars has been a puzzle for many years and their formation mechanism is not completely understood, yet. Two mechanisms have been proposed to produce BSS: (i) the mass transfer in binary systems; and ((ii) the merger of two stars induced by stellar interactions. In this contribution we schematically report on the main properties of BSS in globular clusters (GCs) in the light of the most recent photometric and spectroscopic observations. These results, combined with dynamical simulations, indicate that both the proposed formation mechanisms play an important role in the production of BSS in GCs.

scholarly journals Accretion in the $\mathsf{\rho}$-Ophiuchi pre-main sequence stars

2006 ◽  
Vol 452 (1) ◽  
pp. 245-252 ◽  
Author(s):  
A. Natta ◽  
L. Testi ◽  
S. Randich
Keyword(s):  
Main Sequence ◽  
Main Sequence Stars ◽  
Rho Ophiuchi

scholarly journals Color-Luminosity Relations for the Resolved Hot Stellar Populations in the Centers of M31 and M32

1999 ◽  
Vol 192 ◽  
pp. 195-202
Author(s):  
Thomas M. Brown ◽  
Henry C. Ferguson ◽  
S. A. Stanford ◽  
Jean-Michel Deharveng
Keyword(s):  
Stellar Population ◽  
Main Sequence ◽  
Uv Spectra ◽  
Agb Stars ◽  
Main Sequence Stars ◽  
Blue Stragglers ◽  
Faint Object ◽  
Luminosity Functions ◽  
Uv Upturn ◽  
Small Field Of View

We present Faint Object Camera (FOC) ultraviolet images of the central 14 x 14″ of Messier 31 and Messier 32. The hot stellar population detected in the composite UV spectra of these galaxies is partially resolved into stars, and we measure their colors and apparent magnitudes. We detect 433 stars in M31 and 138 stars in M32, down to limits of mF275W = 25.5 mag and mF175W = 24.5 mag. We investigate the luminosity functions of the sources, their spatial distribution, their color-magnitude diagrams, and their total integrated far-UV flux. Although M32 has a weaker UV upturn than M31, the luminosity functions and color-magnitude diagrams of M31 and M32 are surprisingly similar, and are inconsistent with a majority contribution from any of the following: post-AGB stars more massive than 0.56 M⊙, main sequence stars, or blue stragglers. The luminosity functions and color-magnitude diagrams are consistent with a dominant population of stars evolving from the extreme horizontal branch (EHB) along tracks of mass 0.47–0.53 M⊙. These stars are well below the detection limits of our images while on the zero-age EHB, but become detectable while in the more luminous (but shorter) post-HB phases. Our observations require that only a very small fraction of the main sequence population (2% in M31 and 0.5% in M32) in these two galaxies evolve though the EHB and post-EHB phases, with the remainder rapidly evolving through bright post-AGB evolution with few resolved stars expected in the small field of view covered by the FOC.

A Mid-Infrared Study of the Young Stellar Population in the NGC 2024 Cluster

2001 ◽  
Vol 121 (3) ◽  
pp. 1512-1521 ◽  
Author(s):  
Karl E. Haisch, Jr. ◽  
Elizabeth A. Lada ◽  
Robert K. Piña ◽  
Charles M. Telesco ◽  
Charles J. Lada
Keyword(s):  
Stellar Population ◽  
Infrared Study ◽  
Mid Infrared

Examples of Comet-Like Spectra among β Pic-Like Stars

1997 ◽  
Vol 161 ◽  
pp. 149-155 ◽  
Author(s):  
Harold M. Butner ◽  
Helen J. Walker ◽  
Diane H. Wooden ◽  
Fred C. Witteborn
Keyword(s):  
Main Sequence ◽  
Interplanetary Dust ◽  
Small Sample ◽  
Dust Particles ◽  
Striking Similarity ◽  
Early Solar System ◽  
Main Sequence Stars ◽  
Interplanetary Dust Particles ◽  
Mid Infrared ◽  
Physical Conditions

AbstractTo assess the physical conditions in our early solar system, we have to study the disks around other stars.βPic is a main sequence star surrounded by a large dust disk,βPic’s mid-infrared spectrum bears a striking resemblance to the silicate emission seen in some cometary spectra. We have selected a sample of main-sequence stars with similar IRAS properties to those ofβPic and undertaken a systematic survey of their physical properties. We obtained mid-infrared spectra covering the range 8 to 13μm at a resolution of 200 in June 1995. We report on the wide variety of silicate emission features we see and compare to the spectra reported for many different interstellar and interplanetary sources. Even among our small sample of stars, we find examples of silicate emission features that bear a striking similarity to those seen in the spectra of some comets like P/Halley and P/Bradfield 1987. These spectra also resemble the laboratory spectra of Interplanetary Dust Particles (IDPs).

scholarly journals Stellar Population Synthesis and Star Counts to Constrain the Galactic Structure

1984 ◽  
Vol 78 ◽  
pp. 325-327
Author(s):  
Annie Robin ◽  
Michel Creze
Keyword(s):  
Stellar Population ◽  
Main Sequence ◽  
Absolute Magnitude ◽  
Galactic Structure ◽  
Red Giants ◽  
Population Synthesis ◽  
Main Sequence Stars ◽  
Space Density ◽  
Stellar Population Synthesis

AbstractOur model of stellar population synthesis allows to derive synthetic star counts and distribution of colors, ages, and spectral types of stars in any given direction of observations. Here we compare results of the model with the distribution of stars in space and in absolute magnitude of stars of Gilmore and Reid. We find a small disagreement between observations of GR and predictions of our model in the space density of stars of 4 < Mv < 5. Ue show that this discrepancy can well be explained by a contamination of their sample of assumed main sequence stars by red giants and subgiants.

scholarly journals Surveys of Spectroscopic Binaries at the Center for Astrophysics

1992 ◽  
Vol 135 ◽  
pp. 110-118
Author(s):  
D.W. Latham
Keyword(s):  
Stellar Population ◽  
Main Sequence ◽  
Open Clusters ◽  
Spectroscopic Binaries ◽  
Main Sequence Stars ◽  
Eccentric Orbits ◽  
Binary Formation ◽  
Wide Range ◽  
Formation And Evolution ◽  
Better Than

Abstract For more than a decade we have been measuring stellar radial velocities with three almost identical digital speedometers on telescopes in Arizona and Massachusetts. By now we have accumulated nearly 100,000 measurements with a typical precision of better than 1 km s-1. One of the main scientific applications has been surveys of binaries in several different stellar environments, to study the frequency and orbital characteristics of binaries in a variety of stellar populations. A main goal is to confront theories of binary formation and evolution with observational results. With various collaborators we have investigated the binary populations among pre-main-sequence stars, in the Hyades and M67 open clusters, and in the Carney-Latham proper-motion sample. Thus, we have data for coeval samples of binaries covering a wide range of ages. One result is clear evidence for evolution of binary orbits. The orbital period at which there is a transition from circular to eccentric orbits gets longer for older samples of binaries, presumably due to tidal circularization. Another result is that the frequency of binaries does not seem to depend on the stellar population. Binaries are just as common among the oldest stars in the halo of our Galaxy as among the younger stars in the disk.

scholarly journals CONSTRAINING THE EXOZODIACAL LUMINOSITY FUNCTION OF MAIN-SEQUENCE STARS: COMPLETE RESULTS FROM THE KECK NULLER MID-INFRARED SURVEYS

2014 ◽  
Vol 797 (2) ◽  
pp. 119 ◽  
Author(s):  
B. Mennesson ◽  
R. Millan-Gabet ◽  
E. Serabyn ◽  
M. M. Colavita ◽  
O. Absil ◽  
...  
Keyword(s):  
Luminosity Function ◽  
Main Sequence ◽  
Main Sequence Stars ◽  
Mid Infrared ◽  
Infrared Surveys

scholarly journals Searching for Faint Exozodiacal Disks: Keck Results and LBTI Status

2013 ◽  
Vol 8 (S299) ◽  
pp. 332-333
Author(s):  
D. Defrère ◽  
P. Hinz ◽  
B. Mennesson ◽  
R. Millan-Gabet ◽  
A. Skemer ◽  
...  
Keyword(s):  
Main Sequence ◽  
Extrasolar Planets ◽  
Habitable Zone ◽  
Main Sequence Stars ◽  
Direct Imaging ◽  
Mid Infrared ◽  
Preliminary Results

AbstractThe possible presence of dust in the habitable zone around nearby main-sequence stars is considered as a major hurdle toward the direct imaging of Earth-like extrasolar planets with future dedicated space-based telescopes (e.g., Roberge et al. 2012). In this context, NASA has funded two ground-based mid-infrared nulling interferometers to combine the large apertures available at the Keck Observatory and the Large Binocular Telescope (LBT). In this poster, we present the preliminary results of the extended survey carried out with the Keck Interferometer Nuller (KIN) between 2008 and 2011 and describe the forthcoming LBTI survey.

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