H-R Diagrams Based on the HD Stars in the Michigan Spectral Catalogue and the<i>Hipparcos</i>Catalog

Sowell, James R.; Trippe, M. L.; Caballero-Nieves, S. M.; Houk, N.

doi:10.1086/520060

Cited by 27 publications

(30 citation statements)

References 13 publications

(10 reference statements)

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“…Under an extinction of AK =0.21, an early-K giant located in the Galactic Bulge would shine at K∼13, an early M giant at K∼10.5, and a late M giant at K∼7.5 (Koornneef 1983, Frogel & Whitford 1987, Sowell et al 2007), amply within the completeness limit for 2MASS. This excludes a giant as the donor star in Nova Oph 2015, while leaves open the possibility for a sub-giant.…”

Section: The Nature Of the Cool Companionmentioning

confidence: 92%

Flash-ionization of pre-existing circumstellar material around Nova Oph 2015

Munari

Walter

2015

Monthly Notices of the Royal Astronomical Society: Letters

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We have obtained daily high resolution Echelle spectroscopy of Nova Oph 2015 during its initial evolution. It reveals the presence of pre-existing circumstellar material around the nova, which is best interpreted as the wind of an evolved companion. On earliest observations, the emission line profiles of Nova Oph 2015 displayed a very narrow emission component (FWHM∼60 km sec −1 ), recombining over a time scale of 5 days and showing constant low velocity (RV ⊙ =−4.5 km sec −1 ), that we interpret as coming from the wind of the secondary recombining after the ionization from the initial UV-flash of the nova. The underlying broad component underwent a marked reduction in both FWHM and width at zero intensity (the latter declining from 4000 to 2000 km sec −1 in ten days) while increasing by 6× in flux, that we believe is the result of the high velocity ejecta of the nova being slowed down while trying to expand within the surrounding wind of the companion. Novae with evolved secondaries are very rare in the Galaxy, amounting to ∼3% of the total according to recent estimates. Among them Nova Oph 2015 is perhaps unique in having displayed a long rise to maximum brightness and a slow decline from it, a FeII-type classification (contrary to prevailing He/N) and a probable sub-giant luminosity class for the secondary (instead of the giant (e.g. RS Oph) or supergiant (e.g. V407 Cyg) class for the others).

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Section: The Nature Of the Cool Companionmentioning

confidence: 92%

Flash-ionization of pre-existing circumstellar material around Nova Oph 2015

Munari

Walter

2015

Monthly Notices of the Royal Astronomical Society: Letters

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“…by Sowell et al (2007) for luminosity class II, the diagram in the lower panel of Fig. 11 is obtained.…”

Section: Absolute Magnitudes and Distancesmentioning

confidence: 99%

A spectroscopic survey of faint, high-Galactic-latitude red clump stars

Valentini

Munari

2010

A&A

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Context. Their high intrinsic brightness and small dispersion in absolute magnitude make red clump (RC) stars a prime tracer of Galactic structure and kinematics. Aims. We aim to derive accurate, multi-epoch radial velocities and atmospheric parameters (T eff , log g, [M/H], V rot sin i) of a large sample of carefully selected RC stars, fainter than those present in other spectroscopic surveys and located over a great circle at high Galactic latitudes. Methods. We acquired data of the program stars of high signal-to-noise ratio (S/N) and high resolution with the Asiago Echelle spectrograph. Radial velocities were obtained by applying cross-correlation and atmospheric parameters via χ 2 fit to a synthetic spectral library. Extensive tests were carried out by re-observing with the same instrument a large number of standard stars taken from a variety of sources in the literature. During these tests, we found that the absolute Tycho V T magnitude of local red clump stars is not dependent on metallicity Results. A total of 277 red clump stars (101 of them with a second epoch observation) of the extended solar neighborhood and 55 calibration stars were observed and included in an output catalog that contains (in addition to relevant support astrometric and photometric data taken from literature) the main output of our survey: accurate multi-epoch radial velocities (σ(RV) ≤ 0.4 km s −1 ), accurate atmospheric parameters (σ(T eff ) = 68 K, σ(log g) = 0.11 dex, σ([M/H]) = 0.10 dex, σ(V rot sin i) = 1.1 km s −1 ), distances, and space velocities (U, V, W).

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“…II stars by a factor of about 500 (Bahcall & Casertano 1986). A set of 80% of all observed stars in a magnitude (m l ≤ 14.5) and distance (M l ≤ 10) limited sample should lie on the main sequence MS I, not just a set of 60% as we observe (Allen 1973;Sowell et al 2007). Nevertheless, the data are adequate statistically to investigate how stellar properties are correlated; this was demonstrated in a previous study where stars classified as Pop.…”

Section: Construction Of the Variability Sample Catalog (Vsc)mentioning

confidence: 55%

“…The traditional HR diagram (HRD) in the (log T e , log L)-plane for a magnitude-limited sample (see, for example, Sowell et al 2007) would obviously permit a more accurate separation of H-burning and He-burning stars; such will be available for our sample once the GAIA space-borne mission is completed around 2020 (Perrymann et al 2000).…”

Section: Calibration Of a Basic 2-d Relation Valid For Stellar Groupsmentioning

confidence: 99%

A variability sample catalogue selected from the Sydney Observatory Galactic Survey

Fresneau

Osborn²

2009

A&A

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Context. A set of 55 × 10 3 stars brighter than about B-magnitude 14 and having at least three observations are identified in the Sydney Observatory Galactic Survey, carried out over the years 1892-1932 along the galactic equator section l ∈ [275. Short-term (30 min) and long-term (decades) magnitude variations in the data set are analyzed. Aims. Evidence is sought for a correlation between short-term and long-term variabilities which would identify stars in a non-quiescent phase. Methods. We use a reduced proper motion diagram to classify the stars in our sample into probable dwarfs, giants and other types. The validity of the kinematical classification is checked using objective-prism spectroscopic classification for 10 × 10 3 early-type stars. A search is made for statistical correlations between our variability indicators and physical and kinematical stellar properties. Results. We find that suspected photospheric activity for giant and dwarf stellar candidates is correlated with the time to cross the galactic thin disk. We estimate a significant apparent B-magnitude variation of ±0.25 over the 40 years of photographic observations, and candidates for monitoring for possible photospheric activity at the present time are selected employing a statistical colour-diagram which uses the total proper motion component as a distance indicator. Conclusions. Follow up studies of our tentative findings are suggested. Toward this aim the derived data for the set of 55 × 10 3 stars with variability information is archived as the variability Sample Catalogue. The data for a set of 2.4 × 10 5 stars along the section of the galactic equator l ∈ [275 • , 335 • ], |b| ≤ 7 • , and a set of of 1.7 × 10 5 stars along the section of the galactic meridian 330 • ± 5 • , b ∈ [−64 • , −7 • ] is also archived as a quick-look facility for seeking long-term magnitude changes since the century-old photographic observations were obtained.

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H-R Diagrams Based on the HD Stars in the Michigan Spectral Catalogue and theHipparcosCatalog

Cited by 27 publications

References 13 publications

Flash-ionization of pre-existing circumstellar material around Nova Oph 2015

Flash-ionization of pre-existing circumstellar material around Nova Oph 2015

A spectroscopic survey of faint, high-Galactic-latitude red clump stars

A variability sample catalogue selected from the Sydney Observatory Galactic Survey

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