Oxygen-enhanced models for globular cluster stars. II - Isochrones and luminosity functions

Bergbusch, Peter A.; VandenBerg, Don A.

doi:10.1086/191690

Cited by 242 publications

(308 citation statements)

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“…Using the stellar models of Bergbusch & Vandenberg (1992), we estimated the brightest possible secondary consistent with our photometry ( K, , and T p 4100 V p 21.7 mass p 0.53 eff M , ). Using the secondary radius, the X-ray luminosity of X5, and the binary separation (from Kepler's Third Law), we estimate that the maximum luminosity from heating of the secondary by the NS (when measured as a fraction of the secondary luminosity) is 2.7%.…”

Section: Discussionmentioning

confidence: 97%

[ITAL]Hubble Space Telescope[/ITAL] Detection of a Quiescent Low-Mass X-Ray Binary Companion in 47 Tucanae

Edmonds

Heinke

Grindlay

2002

The Astrophysical Journal

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We present the results of a search for optical counterparts to the two quiescent low-mass X-ray binaries (X5 and X7) in the globular cluster 47 Tucanae, using high-quality Chandra and Hubble Space Telescope images. A faint blue ( ; UϪ ) star within 0Љ .03 of the eclipsing system X5 shows variability on both short V p 21.7 V p 0.9 and long timescales and is the counterpart of the X-ray source. The colors and variability of this object are consistent with the combination of light from an accretion disk and a red main-sequence star (possibly somewhat larger than a normal main-sequence star with similar luminosity). No evidence is found for a star showing either variability or unusual colors near the position of X7, but a probable chance superposition of a star with V p limits the depth of our search. 20.25

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Section: Discussionmentioning

confidence: 97%

[ITAL]Hubble Space Telescope[/ITAL] Detection of a Quiescent Low-Mass X-Ray Binary Companion in 47 Tucanae

Edmonds

Heinke

Grindlay

2002

The Astrophysical Journal

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“…The mass function of the stars in the tails should therefore be very close to that measured for the cluster. The model isochrone of Bergbusch & Vandenberg (1992) closest to Pal 5, [Fe/H] = À1.48 and age 14 Gyr, predicts that the main-sequence mass range of Pal 5 stars present in the data in the range 15 < r* < 22 is approximately 0.83 > M > 0.72, where a distance of 21 kpc (Sandage & Hartwick 1977) and the photometric transformations in Fukugita et al (1996) were used to compare the data with the model. Therefore, the effect of mass segregation on this analysis would be small in any case, since there is very little sensitivity to the mass function in these data.…”

Section: Filter Functionsmentioning

confidence: 99%

A Matched-Filter Analysis of the Tidal Tails of the Globular Cluster Palomar 5

Rockosi

Odenkirchen

Grebel

et al. 2002

The Astronomical Journal

213

217

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The tidal tails of the globular cluster Palomar 5 are analyzed over a 41 deg 2 area of the Sloan Digital Sky Survey photometric catalogs. The matched filter algorithm provides the maximum possible signal-to-noise detection of the cluster stars over the measured background, and the expected and actual effectiveness of the technique in the context of this data set is discussed. The stellar background is examined in some detail for systematic variation as a function of Galactic position in order to assess its effect on the detection efficiency. Of the total number of Pal 5 stars detected, 45% are out in the tails. The tails are found as the only additional 3 overdensity of cluster stars over the entire 41 deg 2 area studied. The annular-averaged density of stars along the tails is fitted to a power law in radius with best-fit index À1.58 AE 0.07, significantly steeper than that predicted from a constant orbit-averaged mass-loss rate.

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“…A much smaller value of _ E E (7:8 Â 10 33 ergs s À1 ) is derived using the linear relation of Becker & Trü mper (1999), L X $ 10 À3 _ E E, derived largely for field MSPs. The stellar evolution models of Bergbusch & Vandenberg (1992) give an approximate guide to the relationship between luminosity and mass for an MS star. We adopt the lowest mass model given by Bergbusch & Vandenberg (1992), a 0.15 M model with T eff ¼ 3300 K and M V ¼ 13:2, and test whether significant heating of such a star is expected.…”

Section: No 2 2002mentioning

confidence: 99%

“…The stellar evolution models of Bergbusch & Vandenberg (1992) give an approximate guide to the relationship between luminosity and mass for an MS star. We adopt the lowest mass model given by Bergbusch & Vandenberg (1992), a 0.15 M model with T eff ¼ 3300 K and M V ¼ 13:2, and test whether significant heating of such a star is expected. We use the measured orbital period, an assumed mass for the NS of 1.4 M , and the above secondary mass to estimate the binary separation from Kepler's third law.…”

Section: No 2 2002mentioning

confidence: 99%

A Millisecond Pulsar Optical Counterpart with Large‐Amplitude Variability in the Globular Cluster 47 Tucanae

Edmonds

Gilliland

Camilo

et al. 2002

ApJ

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Using extensive Hubble Space Telescope imaging, combined with Chandra X-ray and Parkes radio data, we have detected the optical binary companion to a second millisecond pulsar (MSP) in the globular cluster 47 Tucanae. This faint (V ¼ 22:3) blue (VÀI = 0.7) star shows a large-amplitude (60%-70%) sinusoidal variation in both V and I. The period (3.19066 hr) and phase of the variation match those of the MSP 47 Tuc W (which does not have an accurate radio timing position) to within 0.5 s and 1.2 minutes, respectively, well within the 1 errors. The phase dependence of the intensity and color implies that heating of a tidally locked companion causes the observed variations. The eclipsing nature of this MSP in the radio, combined with the relatively large companion mass (greater than 0.13 M ) and the companion's position in the color-magnitude diagram, suggests that the companion is a main-sequence star, a rare circumstance for an MSP companion. This system is likely to have had a complex evolution and represents an interesting case study in MSP irradiation of a close companion. We present evidence for another optical variable with similar properties to the companion of 47 Tuc W. This variable also may be an MSP companion, although no radio counterpart has yet been detected.

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Oxygen-enhanced models for globular cluster stars. II - Isochrones and luminosity functions

Cited by 242 publications

References 0 publications

[ITAL]Hubble Space Telescope[/ITAL] Detection of a Quiescent Low-Mass X-Ray Binary Companion in 47 Tucanae

[ITAL]Hubble Space Telescope[/ITAL] Detection of a Quiescent Low-Mass X-Ray Binary Companion in 47 Tucanae

A Matched-Filter Analysis of the Tidal Tails of the Globular Cluster Palomar 5

A Millisecond Pulsar Optical Counterpart with Large‐Amplitude Variability in the Globular Cluster 47 Tucanae

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