Products

Quality engineered excellence since 1987.

horizontal branch stars

Horizontal branch - Wikipedia

The horizontal branch (HB) is a stage of stellar evolution that immediately follows the red-giant branch in stars whose masses are similar to the Sun's. Horizontal-branch stars are powered by helium fusion in the core (via the triple-alpha process) and by hydrogen fusion (via the CNO cycle) in a shell surrounding the core. The onset of core helium fusion at the tip of the red-giant branchcauses

More

Horizontal Branch Stars - an overview ScienceDirect Topics

IV.D H-R Diagrams and Aggregate Properties. Two important observational features dominate the study of these clusters. One is the fact that the morphology of the H-R diagram appears to depend on the metallicity of the stars. The stage of the helium core burning is represented in clusters by a horizontal branch (HB), which lies about a magnitude ...

More

Horizontal branch stars: the interplay between observations and theory

We review and discuss horizontal branch (HB) stars in a broad astrophysical context, including both variable and non-variable stars. A reassessment of the Oosterhoff dichotomy is presented, which provides unprecedented detail regarding its origin and systematics. We show that the Oosterhoff dichotomy and the distribution of globular clusters in the HB morphology-metallicity

More

The ages of stars: The horizontal branch - Cambridge

The ages of stars: The horizontal branch M. Catelan†‡ Pontificia Universidad Cat´olica de Chile, Departamento de Astronom´ıa y Astrof´ısica, Av. Vicu˜na Mackenna 4860, 782-0436 Macul, Santiago, Chile email: [email protected] Abstract.Horizontal branch (HB) stars play a particularly important role in the “age debate,”

More

Horizontal branch stars Article about Horizontal branch stars by

horizontal branch. [ ‚härə′zäntəl ′branch] (astronomy) A region in the Hertzsprung-Russell diagram of a typical globular cluster that extends in the blue direction from the giant branch at an absolute bolometric magnitude of 0.3 and consists of stars that are burning helium in their cores and hydrogen in their surrounding envelopes.

More

Horizontal branch A- and B-type stars in globular

Horizontal branch stars in globular clusters 397 Figure 1. The results of Crocker et al. (1988, M3, M5, M92, NGC288), de Boer et al. (1995, NGC6397), Moehler et al. (1995, 1997a, M15), and Moehler et al. (1997b, NGC6752) compared with evolutionary tracks from Dorman et al. (1993). ZAHB and TAHB stand respectively for

More

The horizontal-branch A stars. - NASA/ADS

Feb 01, 1979  The observational determination of astrophysical parameters of horizontal-branch A stars is discussed. Effective temperatures, surface gravities, and bolometric magnitudes are determined for seven field horizontal-branch A stars, and their masses are calculated. The mean mass for these seven stars is 0.6 + or - 0.4 solar mass. This value is in

More

Red Giant, Horizontal Asymptotic Giant Branch Stars -

Horizontal Branch Stars Since less energy is being released by the star, its outer layers will contract as well. When they contract, they increase in temperature, and thus the star's surface ...

More

The Horizontal Branch - University of Tennessee

Horizontal Branch Distribution. The distribution of stars horizontally on the HB branch of a cluster HR diagram is because of differences in detailed structure, in particular the mass of the envelope. The left end of the branch corresponds to stars with lower mass envelopes and the right end to stars with higher mass envelopes.

More

The Hot Horizontal-Branch Stars in NGC288 - Effects of ...

Context. NGC288 is a globular cluster with a well developed blue horizontal branch covering the so-called u-jump which indicates the onset of diffusion. It is therefore well suited to study the effects of diffusion in blue horizontal branch (HB) stars. Aims. We compare observed abundances to predictions from stellar evolution models calculated with diffusion and from

More

A-Type Horizontal-Branch Stars SpringerLink

The observational criterion for field horizontal-branch stars can be large space motion relative to the sun or location distant from the galactic plane, which both are the kinematical characteristics of population-II stars. When we further select early-type stars, there is a high probability that horizontal-branch stars will be found.

More

IDENTIFYING BLUE HORIZONTAL BRANCH STARS USING

Blue horizontal branch stars (BHBs) are helium core-burning stars, typically about 0.7 M and 3 R, which exist at a near-constant absolute g-band magnitude of about 0.7 (Yanny et al. 2000). Since they are such luminous objects with a predictable brightness, they are frequently used as standard candles to

More

(PDF) The Origin of Extreme Horizontal Branch Stars

Strong mass loss on the red giant branch (RGB) can result in the formation of extreme horizontal branch (EHB) stars. The EHB stars spend most of their He core and shell burning phase at high ...

More

Hot Horizontal-Branch Stars The Ubiquitous Nature of the ...

Apr 03, 1999  hot Horizontal Branch stars in globular clusters ...ubiquitous for stars of almost all mass and ...Around 25 000 K, a jump in the mass-loss .....of an Unbound Hyper-Velocity Star in the Milky W... The star is either a hot blue horizontal branch...mechanism and the nature of the Galactic center....jump (Kinman et al. 1994), and the widths ...

More

(PDF) Blue Horizontal‐Branch Stars in Old, Metal‐rich ...

Blue Horizontal‐Branch Stars in Old, Metal‐rich Stellar Systems. Download. Related Papers. Hubble Space Telescope Observations of the Oldest Star Clusters in the LMC. By J. Hesser. Stellar Variability in the Globular Cluster Terzan 5. By Jonathan Grindlay.

More

Clean catalogues of blue horizontal-branch stars using ...

Aug 11, 2021  Context: Blue horizontal-branch stars are very old objects that can be used as markers in studies of the Galactic structure and formation history. To create a clean sky catalogue of blue horizontal-branch stars, we cross-matched the Gaia data release 2 (DR2) dataset with existing reference catalogues to define selection criteria based on Gaia DR2 parameters.

More

The Final Stages of the Evolution of a Sun-like Star ...

The horizontal branch phase of a star's life is much shorter than the Main Sequence phase of its lifetime. The star will convert all of its core helium into carbon and oxygen, and then fusion will end once again. The core will again begin to collapse inward with no radiation pressure to support it. Because there is still so much helium and ...

More

Lecture 40: The Once and Future Sun - Ohio State University

Mar 05, 2006  1 M sun Main-Sequence Star: 11 Gyr Red Giant Star: 1.3 Gyr Horizontal Branch Star: 100 Myr Asymptotic Giant Branch Star: 20 Myr Thermal Pulsation Phase: 400,000 yrs Planetary Nebula Phase: ~10,000 yrs 0.54 M sun White Dwarf as the final state.

More

Red-giant branch - Wikipedia

The red-giant branch runs from the thin horizontal subgiant branch to the top right, with a number of the more luminous RGB stars marked in red. The red-giant branch (RGB), sometimes called the first giant branch, is the portion of the giant branch before helium ignition occurs in the course of stellar evolution .

More

Side Bar: Asymptotic Giant Branch (AGB) Stars

For stars less massive than about nine times the mass of the sun, the last major phase of life is as an Asymptotic Giant Branch (AGB) star. This final phase of hydrogen burning happens after the star has moved from the Main sequence, through the Red Giant Phase and past the Horizontal Branch (see figure 1).At this point they are characterized by an inert carbon

More

Kinematical trends among the field horizontal branch stars ...

Horizontal branch (HB) stars in the field of the Milky Way can be used as tracers for the study of early stages of the evolution of our galaxy. Since the age of individual HB stars is not known a priori, we have studied the kinematics of a sample of field HB stars measured with Hipparcos to look for signs of age and population nature. Our sample comprises 14 HBA, 2 HBB and 5 sdB/O stars.

More

Hertzsprung-Russell diagram

Among the few types of object that populate this gap are RR Lyrae stars. Horizontal branch . Location of the horizontal branch on the H-R diagram. The horizontal branch is the part of the Hertzsprung-Russell diagram of occupied by the stars in a typical globular cluster. It contains stars with masses of 0.6 to 0.8 solar masses that are hotter ...

More

(PDF) Blue Horizontal-Branch Stars and Simple Stellar ...

Oct 08, 2002  The hot He-burning horizontal-branch (HB) stars and their progeny are most likely dominant ultraviolet (UV) sources in the old stellar

More

A DETAILED STUDY OF GIANTS AND HORIZONTAL BRANCH

possesses an extended blue horizontal branch (EHB)(Durrell Harris 1993). This is also reflected in the horizontal branch ratio, defined to be the ratio of horizontal branch stars to red giant stars, for both clusters. For M15, this ratio is 0.67, while for M68 it is only 0.17 (Zinn 1986, Harris 1996). Such

More

In what stage is a star when it is in the horizontal branch?

The horizontal-branch (HB) is the region of the Hertzsprung–Russell diagram occupied by evolved stars – after the red giant stage – of low mass and low metallicity (abundance of elements heavier than He less than 0.1 that of the Sun), during their central He-burning (He-fusion) phase.

More

IDENTIFYING BLUE HORIZONTAL BRANCH STARS USING

Blue horizontal branch stars (BHBs) are helium core-burning stars, typically about 0.7 M and 3 R, which exist at a near-constant absolute g-band magnitude of about 0.7 (Yanny et al. 2000). Since they are such luminous objects with a predictable brightness, they are frequently used as standard candles to

More

Blue Horizontal Branch Stars in Four Globular Clusters ...

Bragaglia A., Cacciari C., Carretta E., Castelli F. (1999) Blue Horizontal Branch Stars in Four Globular Clusters. In: Spite M. (eds) Galaxy Evolution: Connecting

More

Hot Horizontal-Branch Stars The Ubiquitous Nature of the ...

Apr 03, 1999  hot Horizontal Branch stars in globular clusters ...ubiquitous for stars of almost all mass and ...Around 25 000 K, a jump in the mass-loss .....of an Unbound Hyper-Velocity Star in the Milky W... The star is either a hot blue horizontal branch...mechanism and the nature of the Galactic center....jump (Kinman et al. 1994), and the widths ...

More

astrophysics - Lifetime of a horizontal branch star ...

There isn't a single value for the lifetime of a horizontal branch star. The lifetime depends upon star mass ( M ), helium core mass ( M c) or helium fraction ( Y ), and metalicity ( Z ), where the masses are in units of solar mass. where f is a convection factor that is approximately 2. In one example of Iben, Y

More

Solved 4. Horizontal branch stars have left the main ...

Horizontal branch stars have left the main sequence, and they are no longer powered by hydrogen fusion in their cores. a. What process(s) powers the luminosity of horizontal branch stars? Where in the star does this energy generation occur? (2 points) b. Sketch the interior of a horizontal branch star.

More

Lecture 16: The Evolution of Low-Mass Stars

Horizontal Branch Phase Structure: He-burning core H-burning shell The Triple-alpha Process is very inefficient at producing energy, so it can only last for about 100 Myr. While it goes on, the star steadily builds up a C-O core, but it is still too cool to ignite Carbon fusion

More

The Final Stages of the Evolution of a Sun-like Star ...

The horizontal branch phase of a star's life is much shorter than the Main Sequence phase of its lifetime. The star will convert all of its core helium into carbon and oxygen, and then fusion will end once again. The core will again begin to collapse inward with no radiation pressure to support it. Because there is still so much helium and ...

More

CH 17 Flashcards Quizlet

8) An H-R diagram for a globular cluster will show a horizontal branch—a line of stars above the main-sequence but to the left of the subgiants and red giants. Which of the following statements about these horizontal branch stars is true? A) They have inert (non-burning) carbon cores. B) Their sole source of energy is hydrogen shell burning.

More

Horizontal branch - Infogalactic: the planetary knowledge core

The horizontal branch ends in a "blue tail" with hotter stars having lower luminosity, occasionally with a "blue hook" of extremely hot stars. The hottest horizontal-branch stars, referred to as extreme horizontal branch, have temperatures of 20,000–30,000K. This is far beyond what would be expected for a normal core helium burning star.

More

Horizontal branch stars Article about Horizontal branch ...

horizontal branch. [ ‚härə′zäntəl ′branch] (astronomy) A region in the Hertzsprung-Russell diagram of a typical globular cluster that extends in the blue direction from the giant branch at an absolute bolometric magnitude of 0.3 and consists of stars that are burning helium in their cores and hydrogen in their surrounding envelopes.

More

Horizontal branch stars - LC Linked Data Service ...

found: Dict. astron., space atmos. phen. (Under Horizontal branch; Stars in an H-R diagram [that demonstrates correlation between spectral type and luminosity of stars], usu. of a globular cluster, representing a range in spectral types but sharing roughly zero absolute magnitude)

More