Editing Red-giant branch (section)

===Properties===
The table below shows the typical lifetimes on the main sequence (MS), subgiant branch (SB) and red-giant branch (RGB), for stars with different initial masses, all at solar metallicity (Z = 0.02). Also shown are the helium core mass, surface effective temperature, radius and luminosity at the start and end of the RGB for each star. The end of the red-giant branch is defined to be when core helium ignition takes place.<ref name=pols>{{cite journal|bibcode=1998MNRAS.298..525P|title=Stellar evolution models for Z = 0.0001 to 0.03|journal=Monthly Notices of the Royal Astronomical Society|volume=298|issue=2|pages=525|last1=Pols|first1=Onno R.|last2=Schröder|first2=Klaus-Peter|last3=Hurley|first3=Jarrod R.|last4=Tout|first4=Christopher A.|last5=Eggleton|first5=Peter P.|year=1998|doi=10.1046/j.1365-8711.1998.01658.x|doi-access=free}}</ref>
{| class="wikitable"
|-
! rowspan=2 | Mass<br/>({{solar mass}}) !! rowspan=2 | MS (GYrs) 
! rowspan="2" |Hook (MYrs)!! rowspan="2" | SB (MYrs) !! rowspan=2 | RGB<br/>(MYrs) !! colspan=4 | RGB<sub>foot</sub><br/> !! colspan=4 | RGB<sub>end</sub><br/>
|-
! Core mass ({{solar mass}}) !! T<sub>eff</sub> (K) !! Radius ({{solar radius}}) !! Luminosity ({{solar luminosity}}) !! Core mass ({{solar mass}}) !! T<sub>eff</sub> (K) !! Radius ({{solar radius}}) !! Luminosity ({{solar luminosity}})
|- style="text-align:right;"
| 0.6 || 58.8 
|N/A|| 5,100 || 2,500 || 0.10 || 4,634 || 1.2 || 0.6 || 0.48 || 2,925 || 207 || 2,809
|- style="text-align:right;"
| 1.0 || 9.3 
|N/A|| 2,600 || 760 || 0.13 || 5,034 || 2.0 || 2.2 || 0.48 || 3,140 || 179 || 2,802
|- style="text-align:right;"
| 2.0 || 1.2 
|10|| 22 || 25 || 0.25 || 5,220 || 5.4 || 19.6 || 0.34 || 4,417 || 23.5 || 188
|- style="text-align:right;"
| 5.0 || 0.1 
|0.4|| 15 || 0.3 || 0.83 || 4,737 || 43.8 || 866.0 || 0.84 || 4,034 || 115 || 3,118
|}

Intermediate-mass stars only lose a small fraction of their mass as main-sequence and subgiant stars, but lose a significant amount of mass as red giants.<ref name=meynet>{{cite journal|bibcode=1993A&AS...98..477M|title=New dating of galactic open clusters|journal=Astronomy and Astrophysics Supplement Series|volume=98|pages=477|last1=Meynet|first1=G.|last2=Mermilliod|first2=J.-C.|last3=Maeder|first3=A.|year=1993}}</ref>

The mass lost by a star similar to the Sun affects the temperature and luminosity of the star when it reaches the horizontal branch, so the properties of red-clump stars can be used to determine the mass difference before and after the helium flash. Mass lost from red giants also determines the mass and properties of the [[white dwarf]]s that form subsequently. Estimates of total mass loss for stars that reach the tip of the red-giant branch are around {{solar mass|0.2–0.25}}. Most of this is lost within the final million years before the helium flash.<ref name=origlia>{{cite journal|bibcode=2002ApJ...571..458O|title=ISOCAM Observations of Galactic Globular Clusters: Mass Loss along the Red Giant Branch|journal=The Astrophysical Journal|volume=571|issue=1|pages=458–468|last1=Origlia|first1=Livia|last2=Ferraro|first2=Francesco R.|last3=Fusi Pecci|first3=Flavio|last4=Rood|first4=Robert T.|year=2002|doi=10.1086/339857|arxiv = astro-ph/0201445 |s2cid=18299018}}</ref><ref name=mcdonald>{{cite journal|bibcode=2011ApJS..193...23M|arxiv=1101.1095|title=Fundamental Parameters, Integrated Red Giant Branch Mass Loss, and Dust Production in the Galactic Globular Cluster 47 Tucanae|journal=The Astrophysical Journal Supplement|volume=193|issue=2|pages=23|last1=McDonald|first1=I.|last2=Boyer|first2=M. L.|last3=Van Loon|first3=J. Th.|last4=Zijlstra|first4=A. A.|last5=Hora|first5=J. L.|last6=Babler|first6=B.|last7=Block|first7=M.|last8=Gordon|first8=K.|last9=Meade|first9=M.|last10=Meixner|first10=M.|last11=Misselt|first11=K.|last12=Robitaille|first12=T.|last13=Sewiło|first13=M.|last14=Shiao|first14=B.|last15=Whitney|first15=B.|year=2011|doi=10.1088/0067-0049/193/2/23|s2cid=119266025}}</ref>

Mass lost by more massive stars that leave the red-giant branch before the helium flash is more difficult to measure directly. The current mass of Cepheid variables such as [[δ Cephei]] can be measured accurately because there are either binaries or pulsating stars. When compared with evolutionary models, such stars appear to have lost around 20% of their mass, much of it during the blue loop and especially during pulsations on the instability strip.<ref name=xu>{{cite journal|bibcode=2004A&A...418..213X|title=Blue loops of intermediate mass stars . I. CNO cycles and blue loops|journal=Astronomy and Astrophysics|volume=418|pages=213–224|last1=Xu|first1=H. Y.|last2=Li|first2=Y.|year=2004|doi=10.1051/0004-6361:20040024|doi-access=free}}</ref><ref name=neilson>{{cite journal|bibcode=2011A&A...529L...9N|arxiv=1104.1638|title=The Cepheid mass discrepancy and pulsation-driven mass loss|journal=Astronomy & Astrophysics|volume=529|pages=L9|last1=Neilson|first1=H. R.|last2=Cantiello|first2=M.|last3=Langer|first3=N.|year=2011|doi=10.1051/0004-6361/201116920|s2cid=119180438}}</ref>