Abundances for NGC6397
Fe-peak elements
- [Fe/H] = -2.0
- There is as yet no evidence for any variation from star to star
- Other Fe-peak
- I found nothing in the literature...
n-capture elements
- Not much data!
- Castilho et al 2000 claim [s/Fe] = -0.2
- No variation from star to star
Alpha elements
- Castilho et al 2000 find mild overabundances
- They looked in TO and subgiant stars
- [O/fe] = 0.15 (others find about 0.2)
- [Ca/Fe] = [Si/Fe] = 0.2
- [Ti/Fe] = 0.4
- Star to star variations below 0.25 dex
- Any scatter can be explained as a combination of observations and atmospheric variation
- Thevenin et al 2001 confirmed these results
C (and N I presume!)
- Briley et al 1990 looked at many stars
- They found slight variation in C (and presumably N). This figure is from Smith andMartell, 2003.
Lithium
- Lots of work here
- Summary is that the MS stars show normal A(Li) = 2.3, consistent with Pop II field stars
- This plot is from Pasquini and Molaro 1996 and shows the A(Li) next to each point in the HRD. Note that giants show depleted Li as expected.
- Li values are consistent with field stars
- Same result found by Castilho et al 2000
Stellar Masses
- Drukier et al showed that mass segregationhas occurred
- Mass function is smooth down to 0.1Msun
- De Marchi et al 2000 claim a turnover in IMF below 0.9Msun
- Similar claim made by Piotto et al 1997
