L10-- stellar pop

Question 1

luminosity relation?

Answer 1

L= 4 pi stephan boltzman const * R^2 * T_eff^4

Question 2

HRD types?

Answer 2

classical: M_abs vs spectral type
CMD: M_abs vs colour
kiell dig: log g (surface grav) vs T_eff

Question 3

HRD evo track?

Answer 3

line/ track of same IMF diff ages/ evo track based on IMF of star

each point on evo track: life/ stage of star

Question 4

lines defining the age of a star?

Answer 4

isochrones on HRD

Question 5

effect of metallicity on evo track?

Answer 5

same mass diff meta; slightly diff path

Question 6

identify main seq turn off point

Answer 6

MSTO: star leaving MS, highest T_eff on isochrone (bluest)

Question 7

IMF? mean? formula? units

Answer 7

HMS / #LMS

dist of stellar mass in a cluster

IMF = 1/N dn/dm
[IMF] = per mass interval

Question 8

logithrimic IMF?

Answer 8

formula?

1/N dn/d_mu

mu= log(m/solar_m)

Question 9

parameterization of IMF? 2 methods?

Answer 9

two standard parametrisations are currently broadly used: A segmented power law with mass-dependent slopes (Kroupa et al. 1993), and a lognormal distribution (Chabrier 2003)

Question 10

why IMF cant be measured directly?

Answer 10

masses not observables

HMS– short life– not represented

Question 11

stellar pop types: SSP, CSP meaning? comparison of age/ metallicities/ isochrone?

Answer 11

SSP: group of stars formed by single gas cloud: same age, same metallicity, diff mass

CSP: superposition of multiple SSPs of different ages and possibly abundances, weighted by their respective mass fractions.

Question 12

what do SP tells?

Answer 12

S Mass
SFR
SF history
S metallicity
metallicity of each element

Question 13

why should IMF follow Gaussian dist?

Answer 13

central limit th:

sum of an infinite number of independent variables can be described by a normal or gaussian distribution function

SF: v complex, many variables
log-m is the sum of a series of possibly independent distribution functions. If the series is infinite and the variables are truly independent, we can then expect the distribution of log-m to follow a gaussian form.

Question 14

challenges in calc IMF?

Answer 14

star count

PDMF

Question 15

challneges in calc IMF: star count?

Answer 15

LMS&raquo_space; # HMS

so v large sample is req to inc HMS

Question 16

challenges in calc IMF: PDMF

Answer 16

stars lifetime finite, sample has stars of diff lifetimes: need to take IMF of present time

HMS have v short lifetime, so when taking PDMF: a lot of HMS wont be in the PDMF

PDMF doesn’t correctly represent HMS population then

Question 17

High mass breakpoint and low mass breakpiunt reasons in IMF?

Answer 17

x

Question 18

8 parameters of IMF?

Answer 18

in paper

Question 19

what defines mass limit?

Answer 19

x

Question 20

are mass limit and breakpoint diff?

Answer 20

x