We report on the first high-resolution spectroscopic analysis of ( catalog HE~0020 $ - $ 1741 ) , a bright ( V = 12.9 ) , ultra metal-poor ( [ \mathrm { Fe } / \mathrm { H } ] = - 4.1 ) , carbon-enhanced ( [ \mathrm { C } / \mathrm { Fe } ] = + 1.7 ) star selected from the Hamburg/ESO Survey .
This star exhibits low abundances of neutron-capture elements ( [ \mathrm { Ba } / \mathrm { Fe } ] = -1.1 ) , and an absolute carbon abundance A ( C ) = 6.1 ; based on either criterion , ( catalog HE~0020 $ - $ 1741 ) is sub-classified as a CEMP-no star .
We show that the light-element abundance pattern of ( catalog HE~0020 $ - $ 1741 ) is consistent with predicted yields from a massive ( M = 21.5 \mathrm { M } _ { \odot } ) , primordial composition , supernova ( SN ) progenitor .
We also compare the abundance patterns of other ultra metal-poor stars from the literature with available measures of C , N , Na , Mg , and Fe abundances with an extensive grid of SN models ( covering the mass range 10 \mathrm { M } _ { \odot } -100 \mathrm { M } _ { \odot } ) , in order to probe the nature of their likely stellar progenitors .
Our results suggest that at least two classes of progenitors are required at [ \mathrm { Fe } / \mathrm { H } ] < -4.0 , as the abundance patterns for more than half of the sample studied in this work ( 7 out of 12 stars ) can not be easily reproduced by the predicted yields .