SharePoint Document Library Edit

Hi , am using SharePoint 2010

have a document Library with emails migrated from public folders ...I have this column Name (linked to document with edit menu  which shows the subject of the email

I want to change this column name - Name (linked to document with edit menu)  to "Subject "..

Please let me know, if there is a way to change this in SharePoint.....did not find it in UI....

I know this is a default column, but want to rename it ...please help