Please do not open links in new tabs/windows without warning users. This breaks the browser’s back button functionality – leaving some users stranded in the new tab/window without any way back to the original site.
Keyboard shortcuts Ctrl+W (Windows and Linux) and ⌘-W (Mac) close a tab or window, though for complete accessibility, such as readers, I’m not sure what the shortcuts are. Something I need to look into.
The important thing is that I hadn’t added the warning, which I thank you for pointing out.