It is interesting to note that in the previous page's drawing of the cover of The Return of the King, which was drawn by Tolkien himself, that the Stars themselves are arranged in the pattern of a five-pointed star.
As the Heir of Elendil, Aragorn along with his Rangers should have worn a Star having five rays or points. We also know from the reference that the same stars with five points were used in the heraldry of Arnor and Gondor. Of course Rangering being a sometimes rough and tumble profession, it might not be wise that said points be sharp so they probably were blunted somehow so as to keep a Ranger from impaling himself should he fall from his horse or upon the ground.
But perhaps some of the most interesting evidence comes with the shape of the Island of Numenor itself, from which the Dunedain had their beginnings.
"The Land of Numenor resembled in outline a five-pointed star, or pentangle, with a central portion of some two hundred fifty miles across, north and south, and east and west, from which extended five penisular promontories."
A Description of the Island of Numenor, Unfinished Tales
Also we know that Elendil used the letters of his name minus the vowels as his personal badge and this same badge was found upon his tomb.
"Then Cirion went up the stair with Eorl and the others followed; and when they came to the summit, they saw there a wide oval space of level turf, unfenced but at its eastern end there stood a low mound ..... then the Lord of Dol Amroth ..... went towards the mound, a saw lying on the grass before it and yet unmarred by weed or weather, a black stone, and on the stone three letters were engraved. Then he said to Cirion, "Is this then a tomb? But what great man of old lies here?"
"Have you not read the letters?" said Cirion
"I have". said the Prince, "And therefore I wonder, for the letters are lambe, amdo, lambe, but there is no tomb for Elendil, nor has any man since his day, dared to use that name."
Nonetheless, this is his tomb" said Cirion, "and from it comes the awe that dwells on this hill and in the woods below".
The letters were
L ND L
Elendil's name without vowel marks which he used as a badge and as a device upon his seal.
Unfinished Tales, Part 3 Chapter 2, Cirion and Eorl and the Friendship of Gondor and Rohan, Note 40
In constructing a Star of the Dunedain as worn by the Rangers of the North and based on the evidence above, one can conclude that seven five pointed stars would have been used. It is very possible that the Rangers would have wanted to promote the knowledge of Aragorn being Elendil's Heir and would have used the sacred name also as a badge upon the Star. And we shouldn't leave the Seven Stars out but how should they be arranged? Not like the later one used by Gondor with the White Tree but in the pentangle pattern as drawn by Tolkien on the cover of
The Return of the King.