That looks awfully familiar. Detailed scan!
Just what I thought: Space Nosferatu.
Space Vampires are nothing new. From Planet of the Vampires to Lifeforce to the Necroscope series, the idea of the vampire as an alien entity has been explored with varying degrees of success. Given the amount of unfiltered cosmic rays in space I would imagine being a space vampire is like being a slug in a salt mine, but what do I know?
Regardless the idea here is that vampires, including the kind that suck energy instead of blood, (which is not really much of a vampire is it? I'm being pedantic here, I know) have been seen in science fiction for a number of years. Aliens can be pretty frightening. Vampires should be pretty frightening. Alien vampires therefore should be at least twice as frightening.
Assessment: All vampires suck and must be destroyed, so why should alien Nosferatu be an exception? There is no coming in peace here. Even if, say, he comes from a planet where he is the native intelligent life form and they all drink blood instead of water that's still a problem to be dealt with using the tried and true methods. What is the probability that we scan this guy and find out that he's not the native inhabitant of his planet but indeed one of the natives infected with the Vampire Virus. Because once you go sci-fi you start labeling supernatural things as virus or mutant and take all the magic out of it. Next thing you know things are sparkling and it's all a big mess. I'm betting that a death ray set to full power will toast this guy up just as quickly as a stake through the heart.
He does have the robe and high collar look, so I suppose he might just be an alien and not a Space Nosferatu. On the other hand...
Computer, enhance segment beta 2, beta 3, gamma 2, gamma 3.
Ha! There is no way in Space Hell that is not a vampire.
Just look at that sucker. Let me see, let me see, Prime Directive...here it is: No identification of self or mission. No interference with the social development of said planet. No references to space or the fact that there are other worlds or civilizations.
Not much help there. But it doesn't specifically say we can't blast this sucker out of existence and since he hailed us that means that...sod it! SET PHASERS TO STAKE! FULL POWER!
That was close. Come back soon for more useful information.