The probe is not immediately destroyed, so that's probably a good thing.

The system is sparse, but not uninhabited. Two gas giants on the outer perimeter with a handful of moons apiece, three small and rocky worlds closer to the star, lambent and red. A scattering of satellites whip around the star in close orbit, and there are industrial activities on the second and fouth planets.

The scientists adjust the probe's scanners and cameras to look at the fourth planet.

They check for technology-level.  Any ships, artificial satellites, or space stations in orbit?

The main installation seems like a storage facility or refinery. Skimmers descend into the cloudy depths and return to discharge their cargo into the massive tanks attached to all sides of the hexagonal station.

And the second planet?

Operations here are focused on research rather than exploitation, with an extensive sensor net across all three continents and their varied biomes.

Based on their findings, the scientists are currently guessing these machines are the work of some civilization originating outside of the system.  

They check for radio waves, hoping to detect a communication frequency to make contact through.

There are no radio signals detectable from the edge of the system.

There are, however, three ships in close formation approaching the portal. Their design is arcane and angular, but they are clearly armed.

The probe sends out a pattern of prime numbers over frequencies that Murune most commonly uses for space, standing still in front of the portal.

The ships pull to a relative stop a respectable distance away, and there's a few hours' pause as the probe and the portal are thoroughly scanned.

The probe is mostly metal, and seems to work through understandable technological means.  Most of its mass is made of a large antenna dish and other sensors that seem to have been made for deep space viewing.  It tries the prime number sequence again every 30 minutes, and noninvasively scans the ships.

The portal is very much magic.  The torus around the edges is only a few feet thick, a narrow band of white around the circle of space showing different stars.  It gives off the same readings as come through from the space on the other side.  

A single unarmed research ship is on the other side.  Owlida design with smooth curves and lines of pastel colors.

Once the corvettes' scans are finished, they preempt the next transmission of numbers with their own, repeating it back to the probe.

Communication!  Sort of.  None of the races in Murune had needed to first communicate through separate and likely-vastly-different computer systems, so they're running on the best ideas their science fiction writers have come up with.  

They begin sending a steady stream of text written in their simplest language, including things like the periodic table which they hope will be easy to recognize.  Presumably a civilization that has both FTL ships and access to lots of other star systems will have better translation than they do, though the research ship does prepare the computers to process anything sent back.  

The other side transmits a reciprocal set of data.

About a day later, a new ship shimmers into being within view of the portal. About as big as the others, but with less obvious armament and two forward-swept arms enclosing a geodesic sphere that glows with inner radiance and seems to be floating unattached to the rest of the ship's structure. Shortly after its appearance, the transmissions become more detailed, and are accompanied by a translation in the portalmakers' language.

With a translation in their computers, the ship composes a message.

"This is the research vessel Dewgather, from the star system Murune.  We are on a mission of exploration and scientific discovery."

A reply comes back: "Research vessel Dewgather, know that you stand on the threshold of the sovereign territory of the Virene Imperium and all these stars are claimed in the name of the Empress's divine majesty."

"Our empire would be interested in opening diplomatic communication between our respective civilizations.  We have received authorization to extend an invitation for a diplomatic ship from the Virene Imperium into the Murune system.  The Kiarasa representative of our crew is also capable of acting as a diplomat, and has been granted the authority to make short-term agreements under the authority of the Champion of Murune.  

"We can also call for a tow-ship to move our portal, if you'd prefer to have it elsewhere.  The current location was placed blindly, as there was no way to determine what would be on the other side."

One of the corvettes peels off and makes for the mining station.

"The Empress has decreed that she will attend this contact in person. The Stooping Falcon goes now to fetch her. She will lead the delegation to your star while an escort assembles here."

"Murune will be honored to host your Empress.

"What atmosphere and temperature would be best for the species making up the delegation?"

Such scientific data can be provided.

Murune prepares.  The champion and high priest make their ways to the palace of Murune's Empress - the high priest by shuttle, the champion by a long sequence of portals and subway systems.  Minor atmospheric changes are made to the main hall, and it's fully sterilized of any potentially dangerous microorganisms.  Not that much can go wrong with a god and a biokinetic on hand, but it wouldn't do to look sloppy.  There's a plan to clear a wide path between MuurKari and the portal of normal traffic.  Police patrols in the area are increased.  

On the other side of the portal, the corvette returns and docks with the science ship briefly. After it breaks off, the science ship powers up its engines and begins to drift gently through the portal.

The ship passes through the portal without incident and are now in Murune's borders. 

Dewgather greets them.  "Our Empress invites you to the Imperial Palace."  They provide a map.  "The portal is about 5000 au away from MuurKari, which is a 13 hour trip via lightwarp.  We aren't familiar with your method of FTL, however."

"Our FTL only functions at the edge of a stellar gravity well. Intra-system travel is slower than light. It will take us approximately five days to cover this distance."

"We haven't been given permission to leave the portal area, but we can request a ship be diverted to pull you in their lightwarp bubble if you'd prefer.  The nearest ship is four hours away."

"That will do."