Star on contacts on my iphone?

That star should be RED in color. This indicates that the contact is listed as an Emergency Contact. The emergency contact appears on your Medical ID.

Add emergency contacts

1. Open the Health app and tap your profile picture .
2. Tap Medical ID. 
3. Tap Edit, then scroll to Emergency Contacts.
4. Tap the Add button  to add an emergency contact.
5. Tap a contact, then add their relationship. 
6. Tap Done to save your changes. 

You can't set emergency services as an SOS contact. 

Remove emergency contacts

1. Open the Health app and tap your profile picture .
2. Tap Medical ID. 
3. Tap Edit, then scroll to Emergency Contacts. 
4. Tap the Delete button  next to a contact, then tap Delete.
5. Tap Done to save your changes. 

Axel F.