Error on assigning a class member by a class reference

Question

This code works:

class Student{
    public:
    int id;
    string name;
    string city;
    Student(int id, string name, string city){
        this->id = id;
        this->name = name;
        this->city = city;
    }
};

class Node{
    public:
    Student* student;
    Node* next;
};

int main(){
    Student s1(1,"abc","def");
    Node n;
    n.student = &s1;
    n.next = NULL;

}

However if I make the following change:

class Node{
    public:
    Student student;
    Node* next;
};

int main(){
    Student s1(1,"abc","def");
    Node n;
    n.student = s1;
    n.next = NULL;

}

I get the error:

<source>: In function 'int main()':
<source>:24:10: error: use of deleted function 'Node::Node()'
   24 |     Node n;
      |          ^
<source>:16:7: note: 'Node::Node()' is implicitly deleted because the default definition would be ill-formed:
   16 | class Node{
      |       ^~~~
<source>:16:7: error: no matching function for call to 'Student::Student()'
<source>:9:5: note: candidate: 'Student::Student(int, std::string, std::string)'
    9 |     Student(int id, string name, string city){
      |     ^~~~~~~
<source>:9:5: note:   candidate expects 3 arguments, 0 provided
<source>:4:7: note: candidate: 'Student::Student(const Student&)'
    4 | class Student{
      |       ^~~~~~~
<source>:4:7: note:   candidate expects 1 argument, 0 provided
<source>:4:7: note: candidate: 'Student::Student(Student&&)'
<source>:4:7: note:   candidate expects 1 argument, 0 provided

I don't understand why when using a reference instead of a pointer would cause an error related to the constructor of Node.