Having an abortion means automatic excommunication from the Church. Are there other sins that carry this penalty?
Yes. In the 1983 Code of Canon Law (CIC) eight other sins carry the penalty of automatic excommunication: apostasy, heresy, schism (CIC 1364:1), violating the sacred species (CIC 1367), physically attacking the pope (CIC 1370:1), sacramentally absolving an accomplice in a sexual sin (CIC 1378:1), consecrating a bishop without authorization (CIC 1382), and directly violating the seal of confession (1388:1).
Apostasy is the total repudiation of the Christian faith. Heresy is the obstinate doubt or denial, after baptism, of a defined Catholic doctrine. Schism is the refusal of submission to the Roman Pontiff or the refusal to be in communion with members of the Church who are in communion with him (CIC 751).
Violation of the sacred species is the throwing away the consecrated species of Christ's body or blood or the taking or retaining of them for a sacrilegious purpose (CIC 1367).
Physically attacking the pope is self-explanatory, as are absolving an accomplice in a sexual sin and consecrating a bishop without authorization from the Vatican.
A direct violation of the seal of confession is one in which both the penitent and the penitent's sin can easily be determined by the confessor's words or behavior. Again, the penalty of automatic excommunication does not apply if no one perceives the disclosure (CIC 1330).
Automatic excommunication for abortion (CIC 1398) applies not only to the woman who has the abortion, but to "all those who commit this crime with knowledge of the penalty attached, and [this] includes those accomplices without whose help the crime would not have been committed" (Evangelium Vitae 62).
No one is automatically excommunicated for any offense if, without any fault of his own, he was unaware that he was violating a law (CIC 1323:2) or that a penalty was attached to the law (CIC 1324:1:9). The same applies if one was a minor, had the imperfect use of reason, was forced through grave or relatively grave fear, was forced through serious inconvenience, or in certain other circumstances (CIC 1324).