A Caltech 'rising star' astrophysics professor who allegedly fell in love with his student and then fired her has resigned

• Caltech professor Christian Ott has resigned after claims he sexually harassed two of his students.

• Ott had been suspended from campus since the fall of 2015.

• His resignation came as the school was deciding whether to allow him to return to campus.

Christian Ott, a "rising star" in the astrophysics department at the California Institute of Technology, has resigned following a sexual harassment investigation, BuzzFeed News reported.

In 2015, Ott was placed on nine-month unpaid leave for "unambiguous gender-based harassment" of two students and restricted from stepping foot on campus until the suspension was up.

Caltech then extended the leave an additional year after he had been found in violation of the terms of suspension for contacting one of the students.

The harassment involved two female graduate students who worked under Ott and brought the harassment complaint to Caltech's Title IX office.

The allegations revolve around Ott's romantic feelings toward Io Kleiser, one of the students, and his inappropriate conversations with the other, Sarah Gossan, over the course of nearly two years.

BuzzFeed previously reported that in 2012, the 22-year-old Kleiser was studying supernovae and conducting research under Ott. When she started struggling to balance her course load with her research responsibilities, Ott began to grow frustrated with Kleiser and told her he was unhappy with the effort she was putting into her research.

"It saddens me that research is coming last ��," he wrote to her one night in 2013, according to BuzzFeed's report.

Shortly after, he set up a meeting with her at a coffee shop - where he allegedly fired her, saying that he no longer wanted to work with her and to find another adviser.

Unbeknownst to Kleiser, Ott's true motive for her dismissal had to do with his romantic feelings for the graduate student. He confided those feelings for Kleiser to another of his graduate students, the 23-year-old Gossan.

Gossan claims that Ott explained to her in a Skype chat that he was in love with Kleiser, according to BuzzFeed. "The reason he had fired her was because he was concerned she was using her sexual influence over him to not do any work," Gossan told BuzzFeed.

BuzzFeed reported that over the course of two years, Gossan says Ott's comments and behavior to her became progressively more hostile. He began to damage her confidence.

"He slowly but surely made me feel worthless," she told the publication.

She eventually went to Caltech's Title IX office - which comes from the federal law that prohibits gender discrimination - to file a complaint.

Ott's resignation came as the university was deciding whether it would allow him to return to campus. "This has been a difficult situation for our community," a Caltech statement sent to students and alumni read.

Ott did not immediately respond to a request for comment from Business Insider.

Caltech's suspension of Ott had been lauded by some who feel it's a positive response for a field that is often dogged with claims that it is unwelcoming for women.

But many, including Kleiser, didn't think Caltech did enough, a fact that has led her to decide to leave academia once she finishes her PhD.

"I didn't see a lot of action on the part of people that I considered to be my role models in my field," Kleiser told BuzzFeed. "So that's kind of difficult, and I think that makes it harder to want to stay and eventually take a permanent position in a place like this."