Que after noun before verb

Question

Sentence: Pero en aquel momento oyó detrás de él un horrible sonido como de arcadas y a tía Petunia que se ponía a gritar.

In the above sentence, what is the function of the word que? Does it have a grammatical name?

Bonus: Why is there an "a" in "ponía a gritar"?

Thanks in advance.

Grant

Update: The que is a relative pronoun. More information here: http://www.studyspanish.com/lessons/relprorev.htm

Ponerse a means "to start" with the implication that it is something the subject is strongly compelled to do.

Answer 1

The word que refers to tía Petunia. It is a relative pronoun meaning that or who depending on context. The verb construction ponerse a means to begin to so a is part of the main verb which requires an infinitive after it to complete the thought.

Answer 2

Pero en aquel momento oyó detrás de él un horrible sonido como de arcadas y a tía Petunia que se ponía a gritar.

What you are missing is that oyó is implicit in the second part:

oyó detrás de él un horrible sonido como de arcadas y oyó a tía Petunia que se ponía a gritar.

From the dictionary three ways to to do that, the third is being done here:

http://www.spanishdict.com/translate/oír

a. to hear los oí hablando o hablar o que hablaban I heard them talking

Que- a conjunction that is introducing a subordinate clause (giving additional information about her, what she was doing) Edit- I will agree with Jubilado- it is a relative pronoun here not a conjunction.

a before Petunia- The personal a, she is the direct object- who someone hears, so you know she is not the subject.

a in ponerse a gritar- ponerse is pronominal in the clause (of which Petunia is the implicit subject)- occupying the object and subject position- so you need a connector (preposition)- "a"- she put herself to screaming.

He heard from behind (himself) a horrible sound like retching and Petunia who began to scream.

You could drop the "who" in English:

He heard from behind (himself) a horrible sound like retching and Petunia began to scream.

And the Spanish then would be

oyó detrás de él un horrible sonido como de arcadas y Petunia se ponía a gritar.

But that was not done. And it doesn't mean the exact same thing or coming of the same place in the previous clause.