Indeed, when retrieving automations in a BU through the API, there seems to be one for journey with an auto-generated name. I faintly remember them being visible some time in the past on the UI, as was a Data Extension per Journey - this has since been changed. Could be wrong about the automation here, but that's anyway anecdotal.
What's clear is that the retrieved automations each have the name of the journey + timestamp at the end, and can be clearly identified by the static
<Description>Event Definition Automation</Description>
It stands to reason (and I confirmed by a test) that these automations are present for each Journey Entry source of type "Data Extension".
I verified that they are not created for an Entry source of type "API Event" or Transactional Journeys.
So pretty clearly, these automations are what's behind the "schedules" in a journey entry source. As an API Entry Source or transactional API entry source has no schedule >> no automation.
Should you delete them? Probably not, if you want the respective journey to function; also, they aren't visible to anyone except API-savvy admins, so what's to gain.
Reproduction - retrieve via SOAP API.
<?xml version="1.0" encoding="UTF-8"?>
<s:Envelope xmlns:s="http://www.w3.org/2003/05/soap-envelope" xmlns:a="http://schemas.xmlsoap.org/ws/2004/08/addressing" xmlns:u="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
<s:Header>
<fueloauth xmlns="http://exacttarget.com">tokentokentoken</fueloauth>
</s:Header>
<s:Body xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<RetrieveRequestMsg xmlns="http://exacttarget.com/wsdl/partnerAPI">
<RetrieveRequest>
<ObjectType>Automation</ObjectType>
<Properties>Name</Properties>
<Properties>Description</Properties>
<Properties>CustomerKey</Properties>
<Properties>IsActive</Properties>
<Properties>ScheduledTime</Properties>
<Properties>Status</Properties>
<Filter xsi:type="SimpleFilterPart">
<Property>IsActive</Property>
<SimpleOperator>equals</SimpleOperator>
<Value>true</Value>
</Filter>
</RetrieveRequest>
</RetrieveRequestMsg>
</s:Body>
</s:Envelope>
Results:
one normal SQL automation, one journey:
<?xml version="1.0" encoding="utf-8"?>
<soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:wsa="http://schemas.xmlsoap.org/ws/2004/08/addressing" xmlns:wsse="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-secext-1.0.xsd" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd">
<env:Header xmlns:env="http://www.w3.org/2003/05/soap-envelope">
<wsa:Action>RetrieveResponse</wsa:Action>
<wsa:MessageID>urn:uuid:a36fe60a-b4be-4fc0-a650-adf00d5db75e</wsa:MessageID>
<wsa:RelatesTo>urn:uuid:3cfc37c8-6069-4eaa-ac4c-7d09016866ae</wsa:RelatesTo>
<wsa:To>http://schemas.xmlsoap.org/ws/2004/08/addressing/role/anonymous</wsa:To>
<wsse:Security>
<wsu:Timestamp wsu:Id="Timestamp-1e720aae-b784-41d7-a800-fae7701bc7de">
<wsu:Created>2022-02-02T07:55:08Z</wsu:Created>
<wsu:Expires>2022-02-02T08:00:08Z</wsu:Expires>
</wsu:Timestamp>
</wsse:Security>
</env:Header>
<soap:Body>
<RetrieveResponseMsg xmlns="http://exacttarget.com/wsdl/partnerAPI">
<OverallStatus>OK</OverallStatus>
<RequestID>e36eb20b-2493-490e-a9fe-16bc68ed4f78</RequestID>
<Results xsi:type="Automation">
<PartnerKey xsi:nil="true" />
<ObjectID xsi:nil="true" />
<CustomerKey>someNormalAutomation</CustomerKey>
<Name>XXXXX</Name>
<Description />
<IsActive>true</IsActive>
<Status>2</Status>
</Results>
<Results xsi:type="Automation">
<PartnerKey xsi:nil="true" />
<ObjectID xsi:nil="true" />
<CustomerKey>8b71df4a-6060-49cd-xxxx-yyyyyyyyy</CustomerKey>
<Name>aJourneyName - 2022-01-24T110411.173</Name>
<Description>Event Definition Automation</Description>
<IsActive>true</IsActive>
<Status>2</Status>
</Results>
</RetrieveResponseMsg>
</soap:Body>
</soap:Envelope>
