Year: 2022
Type: article
Abstract: ABSTRACT We present a new SOFIA/FORCAST mid-infrared survey of luminous protostars and crowded star-forming environments in Cygnus X, the nearest million-solar mass molecular cloud complex. We derive bolometric luminosities for over 1000 sources in the region with these new data in combination with extant Spitzer and UKIDSS photometry, with 63 new luminous protostar candidates identified by way of the high-quality SOFIA/FORCAST data. By including FORCAST data, we construct protostellar luminosity functions (PLFs) with improved completeness at the high luminosity end. The PLFs are well described by a power-law function with an index of ∼−0.5. Based on the Herschel temperature and column density measurements, we find no obvious dependence of the PLFs on the local gas temperature, but PLFs in regions of high stellar density or gas column density exhibit some excess at higher luminosities. Through the comparison between our observed PLFs and existing accretion models, both the turbulent core and the competitive accretion models are consistent with our results, while the isothermal sphere model is disfavoured. The implications of these results on the star formation process are discussed.
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1134310069, G131639412, RECONCILING THE CENSUS OF FORMING STARS IN GOULD'S BELTWE SEEK FUNDING TO CONSTRUCT A SET OF NEW PUBLICLY AVAILABLE VALUE-ENHANCED DATA PRODUCTS FOR THE 37 DEG2 OF ARCHIVAL SPITZER IRAC 3-8 MICRON AND MIPS 24 MICRON IMAGING FROM THE SPITZER LEGACY SURVEYS FROM MOLECULAR CORES TO PLANET-FORMING DISKS AND THE SUBSEQUENT GOULD'S BELT: STAR FORMATION IN THE SOLAR NEIGHBORHOOD. THESE SURVEYS COMPRISE OUR CANONICAL VIEW OF LOW-MASS STAR FORMATION ENCOMPASSING MOST OF THE NEAREST (<400PC) MOLECULAR CLOUDS OTHER THAN TAURUS. FROM THE PROPOSED C2D/GB REPROCESSING WE WILL PRODUCE AND DELIVER THE FOLLOWING PRODUCTS TO THE INFRARED SCIENCE ARCHIVE (IRSA) AT IPAC FOR COMMUNITY ACCESS: - ARTIFACT-MITIGATED ASTROMETRICALLY-REFINED SPITZER MOSAICS AT 3.6 4.5 5.8 8.0 AND 24 MICRONS FOR ALL 18 CLOUDS IN C2D/GB; - COMPLETE BAND-MERGED POINT SOURCE CATALOGS IN ALL FIVE SPITZER BANDS CONSIDERED COMBINED WITH 2MASS AND WISE PHOTOMETRY WHERE AVAILABLE AND A CENSUS OF YOUNG STELLAR OBJECTS (YSOS) WITH EXCESS INFRARED EMISSION THAT ARE SELECTED VIA THE GUTERMUTH ET AL. (2009; G09) YSO IDENTIFICATION AND CLASSIFICATION TECHNIQUES FROM THE FULL CATALOGS; - POINT SOURCE COMPLETENESS DECAY DATA CUBES AT 30'' RESOLUTION FOR ALL SPITZER MOSAICS AND MID-IR LUMINOSITY COMPLETENESS IMAGES BUILT FROM THE FIVE-BAND COMPLETENESS CUBES FOR A WIDE RANGE OF MID-IR SPECTRAL ENERGY DISTRIBUTION (SED) SHAPES. OUR OVERARCHING GOAL IS TO PROVIDE A PRECISE OBSERVATIONAL PRODUCT THAT CONTAINS THE MEANS TO TEST EVER MORE DETAILED SIMULATIONS OF STAR FORMATION AND GUIDE AND SUPPLEMENT FUTURE OBSERVATIONS OF NEARBY STAR-FORMING REGIONS AND CLOUDS AT ALL WAVELENGTHS. A COMPLETE INTERNALLY CONSISTENT CENSUS OF ALL YSOS EXHIBITING EXCESS INFRARED EMISSION AND A DETAILED MAPPING OF THE LIMITS OF NONDETECTIONS BY YSO EVOLUTIONARY STAGE FOR ALL MOLECULAR CLOUDS AND STAR-FORMING COMPLEXES OBSERVED BY SPITZER WITHIN 2 KPC WILL HAVE INCREDIBLE VALUE FOR BOTH GOALS. WITH A FULL YSO CENSUS AND A CLEARER UNDERSTANDING OF HOW TO INTERPRET ANY LACK OF YSOS SPATIALLY WITHIN A WIDE RANGE OF CLOUDS WE WILL ADDRESS THREE FUNDAMENTAL LINES OF INQUIRY ACROSS A WIDE RANGE OF LOCAL STAR-FORMING ENVIRONMENTS: - WHAT IS THE PROTOSTELLAR PHASE LIFETIME? HOW DOES IT CORRELATE WITH THE STAR FORMATION EFFICIENCY OF MOLECULAR GAS? - WHAT IS THE SHAPE OF THE PROTOSTELLAR LUMINOSITY FUNCTION? DOES IT VARY WITH MOLECULAR GAS PROPERTIES? - WHICH DENSE PRE-STELLAR GAS CORES ARE STARLESS ? MORE SPECIFICALLY WHAT YSO LUMINOSITY LIMITS CAN WE EXCLUDE IN STARLESS CORES WITH THE SPITZER SURVEYS? MOST OF THE C2D/GB CLOUD SURVEYS HAVE BEEN ANALYZED AND PUBLISHED BY THE ORIGINAL TEAMS AND THEY HAVE NOW LARGELY DISPERSED (TWO OF THIS PROPOSAL'S INVESTIGATORS WERE MEMBERS OF ONE OR BOTH SURVEYS). IN PARALLEL THE G09 TECHNIQUES THAT WERE DEVELOPED FOR A SURVEY OF 36 NEARBY STAR-FORMING CLUSTERS AND GROUPS WERE ADOPTED FOR A WIDE ARRAY OF YSO SURVEYS OF MORE DISTANT STARFORMING MOLECULAR CLOUDS (400-2000PC). THESE ARE OBSERVED SIMILARLY TO THE C2D/GB SURVEYS AND THUS THE G09 TECHNIQUES ARE READILY APPLICABLE TO THE NEAREST CLOUDS. INDEED THE C2D/GB YSO CENSUS OVERLAPS WITH SEVERAL CLUSTERS IN THE ORIGINAL G09 CLUSTERS SURVEY AND SUBSTANTIAL INCONSISTENCIES HAVE BEEN FOUND BETWEEN THE CORRESPONDING YSO CATALOGS. ATTEMPTS TO CONDUCT BROAD COMPARISONS AND INTERPRETATION AMONG C2D/GB AND G09-FAMILY CATALOGS HAVE BEEN CLEARLY LIMITED BY METHOD-DEPENDENT DIFFERENCES. RECONCILIATION OF THESE DISCREPANCIES IS ESSENTIAL TO ESTABLISH A CONSISTENT CENSUS OF YSOS AND ENABLE FURTHER SCIENTIFIC PROGRESS ON THESE TOPICS., WE PROPOSE A SPITZER AND 2MASS ARCHIVAL PROGRAM TO PERFORM A UNIFORM ANALYSIS OF ALL OF THE KNOWN STAR FORMING REGIONS THAT ARE 400-1000PC AWAY, CREA, G2059117396, G314217133, G4023115690, THIS PROPOSAL REQUESTS SUPPORT TO PRODUCE, DOCUMENT, AND DISTRIBUTE A POINT SOURCE CATALOG DERIVED FROM THE SPITZER SPACE TELESCOPE MIPSGAL SURVEY OF, INVESTIGATING STAR-GAS CORRELATION AND EVOLUTION IN THE 100PC CYGNUS X COMPLEX. WE REQUEST SUPPORT TO PURSUE A SUBSTANTIAL REFINEMENT OF THE ONGOING
OpenAlex ID: W4212920231