Manuel Merello

An analysis of the environments of FU orionis objects with Herschel

We present Herschel-HIFI, SPIRE, and PACS 50-670 µm imaging and spectroscopy of six FU Orionis-type objects and candidates (FU Orionis, V1735 Cyg, V1515 Cyg, V1057 Cyg, V1331 Cyg, and HBC 722), ranging in outburst date from 1936-2010, from the “FOOSH” (FU Orionis Objects Surveyed with Herschel) program, as well as ancillary results from Spitzer-IRS and the Caltech Submillimeter Observatory. In their system properties (Lbol, Tbol, line emission), we find that FUors are in a variety of evolutionary states. Additionally, some FUors have features of both Class I and II sources: warm continuum consistent with Class II sources, but rotational line emission typical of Class I, far higher than Class II sources of similar mass/luminosity. Combining several classification techniques, we find an evolutionary sequence consistent with previous mid-IR indicators. We detect [O I] in every source at luminosities consistent with Class 0/I protostars, much greater than in Class II disks. We detect transitions of 13 CO (Jup of 5 to 8) around two sources (V1735 Cyg and HBC 722) but attribute them to nearby protostars. Of the remaining sources, three (FU Ori, V1515 Cyg, and V1331 Cyg) exhibit only low-lying CO, but one (V1057 Cyg) shows CO up to J = 23 ! 22 and evidence for H2O and OH emission, at strengths typical of protostars rather than T Tauri stars. Rotational temperatures for “cool” CO components range from 20-81 K, for � 10 50 total CO molecules. We detect [C I] and [N II] primarily as diffuse emission. Subject headings: stars: pre-main sequence — stars: variables: T Tauri — ISM: jets and outflows — submillimeter: ISM — stars: individual (HBC 722, FU Orionis, V1057 Cyg, V1735 Cyg, V1331 Cyg, V1515 Cyg)

THE BOLOCAM GALACTIC PLANE SURVEY. XI. TEMPERATURES AND SUBSTRUCTURE OF GALACTIC CLUMPS BASED ON 350 μM OBSERVATIONS

We present 107 maps of continuum emission at 350 μm from Galactic molecular clumps. Observed sources were mainly selected from the Bolocam Galactic Plane Survey (BGPS) catalog, with three additional maps covering star-forming regions in the outer Galaxy. The higher resolution of the SHARC-II images (8.″5 beam) compared with the 1.1 mm images from BGPS (33″ beam) allowed us to identify a large population of smaller substructures within the clumps. A catalog is presented for the 1386 sources extracted from the 350 μm maps. The color temperature distribution of clumps based on the two wavelengths has a median of 13.3 K and mean of 16.3 ± 0.4 K, assuming an opacity law index of 1.7. For the structures with good determination of color temperatures, the mean ratio of gas temperature, determined from NH3 observations, to dust color temperature is 0.88 and the median ratio is 0.76. About half the clumps have more than 2 substructures and 22 clumps have more than 10. The fraction of the mass in dense substructures seen at 350 μm compared to the mass of their parental clump is ∼0.19, and the surface densities of these substructures are, on average, 2.2 times those seen in the clumps identified at 1.1 mm. For a well-characterized sample, 88 structures (31%) exceed a surface density of 0.2 g cm−2, and 18 (6%) exceed 1.0 g cm−2, thresholds for massive star formation suggested by theorists.

CALIBRATION OF EVOLUTIONARY DIAGNOSTICS IN HIGH-MASS STAR FORMATION

The evolutionary classification of massive clumps that are candidate progenitors of high-mass young stars and clusters relies on a variety of independent diagnostics based on observables from the near-infrared to the radio. A promising evolutionary indicator for massive and dense cluster-progenitor clumps is the L/M ratio between the bolometric luminosity and the mass of the clumps. With the aim of providing a quantitative calibration for this indicator we used SEPIA/APEX to obtain CH3C2H(12-11) observations, that is an excellent thermometer molecule probing densities > 10^5 cm^-3 , toward 51 dense clumps with M>1000 solar masses, and uniformly spanning -2 < Log(L/M) < 2.3. We identify three distinct ranges of L/M that can be associated to three distinct phases of star formation in massive clumps. For L/M 10 we detect all the clumps, with a gas temperature rising with Log(L/M), marking the appearance of a qualitatively different heating source within the clumps; such values are found towards clumps with UCHII counterparts, suggesting that the quantitative difference in T - L/M behaviour above L/M >10 is due to the first appearance of ZAMS stars in the clumps.

The bolocam galactic plane survey. XIII. Physical properties and mass functions of dense molecular cloud structures

We use the distance probability density function (DPDF) formalism of Ellsworth-Bowers et al. (2013, 2015) to derive physical properties for the collection of 1,710 Bolocam Galactic Plane Survey (BGPS) version 2 sources with well-constrained distance estimates. To account for Malmquist bias, we estimate that the present sample of BGPS sources is 90% complete above 400

PHYSICAL CHARACTERISTICS OF G331.5-0.1: THE LUMINOUS CENTRAL REGION OF A GIANT MOLECULAR CLOUD

M_\odot

G331.512-0.103: An Interstellar Laboratory for Molecular Synthesis. I. the Ortho-to-para Ratios for CH3OH and CH3CN

and 50% complete above 70

The Bolocam Galactic Plane Survey: λ = 1.1 and 0.35 mm Dust Continuum Emission in the Galactic Center Region

M_\odot

The Bolocam Galactic Plane Survey. IX. Data Release 2 and Outer Galaxy Extension

. The mass distributions for the entire sample and astrophysically motivated subsets are generally fitted well by a lognormal function, with approximately power-law distributions at high mass. Power-law behavior emerges more clearly when the sample population is narrowed in heliocentric distance (power-law index

THE BOLOCAM GALACTIC PLANE SURVEY. III. CHARACTERIZING PHYSICAL PROPERTIES OF MASSIVE STAR-FORMING REGIONS IN THE GEMINI OB1 MOLECULAR CLOUD

\alpha = 2.0\pm0.1

DISENTANGLING THE ENVIRONMENT OF THE FU ORIONIS CANDIDATE HBC 722 WITH HERSCHEL

for sources nearer than 6.5 kpc and