LUMINOSITY FUNCTIONS OF<i>SPITZER</i>-IDENTIFIED PROTOSTARS IN NINE NEARBY MOLECULAR CLOUDS

Kryukova, E.; Megeath, S. Thomas; Gutermuth, Robert; Pipher, J. L.; Allen, Thomas S.; Allen, Lori; Myers, Philip C.; Muzerolle, James

doi:10.1088/0004-6256/144/2/31

Cited by 105 publications

(187 citation statements)

References 89 publications

(153 reference statements)

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“…Within the fields observed by HOPS, Stutz et al (2013, hereafter ST13) serendipitously identified 11 protostars with bright 70 μm and 160 μm emission that were not part of the original Spitzer-selected sample. At 24 μm, these sources were either non-detections (8 sources) or so faint that they were flagged as potential extragalactic contamination in the Spitzer surveys Kryukova et al 2012). Moreover, within the original HOPS sample, seven protostars had [24 μm]-[70 μm] colors (in log (λF λ ) space) redder than 1.65, consistent with the Herschel-detected sources.…”

Section: Introductionmentioning

confidence: 75%

CHARACTERIZING THE YOUNGESTHERSCHEL-DETECTED PROTOSTARS. I. ENVELOPE STRUCTURE REVEALED BY CARMA DUST CONTINUUM OBSERVATIONS

Tobin

Stutz

Megeath

et al. 2015

ApJ

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We present Combined Array for Research in Millimeter-wave Astronomy 2.9 mm dust continuum emission observations of a sample of 14 Herschel-detected Class 0 protostars in the Orion A and B molecular clouds, drawn from the PACS Bright Red Sources (PBRS) sample. These objects are characterized by very red 24-70 μm colors and prominent submillimeter emission, suggesting that they are very young Class 0 protostars embedded in dense envelopes. We detect all of the PBRS in 2.9 mm continuum emission and emission from four protostars and one starless core in the fields toward the PBRS; we also report one new PBRS source. The ratio of 2.9 mm luminosity to bolometric luminosity is higher by a factor of ∼5 on average, compared to other well-studied protostars in the Perseus and Ophiuchus clouds. The 2.9 mm visibility amplitudes for 6 of the 14 PBRS are very flat as a function of uv distance, with more than 50% of the source emission arising from radii <1500 AU. These flat visibility amplitudes are most consistent with spherically symmetric envelope density profiles with ρ ∝ R −2.5 . Alternatively, there could be a massive unresolved structure like a disk or a high-density inner envelope departing from a smooth power law. The large amount of mass on scales <1500 AU (implying high average central densities) leads us to suggest that that the PBRS with flat visibility amplitude profiles are the youngest PBRS and may be undergoing a brief phase of high mass infall/accretion and are possibly among the youngest Class 0 protostars. The PBRS with more rapidly declining visibility amplitudes still have large envelope masses, but could be slightly more evolved.

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Section: Introductionmentioning

confidence: 75%

CHARACTERIZING THE YOUNGESTHERSCHEL-DETECTED PROTOSTARS. I. ENVELOPE STRUCTURE REVEALED BY CARMA DUST CONTINUUM OBSERVATIONS

Tobin

Stutz

Megeath

et al. 2015

ApJ

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“…The dark cloud of ρ Ophiuchi has been observed with Spitzer as part of the "Cores to Disks"' (C2D) program (Evans et al 2003), devoted to a deep IR scrutiny of the YSOs in the closest star-forming regions (Gutermuth et al 2009(Gutermuth et al , 2011Kryukova et al 2012). However, the region around ρ Ophiuchi and in the field of view of our XMM-Newton observation has not been observed with Spitzer IRAC.…”

Section: Infrared Counterparts To X-ray Sourcesmentioning

confidence: 90%

First stars of theρOphiuchi dark cloud

Pillitteri

Wolk

Chen

et al. 2016

A&A

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Star formation in molecular clouds can be triggered by the dynamical action of winds from massive stars. Furthermore, X-ray and UV fluxes from massive stars can influence the life time of surrounding circumstellar disks. We present the results of a 53 ks XMMNewton observation centered on the ρ Ophiuchi A+B binary system. ρ Ophiuchi lies in the center of a ring of dust, likely formed by the action of its winds. This region is different from the dense core of the cloud (L1688 Core F) where star formation is at work. X-rays are detected from ρ Ophiuchi as well as a group of surrounding X-ray sources. We detected 89 X-ray sources, 47 of them have at least one counterpart in 2MASS+All-WISE catalogs. Based on IR and X-ray properties, we can distinguish between young stellar objects (YSOs) belonging to the cloud and background objects. Among the cloud members, we detect three debris-disk objects and 22 disk-less − Class III young stars. We show that these stars have ages in 5−10 Myr, and are significantly older than the YSOs in L1688. We speculate that they are the result of an early burst of star formation in the cloud. An X-ray energy of ≥5 × 10 44 erg has been injected into the surrounding medium over the past 5 Myr, we discuss the effects of such energy budget in relation to the cloud properties and dynamics.

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“…Variable or episodic accretion is the leading explanation for the wide range of protostellar luminosities observed in largescale surveys (Kenyon et al 1990;Evans et al 2009;Kryukova et al 2012;Fischer et al 2013;Dunham et al 2014) …”

Section: Introductionmentioning

confidence: 99%

Chemical tracers of episodic accretion in low-mass protostars

Visser

Bergin

Jørgensen

2015

A&A

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Aims. Accretion rates in low-mass protostars can be highly variable in time. Each accretion burst is accompanied by a temporary increase in luminosity, heating up the circumstellar envelope and altering the chemical composition of the gas and dust. This paper aims to study such chemical effects and discusses the feasibility of using molecular spectroscopy as a tracer of episodic accretion rates and timescales. Methods. We simulate a strong accretion burst in a diverse sample of 25 spherical envelope models by increasing the luminosity to 100 times the observed value. Using a comprehensive gas-grain network, we follow the chemical evolution during the burst and for up to 10 5 yr after the system returns to quiescence. The resulting abundance profiles are fed into a line radiative transfer code to simulate rotational spectra of C 18 O, HCO + , H 13 CO + , and N 2 H + at a series of time steps. We compare these spectra to observations taken from the literature and to previously unpublished data of HCO + and N 2 H + 6−5 from the Herschel Space Observatory. Results. The bursts are strong enough to evaporate CO throughout the envelope, which in turn enhances the abundance of HCO + and reduces that of N 2 H + . After the burst, it takes 10 3 -10 4 yr for CO to refreeze and for HCO + and N 2 H + to return to normal. The H 2 O snowline expands outwards by a factor of ∼10 during the burst; afterwards, it contracts again on a timescale of 10 2 -10 3 yr. The chemical effects of the burst remain visible in the rotational spectra for as long as 10 5 yr after the burst has ended, highlighting the importance of considering luminosity variations when analyzing molecular line observations in protostars. The spherical models are currently not accurate enough to derive robust timescales from single-dish observations. As follow-up work, we suggest that the models be calibrated against spatially resolved observations in order to identify the best tracers to be used for statistically significant source samples.

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LUMINOSITY FUNCTIONS OFSPITZER-IDENTIFIED PROTOSTARS IN NINE NEARBY MOLECULAR CLOUDS

Cited by 105 publications

References 89 publications

CHARACTERIZING THE YOUNGESTHERSCHEL-DETECTED PROTOSTARS. I. ENVELOPE STRUCTURE REVEALED BY CARMA DUST CONTINUUM OBSERVATIONS

CHARACTERIZING THE YOUNGESTHERSCHEL-DETECTED PROTOSTARS. I. ENVELOPE STRUCTURE REVEALED BY CARMA DUST CONTINUUM OBSERVATIONS

First stars of theρOphiuchi dark cloud

Chemical tracers of episodic accretion in low-mass protostars

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