STUDYING COMPACT RADIO SOURCES ASSOCIATED WITH UCHII REGIONS

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1 STUDYING COMPACT RADIO SOURCES ASSOCIATED WITH UCHII REGIONS Josep Maria Masqué Saumell Departamento de Astronomía Universidad de Guanajuato Collaborators: Universidad de Guanajuato: Miguel Angel Trinidad, Carlos A. Rodríguez Instituto de RadioAstronomía y Astrofísica (UNAM): Luís F. Rodríguez, Stan Kurtz, Laurent Loinard Max Planck Institut für Radioastronomie: Sergio A. Dib

2 The formation of high mass protostars LOW MASS PROTOSTARS Observations of nearby low mass regions (less than 500 pc): Taurus, Ophicus, Pipe Nebula

3 The formation of high mass protostars HIGH MASS PROTOSTARS Massive stars reach the main sequence before the end of accretion Additional stellar feedbacks: Strong radiation pressure Strong winds (mass loss rates > Msun/yr) Giant outflows (released energies > ergs) Ionization of the surrounding medium (M > 15 Msun) However: Massive stars provides an important feedback on their surroundings and, even, in the interstellar medium of the whole Galaxy

4 A multi-wavelength The formation study of of high the mass HH 80N protostars core THE UCHII STAGE Protostars with mass larger than 15 Msun ionize their own accreting flow: is the protostellar infall halted? There are too many UCHII regions in the Galaxy

5 A multi-wavelength study of the HH 80N core UCHII regions UCHII regions Sizes < 0.1 pc Electron densities > 10 4 cm -3 Ionized mass 0.01 Msun Expected lifetime 10 4 yr * *Assuming that the region is expanding at the sound speed Kurtz et al Protostars with masses larger than 15 Msun ionize their own accreting flow: is the protostellar infall halted? There are too many UCHII regions in the Galaxy (Wood & Chuchwell 1989)

6 UCHII regions Possibilities: The UCHII (or HCHII) region is gravitationally trapped by the massive protostar (Keto 2002, 2003). In the competitive accretion scenario, a large amount of gas from the ambient cloud is accreting continuously onto the protostellar core hindering the free expansion of the HII region (e.g.g n: Galvan-Madrid et al. 2009). The protostar has an evaporating disk that supplies ionized gas to the compact region as its material is freely expanding (Hollenback et al. 1994). Diagnostics: Non-Spherical morphologies and/or irregular structure, time variability, protostellar activity We need to resolve the substructure (if exists) of UCHII regions

7 A multi-wavelength study of the HH 80N core Compact sources associated with UCHII regions INTERFEROMETRIC OBSERVATIONS HII regions are strong free-free emitters specially at cm wavelengths We are interested only in the largest baselines in order to remove the extended emission

8 Examples A multi-wavelength of Compact study Radio of Sources: the HH NGC 80N 6634 core COMPACT RADIOSOURCES Stellar wind? Carral et al Presence of compact radio sources with puzzling nature (see also Rodríguez et al. 2014)

9 Examples A multi-wavelength of Compact study Radio of Sources: the HH 80N W3 (OH) core COMPACT RADIOSOURCES Photoevaporating disk? Dzib et al. 2013a Positive spectral index marginally resolved

10 Examples A multi-wavelength of of Compact study Radio of Sources: the HH NGC 80N W (OH) core COMPACT RADIOSOURCES Elephant trunk Dzib et al. 2013a VLA 7 mm@a configuration

11 Examples of Compact Radio Sources: NGC 6634 COMPACT RADIOSOURCES Shocked wind collision region between contact binaries? Ortiz-León 2011, Dzib et al. 2013b Non-thermal emision

12 Examples of Compact Radio Sources: M8 LAGOON NEBULA (M8) Wood and Chuchwell (1989) associated the radio emission peak as an UCHII region. However, Stecklum et al found evidence that this source is a photo evaporating disk (i.e. proplyd). Stecklum et al. 1998

13 Examples of Compact Radio Sources: M8 VLA OBSERVATIONS OF M8 Her 36 is a múltiple star (Arias et al. 2010). The radio emission falls between the two stars. Shocked wind region? The morphology of the G5.97 proplyd is resolved Detection of non-thermal emission! Masqué, Dzib & Rodríguez et al. 2014

14 The nature of compact radio sources Rodríguez et al. 2013?

15 A multi-wavelength study of the HH 80N core Observational campaign VLA OBSERVATIONS We need to observe with: How rare are these compact sources? Good sensitivity (we are using the most noisy baselines) High angular resolution (sizes of 0.1 Good UV coverage (high fidelity maps) Regions optically thin (they are expected to have high emission measures) VLA with extended configurations and high frequency bands

16 A multi-wavelength study of the HH 80N core Recent results (Masqué et al. 2017) VLA 1.3 cm observations with A configuration

17 A multi-wavelength Recent results study (Masqué of the Recent HH et al. 80N results 2017) core We found 13 compact sources in 12 UCHII regions Only 3 UCHII lack of compact sources

18 A multi-wavelength Recent results study (Masqué of the Recent HH et al. 80N results 2017) core

19 Recent results TYPE I SOURCES They are spatially associated (at least in projection) with the UCHII emission

20 A multi-wavelength study of the Recent HH 80N results core G28.29-VLA1 Possible but unlikely association with IR 2MASS point source. It is the largest source of Type I dataset (300 AU) Unlikely HCHII region External ionization/ photoewvaporation (?)

21 A multi-wavelength study of the Recent HH 80N results core G35.20-VLA1 It is the densest source of our dataset (2 x 10 6 cm -3 ) It is compact (200 x 100 AU) but slightly resolved Size smaller than the gravitational radius of a B1 star: internal ionization (?) Photoionizing disk around exciting star?

22 A multi-wavelength study of the Recent HH 80N results core TYPE II SOURCES They appear scattered around the UCHII region They may belong to the main region but are unrelated to the dense gas of UCHII region.

23 A multi-wavelength study of the Recent HH 80N results core TYPE II SOURCES Some have IR association Most of them appear unresolved We did not detect circular polarization but detectio limit no stringent. Proplyds? Gyrosynchrotron activity on the stellar surface? Small HII regions? Shocked wind regions between contact binaries?

24 A multi-wavelength study of Very the recent HH 80N results core G Marco Salazar s Master Thesis Type II source that splits into two smaller sources (jet?, background radiogalaxy? Binary?)

25 A multi-wavelength study of Very the recent HH 80N results core Q band observations at B configuration Spectral índex 0.6 Spectral índex 0.3 Spectral índex VLA1 0.9 Spectral índex 1.5 Spectral índex VLA2-0.3 Similar angular resolution than K band observations at A configuration

26 A multi-wavelength study of the Interpretation HH 80N core G5.97-Proplyd Type II source, photo evaporating object G5.97-Her36 SE Type II source, shocked wind collision region G5.97-Her 36N Type II source, radio star G20.08-VLA1 Uncertain, HCHII region G28.29-VLA1 Type I, photo evaporating neutral globule (density gradient?) G35.20-VLA1 Type I, photo evaporating disk around the exiting star G60.88-VLA1 Type II, unresolved HCHII region G61.48-VLA1 Type II, proplyd G61.48-VLA2 Type II, radiostar, unresolved shock? G78.44-VLA4 Type II, small HCHII region G78.44-VLA1 Type II, radiostar

27 A multi-wavelength study of the Interpretation HH 80N core G76.18-VLA1 Type I source, uncertain, negative spectral index G76.38-VLA1 Type I source, photo ionizing disk G111 HCHII regions? spectral indices rule out the radio jet possibility

28 A multi-wavelength study of the Recent Interpretation HH 80N results core PROPLYDS AND FOTOEVAPORATING GLOBULES Type I sources Type II sources Photoevaporating rates of MSun/yr Lifetimes of yr (assuming 0.1 Msun) Photoevaporating rates of MSun/yr Lifetimes of yr (assuming 0.1 Msun)

29 A multi-wavelength study of the Recent Interpretation HH 80N results core De Pree An UCHII region would be an observational feature of a photoevaporating object with very high mass depletion rates

30 A multi-wavelength study of the Recent Interpretation HH 80N results core ONC RADIO SOURCES The variety of radio sources of Type II is remains the richness of Orion radio sources Better detectability ( times) 556 sources (S/N > 5) See also: Forbrich et al Kounkel et al Zapata et al Garay et al Chuchwell et al. 1987

31 A multi-wavelength study of the HH 80N core Conclusions and future aims The presence of radio sources associated with UCHII could be a common phenomenon in this kind of regions. Some of the compact sources appear to be photo ionizing objects with mass depletion rates of < 10-6 Msun/yr. In this scenario, the UCHII region itself would be an observational signpost as a result of the huge amount of photo evaporating material This possibility apparently solves the life time problem for the UCHII regions. There is a rich family of objects around the UCHII regions, some of them could be photo evaporating objects with slow mass accretion rates, or more evolved object such as radiostars. Massive star forming regions possibly are populated with a rich variety of radio sources, as reminiscent of the multiplicity inherent with massive star formation. Future aims: Look for molecular material, modeling, maser emission (kinematics), deep integrations of star forming regions.