Molecular outflows and jets from protostars.

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1 Astronomy & Astrophysics manuscript no. report c ESO 2009 July 19, 2009 Molecular outflows and jets from protostars. Optical, infrared and radio observations of the Ser/G3-G6 region in the Serpens Cauda Clouds. H. Zinnecker 1, A. Barzdis 2, T. Liimets 3, L. R. Petersen 4, and E. A. Rastorgueva 5 1 Astrophysikalisches Institut Potsdam, An der Sternwarte 16, D Potsdam, Germany, hzinnecker@aip.de 2 Institute of Astronomy, University of Latvia, Boulevard Rainis 19, LV 1586 Riga, Latvia; arturslv@inbox.lv 3 Nordic Optical Telescope, Apartado 474, E Santa Cruz de La Palma, Santa Cruz de Tenerife, Spain; tiina@not.iac.es 4 Niels Bohr Institute, University of Copenhagen, Rockefeller Komplekset, Juliane Maries Vej 30, 2100 København Ø, Denmark; linus@astro.ku.dk 5 Tuorla Observatory, Dept. of Physics and Astronomy, University of Turku, Väisäläntie 20, Piikkiö, Finland; eliras@utu.fi Received /Accepted ABSTRACT Context. This is the project report of the Group 1 Molecular outflows and jets from protostars of the Nordic-Baltic Optical/NIR and Radio Astronomy Summer School 2009, held in the Tuorla Observatory, Turku, Finland on 8th-18th June Aims. We, students, had to learn how to plan, prepare, and carry out optical, infrared and single dish radio observations as well as reduce the obtained data. Methods. Under the supervision of H. Zinnecker and operators of the telescopes, we independently made remote observations and performed data reduction. Results. We successfully carried out observations of our target Serpens cloud region Ser/G3-G6 in the optical and infrared bands using Nordic Optical Telescope and in radio band using Onsala 20-m radio telescope. We obtained optical, infrared and radio images of the chosen region, which helped us to detect structure and kinematic of the outflow. Conclusions. During the school we have learned observational techniques and data reduction procedures. Also we learned how to extract scientific information from the observed data. Key words. Summer school molecular outflows young stellar objects Serpens region 1. Introduction Located at a distance of 225±55 pc (Straižys et al. 2003), the Serpens Cauda Clouds are among the darkest regions in the Aquila Riff complex of clouds (Dame & Thaddeus 1985). The embedded Serpens cloud core, first recognized by Strom et al. (1974), is one of the most active nearby star-forming regions that has been frequently studied in the past (see Eiroa et al. 2008, for a review). The core contains a dense cluster with years (Kaas et al. 2004), Class I and 0 protostars with ages 10 4 to 10 5 years and many protostellar condensations as well (Casali et al. 1993; Hurt & Barsony 1996; Testi & Sargent 1998). HH objects and molecular outflows are also present in this star forming region. Roughly 45 to the south of this core is found a close group of 4 optically visible T-tauri stars which they called Ser/G3- G6 (Cohen & Kuhi 1979). This is a second region with active star formation in the Serpens Cauda Clouds, also called Cluster B by Harvey et al. (2006). By mapping the region in the ammonia 1,1 emission line Clark (1991) uncovered two NH3 cores, Ser/G3-6NE and Ser/G3-6SW. Close to the Ser/G3- G6SW core a Herbig-Haro object HH476 was discovered by Ziener & Eislöffel (1999), and Wu et al. (2002) identified IRAS as the energy source of HH 476. A H 2 O maser emission from the HH 476 was detected by Persi et al. (1994). Djupvik et al. (2006) have detected about 40 IR excess sources in a field centered on the Ser/G3-G6 region. Most of them are Class II sources, but Class I sources are also present. 2. Observations and data reduction We observed our target Ser/G3-G6 (position: 18:29: :30:33.6 J2000.0) using Nordic Optical Telescope (NOT) in Infrared with H 2 (in the K -band) and optical in H α. We also performed spectral radio observations of the source Serpens/G3-G6 with Onsala 20-m radio telescope in the 86 GHz frequency band in April and June In April 2009, molecular line CO(2-1) was observed, and in June 2009 observations of CS(2-1) and HCO+ were made. Also, at second epoch we attempted to observe the SiO line, but it was not detected IR (NOTCAM) We observed the target Ser/G3-G6 in H 2 (NOTCAM Filter 218; λ central = 2.121µm) with 3 runs of 6x10 seconds on target and the same off target using beam-switch mode with NOTCAM. All of this with a 3x3 dither pattern with a slewing of 3. This combines

2 2 H. Zinnecker et al.: Molecular outflows and jets from protostars. to give us a total exposure of 1 minute on each position with a total of 18 minutes per run. In run 2 we had one sky too few (sky 7 was missing). We then observed one run of a 3x3 dither pattern with slew 3 of time 6x10 seconds with no sky since we were running low on time Optical (ALFOSC) For our first data we started with H alpha and took two exposures of 10 seconds followed by one 900 seconds exposure at target. This we followed with an approximation of the NOTCam dither pattern since there is no script for dither in ALFOSC. The last exposure in H α was at the same position and exposed for 800 seconds Radio We used GHz receiver together with the low resolution ACS. At both epochs we used 80 MHz band, frequency switching with the 20 MHz throw was performed. The parameters of observations were following: CO(2-1): 7x7 beam separated map, 3 scans 30 seconds integration on each position, 1.22 h on-source time. CS(2-1): 7x7 beam separated map, 4 scans 30 seconds integration on each position. In the SW corner of the field the total of 15 additional pointings with 4 scans 30 seconds integration each were added in order to cower bright source. The total on-source time is 2.1 h. HSO+: 5x5 beam separated map, 6 scans 30 seconds integration on each position, 1.25 h on-source time in total Data reduction Data reduction was done using IRAF package with visualization in DS9 (Former SAOImage) for the infrared and optical data and using XS package for the radio data IR To reduce the infrared data we used the NOTCAM package in IRAF, more specifically the reduce bs script to reduce the beamswitched data (the first 3 runs) and the script reduce for the last run. The reduce scripts asks for and gets the following input in our case: - Input: Filename without extension - Total number of files: 18 - Output: out (name of output file) - Flat Field Image: Name of flat image done earlier that night. - Scaling Sky: Mult - Find and combine: Median - Skip first image when combine: No - Manually select stars for alignment: Yes Table 1. Signal-to-Noise ratios. V is central velocity of the line, I Peak is a peak intencity, I Int is integrated intensity of the line Line V I Peak Spectral I Int Integrated (km/s) K S/N K S/N CO SC HCO Trim shifted image: No After this we had our reduced data Optical The optical data was reduced manually, since there are no script for ALFOSC like the reduce scripts for NOTCAM. We began by combining our BIAS images into a masterbias with the IRAF task imcombine and substracting it from our data images using the task imarith. Then we did the same to our flatfields and substracted them from the bias reduced science images. These where then combined into one image Radio Radio data reduction was done using the standard procedure: averaging of scans over the same position, baseline fitting (polynomials of third order were used), folding of the spectrum, after which the central part of the band, containing line emission, was cut out. After that the data were redressed down to the resolution of 0.5 km/s, and again baseline was removed. The Table 1 represents signal-to-noise ratio for each spectral line, measured for the centre of the map. 3. Results Our aim was to map the weakly-studied region of the Serpens cloud around MMS2 and MMS3 in optical, infrared and radio bands Radio observations Our radio images are centred around the point between those two point sources MMS2 and MMS3 (see Fig. 1). The field we wanted to image has size 4 x4. The Onsala 20-m telescope beam is 30, we tried to cover the whole region observed in other wavebands. In the CO image (Fig. 2) the clear peak with the value of 2 K and S/N of 8 at velocity of 10 km/s is observed. Also there is a tentative evidence of the second peak in the spectra at 6.9 km/s, however this peak is observed only in the central field because of the longer (double) exposure (6 scans by 30 seconds, 3 minutes on-source). On the other positions it is not detected due to the short integration time. The CS(2-1) line shown a clear 1 K peak around the velocity of 7 km/s with the S/N 6.8. Integrated intensity map of the CS(2-1) emission (Fig. 3) shows clear bright structure at the SW corner of the image, elongated towards the centre, and elongated feature with two maxima near the centre of the map. We have to note, that SC spectral line has a double-peak structure. For example, in the brightest feature on the map in the SW corner spectral

3 H. Zinnecker et al.: Molecular outflows and jets from protostars. 3 Fig. 3. CS total intensity map. Fig. 1. Optical-infrared and radio fields of view. Underlying image is H 2 (λ=2.122µm) map, green cross marks centre of the radio (CS and HCO+) FOV. Red frame shows boundaries of the HCO+ map, and blue frame corresponds to the CO and CS maps. Fig. 4. HCO+ total intensity map. 4. Discussion Fig. 2. CO total intensity map. line had two clearly distinguished peaks around velocities of 7.2 and 8.1 km/s. They had equal peaks of 0.81 K. In the maxima of elongated feature the double-peak spectral line had the following parameters: peak at 7.4 km/s with intensity of 0.9 K and peak at 8.4 km-s with intensity of 0.7 K. HCO+ line has peak of 1.6 K around velocity of 7 km/s. Intensity map demonstrates elongated structure with one peak (Fig. 4) Radio structure and kinematics In the Fig. 5 you can see the CO emission overlaid on the H 2 (IR) image of the source. It is clear that the structure on the map does not coincide with any emission in optical or infrared band. Also, CO line displays the velocity of 10.5 km/s while CS and HCO+ demonstrate common velocity of approximately 7 km/s. This suggests that CO emission traces different gas cloud or gas shell, than H 2, CS and HCO+. It could be separate cloud, moving towards us along the line of sight, not connected with the Serpens region as well as a signature of the jet moving towards us. We have to note that the bright feature on the CO total intensity map coincides with one of the maxima of the elongated

4 4 H. Zinnecker et al.: Molecular outflows and jets from protostars. Fig. 5. Contours: CO total intensity map. Underlying image: H2 total intensity map. Fig. 6. Contours: CS total intensity map. Underlying image: H2 total intensity map. feature at the SC total intensity map, but it also could be due to a projection effect. Fig. 6 demonstrates SC emission overlaid with the H2 image. Elongated feature does not have any IR counterpart, but the bright extended component in the SW corner of the image coincides with the bright compact sources, observed in the infrared, both in H2 line and µm continuum (Djupvik et al. 2006, see). Also contours of this component seem to follow fuzzy IR emission, marginally detected in the SW corner of the optical-ir field. At the same time, HCO+ emission seems to follow weaker extended features on the SC total intensity map Fig Optical and IR Fig. 8 shows the NOTCAM H2 image. For a comparison the optical image in Halpha is presented in Fig. 9. As can be seen from the last two images the Ser/G3-G6 is a dark cloud in optical. The pure line emission features are visible (see the Fig. 13 in Djupvik et al. (2006)) only in IR. We propose there are two jets. One in North-South (NS) direction and the other in NE-SW direction. On Fig. 10 the overview of the NOTCam on and off positions is shown, for the observations of the Ser/G3-G6 in IR. North is up, east to the left. The target is in the lower middle. Off positions are above, left, and right of the target. On the above off position image, lower left corner, an additional part of the jet is visible. The NS jet is expanding further to the north than ever been noted before Proper motions The proper motions for both jets were measured. For a second epoch we used an image taken on 2003 (see figure 11). Fig. 7. Purple contours: HCO+ total intensity map. Underlying image: CS total intensity map. Images were registered in IRAF using tasks ccdfind, ccmap, and ccsetwcs. The coordinates of 40 stars from 2MASS astrometrical catalog were used. The precision (RA/DEC fit rms) for 2003 image was 0.02 and 0.07 arcseconds in RA and DEC respectively. For 2009, 0.07 and 0.07 arcseconds respectively.

5 H. Zinnecker et al.: Molecular outflows and jets from protostars. 5 Fig. 8. NOTCam H 2 line image of Ser/G3-G6. North up, east to the left. See Fig. 13 in Djupvik et al. (2006) for the explanation of the different features. In total 7 line emission features of NS jet were considered to be reasonable good for measuring the proper motions, and 8 features of NE-SW jet. See the Fig. 13 in Djupvik et al. (2006) for placement of the line emission features. All the chosen features had to be well defined on both epochs (2003 and 2009). Measurements were done in IRAF using a task imexam, if possible or by a visual inspection. We note strongly subjective definition of the exact position of the features. More thorough analyse is needed which was not feasible in the limited time given in the summer school. The proper motions are presented in the Table 2 and graphically on Fig. 12. From the Fig. 12 it can be seen that one measurement (jet NE-SW, RA=0.554 and Dec=0.140) is clearly not in correspondence with the other measured features. Therefor a Fig. 13 is presented without the latter and it is not used for the oncoming calculations. The average proper motions during the 5 years period in RA are and arcseconds for the NS and NE-SW jet respectively. In DEC the proper motions are and arcseconds respectively. Proper motions are similar for both jets. Therefor we can conclude the jets are hosted by the same object. 5. Conclusions We study the region of the Serpens clouds around MMS2 and MMS3. For that the observations with the Nordic Optical Telescope in optical and infrared wavelength were done. With Onsala radio telescope 86 GHz frequency band was observed. In infrared two jets are visible. One in North-South the other in NE-SW direction. We discover the NS jet to extend to the north more than stated before. In optical the clouds are dark. The measured proper motions are similar for the both jet referring to the same origin. Fig. 9. ALFOSC H alpha image of Ser/G3-G6, total exposure time 58 minutes. North up, east to the left. See Fig. 15 in Djupvik et al. (2006) for the explanation of the different features. Fig. 10. Total overview of the NOTCam on and off positions for beamswitching mode. The target, Ser/G3-G6, is in the lower middle. See text for more explanation. Table 2. The results of the proper motion measurements during the five years epoch ( ). The NS jet measurements are from north to south from top to bottom, NE-SW jet north-east to south-west respectively. NS NE-SW RA DEC RA Dec

6 6 H. Zinnecker et al.: Molecular outflows and jets from protostars. Proper motions during the years delta DEC (arcsecond) NS NE-SW delta RA (arcsecond) Fig. 13. Proper motions during the years Fig. 11. NOTCam H 2 line image of Ser/G3-G6 from delta DEC (arcsecond) Proper motions during the years NE NE-SW delta RA (arcsecond) Fig. 12. Proper motions during the years The observed CO emission does not coincide with any emission in optical or infrared. As well, CO line shows the velocity of 10.5 km/s while CS and HCO+ demonstrate similar velocity of approximately 7 km/s. This suggests a different gas cloud or shell traced in CO than H 2, CS and HCO. The bright extended component in the SW corner of the SC emission images (Fig. 6) coincides with the bright compact source visible in the IR images. HCO+ emission is following the weak extended features on the SC total intensity map Fig. 7. We want to thank Amanda Djupvik for her informative support before and during the school, invaluable help with the observations preparations and useful tips for the data reduction. We want to thank Tapio Pursimo for the on-line observations help and musical support. We thank Francesco Costagliola for his selfless work on radio observations despite the tiredness and constant support and help with data reduction. Also, other members of the group want to thank our informal leader Tiina Liimets for her tireless work and unshakeable optimism and enthusiasm. We thank the Finnish pop-music band Nylon Beat for the encouraging rhythms. The last but not the least, we want to thank all the organisers of the school, especially Raine Karjalainen, Leo Takalo and Kaj Wiik for optimal organization of our work and leasure and constant technical and moral support. References Casali, M. M., Eiroa, C., & Duncan, W. D. 1993, A&A, 275, 195 Clark, F. O. 1991, ApJS, 75, 611 Cohen, M. & Kuhi, L. V. 1979, ApJS, 41, 743 Dame, T. M. & Thaddeus, P. 1985, ApJ, 297, 751 Djupvik, A. A., André, P., Bontemps, S., et al. 2006, A&A, 458, 789 Eiroa, C., Djupvik, A. A., & Casali, M. M. 2008, The Serpens Molecular Cloud, ed. B. Reipurth, Harvey, P. M., Chapman, N., Lai, S.-P., et al. 2006, ApJ, 644, 307 Hurt, R. L. & Barsony, M. 1996, ApJ, 460, L45+ Kaas, A. A., Olofsson, G., Bontemps, S., et al. 2004, A&A, 421, 623 Persi, P., Palagi, F., & Felli, M. 1994, A&A, 291, 577 Straižys, V., Černis, K., & Bartašiūtė, S. 2003, A&A, 405, 585 Strom, S. E., Grasdalen, G. L., & Strom, K. M. 1974, ApJ, 191, 111 Testi, L. & Sargent, A. I. 1998, ApJ, 508, L91 Wu, J.-W., Wu, Y.-F., Wang, J.-Z., & Cai, K. 2002, Chinese Journal of Astronomy and Astrophysics, 2, 33 Ziener, R. & Eislöffel, J. 1999, A&A, 347, 565 Acknowledgements. This work is based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. Group 1 wants to thank Hans Zinnecker for his help, constant support and professional advice.