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Observations towards early-type stars in the ESO-POP Survey – II. Searches for intermediate- and high-velocity clouds

Smoker, J. V. and Hunter, I. and Kalberla, P. M. W. and Keenan, F. P. and Morras, R. and Hanuschik, R. and Thompson, H. M. A. and Silva, D. and Bajaja, E. and Poppel, W. G. L. and Arnal, M. (2007) Observations towards early-type stars in the ESO-POP Survey – II. Searches for intermediate- and high-velocity clouds. Monthly Notices of the Royal Astronomical Society, 378 (3). pp. 947-954. ISSN 0035-8711. doi:10.1111/j.1365-2966.2007.11807.x. https://resolver.caltech.edu/CaltechAUTHORS:20100210-152549946

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Abstract

We present Ca II K and Ti II optical spectra of early-type stars taken mainly from the ultraviolet and visual echelle spectrograph (UVES) Paranal Observatory Project, plus H I 21-cm spectra, from the Vila-Elisa and Leiden-Dwingeloo Surveys, which are employed to obtain distances to intermediate- and high-velocity clouds (IHVCs). H I emission at a velocity of −117 km s^(−1) towards the sightline HD 30677 (l, b = 190°.2, −22°.2) with column density ~1.7 × 10^(19) cm^(−2) has no corresponding Ca II K absorption in the UVES spectrum, which has a signal-to-noise ratio (S/N) of 610 per resolution element. The star has a spectroscopically determined distance of 2.7 kpc, and hence sets this as a firm lower distance limit towards Anti-Centre cloud ACII. Towards another sightline (HD 46185 with l, b = 222°.0, −10°.1), H I at a velocity of +122 km s^(−1) and column density of 1.2 × 10^(19) cm^(−2) is seen. The corresponding Ca II K spectrum has a S/N of 780, although no absorption is observed at the cloud velocity. This similarly places a firm lower distance limit of 2.9 kpc towards this parcel of gas that may be an intermediate-velocity (IV) cloud. The lack of IV Ca II absorption towards HD 196426 (l, b = 45°.8, −23°.3) at a S/N of 500 reinforces a lower distance limit of ~700 pc towards this part of complex gp, where the H I column density is 1.1 × 10^(19) cm^(−2) and velocity is +78 km s^(−1). Additionally, no IV Ca II is seen in absorption in the spectrum of HD 19445, which is strong in H I with a column density of 8 × 10^(19) cm^(−2) at a velocity of ~−42 km s^(−1), placing a firm although uninteresting lower distance limit of 39 pc to this part of IV South. Finally, no high-velocity Ca ii K absorption is seen towards HD 115363 (l, b = 306°.0, −1°.0) at a S/N of 410, placing a lower distance of ~3.2 kpc towards the HVC gas at velocity of ~+224 km s^(−1) and H I column density of 5.2 × 10^(19) cm^(−2). This gas is in the same region of the sky as complex WE (Wakker 2001), but at higher velocities. The non-detection of Ca ii K absorption sets a lower distance of ~3.2 kpc towards the HVC, which is unsurprising if this feature is indeed related to the Magellanic System.


Item Type:Article
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URLURL TypeDescription
http://dx.doi.org/10.1111/j.1365-2966.2007.11807.xDOIArticle
Additional Information:© 2007 The Authors. Journal compilation © 2007 RAS. Accepted 2007 March 29; received 2007 March 28; in original form 2006 August 28. We would like to thank the staff of the Very Large Telescope, Paranal for the large amount work involved in producing the POP Survey [ESO DDT programme ID 266.D-5655(A), http://www.sc.eso.org/santiago/uvespop]. Especially, due thanks are to S. Bagnulo, R. Cabanac, E. Jehin, C. Ledoux and C. Melo. In addition, we are grateful to the staffs of Dwingeloo/Leiden and the Villa-Elisa Telescope for producing the HI all-sky surveys. JVS and HMAT thank the support staff at La Silla for their help with the FEROS observations. FPK is grateful to AWE Aldermaston for the award of a William Penney Fellowship. This research has made use of the SIMBAD data base, operated at CDS, Strasbourg, France. JVS acknowledges financial support from the Particle Physics and Astronomy Research Council with HMAT and IH thanking the Department of Education and Learning for Northern Ireland. JVS thanks M. Garcıa Muniz, L. Salinas and I. Dino for discussions and an anonymous referee for comments.
Funders:
Funding AgencyGrant Number
William Penney FellowshipUNSPECIFIED
Particle Physics and Astronomy Research CouncilUNSPECIFIED
Subject Keywords:stars : early-type; ISM : abundances; ISM : clouds; ISM : general; ISM : structure
Issue or Number:3
DOI:10.1111/j.1365-2966.2007.11807.x
Record Number:CaltechAUTHORS:20100210-152549946
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20100210-152549946
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17448
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:11 Feb 2010 19:51
Last Modified:08 Nov 2021 23:35

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