Vaidya, Kaushar, Chu, You-Hua, Gruendl, Robert A., Chen, C. -H. Rosie, Looney, Leslie W.
We have used archival HST H$\alpha$ images to study the immediate environments of massive and intermediate-mass young stellar object (YSO) candidates in the Large Magellanic Cloud (LMC). The sample...
High and Intermediate-Mass Young Stellar Objects in the Large Magellanic Cloud (2009)
Gruendl, Robert A., Chu, You-Hua
(Abridged) Photometry of archival Spitzer observations of the Large Magellanic Cloud (LMC) are used to search for young stellar objects (YSOs). Simple mid-infrared selection criteria were used to...
Seale, Jonathan P., Looney, Leslie W., Chu, You-Hua, Gruendl, Robert A., Brandl, Bernhard, Chen, C.-H. Rosie, ...
We present and categorize Spitzer infrared spectrometer spectra of 294 objects in the Large Magellanic Cloud (LMC) to create the largest and most complete catalog of massive young stellar object...
The Evolution of Massive YSOs in the LMC: Part I. Identification and Spectral Classification (2009)
Seale, Jonathan P., Looney, Leslie W., Chu, You-Hua, Gruendl, Robert A., Brandl, Bernhard, Chen, C. -H. Rosie, ...
We present and categorize Spitzer IRS spectra of 294 objects in the Large Magellanic Cloud (LMC) to create the largest and most complete catalog of massive young stellar object (YSO) spectra in the...
Star formation around supergiant shells in the large magellanic cloud (2009)
Book, Laura G., Chu, You-Hua, Gruendl, Robert A., Fukui, Yasuo
We examine the recent star formation associated with four supergiant shells in the Large Magellanic Cloud (LMC): LMC 1, 4, 5, and 6, which have been shown to have simple expanding-shell structures. H...
Spitzer View of Young Massive Stars in the LMC HII Complex N44 (2009)
Chen, C. -H. Rosie, Chu, You-Hua, Gruendl, Robert A., Gordon, Karl D., Heitsch, Fabian
The HII complex N44 in the Large Magellanic Cloud (LMC) provides an excellent site to perform a detailed study of star formation in a mild starburst, as it hosts three regions of star formation at...
Star Formation Around Supergiant Shells in the LMC (2009)
Book, Laura G., Chu, You-Hua, Gruendl, Robert A., Fukui, Yasuo
We examine the recent star formation associated with four supergiant shells (SGSs) in the Large Magellanic Cloud (LMC): LMC 1, 4, 5, and 6, which have been shown to have simple expanding-shell...
Seale, Jonathan P., Looney, Leslie W., Chu, You-Hua, Gruendl, Robert A., Brandl, Bernhard, Rosie Chen, C. H., ...
We present and categorize Spitzer infrared spectrometer spectra of 294 objects in the Large Magellanic Cloud (LMC) to create the largest and most complete catalog of massive young stellar object...
Ezoe, Yuichiro, Hamaguchi, Kenji, Gruendl, Robert A., Chu, You-Hua, Petre, Robert, Corcoran, Michael F.
The eastern tip region of the Carina Nebula was observed with the Suzaku XIS for 77 ks to conduct a high-precision spectral study of extended X-ray emission. XMM-Newton EPIC data of this region were...
NGC 346 in the Small Magellanic Cloud. IV. Triggered star formation in the H II region N66 (2008)
Gouliermis, Dimitrios A., Chu, You-Hua, Henning, Thomas, Brandner, Wolfgang, Gruendl, Robert A., Hennekemper, Eva, ...
Stellar feedback, expanding H II regions, wind-blown bubbles, and supernovae are thought to be important triggering mechanisms of star formation. Stellar associations, being hosts of significant...
Were All Massive Stars Born in OB Associations and Clusters? (2007)
Chu, You-Hua, Gruendl, Robert A.
It has been commonly conjectured that all massive >10 Msun stars are born in OB associations or clusters. Many O and B stars in the Galaxy or the Magellanic Clouds appear to exist in isolation,...
Structure of Supergiant Shells in the Large Magellanic Cloud (2007)
Book, Laura G., Chu, You-Hua, Gruendl, Robert A.
Nine supergiant shells (SGSs) have been identified in the Large Magellanic Cloud (LMC) based on H-alpha images, and twenty-three SGSs have been reported based on HI 21-cm line observations, but these...
NGC 346 in The Small Magellanic Cloud. IV. Triggered Star Formation in the HII Region N66 (2007)
Gouliermis, Dimitrios A., Chu, You-Hua, Henning, Thomas, Brandner, Wolfgang, Gruendl, Robert A., Hennekemper, Eva, ...
Stellar feedback, expanding HII regions, wind-blown bubbles, and supernovae are thought to be important triggering mechanisms of star formation. Stellar associations, being hosts of significant...
Large-Scale Gravitational Instability and Star Formation in the Large Magellanic Cloud (2007)
Yang, Chao-Chin, Gruendl, Robert A., Chu, You-Hua, Mac Low, Mordecai-Mark, Fukui, Yasuo
Large-scale star formation in disk galaxies is hypothesized to be driven by global gravitational instability. The observed gas surface density is commonly used to compute the strength of...
X-ray Observations of the Bipolar PNe NGC 2346 and NGC 7026 (2006)
Gruendl, Robert A., Guerrero, Martin A., Chu, You-Hua, Williams, Rosa M.
We have obtained X-ray observations of the bipolar planetary nebulae (PNe) NGC 2346 and NGC 7026 with XMM-Newton. These observations detected diffuse X-ray emission from NGC 7026 but not from NGC...
Resolving the nature of the Rosette HH1 jet facing strong UV dissipation (2006)
Li, Jin Zeng, Chu, You-Hua, Gruendl, Robert A., Bally, John, Su, Wei
The Rosette HH1 jet is a collimated flow immersed in the strong UV radiation field of the Rosette Nebula. We investigate the physical properties of the Rosette HH1 jet using high-quality narrow-band...
Ramsey, Caitlin J., Williams, Rosa M., Gruendl, Robert A., Chen, C. -H. Rosie, Chu, You-Hua, Wang, Q. Daniel
We have studied the stellar and interstellar environments of two luminous X-ray sources and five ultraluminous X-ray sources (ULXs) in order to gain insight into their nature. Archival Hubble Space...
Chu, You-Hua, Gruendl, Robert A., Williams, Rosa M., Gull, Theodore R., Werner, Klaus
We have detected an ionized nebula around the hot DO white dwarf KPD 0005+5106, and used the [OIII]/H-alpha ratios and nebular velocities to separate this nebula from the background HII region of AO...
Physical Structure of Planetary Nebulae. III. The Large and Evolved NGC 1360 (2004)
Goldman, Daniel B., Guerrero, Martin A., Chu, You-Hua, Gruendl, Robert A.
NGC 1360 is a large planetary nebula (PN) without an obvious shell morphology. We have analyzed H-alpha images and high-dispersion echelle spectra of NGC 1360 in order to construct spatio-kinematic...
Chu, You-Hua, Gruendl, Robert A., Stockdale, Christopher J., Rupen, Michael P., Cowan, John J., Teare, Scott W.
The nature of SN 1961V has been uncertain. Its peculiar optical light curve and slow expansion velocity are similar to those of super-outbursts of luminous blue variables (LBVs), but its nonthermal...
The wind of the B[e] supergiant Henize S22 viewed through a reflection nebula in DEM L106 (2003)
Chu, You-Hua, Chen, Chang-Hui Rosie, Danforth, Charles, Dunne, Bryan C., Gruendl, Robert A., Naze, Yaël, ...
Narrowband HST WFPC2 images reveal a bow-shock-like halo around the H II region N30B toward the B[e] supergiant Hen S22 located within the larger DEM L106 nebula in the Large Magellanic Cloud....
An Inside Out View of Bubbles (2002)
Chu, You-Hua, Gruendl, Robert A., Guerrero, Martin A.
Fast stellar winds can sweep up ambient media and form bubbles. The evolution of a bubble is largely controlled by the content and physical conditions of the shocked fast wind in its interior. This...
Structure and Dynamics of Candidate O Star Bubbles in N44 (2002)
Naze, Yael, Chu, You-Hua, Guerrero, Martin A., Oey, M. S., Gruendl, Robert A., Smith, R. Chris
Dynamical studies of superbubbles and Wolf-Rayet ring nebulae show discrepancies from the standard, adiabatic model for wind-blown bubbles. We therefore study the physical properties and kinematics...
Diffuse X-ray emission from the planetary nebula NGC 7009 (2002)
Guerrero, Martin A., Gruendl, Robert A., Chu, You-Hua
XMM-Newton EPIC observations of the planetary nebula (PN) NGC 7009, the Saturn Nebula, have detected extended X-ray emission in its central cavity. The diffuse X-ray emission must originate in the...
X-ray and UV Views of Hot Gas in Planetary Nebulae (2002)
Chu, You-Hua, Guerrero, Martin A., Gruendl, Robert A.
The interior of a planetary nebula (PN) is expected to be filled with shocked fast wind from the central star. This hot gas plays the most important role in the dynamical evolution of the PN;...
Narrow Lines in Type II Supernovae -- Probing the Circumstellar Nebulae of the Progenitors (2002)
Gruendl, Robert A., Chu, You-Hua, Van Dyk, Schuyler D., Stockdale, Christopher J.
We have carried out a high-dispersion (R~30,000) echelle spectroscopic survey of 16 Type II supernovae (SNe) to search for narrow emission lines from circumstellar nebulae ejected by their massive...
Distorted HI Gas in the Widely Separated LIRG Arp 256 (2001)
Chen, Jacqueline, Lo, K. Y., Gruendl, Robert A., Peng, Miao-Ling, Gao, Yu
We present new interferometric HI and CO (1-0) observations of the luminous infrared source, Arp 256. Arp 256 consists of two spiral galaxies in an early stage of merging, with a projected nuclear...
Variable H-alpha Line Emission from the Central Star of the Helix Nebula (2001)
Gruendl, Robert A., Chu, You-Hua, O'Dwyer, Ian J., Guerrero, Martin A.
The central star of the Helix Nebula is a hot white dwarf with unexpected hard X-ray emission. With an effective temperature of ~100,000 K, the star is a powerful source of H-ionizing radiation; the...
The Enigmatic X-ray Point Sources at the Central Stars of NGC 6543 and NGC 7293 (2001)
Guerrero, Martin A., Chu, You-Hua, Gruendl, Robert A., Williams, Rosa M., Kaler, James B.
Recent Chandra ACIS-S observations have detected a point source at the central star of NGC 6543 and confirmed the point source nature of the hard X-ray emission from NGC 7293. The X-ray spectra of...
Gas Distribution and Starburst Activity in the Widely Separated Interacting Galaxies NGC 6670 (2001)
Wang, Wei-Hao, Lo, K. Y., Gao, Yu, Gruendl, Robert A.
We present high resolution H I 21 cm line, 20 cm radio continuum, and CO(1-0) line observations of the luminous infrared galaxy NGC 6670. NGC 6670 consists of two edge-on disk galaxies (NGC 6670E and...
A Morphological Diagnostic for Dynamical Evolution of Wolf-Rayet Bubbles (2000)
Gruendl, Robert A., Chu, You-Hua, Dunne, Bryan C., Points, Sean D.
We have observed H-alpha and [OIII] emission from eight of the most well defined Wolf-Rayet ring nebulae in the Galaxy. We find that in many cases the outermost edge of the [OIII] emission leads the...
ROSAT observations of X-ray emission from planetary nebulae (2000)
Guerrero, Martin A., Chu, You-Hua, Gruendl, Robert A.
We have searched the entire ROSAT archive for useful observations to study X-ray emission from Galactic planetary nebulae (PNs). The search yields a sample of 63 PNs, which we call the ROSAT PN...
HST WFPC2 Imaging of Shocks in Superbubbles (1999)
Chen, C. -H. Rosie, Chu, You-Hua, Gruendl, Robert A., Points, Sean D.
Bright X-ray emission has been detected in superbubbles in the Large Magellanic Cloud (LMC), and it is suggested that supernova remnants (SNRs) near the inner shell walls are responsible for this...
What Produced the Ultraluminous Supernova Remnant in NGC 6946? (1999)
Dunne, Bryan C., Gruendl, Robert A., Chu, You-Hua
The ultraluminous supernova remnant (SNR) in NGC 6946 is the brightest known SNR in X-rays, ~1000 times brighter than Cas A. To probe the nature of this remnant and its progenitor, we have obtained...
X-rays from Planetary Nebulae (1999)
Chu, You-Hua, Guerrero, Martin A., Gruendl, Robert A.
Two sources of X-ray emission are expected from planetary nebulae: the hot central stars with $T_{eff} > 10^5$ K, and shocked fast stellar winds at temperatures of 10$^6 - 10^7$ K. The stellar...
Mid-Infrared Images of Luminous Infrared Galaxies in a Merging Sequence (1998)
Hwang, Chorng-Yuan, Lo, K. Y., Gao, Yu, Gruendl, Robert A., Lu, Nanyao Y.
We report mid-infrared observations of several luminous infrared galaxies (LIGs) carried out with the Infrared Space Observatory. Our sample was chosen to represent different phases of a merger...
Pre-Starbursts in Luminous IR Galaxies ? (1996)
Gao, Yu, Gruendl, Robert A., Lo, K. Y., Hwang, C. Y., Veilleux, S.
We present first results of our on-going BIMA Key Project: imaging the CO(1-0) emission from a sample of 10 luminous IR galaxies (LIRGs) that are at various merging stages, with special emphasis on...
Arp 302: Non-starburst Luminous Infrared Galaxies (1996)
Lo, K. Y., Gao, Yu, Gruendl, Robert A.
Arp 302, a luminous infrared source (L_{IR} = 4.2x10^{11} Lsun), consisting of two spiral galaxies (VV340A and VV340B) with nuclear separation of 40'', has the highest CO luminosity known....