Publications

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May 2021

The excess of cool supergiants from contemporary stellar evolution models defies the metallicity-independent Humphreys-Davidson limit

Gilkis, Avishai, Shenar, Tomer, Ramachandran, Varsha, Jermyn, Adam S., Mahy, Laurent, Oskinova, Lidia M., Arcavi, Iair, Sana, Hugues

#stars: evolution #stars: massive #supergiants #Astrophysics - Solar and Stellar Astrophysics

Feb 2021

Discovery of O stars in the tidal Magellanic Bridge. Stellar parameters, abundances, and feedback of the nearest metal-poor massive stars and their implication for the Magellanic System ecology

Ramachandran, V., Oskinova, L. M., Hamann, W. -R.

#stars: massive #stars: fundamental parameters #stars: abundances #Magellanic Clouds #techniques: spectroscopic #stars: atmospheres #Astrophysics - Astrophysics of Galaxies #Astrophysics - Solar and Stellar Astrophysics

Sep 2020

Phase-dependent Study of Near-infrared Disk Emission Lines in LB-1

Liu, Jifeng, Zheng, Zheng, Soria, Roberto, Aceituno, Jesus, Zhang, Haotong, Lu, Youjun, Wang, Song, Hamann, Wolf-Rainer, Oskinova, Lida M., Ramachandran, Varsha, Yuan, Hailong, Bai, Zhongrui, Wang, Shu, McKee, Brendan J., Wu, Jianfeng, Wang, Junfeng, Lattanzi, Mario, Belczynski, Krzysztof, Casares, Jorge, González Hernández, Jonay I., Rebolo, Rafael

#Black holes #black hole physics #Stellar evolution #Be stars #162 #159 #1599 #142 #Astrophysics - Solar and Stellar Astrophysics

Sep 2020

The Wolf-Rayet binaries of the nitrogen sequence in the Large Magellanic Cloud. Spectroscopy, orbital analysis, formation, and evolution (Corrigendum)

Shenar, T., Sablowski, D. P., Hainich, R., Todt, H., Moffat, A. F. J., Oskinova, L. M., Ramachandran, V., Sana, H., Sander, A. A. C., Schnurr, O., St-Louis, N., Vanbeveren, D., Götberg, Y., Hamann, W. -R.

#stars: massive #stars: Wolf-Rayet #Magellanic Clouds #binaries: close #binaries: spectroscopic #errata #addenda

May 2020

Catching wind with the HST: novel UV spectroscopy of a bona fide ultraluminous X-ray source

Oskinova, Lida, Bozzo, Enrico, Bulik, Tomasz, Gies, Douglas Russell, Hamann, Wolf-Rainer, Massa, Derck L., Ramachandran, Varsha, Sander, Andreas, Shenar, Tomer, Torrejon, Jose Miguel

May 2020

Wolf-Rayet stars in the outskirts of M33: unveiling helium-star evolution and feedback at subsolar metallicity

Sander, Andreas, Pritzkuleit, Max, Hainich, Rainer, Hamann, Wolf-Rainer, Higgins, Erin Rose, Ignace, Richard, Oskinova, Lida, Ramachandran, Varsha, Shenar, Tomer, Todt, Helge, Vink, Jorick

May 2020

The multiplicity and properties of the LMC WC stars: the immediate progenitors of black holes and stripped supernovae

Shenar, Tomer, Dsilva, Karan, Gilkis, Avishai, Hainich, Rainer, Hamann, Wolf-Rainer, Janssens, Soetkin, Mahy, Laurent, Marchant Campos, Pablo Ignacio, Oskinova, Lida, Ramachandran, Varsha, Sander, Andreas, Todt, Helge

Jan 2020

Testing massive star evolution, star-formation history, and feedback at low metallicity. Photometric analysis of OB stars in the SMC Wing

Fulmer, Leah M., Gallagher, John S., Hamann, Wolf-Rainer, Oskinova, Lida M., Ramachandran, Varsha

#galaxies: stellar content #stars: formation #galaxies: individual: Small Magellanic Cloud #Astrophysics - Astrophysics of Galaxies #Astrophysics - Solar and Stellar Astrophysics

Jul 2019

The Wolf-Rayet binaries of the nitrogen sequence in the Large Magellanic Cloud. Spectroscopy, orbital analysis, formation, and evolution

#stars: massive #stars: Wolf-Rayet #Magellanic Clouds #binaries: close #binaries: spectroscopic #stars: evolution #Astrophysics - Solar and Stellar Astrophysics

Jun 2019

The HST follows galactic influencers: a COS UV survey of the most massive O-stars in the SMC

Oskinova, Lida, Hainich, Rainer, Hamann, Wolf-Rainer, Massa, Derck L., Prinja, Raman K., Ramachandran, Varsha, Rickard, Matthew J., Sander, Andreas, Shenar, Tomer, Todt, Helge

May 2019

Testing massive star evolution, star formation history, and feedback at low metallicity. Spectroscopic analysis of OB stars in the SMC Wing

Ramachandran, V., Hamann, W. -R., Oskinova, L. M., Gallagher, J. S., Hainich, R., Shenar, T., Sander, A. A. C., Todt, H., Fulmer, L.

#stars: evolution #stars: massive #stars: mass-loss #Magellanic Clouds #Hertzsprung-Russell and C-M diagrams #techniques: spectroscopic #Astrophysics - Solar and Stellar Astrophysics #Astrophysics - Astrophysics of Galaxies

May 2019

The Galactic WN stars revisited. Impact of Gaia distances on fundamental stellar parameters

Hamann, W. -R., Gräfener, G., Liermann, A., Hainich, R., Sander, A. A. C., Shenar, T., Ramachandran, V., Todt, H., Oskinova, L. M.

#stars: mass-loss #stars: winds #outflows #stars: Wolf-Rayet #stars: atmospheres #stars: evolution #stars: distances #Astrophysics - Solar and Stellar Astrophysics

Apr 2019

VizieR Online Data Catalog: Stellar parameters of OB stars in SMC wing (Ramachandran+, 2019)

Ramachandran, V., Hamann, W. -R., Oskinova, L. M., Gallagher, J. S., Hainich, R., Shenar, T., Sander, A. A. C., Todt, H., Fulmer, L.

#Magellanic Clouds #Stars: OB #MK spectral classification

Apr 2019

VizieR Online Data Catalog: Of-type stars in N206 in the LMC (Ramachandran+, 2018)

Ramachandran, V., Hainich, R., Hamann, W. -R., Oskinova, L. M., Shenar, T., Sander, A. A. C., Todt, H., Gallagher, J. S.

#Magellanic Clouds #Stars: OB #MK spectral classification

Jan 2019

The Galactic WC and WO stars. The impact of revised distances from Gaia DR2 and their role as massive black hole progenitors

Sander, A. A. C., Hamann, W. -R., Todt, H., Hainich, R., Shenar, T., Ramachandran, V., Oskinova, L. M.

#stars: evolution #stars: mass-loss #stars: Wolf-Rayet #stars: massive #stars: distances #Galaxy: stellar content #Astrophysics - Astrophysics of Galaxies #Astrophysics - Solar and Stellar Astrophysics

Jan 2019

PoWR grids of non-LTE model atmospheres for OB-type stars of various metallicities

Hainich, R., Ramachandran, V., Shenar, T., Sander, A. A. C., Todt, H., Gruner, D., Oskinova, L. M., Hamann, W. -R.

#stars: massive #stars: early-type #stars: atmospheres #stars: winds #outflows #stars: mass-loss #radiative transfer #Astrophysics - Solar and Stellar Astrophysics

Jan 2019

The extreme O-type spectroscopic binary HD 93129A. A quantitative, multiwavelength analysis

Gruner, D., Hainich, R., Sander, A. A. C., Shenar, T., Todt, H., Oskinova, L. M., Ramachandran, V., Ayres, T., Hamann, W. -R.

#stars: individual: HD 93129A #stars: atmospheres #stars: fundamental parameters #stars: early-type #Astrophysics - Solar and Stellar Astrophysics

Sep 2018

VizieR Online Data Catalog: OB stars in N206 in the LMC (Ramachandran+, 2018)

Ramachandran, V., Hamann, W. -R., Hainich, R., Oskinova, L. M., Shenar, T., Sander, A. A. C., Todt, H., Gallagher, J. S.

#Magellanic Clouds #Molecular clouds #Stars: masses #Radial velocities #Rotational velocities

Aug 2018

The shortest-period Wolf-Rayet binary in the Small Magellanic Cloud: Part of a high-order multiple system. Spectral and orbital analysis of SMC AB 6

Shenar, T., Hainich, R., Todt, H., Moffat, A. F. J., Sander, A., Oskinova, L. M., Ramachandran, V., Munoz, M., Pablo, H., Sana, H., Hamann, W. -R.

#stars: massive #binaries: spectroscopic #stars: Wolf-Rayet #Magellanic Clouds #stars: individual: SMC AB 6 #stars: atmospheres #Astrophysics - Solar and Stellar Astrophysics

Jul 2018

Stellar population of the superbubble N 206 in the LMC. II. Parameters of the OB and WR stars, and the total massive star feedback

Ramachandran, V., Hamann, W. -R., Hainich, R., Oskinova, L. M., Shenar, T., Sander, A. A. C., Todt, H., Gallagher, J. S.

#stars: massive #Magellanic Clouds #stars: winds #outflows #Hertzsprung-Russell and C-M diagrams #techniques: spectroscopic #ISM: bubbles #Astrophysics - Astrophysics of Galaxies #Astrophysics - Solar and Stellar Astrophysics

Jan 2018

Stellar population of the superbubble N 206 in the LMC. I. Analysis of the Of-type stars

Ramachandran, Varsha, Hainich, R., Hamann, W. -R., Oskinova, L. M., Shenar, T., Sander, A. A. C., Todt, H., Gallagher, J. S.

#stars: early-type #Magellanic Clouds #stars: atmospheres #stars: winds #outflows #stars: mass-loss #stars: massive #Astrophysics - Solar and Stellar Astrophysics #Astrophysics - Astrophysics of Galaxies

Jan 2018

Skyscrapers in the Desert: Observing Ongoing, Active Star Formation in the Low-Density Wing of the Small Magellanic Cloud

Fulmer, Leah M., Gallagher, John S., Hamann, Wolf-Rainer, Oskinova, Lida, Ramachandran, Varsha

Nov 2017

Massive stars in advanced evolutionary stages, and the progenitor of GW150914

Hamann, Wolf-Rainer, Oskinova, Lidia, Todt, Helge, Sander, Andreas, Hainich, Rainer, Shenar, Tomer, Ramachandran, Varsha

#stars: atmospheres #stars: early-type #stars: evolution #stars: fundamental parameters #Hertzsprung-Russell diagram #stars: mass loss #stars: winds #outflows #stars: Wolf-Rayet #Astrophysics - Solar and Stellar Astrophysics

Mar 2017

Radio and infrared study of the star-forming region IRAS 20286+4105

Ramachandran, Varsha, Das, S. R., Tej, A., Vig, S., Ghosh, S. K., Ojha, D. K.

#stars: formation #H II regions #ISM: individual objects: IRAS 20286+4105 #radio continuum: ISM

Jan 2017

Stellar Evolution of the Star Cluster NGC 602 and Massive Star Formation in the Low-Density Wing of the SMC

Fulmer, Leah, Oskinova, Lida, Ramachandran, Varsha, Hamann, Wolf-Rainer, Gallagher, John S.