# Olga V. Vovk , Olga Vovk

16 posts · 11,448 views

I am a physicist who has always been interested in writing, particularly science writing, and, finally, made it my profession. Currently I am working on my second degree (in Astronomy).

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• March 15, 2013
• 03:20 PM
• 147 views

# Passive Radio Ice Depth Experiment

I would like to discuss one method used for estimate thickness of Antarctic ice, which could be easily adopted for space exploration and could be used to estimate the thickness of ice mantle on extraterrestrial planets, on Ceres and other bodies in the main asteroid belt, and on Jovian moons.... Read more »

• May 25, 2012
• 03:14 PM
• 658 views

# Once upon a time there was a star

Once upon a time there was a star. It was big, hot, luminous, and very proud of itself. It was the First Star. It had already devoured all the gas around, so no other stars could be born nearby. No neighbor stars were visible in vicinity either. It was lonely. The First Star spent its life in grief burning H and He and died shortly in pair-instability supernova. Or maybe it died quietly in a black hole. Or maybe I should tell another story. . .

Why do we think that Population III stars exist?........ Read more »

ResearchBlogging.org, & Bromm V. and Larson R. (2009) The First Stars in the Universe . Scientific American. info:/

Stacy, A., Greif, T., & Bromm, V. (2010) The first stars: formation of binaries and small multiple systems. Monthly Notices of the Royal Astronomical Society, 403(1), 45-60. DOI: 10.1111/j.1365-2966.2009.16113.x

• March 13, 2012
• 02:00 PM
• 678 views

# On March 15, 5 suborbital sounding rockets are scheduled to launch from the NASA Wallops Facility, VA

This is part of a study of the upper level jet stream located in the mesosphere.

These five rockets will release an aluminum based chemical into the upper layers of atmosphere (the mesosphere) that will form milky-white clouds that will trace winds in space. These clouds might be visible for public up to 20 minutes by East coast residents from southern parts of New Hampshire and Vermont till South Carolina.... Read more »

Larsen, M. F., and C. G. Fesen. (2009) Accuracy issues of the existing thermospheric wind models: Can we rely on them in seeking solutions to wind-driven problems?. Ann. Geophys., 27, 2277–2284. info:/

• February 21, 2012
• 02:44 PM
• 1,001 views

# Drilling Lake Vostok

On February 5th, 2012, the Russian team has finally managed to penetrate through almost 4000 m (3,768 m) of Antarctica’s ice and reach the surface of lake Vostok.... Read more »

• November 30, 2011
• 02:31 PM
• 916 views

# The biggest Mars mission launched

On Nov. 26, 2011 at 10:02 AM EST the Mars Science Laboratory (MSL) launched successfully from Cape Canaveral using Atlas V 541 rocket and began its journey to Mars. MSL carries the biggest and the most robust Mars rover ever built.... Read more »

Golombek, et al. (2004) Surfical geology of the Spirit rover traverse in Gusev Crater: dry and desiccating since the Hesperian. Second Conference on Early Mars . info:/

Squyres SW, Arvidson RE, Bell JF 3rd, Brückner J, Cabrol NA, Calvin W, Carr MH, Christensen PR, Clark BC, Crumpler L.... (2004) The Opportunity Rover's Athena science investigation at Meridiani Planum, Mars. Science (New York, N.Y.), 306(5702), 1698-703. PMID: 15576602

• November 23, 2011
• 12:03 PM
• 1,002 views

# O Brother, Where Art Thou? – Estimating fp

In Drake equation, fp stays for a fraction of stars that have planets. The Drake estimate for this parameter was fp=0.5. Which means that 50% of stars in Milky Way may have planets. In its modern estimate fp~ 0.4 (Marcy et al , 2005), however this number can become much higher with developing more precise techniques for planet detection.... Read more »

• November 23, 2011
• 10:18 AM
• 815 views

# Signal received from the lost Russian Phobos-Grunt Mars probe

Signal received from the lost Russian Phobos-Grunt Mars probe... Read more »

Harvey, Brian. (2007) The rebirth of the Russian space program 50 years after Sputnik, new frontiers . Springer-Praxis books in space exploration. info:other/

• November 23, 2011
• 10:08 AM
• 233 views

# Signal received from the lost Russian Phobos-Grunt Mars probe

Harvey, Brian. (2007) The rebirth of the Russian space program 50 years after Sputnik, new frontiers . Springer-Praxis books in space exploration. info:other/

• November 16, 2011
• 03:50 PM
• 936 views

# Be/X-ray binaries and 2 types of supernovae

two subpopulations of Be/Xray binaries can associated with the two types of Type II supernovae providing different mechanisms for neutron star formation where electron-capture supernovae are responsible for low-mass neutron stars in X-ray binaries with short spin periods, short orbital periods and low eccentricities, while iron-core-collapse supernovae produce high-eccentricity binaries containing high-mass neutron stars, with longer spin periods.... Read more »

Christian Knigge, Malcolm Coe, & Philipp Podsiadlowski. (2011) Two Populations of X-ray Pulsars Produced by Two Types of Supernovae. Nature. arXiv: 1111.2051v1

• October 5, 2011
• 09:34 AM
• 382 views

# Nobel Prize in physics and ESA Cosmic Vision

Two things happened on October 4, 2011 – the Nobel committee announced that its physics award goes to Saul Perlmutter and Adam Riess of the US and Brian Schmidt from Australia for  the research that identified the "accelerating expansion of the Universe", see http://www.bbc.co.uk/news/science-environment-15165371ESA Cosmic Vision panel approved two middle size missions as a part of its Cosmic Vision 2015-2025 plan. These are Euclid and Solar Orbiter. Saul Perlmutt........ Read more »

S. Perlmutter, G. Aldering, G. Goldhaber, R.A. Knop, P. Nugent, P.G. Castro, S. Deustua, S. Fabbro, A. Goobar, D.E. Groom, I. M. Hook, A.G. Kim, M.Y. Kim, J.C. Lee, N.J. Nunes, R. Pain, C.R. Pennypacker, R. Quimby, C. Lidman, R.S. Ellis, M. Irwin, R.G. Mc. (1998) Measurements of Omega and Lambda from 42 High-Redshift Supernovae. Astrophysical Journal. info:/

• May 28, 2011
• 12:11 AM
• 1,115 views

# Observing Sgr A*

Our image of Sgr A* is constrained by what we see and what we do not see (the later is even more important).In 1974, two American radio astronomers Bruce Balick and Robert Brown, while conducted the observations of the center of Milky Way, discovered a compact and variable radio source that looked like a faint quasar. Because it appeared to be inside a large, extended radio source already known as Sagittarius A, they named it Sagittarius A* (or Sgr A*).  Here I should make ........ Read more »

Doeleman, S., Weintroub, J., Rogers, A., Plambeck, R., Freund, R., Tilanus, R., Friberg, P., Ziurys, L., Moran, J., Corey, B.... (2008) Event-horizon-scale structure in the supermassive black hole candidate at the Galactic Centre. Nature, 455(7209), 78-80. DOI: 10.1038/nature07245

F. Yusef-Zadeh, H. Bushouse, C. D. Dowell, M. Wardle, D. Roberts, C. Heinke, G. C. Bower, B. Vila Vilaro, S. Shapiro, A. Goldwurm.... (2005) A Multi-Wavelength Study of Sgr A*: The Role of Near-IR Flares in Production of X-ray, Soft $\gamma$-ray and Sub-millimeter Emission. Astrophys.J.644:198-213,2006. arXiv: astro-ph/0510787v2

• May 5, 2011
• 09:56 PM
• 1,132 views

# Saggitarius A*: distance and mass estimates

Center of Milky Way. Credit: Stefan Gillessen, Reinhard Genzel, Frank EisenhauerKnowing distance to Sgr A* (Ro) is very important, because it sets the distance scale for every other distance within Milky Way. The total Galaxy's mass, the Sun's orbital velocity, and luminosities of distant stars rely upon the accurate measurement of Ro.A variety of methods have been employed by astronomers to determine Ro. These can be separated into three broad categories: 1.    The Shapley m........ Read more »

Gillessen, S., Eisenhauer, F., Trippe, S., Alexander, T., Genzel, R., Martins, F., & Ott, T. (2009) MONITORING STELLAR ORBITS AROUND THE MASSIVE BLACK HOLE IN THE GALACTIC CENTER. The Astrophysical Journal, 692(2), 1075-1109. DOI: 10.1088/0004-637X/692/2/1075

F. Eisenhauer, R. Genzel, T. Alexander, R. Abuter, T. Paumard, T. Ott, A. Gilbert, S. Gillessen, M. Horrobin, S. Trippe.... (2005) SINFONI in the Galactic Center: young stars and IR flares in the central light month. Astrophys.J. 628 (2005) 246-259. arXiv: astro-ph/0502129v1

• May 3, 2011
• 02:20 PM
• 635 views

# Early stars

The first generation of stars that formed right after the Big Bang were probably massive luminous stars made of hydrogen and very little helium, they lived short lives (about 30 million years) and after they deaths they provided the Universe with the first heavy (in astronomical terms) elements.   It was long thought that these stars lived mostly solitary lives, or formed a very wide binary system. The modern studies suggest that these stars were not only very massive, but........ Read more »

Clark, P., Glover, S., Smith, R., Greif, T., Klessen, R., & Bromm, V. (2011) The Formation and Fragmentation of Disks Around Primordial Protostars. Science, 331(6020), 1040-1042. DOI: 10.1126/science.1198027

Chiappini, C., Frischknecht, U., Meynet, G., Hirschi, R., Barbuy, B., Pignatari, M., Decressin, T., & Maeder, A. (2011) Imprints of fast-rotating massive stars in the Galactic Bulge. Nature, 472(7344), 454-457. DOI: 10.1038/nature10000

• May 1, 2011
• 07:15 PM
• 603 views

# Milky Way: a Distance to the Galactic Center - 3

First attempts to estimate the distance to the galactic centerIn the late 18th century William Herschel made an attempt to locate the position of Solar System in the Milky Way. His approach was that the center of the galaxy is the place with the highest concentration of stars and by locating such a region he can locate the center of our galaxy. So he looked at all directions and did not find any area of the sky that had a higher concentration of stars than any other area . Based on these observa........ Read more »

• April 29, 2011
• 10:03 PM
• 543 views

# Milky Way: a Distance to the Galactic Center - 2

Why distance to the galactic center is so important?The distance from Sun and the center of Milky Way is used as a reference stick for many other extragalactic distance calculations, making its accurate determination a matter of extreme importance.The only direct method to determine distances to cosmic objects outside the Solar System is trigonometrical parallax. Ground-based telescopes allow to measure parallaxes up to ~0.01-arcsec, which allowed the distance estimates up to 100 pc. We can obse........ Read more »

Percival, S., Salaris, M., & Kilkenny, D. (2003) Why distance to the galactic center is so important?. Astronomy and Astrophysics, 400(2), 541-552. DOI: 10.1051/0004-6361:20030092

• April 11, 2011
• 05:30 PM
• 652 views

# Measuring stellar distances for stars more than 1000 pc away

This post was inspired by my colleague SAO student, who asked on how we can measure stellar distances for stars which are so far away that their parallaxes are not measurable yet.For stars more than 1000 pc away parallaxes are not measurable yet, so the only way to estimate distances is using photometry. The connection between star brightness and its distance is known as the inverse-square-law (Equation 1.).Equation 1.B=(L/2Pid2)dL=(L/4PiB)1/2Where, B is the star’s apparent brightness, L is it........ Read more »

Carretta, E., Gratton, R., Clementini, G., & Fusi Pecci, F. (2000) Distances, Ages, and Epoch of Formation of Globular Clusters. The Astrophysical Journal, 533(1), 215-235. DOI: 10.1086/308629