Talk:V491 Car/Archive 2006-06-08

We thought the faint component in V491 Car was moving with huge speed. Below is the discussion on this fals alarm....

Infos from SIMBAD
Since it seems that this star, actually the faint component, may have a HUGE space velocity, I got some infos from SIMBAD on the star. The link is here.

HIP	 48665	 	Hipparcos (Cat. I/239) number m_HIP	A	 	 [ABCDE] Component identification n_HIP	2	 	 [1,4] number of components in this system Hpmag	 9.829	mag	Hp magnitude plx	 18.0	mas	 Parallax pmRA	 40.7	mas/a	 Proper motion in RA*cos(DE) pmDE	 -98.0	mas/a	 Proper motion in DE e_Hpmag	 0.028	mag	rms uncertainty on Hp magnitude e_RAdeg	 7.4	mas	rms uncertainty on right ascension e_DEdeg	 8.2	mas	rms uncertainty on declination e_plx	 6.0	mas	 rms uncertainty on parallax e_pmRA	 5.1	mas/a	 rms uncertainty on pmRA e_pmDE	 6.1	mas/a	 rms uncertainty on pmDE Nobs	143	 	 Number of observations available Rej	14	%	 Percentage of observations rejected ref	 	 	 [ABC] reference component for PA, Sep PA	 	deg	 Position angle Sep	 	arcsec	 Separation flag1	n	 	 [lnx] See Note (Note 1) flag2	 	 	 [RU] See Note (Note 2)

In particular, check the paralax. This means the "star" is 55.5 pc away. I guess Hipparcos measured the bright component. Isn't the faint related to it? More very soon. -- C édric T alk  05:08, 6 June 2006 (CLT)

Of course, this HIPPARCOS measurement is certainly associated with the bright component. However, I've found a cluster quite close to the target! NGC 3293 (SIMBAD entry)



The distance of NGC 3293 is 2327 pc (see Webda entry). Which means that at a speed of -770 km/s, the star will be at its closest distance from the Sun in 2.955 million years, not accounting for the motion already done by the star since it has been ejected from the cluster (assuming I'm right that the faint comp. of V491 Car is coming from NGC 3293). We must find the age of the star! It also means that we have certainly a huge speed neutron star or black hole moving with the opposite direction, since I don't think such speed can be achievable with simple cluster encounters! A wonderful object and perfectly fitting into the "special object we will stumble upon in VSOP!!!. -- C édric T alk  05:39, 6 June 2006 (CLT)

Thanks to SIMBAD, we can compute the apparent distance between the star and the cluster, which is about 5.43 degrees. Quite a lot. At a distance of 2327 pc, it means a distance of 22 pc. Assuming that the object has a transverse velocity identical to the RV (770 km/s), the star has been ejected (assuming straight line trajectory...) 27.9 thousand years ago, which is quite young. -- C édric <font color="#006AD5">T <font color="#46A3FF">alk  05:54, 6 June 2006 (CLT)

Just one more reference before going to lunch: The VLT-FLAMES survey of massive stars: Observations in the Galactic clusters NGC 3293, NGC 4755 and NGC 6611. -- <font style="font-size: 100%;"><font color="#006AD5">C <font color="#46A3FF">édric <font style="font-size: 80%;"><font color="#006AD5">T <font color="#46A3FF">alk  06:13, 6 June 2006 (CLT)

We beat the record!
Guys, at -770 km/s, it means 2.77 millions of kilometers per hour, which is slightly higher than the highest speed observed in a star. Check the ESO press release on this latter star! And ours is in the Galactic plane. One question: is this faint star a binary? We must check if the system is still bound (very unlikely), and if not, we should have a BH/NS pseeding at the opposite direction. -- <font style="font-size: 100%;"><font color="#006AD5">C <font color="#46A3FF">édric <font style="font-size: 80%;"><font color="#006AD5">T <font color="#46A3FF">alk  10:28, 6 June 2006 (CLT)